Friday, March 02, 2007

Oh Yeah, The Lactose Thing

OK, OK. I guess I let the cart get a little before the horse in my last entry leading to some testy reader comments. I referenced lactose intolerance before I actually wrote the article about it. Well, here's the article.

I was staying in Boulder for a wedding. My girlfriend and I (now my wife) went to a Southwestern themed restaurant and I ordered red beans and rice, which I ate with hot sauce (of course) and only finished half of. After dinner, we went back to our room and read books. Wild, I know. I remember sitting there reading when the first bout of "wind" hit. Within an hour or so, my bout of wind had grown to epic proportions. I mean, startling proportions, really. I mean, wow!! I actually woke myself up several times in the night, startled, because of the blasts. Before the return flight home I finished the red beans and rice, because, you know, they were delicious! I'll let you imagine the flight.

The medical industry is constantly telling me to eat more beans, vegetables, garlic, onions, all of which are loaded with indigestible carbohydrates and all of which can cause flatulence, bloating, etc. In fact, according to the "Garlic the wonder food website, "individuals who are sensitive to garlic may experience heartburn and flatulence." And garlic is a wonder food, right? says that legumes(beans), milk and milk products, vegetables, root vegetables, fruits, cereals and breads all contribute to flatulence.

Why? Here's as good a primer as any. Basically, there are lots of carbohydrates that people can't digest in our food. These include the oligosaccharides found in beans and vegetables as well as inulin found in garlic and onions and lactose found in milk. These products make it through the small intestine to the large intestine where bacteria digest them and give off methane gas. This methane production leads to gasiness, flatulence, bloating, intestinal cramps, loose stools and the other symptoms if we get a high enough dose.

But here's the thing. Of all of the foods containing indegestible carbohydrates, dairy products are the only ones who are racially selective in who they bother. Not completely, of course. 1 of 4 Africans can and 1 of 5 Europeans can't digest lactose. Latinos are about fifty-fifty, but certainly don't shy away from dairy products. There are populations in Asia - specifically Tibet and Mongolia - and Africa - like the Masai - where most people can. Furthermore, there are lots of dairy products in which the lactose has been pre-digested by bacteria or removed in the whey and thus is of no harm to anyone, including yogurt, sour cream, butter (traditionally, butter is both fermented and drained - modern butter is not fermented and therefore contains trace quantities of lactose) and most cheeses. But the racial thing is why people get so fired up about it. Yet the symptoms of lactose intolerance are no more severe than the symptoms that anyone would get from eating beans or garlic.

If you think I'm just talking trash I'll refer you to a peer reviewed meta-analysis of lactose intolerance studies in the April 2006 edition of the Journal of Nutrition, Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration. It concludes, "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." I rest my case.

I'll let the words of Jeffrey Steingarten take it out because he said it far more eloquently than I would. This is from the introduction to The Man Who Ate Everything.

By closing ourselves off from the bounties of nature, we become failed omnivores. We let down the omnivore team .... Overnight, everybody you meet has become lactose intolerant. It is the chic food fear of the moment. But the truth is that very, very few of us are so seriously afflicted that we cannot drink even a whole glass of milk a day without ill effects .... I cannot figure out why, but the atmosphere in America today rewards this sort of self-deception. Fear and suspicion of food have become the norm. Convivial dinners have dissappeared and with them the sense of festivity and exchange, of community and sacrement."

Amen, Jeffrey.

Wednesday, February 28, 2007

The Modern Nutritional Fallacies

I love news days like this. The two top health stories on 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.

Monday, January 29, 2007

A comment on Micheal Pollan's "Unhappy Meals"

I've just finished reading Micheal Pollan's New York Times Magazine article "Unhappy Meals". The first line of the article is, "Eat food. Not too much. Mostly plants." I couldn't agree more with his advice to "Eat Food", food being defined as anything your great-great-grandmother would have recognized as food. And it's probably good advice to not eat too much. But the last line, "Mostly Plants", irks me.

I am, unabashedly, a meat and dairy eater. I do not agree that "meat is bad" based on what I consider to be sound scientific evidence as well as some fairly convincing circumstantial evidence. (See my prior entries.) Pollan simply states that meat is bad and uses it as a truism throughout the article. His evidence is based on the findings of a 1977 senate subcommittee that was apparently swayed by the arguments that "while rates of coronary heart disease had soared in America since World War II, other cultures that consumed traditional diets based largely on plants had strikingly low rates of chronic disease. Epidemiologists also had observed that in America during the war years, when meat and dairy products were strictly rationed, the rate of heart disease temporarily plummeted." Is that the best he's got? He wants me to base my diet on the findings of a senate subcommittee?? One who based their findings on circumstantial evidence??? I'll give you circumstantial evidence: In Russia, following the collapse of communism, heart disease rates have exploded while meat and dairy consumption have declined. In Japan, heart disease rates have dropped for fifty years while beef and pork consumption are on the increase. And in Japan, they eat their beef and pork as fatty as they can get them. There are cultures with strikingly low rates of chronic disease whose diets are high in milk, meat and fat, like the Masai of Africa, the Inuit, traditional native american cultures like the Cree, and the Chinese citizens of Tuoli county. Not to mention the French, Swiss and Italians. I can name more.

He later states that "populations that eat diets high in meat have higher rates of coronary heart disease and cancer than those that don’t." Really? Which ones? I've already named a handful for which this is not true.

