Friday, November 30, 2007

Jog your brain fit

senior playing tennis
Jogging, dancing, playing tennis and more is good for the brain because variation as well as intensity of physical activity helps to keep it fit whereas time spent active is less important.

This is the result of a study in nearly two thousand Dutch men and women aged forty-five to seventy. All have been asked extensively about their physical activities, and their memory, mental flexibility and speed of information processing have been assessed with a battery of various tests.

Those who performed best in these tests were most likely those who engaged in intensive activities and who did so in a number of different sports and leisure occupations. In contrast, the time spent on physical activities did not show a significant link to mental fitness in this study. It seems that the brain (more than the heart) is tuned on high intensity, and it is no surprise that variation helps to keep it fit an to prevent Alzheimer's disease and other forms of dementia.

Photo credit: flickr.com/photos/scubapup/866372817/

Thursday, November 29, 2007

Eat more often, gain less weight

breakfast
Obeying the natural needs of the body as a simple way to a stable and healthy weight has been found in Dutch youngsters: More than thirty thousand girls and boys have been studied, and it came out that those who use to skip breakfast are at risk of gaining most weight. Breakfast skipping turned out to be the most important risk factor, even more than physical inactivity.

Healthy young people have a good appetite in the morning because the body needs a lot of new energy after the long night fasting period. If this natural need is not met, energy regulation may get out of balance because the body gets signals of energy shortness, resulting in more fat storage. One of the reasons of breakfast skipping is hurry and stress which both are not very healthy conditions.

In people who have gained much weight, a number of health problems have been observed, and the "overweight" or "obesity" has been blamed as a risk factor. But the real problems may not be the weight itself but rather the out of balance energy regulation or the stress.

And this Dutch study has shown that healthy living may be much easier and much less focused on fears than you may have thought: Just eat your breakfast and do not care about fats or calorie counting or diets, and you have best chances to maintain your healthy weight.

Photo credit: flickr.com/photos/honey-bee/323675939/

Wednesday, November 28, 2007

Big risk factor contest

boxing match
This match between two unequal opponents, body fat and passive smoking, goes over the full distance of twelve rounds, and there is a clear winner on points.

Background: I have blogged about both subjects that share some aspects like epidemiology and risk statistics but are fundamentally different in many other features. In order to check all again, I am ready for a roundup. I am using a boxing metaphor because of the controversy in both subjects, sometimes with unfair arguments (aka deep hits), hard facts (aka real hits) as well as biased claims (aka futile attacks), and a number of aspects (aka rounds) where both subjects may perform differently, but in the end we should be able to decide which of both, body fat or passive smoking, is the more important risk factor for health.

So let the match begin now, and like a pro match, this one goes over twelve rounds:

  1. Which condition is more prevalent?
  2. How is the actual trend?
  3. How many diseases have been linked to them?
  4. Which of both reaches higher relative risks?
  5. What about the absolute risk of being killed by a disease?
  6. How is the relation between dose (the amount of the risk factor) and response (disease)?
  7. Is there a safe level that is causing no harm?
  8. How is the interaction between the two conditions?
  9. Is there a causality or only a correlation?
  10. Can the effect be explained by biological mechanisms?
  11. What about the integrity of the research and possible conflicts of interest?
  12. Have interventions against the risk factors been successful?
1. Prevalence
In countries without smoke-free regulations in public places, more than fifty percent of the population are exposed to secondhand smoke regularly. In the United States, about thirty percent of the population are obese; in other countries, this amount is considerably lower.
Judge 1: "In many places, the exposure to secondhand smoke has diminished due to legislation, but this is the result of an intervention and must not be taken into account here. The facts are clear, passive smoking is more prevalent than obesity." The other judges agree.
Unanimous verdict: Passive smoking wins the first round.
Reporter: "The audience seems to favour body fat, but the judges obviously are not very impressed by his futile attacks, based on the BMI 25+ definition of overweight, and only count the BMI 30+ obesity as real hits. Passive smoking is leading 1-0."

2. Trend
In many parts of the world, people are getting fatter. The exposure to secondhand smoke, on the other hand, is decreasing because of smoking bans in many public and working places.
Judge 1: "Most countries have ratified the WHO Framework Convention on Tobacco Control. The winning trend is fat." Judge 2: "Fat goes up, secondhand smoke goes down." Judge 3: "Agreed."
Unanimous verdict: Body fat wins the second round.
Reporter: "The optical advantage of the first round has materialized now, allowing body fat to equalize to a 1-1 draw."

3. Number of diseases
Passive smoking has been linked to diseases of the heart and the lungs, to lung cancer and other cancers, and to stroke. Obesity has been linked to the same diseases plus those of digestive tract, kidneys, rheumatic diseases and psychic disorders.
Judge 1: "A clear lead for body fat." Judge 2: "A draw in the big killers, and there is poor evidence for causality in the body fat." Judge 3: "Causality is of no concern in this round, only the number of diseases linked to the risk factors, and this number is considerably higher for body fat."
Split verdict: Body fat wins the third round.
Reporter: "After a bad start, body fat is gaining the upper hand now, leading 2-1."

4. Relative risk
Extreme obesity has been linked to relative risks of 2 and more for various diseases, compared to only 1.3 on average in the case of passive smoking.
No dispute among the judges.
Unanimous verdict: Body fat wins the fourth round with a big lead.
Reporter: "This time, the judges agree with the audience. Body fat has been the darling of the media and it seems that he is living up to the reputation now, pulling away by 3-1."
References: Passive smoking math, body fat math

5. Absolute risk
Both factors, passive smoking as well as body fat, have been linked to the big killer diseases like heart attacks and cancer who also have the highest lifetime risks: Every second man and every third woman will be affected by one of these diseases.
Judge 1: "I would weigh body fat higher for disease number and relative risk but these have already been judged in rounds three and four, therefore a draw." Judge 2: "I would weigh passive smoking higher because of better causal evidence but this will be judged in round nine, therefore a draw." Judge 3: "Draw."
Unanimous verdict: Draw.
Reporter: "Passive smoking is trying hard for not losing, but it does not look good for him. Body fat maintains his lead by 3-1."

6. Dose-response
Lowest levels of secondhand smoke are linked to lowest risk of disease, and the curve is steady and /-shaped, and there is no optimal level of secondhand smoke. Lowest levels of body weight, as well as highest levels, are linked to higher risk of disease, and the curve is J- or even U-shaped, and there is something like an optimal level, called the ideal weight.
Judge 1: "Secondhand smoke is a risk factor in its strict sense but body fat is not." Judge 2: "Too low body fat may also be a risk factor, weakening the punch of body fat." Judge 3: "Very strong straight jab wins against weak hooks."
Unanimous verdict: Passive smoking wins the sixth round.
Reporter: "Oops this has been clear but body fat is still ahead by 3-2."

