Wednesday, February 28, 2007

The Modern Nutritional Fallacies

I love news days like this. The two top health stories on news.google.com are about studies that throw into question the legitimacy of two major tenets of mainstream nutritional advice: avoid saturated fat and get lots of antioxidants.

The first study shows that women who ate the most high fat dairy foods were protected from fertility problems whereas women who ate lots of low fat dairy products were as much as 85% more likely to have fertility problems. The second study showed that using the antioxidant supplements Vitamin A, Vitamin E and Beta Carotene certainly does not increase longevity and might actually increase your risk of dying. Whoops!

Here's the most interesting paragraph in the first article:

Intakes of lactose, calcium, phosphorus, and vitamin D were unrelated to anovulatory infertility, the researchers reported. It had been thought that dairy fat and lactose might impair fertility by affecting ovulatory function, they said. However, few studies have been conducted in humans, and the results are inconsistent.


In other words, even though there's no supporting evidence, the prevailing wisdom is that dairy fat is bad for fertility because saturated fat is always bad and lactose is bad because everyone is scared of the dreaded lactose intolerance. Never mind that there's essentially no lactose in yogurt or cheese and that people who are lactose intolerant can tolerate quite a bit of lactose before experiencing any major health problems like flatulence. Turns out the prevailing wisdom is wrong on both counts. That's hardly surprising because, like I said, the prevailing wisdom isn't based on scientific evidence. In nutrition, it seems, even the scientists tend to be more swayed by emotional arguments that they are by hard data.

These papers highlight several of the prevailing fallacies of modern nutritional advice. Let's take a look.



Preferential Citation.



The dominant belief that saturated fat is bad is inevitably tied to the Seven Countries Study, a study that the late Dr. George V. Mann referred to as "a classroom demonstration in naivete" in his scathing 1977 New England Journal of Medicine review, "Diet-Heart: end of an era". There have been many more modern, better controlled studies that have contradicted these findings but yet the seven countries study world view remains the dominant paradigm despite all of its methodological issues (ie, Dr. Ancel Keys hand picked the seven populations. Why didn't he choose any populations in France, Switzerland or Poland?). My current favorite study that refutes the seven countries study findings is Low-carbohydrate-diet score and the risk of coronary heart disease in women.

Incidentally, this one is very insidious, because before too long a preferentially cited paper becomes common knowledge. At this point it is VERY hard to fight, no matter WHAT the data says.



Foods are the sum of their component parts.



The supplement article is more guilty of this, but they're both guilty. No one has ever sat down to a meal of saturated fat. The fallacy works like this. A study comes out showing that people who eat lots of green leafy vegetables have lower rates of heart disease. Scientists say, "Ooh! Look at that! It must be because of the antioxidants/vitamin E/beta carotene/whatever." Experiments are done with supplemental antioxidants/vitamin E/beta carotene/whatever. They fail. It never seems to dawn on American scientists that perhaps the beneficial heart effects lie in the food itself and not some extract of it. For instance, maybe the leafy vegetables are replacing a starchy baked potato or french fries. Maybe the key is the specific proportions of nutrients in the vegetable. Or even more radically, maybe people who eat green leafy vegetables tend to sit down with their families and enjoy an unhurried meal. Additionally, there are lots of components in vegetables that scientists don't even know about - what if the "magic bullet" is one of them. Don't worry, though, scientists won't stop looking for the magic bullet.

Incidentally, if our health officials want us to eat more vegetables, they really need to get off the avoid saturated fat thing. The reason they eat so many vegetables is France is that they cook them with pork fat or butter. Delicious! Last week I hate a cabbage braised in pork fat for dinner. The entire cabbage! How many vegetable servings is that? The recommendations that we should a) eat more veggies and b) steam or boil them are mutually exclusive.



Hypothesis Creep.



The Seven Countries Study led to the hypothesis that saturated fat was a causal agent in heart disease. Then everybody just started applying it to other areas. So the original assumption creeps into the arena of female fertility, "Well, if saturated fat causes heart disease, maybe it also causes infertility." Even if saturated fat did cause heart disease in old men why does it logically follow that it would also cause fertility problems in young women?

You might think that's a bizarre assumption, and you're right. But from the perspective of a researcher, it's a very easy hypothesis to test, your study will get some press because it's about saturated fat, which everyone is interested in, and it might get you a job. And you don't even have know anything about fertility!



The End Result



When scientists and doctors put all of these fallacies together, as they so frequently do, you end up with non-sensical crap like this quote from the first article. I'll leave it to you to find the fallacies from here on out.

Dr Chavarro's advice to women trying to conceive is to change their diet for a while. He said "They should consider changing low-fat dairy foods for high-fat dairy foods; for instance, by swapping skimmed milk for whole milk and eating ice cream, not low fat yoghurt." Once they have become pregnant, then they should probably switch back to low-fat dairy foods as it is easier to limit intake of saturated fat by consuming low-fat dairy foods," said Dr Chavarro.


Can you imagine? Ok, a young woman, we'll call her Sue, goes to the doctor with a fertility problem:

Sue:I can't conceive

Dr. Chavarro:You should eat more full fat dairy products.