His lack of evidentiary support gets him into trouble when he's trying to explain the findings of the Women's Health Initiative, a large, recently published study that failed to find any evidence that women who reduced their fat intakes as a percent of calories were protected against heart disease or breast cancer. He cites two scientists who think that the "culprits" in meat and milk might not be fat at all, but animal proteins or steroids. And here's the irony. The two scientistst are T. Colin Campbell, whose China Health Study failed to find any link between meat consumption and heart disease and Walter Willett, whose recently published "Low-Carbohydrate Diet Score and the Risk of Coronary Heart Disease in Women," failed to show any connection between a high meat, high fat diet and heart disease.

OK, I'm going to restate that point in it's own paragraph for effect. In order to explain why a recent study failed to show any benefit associated with a low fat diet, Pollan offers us the OPINIONS of two scientists whose studies failed to show any connection between diets high in meat and animal fat with heart disease and zero scientific evidence.

Pollan also claims that the Womens Health Initiative is poorly controlled. I agree, but Dr. Campbell's and Dr. Willett's studies are much better and had the same result. Let's not pretend that the Nurses Health Initiative is the ONLY one to have failed to show the link between meat and chronic disease.

Other than my point about meat consumption, I agree with Pollan entirely. I particularly agree with his concluding point number seven: Eat more like the French. In particular, enjoy "communal meals — and the serious pleasure taken in eating."

Wednesday, March 22, 2006

On Nurses, Pork Fat and Potatoes

Dr. Walter Willett is a guy who almost gets it. The Harvard physician is maybe the most outspoken mainstream researcher in questioning the tenets of the USDA Food Pyramid. The results of his studies frequently call into question the wisdom of the dietary guidelines provided to us by the USDA, and Willett is not afraid to speak up about what he sees as flawed dietary advice. For instance, he questions whether we should be relying on carbohydrates for so many of our calories. And he says the pyramid's insistence that all fat is bad is wrong - he emphasizes the benefits of polyunsaturated fats and says the only fats we should be avoiding are saturated fats and trans fats. Which is where we differ. Not on the trans fat thing, of course. Trans fats are deadly and you shouldn't eat them. Throw out your margarine and Crisco. But Dr. Willett continues to hang onto the incorrect notion that you should avoid saturated fat despite the results of his research.

Dr. Willett lays out his anti food pyramid argument in a 2003 "Eating Well" article called "Razing the Pyramid": "We actually see in the Nurses' Health Study that people who use full-fat salad dressings most days have a 40 percent lower risk of a fatal heart attack ... In some sense we've created a whole national feedlot on this low-fat, high-starch diet ... Probably millions of people have died prematurely from all the trans fats that have been included in our diet ... Unless you are extremely lean and extremely active, you can't tolerate [potatoes]." I've got no qualm with any of that, the occasional plate of butter-fried new potatoes notwithstanding.

NOTE: Eating Well conveniently removed that article from their website as I was publishing this. You can still order the PDF of that article if you want. This PBS article is just as good. I still have the same complaints with his logic.

But when asked what he thinks about the Atkins diet he makes a very interesting statement: "Atkins is partly right in that high intake of carbohydrate, particularly if it is refined, has adverse effects, and that we saw no increase in risk with butter consumption (and only a small increase in risk with saturated fat compared to carbohydrate). However, high intake of saturated fat is not part of an optimal diet because risk of cardiovascular disease and diabetes will be reduced if saturated fat (or carbohydrate) is replaced with either polyunsaturated or monounsaturated fats. Thus, Atkins has mainly compared two unhealthy forms of calories [saturated fat and refined carbohydrates]. The answer is to emphasize healthy fats."

So Dr. Willett is arguing that eating saturated fat is not really worse for you than eating carbohydrates, but you shouldn't eat it anyway, because there are choices that might give more benefit in terms of avoiding heart disease. This argument is wrong-headed on several counts. First, his research clearly shows that refined carbohydrates are far more dangerous for your heart than saturated fat. Second, you have to eat something, right? We can't replace all saturated fat and carbohydrate with polyunsaturated fat. Soybean oil shots, anyone? Most subtly, though, his argument that we should replace saturated fat with unsaturated fats is misleading. For instance, although you wouldn't know it from the mainstream press, 61% of pork fat is, by Dr. Willett's definition, "healthful". It turns out that eating "saturated fat" isn't actually a choice. Read on.

The rest of the article will explore these points. First off, an introduction to Dr. Willett's research:

"The Nurses Health Study" is Dr. Willett's study of the habits and disease patterns of over 80,000 nurses that has been ongoing since 1980. The study gives nurses questionnaires about what they eat, how much they exercise, whether they smoke, etc. The nurse's medical records are tracked and then correlations can be made between lifestyle choices and disease risks. Nurses were chosen as the study group because they are presumably reliable and have good medical records, among other reasons.

NOTE:If you're interested in learning about the statistical methods used by the Willett group, see the statistical discussion at the end of this paper.

Now onto Dr. Willett's statement. The first part is, "Atkins is partly right in that high intake of carbohydrate, particularly if it is refined, has adverse effects, and that we saw no increase in risk with butter consumption (and only a small increase in risk with saturated fat compared to carbohydrate)."

Willett is clearly justified in suggesting that a high intake of refined carbohydrates is detrimental to heart health. This is shown in his paper, "A Prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women."