7. Safe level
There is no safe level for secondhand smoke, even small amounts do harm. On the other hand, body fat is not a risk factor but a vital element. No discussion.
Unanimous verdict: Passive smoking wins the seventh round.
Reporter: "Body fat is groggy, tumbling. Oh, oh, oh. A bad weakness has been hit. We see a 3-3 draw now, and passive smoking is gaining momentum."
Reference: The vital importance of body fat

8. Interaction
For active smokers, and most likely for passive smokers as well, higher levels of body fat seem to be protective rather than harmful. Thus, smoking as a risk factor weakens body fat as a risk factor. No discussion.
Unanimous verdict: Passive smoking wins the eight round.
Reporter: "Both have been in clinch, but passive smoking wins the infight and is leading now by 4-3."
Reference: Positive outcomes linked to body fat

9. Causality
The noxious substances from secondhand smoke are most likely the causes of harm. Body fat is not at the beginning of a causal chain but somewhere in between, the causality remains unclear. No discussion.
Unanimous verdict: Passive smoking wins the ninth round.
Reporter: "Body fat is on the ropes. The score is 5-3."
Reference: Storks and babies, fat and cancer cells

10. Biological mechanisms
The mechanisms leading to artery disease and cancer are well-understood in the case of fine dust and mutagenous substances from secondhand smoke but not so in the case of body fat. No discussion.
Unanimous verdict: Passive smoking wins the tenth round.
Reporter: "This hurts. A clear lead by 6-3."

11. Integrity
Big Tobacco has tried to undermine secondhand smoke research. Big Food, as well as Big Pharma, make a lot of profit with weight loss.
Judge 1: "Refutations of passive smoking results are deep hits and must not be counted." Judge 2: "Body fat has been doped by Big Pharma." Judge 3: "Obesity denial is deep hit of fast food chains and must not be counted."
Split verdict: Passive smoking wins the eleventh round.
Reporter: "This is the end of the story. 7-3."

12. Intervention success
Smoking bans have reduced harm from passive smoking to a measurable extent. The success of weight loss attempts is poor, resulting in yo-yo and failing to show a positive effect on health in most cases and if so, it may be due to better fitness or healthy food or metabolic changes rather than reduced body fat. No discussion.
Unanimous verdict: Passive smoking wins the last round.
Reporter: "Body fat had some strong rounds in the beginning, but the weaknesses have been too obvious. On the other hand, passive smoking has shown to be a true risk factor that must be respected. A clear win on points by 8-3."
Reference: About a mechanism of yo-yo

Photo credit: Wikipedia

Tuesday, November 27, 2007

Doing the math on secondhand smoke

slide rule
In the case of passive smoking, a relative risk increase of 30 percent is important because it affects the number one disease, because it affects innocent people against their will, and because it is easily preventable.

The evidence is overwhelming. In a review of 29 studies, Barnoya and Glantz (Circulation 2005) have calculated a relative risk of 1.3, that is an increase by 30 percent, for coronary heart disease, caused by long-term exposure to secondhand smoke. Coronary heart disease will affect every second man and every third woman after forty years of age. Translated to absolute lifetime risks, passive smoking may increase them by 15 percent in men (every seventh) and by 10 percent in women (every tenth) in case of a lifelong exposure. This is highly relevant, completely different from the cancer and obesity case reported earlier - "Selling molehills as mountains".

Paid scientists and skeptics

In the past years, the tobacco industry has tried to sow controversy about the facts, paying scientists and funding research. Some results of flawed studies reporting a null effect of secondhand smoke have been published, and paid skeptics have done their best in denying the dangers of passive smoking.

Is Michael Siegel who runs the Tobacco Analysis blog one of them? When I first visited his blog, back in April, I couldn't make up my mind. The comments on his blog are mainly from tobacco freedom activists and I have seen much applause from this side. But then I came to the conclusion that he is honest and not a paid skeptic. I just have visited his blog again today and have seen that he is being trolled by them. This, and his most recent publication, convince me that I judge him properly: He says that "chronic exposure to secondhand smoke has been well recognized as a cause of heart disease in nonsmokers" but he blames the anti tobacco activists for having made exaggerated claims about short-term effects of passive smoking. Overstated claims undermine credibility and help Big Tobacco. Thus, I conclude that he is doing a good job.

Harm against their wills

Besides math and health statistics, the legal aspect is another big point here. Passive smoking harms people against their wills. Smokers can decide not to smoke, passive smokers cannot. They are forced to breathe the contaminated air, filled with fine dust and poisons. Many of them are children or older people. Some are particularly vulnerable like asthmatics and other lung patients.

Easily preventable

All over the world, public smoking bans have been accepted by smokers with a nearly hundred percent compliance. The positive effect of such bans are beyond any doubt. And the majority of the population wants such regulations. Here in Switzerland, lagging behind the most part of Europe, two cantons have voted for public smoking bans last weekend, and a national legislation is under way.

The effect can already be seen in health studies: A study on secondhand smoke and heart attacks failed to show a connection because the exposure, due to smoking bans, has declined sharply in the recent years.

Photo credit: flickr.com/photos/rogersmith/53912456/

Monday, November 26, 2007

Fat facts which nobody can deny

cherries
The Hoofnagles are jolly good fellows, debunking those cranky guys who deny that HIV causes Aids and that vaccines save lives and the like, uncovering the tactics they use but they happen to use one of such tactics themselves, cherry picking.

Skepticism is a good thing and vital for science and health, the problem is that those cranks, HIV denialists and antivaxers boast to be the real skeptics. The Hoofnagles try their best debunking those debunkers. Mark Hoofnagle has criticized me for having accepted Sandy Szwarc to Skeptics' Circle. I did so because I share her skepticism in the obesity issue which is an important one in these times. I did so because I think this is sound skepticism, based on facts. And this does not mean that I agree with all statements on her blog.

Mark Hoofnagle has attacked Sandy for a post suggesting that case numbers in various diseases have been increased just by altering the diagnostic criteria. Again, I am not going to comment on non-obesity issues over there because I have not (yet) studied the details. The only point I am going to discuss here is the definition of body mass index (BMI) 25 as general upper limit of normal weight and the claim that every weight beyond that limit is to be called "overweight" and is bad for health.