Sue:But I thought saturated fat was bad for me.

Dr. Chavarro:It is. So you should stop eating it after you've conceived.

Sue:So you want me to eat something that's bad for me?

Dr. Chavarro:Yes. But don't worry, it will make you more fertile.

Sue:Doesn't that suggest that saturated fat is good for young women?

Dr. Chavarro:No, it just helps you conceive.

Sue:Um... Well..... OK?

Dr. Chavarro:Exactly.


18 Comments:

Anonymous Anonymous said...

>>It never seems to dawn on American scientists that perhaps the beneficial heart effects lie in the food itself and not some extract of it.

This isn't accurate. All the recent science recommends you get as much nutrition as possible from food rather than supplements for this exact reason! Hence the existence of nutritional analysis tools like the CRON-o-meter.

Science based health fanatics keep track of their diet and do precision supplementing. It's funny that the very supplments this study was using, A and E, are the very supplements that are not recommended for anyone to take!

http://www.calorierestriction.org/files/conference/2004/summaries/cr3-07-summary.html

5:47 PM  
Anonymous chris whitcoe said...

Excellent Article! You bring light to a few of the many misconceptions of what constitutes "healthly" eating. I think the correct question is NOT "which foods are good and which foods are bad", but rather, the quality of food. Modern food science seems to lump all foods together, without specific considerations as freshness, organic, gmo, alive vs. cooked, etc. My experience is that the closer we get to the original form of the food, the better our DNA seems to understand what to do with it. I would say that fresh, unpasteurized milk taken lovingly from a cow that has been grazing exclusively on wild, non-chemically treated grass is "healthy"; whereas standard milk that has be painfully extracted from an industrialized dairy cow, which has been fed chemically treated, genetically modified food that has been grown in chemically treated soil and spayed with poisons to reduce "pests", and at the same time that cow has been given recombinant bovine growth hormone (rBGH) to unaturally increase the milk capicity, I would classify as "bad". Even water can be good, when it is mountain spring water, or bad, when it is stagnant.

Not to mention that fact that people have slightly different physiological metabolisms, and what is "good" for certain physiologies is "bad" for others.

Modern science needs to look at health as what it is: a function of a larger ecosystem.

9:51 PM  
Anonymous Anonymous said...

I had to stop reading at the point you mentioned fear of lactose intolerance. No one is afraid of it. It just is. I can't take anyone seriously who would write that.

I as well as most of the planet's population lost our ability to drink milk during young adulthood. There's nothing weird or wrong about that. By definition milk is for babies. It was merely an evolutionary advantage for northern Europeans too dumb or obstinate to find a warmer place to live.

Most of us with this "affliction" are well aware we can eat yogurt and cheese without trouble. It is true that most of us can deal with a small amount of lactose, but certainly much less than you'd find in a bowl of ice cream or even a glass of normal cow's milk.

10:01 PM  
Anonymous Anonymous said...

Never mind that there's essentially no lactose in yogurt or cheese and that people who are lactose intolerant can tolerate quite a bit of lactose before experiencing any major health problems like flatulence.

I think you need to spend more time researching. From Wikipedia: Many people are more tolerant of yogurt than milk because it contains lactase produced by the bacterial cultures used to make the yogurt. Also, hard cheeses (e.g. Swiss) produce far less reaction than the equivalent amount of milk because the cheese making and ageing processes greatly reduce the amount of lactose. A typical Swiss or Cheddar might contain 5% of the lactose found in whole milk, while long-aged cheeses contain almost no lactose at all.[6]

Fresh cheeses like a raw mozzarella still contain substantial amounts of lactose where a five year aged gouda contains virtually none.

Such a major flaw in your argument that took, literally, under ten seconds to refute. I don't what you said after that as I pretty much stopped reading dead on that paragraph.

If you're going to be exposing the flaws of modern nutritional thought you might want to examine your own thinking first.

9:47 AM  
Blogger Brad Marshall said...

Hey guys,

On the lactose front, I think I'm on pretty firm ground. I know it's a touchy subject for some reason, but stick with me for a second.

According to the meta-analysis Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration, "the results indicate that lactose is not a major cause of symptoms for lactose maldigesters following usual intakes of dairy foods, that is, 1 cup."

So indeed, I think that a lactose intolerant person could indeed eat some mozzarela or a serving of ice cream without major problems according to the best medical research.

Also, is lactose intolerance any different than "bean intolerance" or "fiber intolerance" or "inulin intolerance"? All of them are carbohydrates that humans can't digest but are present in common foods like milk, beans, grain and vegetables(fiber), garlic and onions (inulin). We're constantly told to eat more fiber, one of the known symptoms of which is looser bowels. Yet "lactose intolerant" people are chastised and warned to avoid lactose because it might lead to loose bowels. Go figure.

Brad

12:43 PM  
Anonymous Spootie said...

Anonymous, you need to get a life and leave Brad alone. If you don't like what he writes you should go have a cube of butter and a jar of mayonaise and go fat in the back room and read wikipedia all night.

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