The paper reports on the risk of eating a diet with a high "glycemic load". The glycemic load is a complicated subject in and of itself, but in a nutshell, it is the measure of your diet's total effect on blood sugar levels. It takes into account both the type and amount of carbohydrates you eat. Basically, foods that are high in carbohydrates and that cause a very fast blood sugar response have a high glycemic load. Foods that are low in carbohydrate or are more slowly absorbed have a lower glycemic load. Interestingly, a potato has a vastly higher glycemic load than an apple despite their similar amounts of total carbohydrates. This is because potato carbohydrate is largely starch, which is easily converted to blood sugar and apple carbohydrate is largely fructose, which is absorbed into the bloodstream only slowly. Conversely, the carbohydrate in carrots is easily absorbed into the blood, but their glycemic load is small because there is relatively little carbohydrate in a carrot. In a nutshell, this describes the difference between the "glycemic index" - how easily the carbohydrate of a food is converted to blood sugar, and "glycemic load" - how easily the carbohydrate of a food is converted to blood sugar times the total amount of carbohydrate in a serving of that food.

You can look at the definitive source on the glycemic load to find the glycemic load of your favorite foods. The first number after the food name is the glycemic index, the next number is the serving size and the last number is the glycemic load, which is what we're largely concerned with here. To give you a rough idea, though, a large slice of white bread has a glycemic load of 10. It's additive, so two large slices of white bread would have a glycemic load of 20. 120 grams of apple has a glycemic load of 6. A 150 gram baked russet potato has a glycemic load of 26. Cornflakes with skim milk and a banana have a glycemic load of 37 (cornflakes (21) plus banana (12) plus skim milk (4)) whereas two eggs, bacon and a slice of toast have a glycemic index of 10. Eggs and bacon, of course, don't contain carbohydrates. Well, OK, egg yolks have a little carbohydrate.

The glycemic load paper found that people who consumed a diet having an average daily glycemic load of 206 were about twice as likely (multivariate RR = 1.98) to have a heart attack as those whose diet had an average glycemic load of 117, all other things being equal. Another way of saying this is that an extra four servings of potatoes a day doubles your risk of a heart attack. People whose diets had a higher glycemic load ate more potatoes, dark bread, white bread, orange juice, cold breakfast cereal and bananas. So I think Dr. Willett's data certainly supports his point that "high intake of carbohydrate, particularly if it is refined, has adverse effects".

Willett openly admits to finding no correlation between butter consumption and heart disease, but says they found a "small increase in risk with saturated fat compared to carbohydrate". That small increase in risk was from the paper Dietary fat intake and the risk of coronary heart disease in women. This paper shows a very small and statistically unconvincing risk for "replacing carbohydrate intake with saturated fat". In 2005, Willett's group published Dietary Fat Intake and Risk of Coronary Heart Disease in Women: 20 Years of Follow-up of the Nurses Heart Study. This paper superseded the previous one and dropped all claims that saturated fat consumption is a risk factor for heart disease. The paper concludes "Polyunsaturated fat intake was inversely associated with CHD risk (multivariate relative risk (RR) for the highest vs. the lowest quintile = 0.75, 95% confidence interval (CI): 0.60, 0.92; p(trend) = 0.004), whereas trans-fat intake was associated with an elevated risk of CHD (RR = 1.33, 95% CI: 1.07, 1.66; p(trend) = 0.01)". In layman's terms, this means that eating lots of polyunsaturated fat reduced the nurses risk of heart attacks by twenty five percent whereas eating lots of trans fat increased their risk of heart attacks by thirty three percent. The paper showed that there was no correlation whatsoever between saturated fat consumption and heart attack risk (multivariate RR = 0.97). Throw out your margarine, though.

I'm going to repeat that in case you missed it. In bold this time. The Nurses Heart Study, one of the largest and longest running health studies ever done, following more than 80,000 nurses for twenty years, found no correlation whatsoever between saturated fat consumption and heart disease risk. Conversely, the same study showed that eating lots of starchy and sugary food roughly doubled heart disease risk.

Which brings us quite nicely to the second part of Willett's statement. "However, high intake of saturated fat is not part of an optimal diet because risk of cardiovascular disease and diabetes will be reduced if saturated fat (or carbohydrate) is replaced with either polyunsaturated or monounsaturated fats. Thus, Atkins has mainly compared two unhealthy forms of calories [saturated fat and refined carbohydrates]. The answer is to emphasize healthy fats."

I disagree strongly with the suggestion that saturated fat and refined carbohydrates are equally bad with regards to heart health. As we have seen from Dr. Willett's own study, a diet high in refined carbohydrates doubled the risk of heart attack whereas a high saturated fat diet showed no risk whatsoever. Enough said.

Then he argues that we should replace saturated fat with mono or polyunsaturated fat, certainly implying that we should avoid pork chops. That's where his argument really starts to break down and this is where we'll clarify the difference between "saturated fat" and "animal fat".

There are no foods made of saturated fat and there are no foods made of polyunsaturated fat. All naturally derived fats are mixtures of saturated, monounsaturated and polyunsaturated fats. Perhaps the mostly widely misunderstood fat is lard (porkfat). Lard, even from factory raised, cornfed hogs, is only 39% saturated according to the USDA. 45% of lard is monounsaturated and 11% is polyunsaturated. (You'll have to ask the USDA why the numbers don't add up to 100%.) So when you eat that big rack of fatty pork ribs, you're consuming some saturated fat along with a larger amount of "healthful" fats. This is part of the reason why a tablespoon of olive oil has about 75% more saturated fat than a pan-fried strip of bacon. Look it up. It may also be why some of Dr. Willett's papers have reported very small, largely insignificant risks for "saturated fat" consumption, but no risk at all for "animal fat" consumption. Animal fat is not saturated fat.