Such obesity skepticism, in Mark's view, is cranky, and he cites two large studies to back his view. The first one, by Calle and co-workers, has been published in the New England Journal of Medicine 1999. The problem with such old data is that they may be outdated meanwhile because, as has been shown by Flegal and co-workers, the link between obesity and mortality has gotten weaker over time. Therefore I am dealing with the newer one, by Adams and co-workers, published 2006 in the same journal. This study is really impressive; more than half a million men and women have been assessed and followed up to ten years. There are many beautiful cherries to pick from this study. Mark has picked this one.

BMI and mortality picked I must admit this is one of the most beautiful J-curves I have ever seen. It shows the relative risk of death for men aged fifty who never have smoked, plotted against BMI. Mark shows this curve to support BMI 25 as an upper border to bad health. Does it really show this? What I see here is a nadir (lowest value) at BMI 23.5 which could be called the ideal weight for this selected group, only 18 percent of the whole cohort. The upper border of the normal weight range must be defined by the mortality value. For BMI 25 we get a relative risk of less than 1.1 in this curve. Symmetry must be postulated, and we look at the lower BMI value with a relative risk of less than 1.1 which is the case at around BMI 22. In other words, with a postulated upper BMI limit of 25, the corresponding lower limit is 22, leading to a normal weight span of only three BMI points. Such a narrow definition of normal weight cannot make any sense. Rather I would accept a lower limit of normal weight at BMI 20 (according to WHO it is even lower, at 18.5). Our curve shows a relative risk of 1.25 which is again found at BMI 27 at the upper end. Thus, our curve suggests a normal weight range of BMI 20-27 for this specially selected group, but not for women, not for younger or older men, not for those who smoke or who have smoked earlier in their lives. We see, not even this best cherry to be picked is able to support the view that bad health begins at BMI 25.

BMI, mortality and smoking status Now let me pick my own cherries, nota bene from the same study. This one shows the curves for men, based on more than three hundred thousand cases, according to their smoking status. For never smokers, we see an ideal weight of BMI 25 and a "normal" weight range of 21 to 30. For former and current smokers, these values have to be shifted upwards by two BMI points. For a former smoker, a BMI 32 appears to be at the upper end of normal weight, rather than "obesity".

BMI, mortality and age This one is even better, showing roughly the same three hundred thousand men, this time sorted by age classes. Looking at the relative risk at the lower end, I am no longer ready to accept a BMI 20 as lower limit of normal weight. The point of ideal weight again has shifted upwards, now to 26, and the range of normal weight (I admit this is my personal view) is between 22.5 and 32.5 for men in their fifties, expanding gradually to 22 and 36 for men in retirement age.

Conclusions: One of the biggest recent studies on weight and mortality does NOT support a general upper limit of BMI 25 but suggests a re-definition of the term "obesity" which should be adapted to age, sex and smoking status. And even claims of so-called cranks must be checked seriously, their grain of truth may be bigger than it seems at first glance.

Open e-mail to Mark Hoofnagle

Dear skeptic colleague

You do a great job with your blog but I cannot agree with your recent post when it comes to overweight and obesity. In particular, I cannot see how you conclude a BMI of 25 as a general upper limit of good health from the study by Adams et al, NEJM 2006, that you have cited. Plus I would like to learn, besides the graph you have commented, how you interpret the other two graphs from the same study, displayed above here.

Looking forward to find your clarifications on your blog soon.
Sincerely,

Christian Bachmann
Med Journal Watch


Photo credit: flickr.com/photos/princess_of_llyr/794277307/

Health Blog Carnival Watch 1:13

Grand Rounds
4:10 at Prudence, M.D.
4:9 at Mexico Medical Student
4:8 at Doctor Anonymous
4:7 at Counting Sheep
4:6 at Running A Hospital

Pediatric Grand Rounds
2:11 at Aetiology

Skeptics' Circle
#74 just here
#73 at Holford Watch
#72 at Quackometer

Friday, November 23, 2007

No worries adding pounds when getting elderly

old happy weight
Most older adults are gaining weight but this is no problem for health in most cases, according to a study in more than five thousand seniors in four states.

The study on weight, mortality, years of healthy life, and active life expectancy in older adults has been conducted by the Department of Biostatistics at the University of Washington in Seattle, using data of the Cardiovascular Health Study. I start with the conclusion of the authors because they disagree with the current view of weight and health:

"Similar to middle-aged populations, older adults are likely to be or to become overweight or obese, but higher weight is not associated with worse health in this age group. Thus, the number of older adults at a 'healthy' weight may be much higher than currently believed."
In the study, the different categories of weight as well as states of health and the number of years spent in each weight and health category have been assessed. It came out, for instance, that healthy women at age 65 on average will live another twenty-two years (seventeen of these in good health) and that they will spend nearly half of this lifespan as "overweight" or "obese". Such higher body weight rarely is associated with poor health in women and in men, whereas being underweight is linked to worse outcomes.

Related posts
Weight benefit in old age
Body mass helps elderly asthmatics to survive

Photo credit: flickr.com/photos/blythe_d/1102173820/

Thursday, November 22, 2007

Fatter women better off with their lungs

woman smiling
After menopause, lung function declines but less so in women with a body mass index well above the values that have been recommended in public health campaigns.

The term "overweight" is becoming more and more dubious as ever new studies are being published showing positive sides of body weight and body fat. Just today I have come across another such study, this time on lung function and menopause.

It is a well-known fact that we have to face: As we get older, our lungs get weaker. This is inevitable and can be measured by the so-called FEV-1 test: Try to exhale as much air as fast as possible in one second; when the exhaled air volume is measured, it gives a good estimate of lung function.

This test has been done in more than four thousand women, aged 45 to 56 and not taking hormones, in Norway. In women, lung function is influenced by the hormones. Thus, women after menopause, on average, perform worse in the FEV-1 test than women still menstruating.

And now we come to the point: The decline of lung function is highest in women with a body mass index (BMI) below 23, and it is lowest in women with BMI 23 to 28. In other words, women who have been (de)classed as "overweight" (BMI 28) are, in many cases, better off than so-called "ideal weight" women (BMI 23), when it comes to the lungs. The ideal weight, according to this study, is the official borderline to "overweight" - BMI 25!

Photo credit: flickr.com/photos/todd_yarling/22665582/

Wednesday, November 21, 2007

Skeptics' Circle #74: The Evolution of Thanksgiving

big turkey

Welcome all, I am very pleased to see you in our meeting, and I have been told that many prominent friends such as James Randi, the Bad Astronomer, Norm Jenson, and others, are watching us from outside. It is a great honour for me, as a newbie in the midst of all you great skeptics, giving my first lecture. Needless to say that I do not expect you to buy all what I am going to say, so don't be shy. Heckle. Make the British Parliament look like a church on a Sunday morning.