So with this in mind, let's think about Dr. Willett's statement that, "risk of cardiovascular disease and diabetes will be reduced if saturated fat (or carbohydrate) is replaced with either polyunsaturated or monounsaturated fats". Now visualize yourself sitting in front of a platter stacked high with perfectly grilled, fatty pork chops on one side and mashed potatoes on the other side. You have the opportunity to "substitute" protein and pork fat for starch or vice versa, depending on how much you take of each. Ignoring the protein for now, let's say you take only pork chops and only eat the fat rind around the edge. Forty percent of your calories are now from saturated fat (supposedly bad) and sixty percent are from unsaturated fat (good). But if you just take the mashed potatoes (without adding butter), you're getting ninety percent of your calories from a high glycemic load starch (definitely bad). So by eating the pork fat aren't you taking Dr. Willett's advice of replacing refined carbs with heart friendly fats?

Of course, Dr. Willett could argue that we'd be better off getting our calories from a salad topped with vegetable oil because then we'd get even more polyunsaturated fat. And what goes better with pork chops than a salad?

Further Reading

If you're interested in digging into this stuff further, here's a little primer on the statistics used in the Willett group's papers. They're actually pretty readable and I recommend it if you're into this sort of thing. Other interesting things that they've found include the fact that coffee drinkers are at significantly less risk for diabetes. Just go here and search for "willett nurses heart disease". Or "willett nurses coffee". Or whatever.

The Willett group's papers are largely concerned with the concept of "relative risk", often referred to as RR. The way relative risk is calculated is to split a group of people up based on some statistic, like how much fat they eat. Then you watch them for ten or twenty years and count how many heart attacks occur in the different groups (or whatever health problem you're interested in - it could be diabetes or gout). The group that eats the least fat is said to be the "baseline" group and is given a RR score of 1. Let's say that after ten years the people in this group have had 100 heart attacks. If the people in the group that eats the most fat have also had 100 heart attacks, their relative risk score would also be 1, and we would say that total fat consumption has no effect on heart disease risk. If the people in the highest fat group have had 200 heart attacks, their RR would be 2 and we say that people in the group that eats the most fat were 100% more likely to have a heart attack compared with those in the group that ate the least. Or if the people in the highest fat group had only 50 heart attacks, the RR score for high fat consumption is 0.5 and we would say that people in the group that ate the most fat were 50% less likely to have a heart attack compared with people who ate the least fat.

Generally, they like to split people into five groups based on their fat consumption (or whatever else is being studied). So people in the group who ate the least fat are said to be in "the lowest quintile" and the group who eats the most fat is said to be in "the highest quintile".

Another thing you need to understand before you can interpret their papers is what a "multivariate RR" is. The problem with studying people is that they're complicated and comparing the raw numbers numbers between two of our "quintiles" of people ends up being an apples to oranges comparison. The reason for this is that, for instance, the people in the highest quintile of fat consumption might also smoke more, get less exercise, drink less alcohol and be less likely to take a multivitamin, etc. (Incidentally, all of those things are true.) What we want to do is compare, for instance, an active forty year old non-smoker in the first (lowest) quintile of fat consumption to an active, forty year old non-smoker in the fifth (highest) quintile of fat consumption. This tell us the effect of the fat consumption itself. Without taking into account factors like exercise and smoking levels into the calculation, you don't know if the people in the highest quintile of fat consumption have more heart attacks because they eat more fat or because they smoke. Incidentally, the "multivariate RR" score is calculated by a statistical model on a computer. The downshot is that anytime you want to make an apples to apples comparison for any risk factor, you should look at the "multivariate RR" score. Usually, the relevant one in a Willett paper is the last one listed for any given category.

Lastly, all statistical scores have a P score, which tells you whether a given correlation is "significant" (real). A non-signifcant correlation is likely due to chance or other factors rather than the risk factor being looked at. A significant correlation should have a low P score. Generally, P scores of less that 0.05 are considered significant and scores less than 0.01 are considered very significant. Incidentally, the P score in the paper that Willett is referring to as his "small
increase in risk with saturated fat compared to carbohydrate" was 0.10, which I would say is statistically insignificant.

Tuesday, December 13, 2005

Is wheat killing us?


Maybe you've heard someone say, "Well, in Asian countries they eat low fat diets and they don't have many heart attacks." This is mainly, mostly true. But interestingly, "The China Study", a recently published book by T. Colin Campbell, a leading researcher into diet and disease in China has one chapter about heart disease and it doesn't even MENTION China. How can that be? In a nutshell, Dr. Campbell is a vegan propagandist that will string together any number of flimsy correlations to support his cause, but not even he is bold enough to try to make it seem like there is a link between heart disease and animal food consumption - meat, milk and eggs - in China. Clearly, there is not.

I am fascinated by "The China Health Study". The whole thing was started in the early 1970's when the Chinese premier, Chou EnLai, was dying of cancer. He initiated a vast study correlating disease rates in China with different geographical areas, culminating in the publishing of a disease atlas of China. Later, the authors of The Study collected dietary and blood data from 65 mostly rural counties in China and correlated them with the data in the disease atlas. Then they printed the data in book form so that you can, for instance, look up myocardial infarction ( heart attack) rates, and see what foods are eaten in areas of China where people are prone to heart attacks. It is a truly epic study and I think it is far more interesting than most Western health studies because of certain factors in China:

1) The people in rural China eat what they grow, so the majority of people in the study have presumably eaten the same diet from birth to death. This contrasts with American diets which tend to change with the dietary breeze.

2) Due to wide variations in climate and therefore which crops can be grown, dietary staples differ by region. Rice is the staple in Southern China, wheat, corn and millet are staples in the middle latitudes and wheat and dairy predominate in the far North. There are pig-raising areas and sweet-potato raising areas. Therefore, we can see correlations of disease patterns among dramatically different diets.

3) There are dramatic differences in disease rates in different areas in China. The disease rates from region to region differ far more than they do in the US.

4) The authors published all of the tabulated data in a "monograph" titled, "Diet, Life-style and Mortality in China." Very few studies give you this type of unfettered access to the raw data. Usually, you only get the authors conclusions from their take on the raw data. You can probably find a copy and have a look yourself if you're REALLY interested.

The Meat of It

Unfortunately, we now have to talk about statistics for a minute. The data in the monograph is published with correlation scores between each pair of factors (like myocardial infarction and fat consumption). The scores range from -100 to 100. A score of 0 means that the two factors are completely unrelated, whereas a cc of 100 represents perfect correlation and a cc of -100 is perfect negative correlation. Come again? OK, so a cc of 100 between fish and myocardial infarction (MI) would mean that anyone who's ever tasted fish has died of a heart attack. That would be considered a "strong positive correlation". A cc of -100 would mean that no one who's tasted fish ever died of a heart attack. That's a "strong negative correlation". And a cc of 0 means that, from the perspective of MI, it made no difference whatsoever whether or not you've eaten fish (no correlation). Of course, in the real world the correlations tend to be a little more ambiguous.

OK, enough teasing. Here are the relevant correlations between dietary factors and MI:

Factors Correlated to Heart Attack Risk (MI)
FactorCorrelation ScoreSignificance
Meat Consumption-28none
Dairy Consumption6none
Rice Consumption-58Strong Negative Correlation
Wheat Consumption67Strong Positive Correlation
Other Grain Consumption39Moderate Positive Correlation
Green Vegetable Consumption5none
Blood Cholesterol4none

Whoah!! Did you catch that? I'll state it as plainly as I can:

The main dietary predictor of heart disease rates in China is the TYPE of grain you eat.

Rice eaters seem protected from heart attacks while wheat, corn and millet eaters are much more prone (the corn link is debatable). Meat, dairy and vegetable consumption play no obvious role. Blood cholesterol plays no role.

But we're not going to believe these statistics are we? Let's look at the raw data.

The first graph simply shows the raw correlation between eating grains other than rice and dying of a heart attack in China. There is a clear positive trend here. The counties with the nine highest rates of heart disease all eat more than 350 grams per day of grain other than rice. The majority of counties where more than 350 g/day of non-rice grain are eaten have a MI death rate of more than 7 per 100,000 per year whereas the majority of rice eating areas have heart disease rates of less than 4 per 100,000 per year.

A problem with any study of this magnitude is that there are so many variables. These variables are very, very tricky to tease apart, but I'll give it a go. In some areas of China, corn and millet are widely eaten. Since the link between wheat and heart disease is particularly strong, it would be interesting to see the link between rice and wheat consumption and heart disease in areas where corn and millet are not eaten. The following graph shows the relationship between wheat consumption and heart disease only in counties where they eat less than 100 grams per day of corn and millet.

Wow, no question about the correlation here!

I'm also trying to tease out the effect of fat consumption. Notice that there are three data series in the graphs. The blue diamonds represent areas where total fat consumption is less than 40 grams per day. The purple squares represent areas where fat consumption is more than 40 grams per day. If fat consumption plays a role in heart disease risk, you would expect to see the purple squares a little higher than the blue diamonds, on average. But as you can see, this is not the case, suggesting that it doesn't matter how much fat is eaten; in China, the more wheat you eat the greater your risk of heart disease, regardless of fat consumption.

The final data point, the yellow triangle, is Tuoli county, where 186 grams of fat are eaten per day, mostly from dairy and meat. If dietary fat plays a role in heart disease risk in China, you would expect that point to be elevated far above the others. It is not. Which brings me to my next topic.

The Forgotten Ones

There are populations in China in and around the steppe whose diets are more American than here in the good ole US of A. They eat wheat, dairy products and meat. And nothing else. You can read about some of them here, but I'll give you this quote as a prelude:

"The vegetables were, incidentally, an accommodation to the visiting lowlander. Self-respecting nomads don't eat plants; it's just not their place on the food chain."

I don't think the people studied in the China Health Study are actually nomadic, but they eat far more saturated fat than we do in America - most of it from dairy and meat. Yet, as you can see by the location of the yellow triangle in the graph, their rates of heart disease seem to be determined solely by how much wheat they eat.

Why do I refer to them as the forgotten ones? In this interview, Dr. campbell had this to say, "Firstly, the kind of diet that was consumed in China is very low in total fat. The range was between 6-24% of calories, for example, whereas in this country the range is more of the order of the high 20s-high 40s. " Actually, the fat content of the diet of the people of Tuoli, according to Dr. Campbell's study, was 45%. Has he forgotten them? My guess is that he simply prefers not to think about them. They don't support his views, you see.