Unidentified voice: "Amen."
So be it. My lecture is about Thanksgiving ...
Orac: "Holy crap!"
Unidentified voices: "Woo." "Woo."
Holford Watch: "Did you tick the appropriate box, eh?"
... and its evolution from the very beginning of mankind. I'll use a narrative style but don't get me wrong. It is all based upon scientific facts and razor-proof hypotheses ...
Infophile (just entering): "Every hypothesis must stand Occam's ..."
Unidentified voices: "Hey sit down first!" "Who is late must wait."
... from radio-carbon, petrified turkeys, prehistorical paintings, to DNA out of stone-age party litter ...
Sandy: "Math, math, don't forget math! If scientists forget using it, they produce a big chunk of junk."
... I could name more of such stuff, thanks Sandy, but let me come right to the point ...
PZ Meyers: "Not yet. There are liars around, fabricating false evidence. Beware of these!"
Evangelical Realism: "Exactly. Just look at the Noah's Ark fake. I've done some math on this one."
... to the point, my friends: It is evolution, and for those celebrating Thanksgiving the hard-core way it may be a big surprise that even their celebration ...
Martin Rundkvist: "All is subject to evolution, even altie medicine."
Orac: "Fascinating idea, Martin! I wish it had been mine!. Woo even has evolved to invade academia like a parasite."
Steven Novella: "You hit upon two big points!"
... has a long evolutionary history. Let's go back to the roots of Homo sapiens.

One hundred thousand years ago

"Why you touch ground with head Maa?" asked the boy.
"Giving thanks to Big Maa", the woman said.
"Show me Big Maa."
The woman pointed to the ground, then to the trees, the grass, the sun, the clouds in the sky. "All this ...
Dikkii: "Happy times that far back, without Big Pharma putting patents on mother nature. I am trying not to get confused by the anti-science approach of the anti-biopiracy movement. But it's not easy."
... is Big Maa."
The boy pointed to his chest. "Also Big Maa?"
The woman scratched her head, thinking. Then she said: "You nothing without Big Maa. We all nothing without Big Maa. Give thanks!"
The boy touched the ground with his head. "Daa not give thanks? Where Daa?"
"Daa out hunting turkey", the woman said.

Twenty thousand years ago

"What are you doing, Dad?" asked the boy.
"Giving thanks to Big Mother", the man replied, dancing and touching the ground.
"Show me Big Mother."
The man shook his head. "We cannot see Her. She is behind all things. Behind the ground, behind the trees, behind the grass, behind the sun and the clouds in the sky."
"Where is Mom?"
"At the fireplace, roasting a big turkey", the man said. "Give thanks, my son!"
The boy scratched his head, thinking. Then, all of a sudden, he broke into laughter, began to dance in a frenzy, pointing to the ground, to the trees, the grass, the sun and the clouds in the sky, shouting: "Big turkey behind, big turkey behind!"
The man stopped dancing, scratched his head, thinking. He remained quiet until they all had eaten the turkey. He grabbed a turkey bone out of the ashes, got up and shouted: "My son is clever! My son is clever! He can see behind all things!" ...
Jakob Punkt: "Haha, great, he got the point, this old guy. Turkey? Goddess? Who cares, it all depends on how you define turkey or goddess."
Bing McGhandi: "No turkey, it is a horse! I have got the proof by e-mail."
Miller: "Oh no, guys! No. No. Listen. Forget turkeys and horses! It's penguins. Ninety percent of the brain is filled with them, according to the ten percent myth. I've got the proof!"
Akusai: "Turkeys? Horses? Penguins? This is all old stuff. I've got something really new: Black Eyed Kids!"
Skeptico: "Seeing behind things is nothing special at all. Anyone can do that. Just try out my Cold Reader Bingo!"

Five thousand years ago

"Come on my son", said the man. "It is time to give thanks to Big Turkey."
"Why can't I see Big Turkey?" asked the boy, ...
Lord Runolfr: "Even if you see you must stay skeptic. Not everything that looks big is big in reality!"
... but the father shook his head: "Thou shalt not put such a question, my son. He in his wisdom hath forbidden us that. Blesseth those whose eyes not see, yet their mind believeth."
"Why do you use such a strange language, Dad?"
"This is not language, this is tongue", the man explained. "We use it in religion."
Mike: "Woo talk has a long history. Reiki woo talk is a modern example."
Bad: "Not to forget supplement quack talk. You may be better off drinking a glass of good French red wine, and this is no paradox."
CAE: "There are more things in science and woo, Horatio, than are dreamt of in your philosophy. Take care of the money to be extracted from your pockets, women!"
John: "Oh, back in September, I have come across a piece of resonant bond quack talk."
Thursday: "Quacks never call quacks quacks because they don't want to be called quacks by quacks but, surprise, surprise, I have found an example of quacks suing quacks for quackery. But don't let them infiltrate our Skeptics' Circle!"
I can reassure you, Thursday, they didn't try.

Two hundred years ago

"Oh is this turkey big", said the boy. "He is so beautiful, please do not kill him!"
But the settler, an Irish immigrant, took his axe. "I'm not the President. I cannot amnesty him."
Down swished the axe, and the headless turkey flapped his wings.
"Why did you kill him?" The boy cried. He sat on the ground, sobbing ...
Zoo Knudsen: "Sobbing? I guess he just had a cough which would have forced his parents to become criminals if you believe what the FDA tells us."
... and looking at his father.
"Because we are celebrating Thanksgiving. Giving thanks to Lord the Big Father in heaven who has given us all these things we have harvested."
"How do you know?" The boy still sobbed. "Did you see him? Maybe he is Big Turkey. And then he will be sad about what you have done." And away he ran.
The settler called his wife, and together they plucked the turkey.
"Hm, our boy", the settler said to his wife. "Are you sure he did not mitch Sunday school?" ...
Revere: "Don't play hooky! Come to my Sunday morning Bible Class. Else you might miss the Big Flying Spaghetti Monster."
Orac: "And don't miss my Sunday afternoon lesson on Homeopathy!"

November 22th, 2007

The man in his best age, a great-grandson of the grandson of the settler's boy, gets up, raising his glass: "And now, let us be quiet for a moment and give thanks to the one who has given us all those things on our table and much more. Let us give thanks to ..." he hesitates, looking at his father who, in all the years before, had brought out the toast, that is, said his prayer. " ... nature, the Great Mother of us all, whose evolution is better than all intelligence of all designers ...
Seth Manapio: "And does a turkey look designed? A watch does, but not a turkey, and this alone refutes the whole Intelligent Design theory."
Infophile: "Every hypothesis must stand Occam's Razor, and the god hypothesis fails according to a bunch of logic."
... and their ideas taken together."
Some murmur of aunts, uncles and in-laws.
His father shakes his head and, in low voice, says to his wife: "I am sure he has been playing hooky on Sunday mornings."