Here's a table comparing three wheat eating areas and the Chinese averages. I have picked three areas with extreme diets to prove my point. The first is Longxian county, the area of China with the highest wheat consumption and below average meat and vegetable consumption, a very tedious diet by American standards. The next is Tuoli, where wheat is eaten along with large portions of meat and dairy but no vegetables. This area represents the stereotypical american diet. The final is Jingxing, an essentially vegan area where they eat a variety of grains other than rice and gorge themselves on green vegetables. Jingxing had by far the highest consumption of green vegetables of any county in this study. I suppose it represents the ideal vegan diet of low fat consumption with lots of vegetables and grains (except rice).

Three Chinese Counties
LongxianTuoliJingxingChinese Median
Rice Cons (g/day)03.96.1398
Wheat (g/day)62937212622.4
Other Grain (g/day)75.16.8342.11.1
Meat (g/day)6.1121020.3
Dairy (g/day)085700
Green Veg (g/day)36.3069176.8

As you can see, Tuoli county had the lowest levels of heart disease and stroke (which is also correlated with wheat consumption) of the three. The three counties followed the general trend:

In China, the more non-rice grain you eat, the higher your risk of heart disease (and stroke). Eating meat, dairy and vegetables don't affect your risk.


Correlation does not imply causation. What this study does NOT tell us is that wheat categorically causes heart disease. It tells us that there is something different about wheat eating people in China that predisposes them to heart disease, which may or not be the wheat itself. For instance, in the study the number of times per year than one ate green vegetables had a strong negative correlation with heart disease risk while the number of times per year that one ate carrots had a strong positive correlation correlation. Should we conclude from this that green vegetables prevent heart disease while carrots cause it? No. First off, the actual amounts of carrots or green vegetables consumed have no correlation with heart disease risk. These two parameters are actually telling us about the length of the growing season in an area. In the South, green vegetables can be grown for more of the year, while in the North carrots have to be grown since they can be kept in a root cellar during the longer winter. Rice growing is confined to the warmer South. So the reason that there is a strong correlation between how often you eat carrots and heart disease risk is that carrots are eaten in wheat growing areas. Wheat is the REAL correlation.

But if you want to show that wheat is really the cause of elevated heart disease risk and not just a marker for something else, you have to look a little deeper. And in China, there are a whole bunch of differences between wheat and rice eating peoples. Wheat eating people are taller and heavier. They tend to have higher levels of blood triglycerides, associated with increased risk of heart disease in the US, and sex hormone-binding globulin(shbg), which the authors of the study claim is a sensitive indicator of insulin resistance. Cholesterol levels were the same in both populations. Wheat eaters had lower levels of monounsaturated fats (like in olive oil) in their blood cell membranes and higher levels of omega 6 fats (like in soybean oil).

So a reasonable possibility, based on the triglyceride and shbg data is that eating wheat and certain other grains leads to insulin resistance, which is associated with increased heart disease risk. But the really interesting thing is why that should be. Why does eating wheat, but not rice, seemingly lead to insulin resistance in China? I don't know. That, my friends, is the million dollar question that we should be asking but aren't.

Where is T. Colin Campbell on this? He doesn't even MENTION the fact in his book! It's not like he didn't notice. His name is on the paper about it from 1996. The only reasonable explanation is that Dr. Campbell is more interested in pushing his agenda than on doing good science.

East and West

Might the difference between heart disease levels in Asia and Western countries be explained by the fact that Western peoples eat more wheat and Asian peoples eat more rice? Maybe partially. It's important to note that even in wheat eating areas of China, heart disease levels were still below those of Western countries.

If the causal link does indeed turn out to be insulin resistance, then there is one other major dietary difference that ought to be noted. In China, virtually no sugar is eaten, so there is nowhere in this study where the carbohydrate intake is similar to the US. In the US, we eat about the same amount of white wheat flour and sugar (or high fructose corn syrup) and not much else as far as carbs. In China they eat rice or wheat or maybe rice and millet or corn and wheat but never wheat and sugar. What if they did?


In China, the main predictor of heart disease rates in a given population is how much wheat flour (and other grains except rice) that population eats. The consumption of vegetables or animal products doesn't play an obvious role in heart disease rates. Tuoli county, where they eat far more saturated fat than in the US, had far less heart attack deaths than the US and no more heart attack deaths than you would suspect based on the amount of wheat they consume compared to their Chinese Colleagues.

A Few Notes

A couple more notes. Sweet potatoes, widely eaten in China, had a neutral effect on heart disease risk.

Apparently, in China, they eat mainly white flour and white rice, so this probably isn't a whole grain versus processed grain issue, although you could argue that the wheat, being ground into flour, is more processed than the whole white rice.

The study didn't publish any figures on physical activity, but it is clear that the Chinese get more physical activity and are less overweight than their Western counterparts. This is interesting in that it may help explain the overall differences between Asia and Europe, but I don't think it affects the relationship between wheat or meat and heart disease. I have no reason to believe that rice eaters got more physical activity than wheat eaters or that meat eaters had more physical activities than non meat eaters.