This brings me to the end of my lecture, giving thanks for your patience and for your contributions. Have a happy Thanksgiving, together with your families, and choose the appropriate way of celebrating from all the options that evolution has to offer. For those outside the United States, giving thanks is a good idea anyway, to whom it may be due. Hope to see you all again at the 75th Skeptics' Circle over at Pro-Science.

Photo credit: flickr.com/photos/master-phillip/311555483/

Tuesday, November 20, 2007

First problems with eating, later with mood

eating disorder
A study on timing of psychic problems in teen girls shows that eating disorders come first, later followed by depression.

Eating disorder and depression go together. This is not new, several studies have shown it. But what comes first, which problem predicts what, has always been unclear - up to this new prospective study on depression and eating disorder symptoms among adolescent girls.

More than seven hundred teen girls from the Minnesota Twin Family Study have been examined at ages eleven, fourteen and seventeen, approximately. For depressive as well as for eating disorder symptoms, the earliest occurrence of low levels have been assessed. It came out that eating disorder symptoms tended to occur earlier than depressive symptoms, and that both were linked. That is, eating disorders are typical precursors of depression.

Eating disorders, in turn, do not develop out of nothing. Besides skinny models in magazines and on billboards, health campaigns that favour a controlled eating style may well promote them.

Related posts


Photo credit: flickr.com/photos/belljar/47129230/

Monday, November 19, 2007

Alcohol, health, and tunnel view

tunnel view
Beware of getting drunk by distilled, isolated findings from medical studies, you may miss important points.

In the food and cancer report, well-known to my regular readers, not each and every finding is likely to be nonsense. I have concentrated on the weakest points and tried to debunk false claims but, given the huge numbers of studies cited in the report, some hard evidence should be around. Where? Let's try to find some.

Alcohol in moderate amounts has no cancer effect in men. In higher amounts, the risks of cancers in the digestive tract begins to rise.

I women, the report says there is no safe threshold. Even moderate amounts of alcohol increase the breast cancer risk, only very little, but measurable in studies with hundreds of thousands of women. But it seems that the style of consumption also must be taken into account. See my earlier post: How many drinks, how many breast cancers?

First, let's do the math job. For breast cancers, a relative risk increase of 5 percent has been calculated out of 13 studies for a consumption of five drinks a week. The lifetime breast cancer risk for a woman in the United States is 12.5 percent or one in eight women. Without alcohol, 87.5 percent of women will stay free of breast cancer until they die from other causes. With one drink a day, this amount diminishes by 0.6 percent to 86.9 percent. I leave it up to you if you like to see a difference here. Yet the food and cancer report concludes:

"There is ample, generally consistent evidence from case-control and cohort studies. A dose-response relationship is apparent. There is robust evidence for mechanisms operating in humans. The evidence that alcoholic drinks are a cause of premenopausal and postmenopausal breast cancer is convincing. No threshold was identified."
You may wonder if they have looked at the same numbers.

Beware of tunnel view

At least, the experts don't fall into the tunnel view trap. They also have looked at the fact that alcohol is protective against heart attacks, and therefore, they recommend:
"If alcoholic drinks are consumed, limit consumption to no more than two drinks a day for men and one drink a day for women."
Alcohol and breast cancer is one, but certainly not the only example. Cholesterol, high blood pressure, body weight and other factors may all be linked with some adverse outcomes on the one hand and beneficial outcomes on the other hand, depending on age, constitution, genetic heritage, and other personal factors. Whenever you come across a study finding some special evidence in a special field, take a broad scope and be aware that the findings may be different in other fields.

Photo credit: flickr.com/photos/98212195@N00/1441627392/

Friday, November 16, 2007

Fat, healthy but not happy

sad woman
All could be fine with quality of life when it comes to health of fat elderly women, were there not psychic problems.

"Obesity" has often been called a disease. Were this true, it should diminish the health-related quality of life - the part of well-being that is affected by the body and its functions, as seen by the affected person. But a Spanish study in postmenopausal women did not show any link between body weight and physical well-being.

More than two hundred women 50 to 64 years of age have been assessed. About eighty percent of them have been "overweight" or "obese", according to WHO standards. When the results of the life quality assessment have been compared to body mass index, no relation was found in the health domain.

But it came out that the fat had more psychic and sexual problems than the lean women. This is no surprise given the negative value of being fat in society and the constant feeling of being not attractive.

Take home: One more study supporting the view that being fat is not a health problem of individuals but an attitude problem of society.

Photo credit: flickr.com/photos/mattcarman/1068056354/

Thursday, November 15, 2007

A little body fat time machine

african girls
In rural Africa, body fat is still very welcome for good health, under conditions that are probably similar to most time of human evolution.

In a small survey, conducted by Swedish and African researchers in Cameroon, fifteen adolescent girls have been interviewed about their food and health perceptions:

  • Rural girls want "to be fat", in order to "live" and for "health".
  • Urban girls in poor areas want "to be a little fat" in order to be "healthy" and for "beauty".
  • Urban girls in rich areas want "to be normal" in order to "have pleasure" and for "beauty".
Quite interesting. In rural areas with a traditional lifestyle, body fat obviously is seen as a vital insurance against starvation, and this has bee the case for tens of thousands of years of human evolution that once has begun down in Africa. Fat means health when food may get short. Being slim in Africa often is equal to being sick, as in the case of Aids.

When rural families migrate to big cities, they arrive in the poor areas. They come into contact with the urban lifestyle and westernized values and perceptions about female beauty. A transition takes place, the time machine runs fast, and the girls no longer want to be really fat, but they still see body fat as a good thing.

In the rich urban areas, girls adopt a western, industrialized lifestyle, they see slim models in magazines and no longer want to be fat. Health is no longer a concern. Being slim is seen as a way to be fit for parties. They know very well that rich city men, in contrast to men in the countryside, prefer slim women. I think, these girls are quite a bit better off than girls in Europe or in the United States: They are not caught in the false belief that slim means healthy.

Related post: The vital importance of body fat.

Photo credit: flickr.com/photos/kool_skatkat/496061515/

Wednesday, November 14, 2007

One cannabis joint equals up to one cig pack

lung emphysema
When it comes to the destruction of lung tissue, smoking one joint of marijuana may cause about the same amount of harm as smoking one pack of cigarettes. This is the conclusion of the leading Swiss thorax surgeon Ralph Alexander Schmid after having seen seventeen young patients at the University Hospital Insel in Berne. He and his team just have published their findings on emphysema and secondary pneumothorax in young adults smoking cannabis.