Some notes about comparing CHD rates in China and Europe/US. The statistics in this paper are done in a much different manner than are the CHD statistics available from the British Hearty Foundation, so the numbers in this article and "The Axis of Paradox" are not comparable. Not being a statistician, I'm not really sure how these CHD rates compare to the ones in Europe, but I'll trust Dr. Campbell on this issue that the areas with the highest CHD levels in China are still lower than European levels. One probable reason for that is that the Chinese life expectancy is significantly shorter than the European life expectancy and the leading causes of death in this study were infectious diseases such as tuberculosis. But you have to die of something, so presumably if infectious diseases in China were cured, life expectancy rates would increase and more people would die of heart attacks.

The Chinese in this study died much more frequently of strokes than heart attacks, which is common in Asian countries. In Asia it is considered honorable to die of a stroke but dishonorable to die of a heart attack, so the bias of the doctors when the cause of death is in doubt in to call it a stroke rather than a heart attack. Presumably the bias of Western doctors is the opposite. I have no idea if there is a real difference where Asians have more strokes and Westerners have more heart attacks (I presume there is), but it's interesting food for thought.

Monday, November 21, 2005

Our National Bird?

"You don't get an eagle by merging two turkeys." -- Tom Peters

Perhaps not, but then why would you want to? Turkeys are beautiful, charismatic, inquisitive, delicious birds. Can you say the same thing about the glorified vulture that we call the bald eagle? True enough, turkeys have gained a reputation for stupidity, but anyone who's really gotten to know them knows that that's not the case. Well, not entirely, anyway. In fact, there was a time when turkeys had a shot at taking their rightful place at the table - so to speak - as our national bird. In the words of Benjamin Franklin:

I wish the bald eagle had not been chosen as the representative of our country; he is a bird of bad moral character; like those among men who live by sharping and robbing, he is generally poor, and often very lousy. The turkey is a much more respectable bird, and withal a true original native of America.

And he went on. According to feathersite:

Benjamin Franklin campaigned to make the turkey the national bird in 1784. He described it as "a Bird of Courage" that would not hesitate to attack a Grenadier of the British Guards "who should presume to invade his Farm Yard with a red Coat on," although he conceded that turkeys are "a little vain and silly, but not the worse emblem for that."

Clearly, Benjamin Franklin understood turkeys (or "turkey lurkeys" if you're not into the whole brevity thing). Had the revolutionary war actually been fought in turkey yards across the country, any British Soldier dressed like this?

Doomed. I mean my god, can you imagine?? Buttoned breeches? Long tailed coat? Flintlock musket? This is like a turkey lurk dream buffet. Can you imagine trying to pack your gunpowder and get a shot off, surrounded by a flock of thirty pound turkeys pecking at your gun, your jacket tails, your buttoned breeches, your powder horn. Those beaks are sharp! And if your uniform had any dangly, shiny metal bits, medals for instance? Forgedaboudit. Turkeys can jump, man!! Certainly, without constant vigilance, the turkeys would at least have your buttoned breeches off in no time. And if the turkeys had been in the pig poo again right before you came marching into that turkey yard.... Just doomed.

Which is why I think that anyone who still seriously thinks that the eagle was the best choice for our national bird is seriously deranged.

My turkey story starts like this:

So I'm in Agway one day, looking at, let's say, chicken waterers. And all spring long Agway has been selling a procession of baby chickens and ducks and geese and whatnot. Today in the cage are these funny looking chicks, and so I'm like what kind of chicks are those?

They're turkeys. (Technically that makes them poults. Technically.)

Really? I'll take two.

You should take at least three. They're driving me nuts.

OK, give me three then.

And that was the start of a beautiful relationship. It turns out that poults think that whoever feeds them is their mom. So as soon as they were big enough to live outside of their little cage, wherever I went they would run after me. So cute!! I had planted some red clover and the little turkey lurks, who were maybe four or five weeks old, would spend hours eating the little baby clovers. As they got older they would spend their days hunting for bugs in a little pack. I could always find them by listening to the "choop", "choop" noise that they would call to each other, back and forth, so that they wouldn't lose each other.

If you want to see turkeys hunting, rent Jurassic Park and imagine the velociraptors with feathers, wattles and snoods. Then you'll be able to see the raptors as my three turkeys hunting in their little pack; looking at you in that cock-eyed way; trying to devour anything that moves in front of them. Clearly the animators of that movie spent a lot of time hanging out with turkey lurks. And if you don't buy that, keep in mind that Dr. Grant first describes a velociraptor as a six foot turkey.


And so I guess you can see that I have a thing for turkeys.

Much has been made recently of pasturing chickens as a way of growing meat more sustainably. It is hard to think of ways in which the turkey is not the superior bird for this task. Turkeys range farther and longer than chickens. They eat more greens, they eat more bugs and they eat whole acorns. Which is pretty cool, by the way, I mean the acorn thing. I have a feeling that once turkeys are six weeks old or so, they really only need supplemental feed as a treat if they have enough access to pasture and woodland. My long term goal is to produce a pound of turkey for each pound of whole corn that I feed. And they're pretty easy to herd, so you can move them around the farm in a rotational scheme if you want. Try herding chickens sometime.

Furthermore, turkeys have wide ranging food preferences that can be utilized in different seasons. They'll make good use of quality pasture spring through fall. They have to be the most efficient way of turning the huge midsummer grasshopper crop into quality food. In the fall, they can fatten on acorns, hazelnuts, hickory nuts, wild grapes and what have you. They also love any type of loose clothing or dangling hair, buttons, anything shiny. They will eat your pen if you're writing near them (or at least they'll try) . They go for screwdrivers and ratchets big time, which can really speed up chores around the farm.