Emphysema is the destruction of the small air sacs, the alveoles, in lung tissue: Their walls disappear and they conflate into ever bigger air sacs. Schmid has seen air sacs up to ten centimeters (four inches) in diameter in the upper part of the lungs, see photo.

Such a damage has never been found before in so young people, between nineteen and forty-three years of age. Rather it is typical for heavy smokers, sixty or more years of age, who have been smoking four or more packs of cigarettes a day for many years. It is this comparison of damage that brings Schmid to the conclusion that one joint of marijuana equals one pack of cigarettes in causing emphysema. The young people in Schmid's study have smoked up to eight cannabis joints a day.

In New Zealand, Sarah Aldington and co-workers have done a similar study on the effects of cannabis on lung functions. According to their estimate, one joint equals three to six cigarettes in its effect on lung function. Emphysema have not been typical in the NZ study where smokers of more than five joint-years have been included - a joint-year is one joint per day for a year. In the Swiss study, the young smokers have consumed thirty or more joint-years. This dose difference most likely explains the discordant findings of the two studies.

Take-away: Cannabis harms the lung; one joint equals five cigarettes up to one pack, depending on the type of harm and on the intensity and duration of exposure.

Photo credit: Swiss TV, Puls

Tuesday, November 13, 2007

Pets may lower or raise allergy risk in kids

kids with dog
The influence of a dog or cat at the time of a baby's birth depends on the allergy history of the family. Most likely, there will be an influence of a pet. It will be positive in families without a history of allergic diseases and negative in the opposite case. This is the result of a German study on pet exposure and allergy in the first two years of life.

Soon after delivery, more than three thousand mothers have been asked whether they kept dogs, cats, birds or other pets at home and whether there have been cases of allergy in their families. Two years later, the same mothers have been asked whether their children had asthma, eczema, or hay fever.

In families without earlier cases of allergy, the early contact with a pet lowered the allergy risk in the baby by about 40 percent, relatively, which translates to a risk reduction from about ten to about six percent.

On the other hand, in families where cases of asthma, eczema, and hay fever have been observed earlier, the allergy risk of the baby was significantly higher if a pet had been around since birth.

Conclusion: For the majority of babies, pets in the household help to prevent allergy.

Photo credit: flickr.com/photos/locomotion/532541663/

Monday, November 12, 2007

Scientists should not believe in the stork

white storks
High insulin, high body fat and high cancer risk are sometimes found together but this link may be of a similar type as in storks and babies.

Trying to "prove" that body fat causes cancer, some scientists have claimed that this is due to substances produced by body fat cells, but the first of the mentioned substances happens to prevent and not to cause cancer.

The authors of the food and cancer report list other examples to prove a cause. Are they more convincing? Let's have a look at insulin, another key witness of the fat cancer prosecutors. They write:

"Obesity influences the levels of a number of hormones and growth factors. Insulin-like growth factor 1 (IGF-1), insulin, and leptin are all elevated in obese people, and can promote the growth of cancer cells."
Insulin is produced by pancreas islet cells and not by body fat cells. Babies come from human mothers and not from storks. Both body fat cells and insulin are abundant in some human organisms, and both storks and babies are abundant in some countries. This looks like a perfect analogue but we still have to consider the possibility that body fat cells, by some substances, trigger the pancreas cells to produce more insulin. Such a mechanism is a mere speculation, and recent research suggests that both high insulin and high body fat are guided by the same genetic causes and are independent of each other, just like storks and babies.

Why lab values may be misleading

Far from being a proven cause, the link between body fat and cancer is not even a direct one. At best, body fat may be linked to some lab values such as insulin level and this lab values in turn may be linked to the cancer risk. If the links to the lab values are not very clear and strong, we have a cascade of weak effects, resulting in an overall effect that is no longer detectable: Here is a case where biomarkers failed to predict stroke.

The Mrs Jones Trick

Those who have read my earlier post about snake oil tricks may wonder if this is such a case. You will need some fantasy but then you may see it: The snake oil peddler (body fat cancer researcher) claims that snake oil (body fat) helps to fight pain (makes cancer grow). He presents Mrs Jones who has applied snake oil and lost her pain (a correlation between fat and cancer) and says this is the prove that snake oil works (body fat causes cancer). When asked how this may work, the peddler (researcher) tells people that genuine Chinese snake oil (body fat) contains (enhances) poly unsaturated fatty acids (cell hormones, insulin) that promote healing (cancer).

I may not be finished with the food and cancer report yet, but it's high time now to deal with other health issues. I'll feel free to come back later with more points and a final conclusion.

Photo credit: flickr.com/photos/yeliseev/646936102/

Saturday, November 10, 2007

Skeptics' Circle call for submissions

The seventy-fourth circle will be held November 21st (one day early due to Thanksgiving) here at Med Journal Watch, and I'll be giving thanks to a plentiful harvest of submissions.

CLOSED. Thanks to all who have submitted.

Friday, November 9, 2007

Storks and babies, fat and cancer cells

stork and baby
Counting and statistics are necessary but not sufficient methods in search of causes, and this still holds true when digging deeper into details.

Scenario 1: Over the past century, the number of storks has diminished in all industrialized countries, and so have birth rates. Today, in countries where storks are abundant, for instance in Africa where they stay in winter, birth rates are also high. There is a clear, highly significant positive correlation between the frequencies of storks and babies. There is also a theory about storks bringing children. Do storks cause births?

Scenario 2: In human populations, under certain conditions, an increase in both fat cells and cancer cells has been observed - not in general but only in some selected studies. This positive correlation between fat cells and cancer cells is weaker than in the stork and baby case. There are also some theories about body fat cells producing substances that may promote tumor growth. Do body fat cells cause cancer?

Scenario 3: In human populations where the number of smoked cigarettes has increased, the number of cancer cells, mainly in the lung, also has increased. There is a clear, highly significant positive correlation between the frequencies of smoked cigarettes and lung cancers. There is also a theory why and how harmful chemicals in tobacco smoke cause damage in lung cells, turning them into cancer cells. This theory has been tested in a huge number of scientific trials, with positive and convincing results. Does tobacco smoking cause cancer?

Cause or not cause, that is the question

The difference in the three scenarios above is not in the correlations but in facts that must be dug out, looking deeper into details. Don't get me wrong, correlations are important, without correlation there cannot be a cause. But correlations, while necessary, are far from being sufficient, as the first scenario shows. The reason storks do not cause births is because this cannot work in detail.

In scenario 3, the cause is generally accepted and can be taken as a proven fact because we know many details about how things work between toxic chemicals and body cells.

Scenario 2 is somewhere in between. There is some amount of correlation, not without doubt, but let's accept it as given for the moment. Some researchers claim having found evidence for mechanisms how body fat cells cause damage that may turn healthy cells to cancer cells. Now let's take a look at these details and see how convincing they are.

Substances from body fat cells

The main theory of how body fat should cause cancer relies on inflammation. In chapter 2, the authors of the food and cancer report tell us how:

"Obesity is characterised by a low-grade chronic inflammatory state, with up to 40 per cent of fat tissue comprising macrophages. The adipocyte (fat cell) produces pro-inflammatory factors, and obese individuals have elevated concentrations of circulating tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, and C-reactive protein, compared with lean people, as well as of leptin, which also functions as an inflammatory cytokine. Such chronic inflammation can promote cancer development."
In short, body fat cells produce a number of substances that go together with inflammation, and inflammation is thought to damage body cells, turning them into cancer cells.

But exactly the first of the mentioned substances, tumor necrosis factor alpha, does not cause cancer but helps preventing it. Necrosis means death, and this factor makes tumor cells die. Other substances may promote cancer, but this one prevents cancer. Thus, the action of all these substances from body fat may be a zero sum game when it comes to cancer.

And when scientists are digging more into details, they may find stork and baby cases even in a deeper level. I'll deal with this question later. Stay tuned.

Photo credit: flickr.com/photos/millan/95188464/

Thursday, November 8, 2007

The science of cherry picking

cherry on top
When two big medical studies show conflicting results on the same subject, selection bias is the most likely cause.

The big global perspective report on food, nutrition, physical activity, and the prevention of cancer, based on the results of more than seven hundred studies, comes to the conclusion that being fat causes cancer.

Another big study by Catherine Flegal and co-workers on cause-specific excess deaths associated with underweight, overweight, and obesity, based on more than half a million person-years of long-term follow-up and on mortality data of more than two million adults from the U.S. population statistics, comes to the conclusion that being fat up to a body mass index of 30 does not cause cancer.

How can two research strategies, both based on databases of similar type and size, come to completely different results? It is even very likely that they rely in part on the same data. Population studies are very expensive, so the same data from Nurses' Health Study, NHANES, Framingham and other surveys are mined over and over again by many researchers with many different questions and hypotheses.

The statistical level of significance, in general, is a probability of 5 percent that a result is due to chance. Mining huge databases for correlations of many different factors will yield a great number of possible results. For every hundred of such correlations, five will be significant just by chance. Now imagine you are a researcher striving for publications. If you are looking for positive results to be published, you may put aside non-existent correlations because you do not find them worthwile. And most likely, if you find a correlation different from zero, you will go ahead and submit it for publication.

Where are the cherries?

Interestingly, in the global food and cancer report, most of the studies are on certain types of cancers and how they are linked to other factors. That is, from the big number of cancer cases, some have been selected by the researchers and some have been left aside. If cherry picking is part of the method, it may be very hard for a researcher to stop it before fist data sets have been analyzed, and not using it as a triage prior to publication.

The Flegal study, on the other hand, has looked at deaths from different causes, not only from cancer, and not sorting out different types of cancers. And this more global approach, with complete absence of cherry picking, has yielded a zero correlation between body weight and cancer deaths.

Death is a zero sum game

If you will not die from cancer, you may die from a heart attack, kidney failure, or Alzheimer's disease. Be it sooner or later. Any advice based on cherry-picked cancer studies will miss this point.

Photo credit: flickr.com/photos/santos/464889901/

Wednesday, November 7, 2007

Bean counting, deaths, and body weight

beans
Some bean counters in public health seem to be focused too much on certain causes of death, it may be time for a re-appraisal of body weight.

The authors of a big new report on food and cancer have claimed body fat to be a cause of cancer, sometimes spotting a clear evidence in data that look quite unclear, to put it mildly. Based on such evidence, they have claimed that you should be as thin as possible to prevent cancer. But this may be an ill advice, even if their cancer claims might be true. Just because cancer is not the only threat to health. In other words, you may be saved from cancer but likely to die from other causes.

This is the conclusion of a new study about death causes associated with body weight: With a body mass index (BMI) of 25 to 30, so-called overweight, about seventy thousand excess deaths from causes other than cancer and heart diseases have been prevented in the United States when compared to the so-called ideal weight of less than BMI 25. And there was no association with deaths from cancer and heart disease in this weight class - a clear contrast to the claims of the food and cancer report. According to this study, the ideal weight should be re-defined as BMI 25 to 30. This sounds like Vietnam and Iraq in the current war on obesity. Let's see how leading public health experts will be dealing with these facts.

Photo credit: flickr.com/photos/amyemilia/414191347/

Tuesday, November 6, 2007

Selling molehills as mountains

BMI and pancreatic cancer
Have a look at this graph and wonder how a group of experts can see there a convincing evidence of body fatness as a cause of cancer. (Taken from page 216 of the report on food and cancer mentioned in a previous post.)

Green dots and lines

The graph shows results of 41 studies on a link between body mass index (BMI) and pancreatic cancers. The square dots represent the relative risk average value of all cases analyzed in the study. The bigger the dot, the more cases. The horizontal lines represent the interval of 95 percent confidence. The shorter the line, the more reliable the values. As expected, the bigger the dots, the shorter the confidence lines in general.

The upper 21 are cohort studies, where body mass and cancer cases have been observed in a great number of persons over a long time. The lower twenty are case-control studies, where cancer cases and matched controls with the same characteristics but without cancer, have been compared. Such studies may be somewhat less reliable than cohort studies.

Pink diamonds

The upper diamond sums up the 21 cohort studies, its center is at a relative risk of 1.14 which means a relative risk increase of 14 percent. The width of the diamond represents the overall 95 percent confidence interval when all studies are taken together.

The lower diamond, summing up the twenty case-control studies, is somewhat wider than the upper one, telling us that these studies in general are somewhat less reliable. But this difference is not really big. The lower diamond is exactly at 1.00 which means that the risk did not change at all.

Conclusion

The results are not looking very consistent. Only one type of study is suggesting a link between BMI and pancreatic cancer, the other type does not show any such link. In both types of studies there are some suggesting even a risk reduction linked to a higher body mass - the dots to the left of the vertical line.

Yet the authors of the report conclude:

"There is ample epidemiological evidence, which is generally consistent, and there is a dose-response relationship. There is evidence for plausible mechanisms that operate in humans. The evidence that greater body fatness is a cause of pancreatic cancer is convincing."
You may wonder if they have looked at the same data. Of course, a pink diamond that does not hit the vertical line means a statistically significant result. This is the case for the upper 21 studies, but the gap between the line and the diamond is only half as wide as the diamond itself. That is, the result is only weak.

Just molehills

In addition, it has already been magnified by a factor of more than hundred. In terms of snake oil tricks, this is selling molehills as mountains: The incidence of pancreatic cancer in the United States is 0.01 percent of the population every year, over a lifetime of 80 years we get a risk of 0.8 percent, and a relative increase of this risk by 14 percent translates to an absolute risk increase of 0.11 percent. The pink diamond, in reality, would be so small to just disappear behind the vertical line.

Of course, not all results of this report are so doubtful. But I have chosen this example to show how the authors deal with facts, and it leaves me with a lot of skepticism about the conclusions. One of my upcoming posts will deal with the question of cause.

Monday, November 5, 2007

Unusual job for a quackbuster

snake oil
Looking for snake oil tricks in a big food and cancer report with a respectable multi authorship.

Last week I have come across this new report on food and cancer and its big media echo. The media spread messages like you should be as slim as possible in order to prevent cancer. Some days ago I had commented on a study finding only a very doubtful link between obesity and breast cancer in women. Obesity, let it be understood, is a lot more than just overweight, and this in turn is far away from "as slim as possible".

All of a sudden, I had a sense of déjà vu, and a scene from a western movie came to my mind: A snake oil peddler in front of a crowd, boasting with exaggerated claims about the benefits of his product. Scientifically proven, of course.

No one would expect to find the big five tricks, as may be described in the snake oil chapter of "Peddler's Handbook", in a serious modern cancer report with a multi-professor authorship. But I couldn't resist having a look for these tricks, and here is what I have found.

1. The China Trick
Make sure to label your product "Genuine Chinese Snake Oil", based upon a medicine that is thousands of years old, and therefore it must help against pain.
The names of organizations and persons behind the food and cancer report are really impressive, and it seems that for most media this alone has been sufficient to take the claims of the report for granted.

2. The Mrs Jones Trick
Present Mrs Jones to the crowd and have her confirm that she applied snake oil and later her pain disappeared. Make sure to have a Mrs Jones in every town.
This is one of the most effective tricks because people have a strong urge to see causes behind things. Thus, most people will believe that the pain of Mrs Jones disappeared because she had applied snake oil. But rheumatic pain comes and goes in phases anyway, and it is just a matter of chance that an application of snake oil is followed by a pain remission.
In the case of the food and cancer report, most data are just correlations of the Mrs Jones type, that is, consumption of certain foods or certain body mass indexes as well as certain cancers occur in the same population groups. Yet the authors of the report claim they have found a cause - more about the details in an upcoming post.

3. The Big List Trick
If people tell you that Mrs Jones is a single case which does not convince them, show them a long list of patients also successfully treated with your snake oil.
The food and cancer report takes together results of many studies of very different quality and size, claiming that the sheer number of studies makes the results more reliable.

4. The Molehill Mountain Trick
Look closely at any small effect and it will grow big. Sell mountains, not molehills.
Most of the data presented in the food and cancer report are presented in the form of relative risk differences, that is, as (bigger) percentage of a (smaller) percentage. By this method, small effects may be magnified by a factor of twenty, fifty, or more.

5. The Crowd Trick
Selling to a crowd is easier than selling at the door. Buying is contagious.
The big media coverage is just one side of this trick but not the only one. It may also have worked in the making of the report because most experts, for instance, share the view that body weight above a certain level is a cause of illness, if not an illness by itself. When such hypotheses are taken for granted, interpretation of data will be biased in some way.

Conclusion: As hard as it may be to believe, but even in this report, based on a huge number of scientific studies, authored by highly respected scientists, some old tricks of snake oil peddlers can be found. Thus, the claims of this report must be viewed with a skeptic eye. Tomorrow we are going to look at some details. Stay tuned.

Photo credit: flickr.com/photos/luobote/59637108/

Friday, November 2, 2007

Are you impressed by the new food and cancer report?

2007 diet cancer report
More than five hundred pages, lots of experts, tons of studies, but is this enough to convince you to stay as slim as possible to prevent cancer?

Here you can download the Report.

This is too much to be handled in one post, I just have downloaded and scanned it, and picked some of the most important or challenging points. I'll take my time and carefully comment on them, one by one, in my upcoming posts.

There are mountains of statistics, but what may come out is just molehills. We shall see. There are conclusions from those statistics, telling us that such factors as certain foods or body weight are without doubt established as causes of cancer. Really? We shall see.

An important point here is one I use to mention all the time: correlation is not cause. In the report, the experts deal with this question, and we shall see how strong the evidence for a cause really is.

And last but not least, the experts are telling us that, within the range of “acceptable" weight, we should stay as slim as possible in order to prevent cancer. Cancer is important, I agree, but not the only important health issue. Weight concerns are another, but not a positive one.

Many points to deal with; stay tuned and return to this blog next week.

Thursday, November 1, 2007

Enjoy your egg sunny side up

bacon and egg
Be cholesterol-smart, stop your worries and have a look at the real facts.

Do not make the same mistake as I did. Years ago, after a medical checkup, my doctor told me that my cholesterol level was too high and that I should care about it. I did. What I knew then was that the main source of cholesterol in food is animal fat. Soon after the checkup I began to dislike eggs. That is, I still liked them but I thought I shouldn't like them any more.

What I did not know then was the fact that only about twenty percent of the cholesterol in human blood comes from food, and that about eighty percent of it is produced by the body itself. The body maintains a cholesterol level according to its needs, and if less comes in from food, it increases the production. So I could have enjoyed my eggs, sunny side up, scrambled, soft boiled or whatever - my body just would have curbed the cholesterol production a little bit.

This is the first thing a cholesterol-smart person should know.

The second thing to know is that the link of cholesterol levels to heart attacks is only weak (see my post commenting on a 0.7 percent risk increase) and that it does not say anything about a cause. We do not know whether cholesterol is the real culprit or just a bystander. In dubio pro reo.

The third thing to know is that cholesterol is a vital substance for the body, otherwise it would not produce it. One important example is the need of cholesterol at the beginning of life.

And here is one more example of this kind: A high cholesterol level comes along with a lower risk of gastric cancer in a Japanese study: For every one millimol per liter cholesterol increase, the risk of gastric cancer decreases by 0.8 percent - about the same amount as seen in the mentioned heart study, but in the opposite direction.

This is not to say that cholesterol does prevent gastric cancer - to say it once again, a link or correlation does not imply a cause. And yes, we should be aware that the incidence of gastric cancer is not the same in Japan as it is in other parts of the world. This said, we conclude that there is also some good news about cholesterol, besides the fact that the bad news may be not so bad after all.

Photo credit: flickr.com/photos/snowriderguy/17018201/