One day I was walking in the pasture when I came upon the turkeys eating a small greenish thing. At first I thought they had killed a frog. Then I realized that they were devouring a pile of pig manure. Then they tried to eat my T-shirt. Ewww! We learned to avoid them when they'd been in the poo again. You can smell it on them. Trust me.

Anyway, we'll be raising more turkeys. Did you guess? We're going to raise 20 heritage models next year, probably the old-fashioned bronze (this year I had broad-breasted bronze birds). Long term we'd like to do many more than that. I'd like to try marketing the smaller turkey hens as a roasting bird in late summer or early fall as an alternative to roasting a chicken for a family meal. They should be a reasonable size then - big enough to feed a family but not your massive holiday bird. Currently, most turkey hens in the big commercial operations never make it past poult stage because the males make a larger holiday bird.

So when I sit down to my Thanksgiving day meal this year, I will give thanks for turkey lurks, our rightful national bird. I'll look forward to the heritage birds we'll be raising next year. I'll hear their soft "chew chew" in my head. I miss them already.

Tuesday, November 15, 2005

The Axis of Paradox

We are constantly being told to avoid "artery clogging" saturated fats, found in delicious foods like butter, eggs, cheese, pork and beef. It's for our health, they say. That's a problem for me, since I have a chest freezer full of beef and pork that I raised. I had steak (grassfed) and eggs (free range) for breakfast. But I'm not worried.

Most of you reading this have probably heard of the "French Paradox", which is the idea that it is paradoxical that the French eat a very high fat diet yet suffer from very low levels of heart disease (CHD). Jefferey Steingarten claims to have been the first one to have popularized this idea. But the French paradox is only a paradox if you believe that eating saturated fat plays a role in causing heart disease. I don't.

After the French paradox became widely known, researchers rushed out to explain why the French were so different from the rest of the world. Maybe they were protected from heart disease by the red wine they drank. Maybe it was the fruits and vegetables that they ate. And on and on.

Apparently no one ever actually bothered to check whether or not France was an outlier, a statistical anomaly. Until now. I looked, and it isn't. In fact, in Europe, the countries that eat the most fat from butter, cheese, pork and other animal sources have the lowest rates of heart disease. France is simply the most dramatic example of this. See for yourself:

How did I create this magical chart? Through tricky statistical manipulations? No, I'm not a statistician and I'm too lazy for that anyways. All I did was go to the British Heart Foundation's international statistics page, then got the FAO food disapearance data to see how much animal fat the people of each European country eat on average each day. I popped the two lists of numbers into Excel and got a scatter plot. You can easily replicate my little experiment given an hour or two.

The axis of paradox is composed of all European countries, whose dietary habits and health profiles stand in direct opposition to the idea that heart disease is primarily caused by the high consumption of saturated fat. On average, the people of Eastern Europe eat about 50 grams of fat from animal sources per day while the men suffer from 435 deaths from heart disease per 100,000 people per year. Their Western European contemporaries enjoy eating about 84 grams of animal fat per day while only losing about 170 men per 100,000 to heart disease each year.

If you'd like, you may bash my little study on the grounds that it's unscientific, but that's loser talk. If eating saturated fat is the primary cause of heart disease, how is it possible that French men have one NINTH the rate of heart disease mortality of Russians despite eating 125% more fat from animal sources? How is it possible that the people of Uzbekistan have four and a half times the rate of heart disease mortality of the Swiss despite eating only one fourth the amount of animal fats? Are the Swiss doctors 18 times better? I don't think so. How is it possible that Belgians have less than a fifth the heart disease mortality of the Ukrainians despite eating twice the fat from animal sources. I could go on, but you can see the chart and the following table - the table lists country, daily consumption of animal fat per capita, then heart disease death rate per 100,000 people among males aged 35-74.

Eastern Europe
CountryAnimal Fat ConsCHD Rate
Armenia 26.2 464
Bulgaria 49.5 296
Croatia 36.8 323
Czech Republic 61.3 294
Estonia 56.4 522
Georgia 27.1 507
Hungary 95.7 356
Kazakstan 44.2 703
Krgyzstan 37.1 439
Latvia 61.2 568
Lithuania 58.9 424
Poland 71.2 272
Romania 47.9 336
Russia 47.9 771
Slovakia 66.7 397
Slovenia 67.5 165
Tajikistan 10.7 331
Ukraine 45.1 839
Uzbekistan 25.8 540
Average 49.5 435

Western Europe
Country Animal Fat ConsCHD Rate
Austria 95.3 177
Belgium 88.5 146
Denmark 108.9 174
Finland 89.3 267
France 108.1 83
Germany 82.6 178
Greece 56.2 175
Ireland 81.8 277
Italy 71.7 117
Netherlands 84.2 151
Norway 89.1 183
Portugal 78.8 103
Spain 64.1 120
Sweden 74 185
Switzerland 96.8 120
UK 79.7 215
Average 84.3 167

And just for the record, the US daily consumption of animal fats was 71.6 grams per in 2002, and American men died of heart attacks at a rate of 230 people per 100,000 in 1999, the last years available for both statistics. You may notice that our animal fat consumption is exactly the same as Italy's, where they eat a "low-fat Mediterranean diet" yet our heart attack death rate is almost exactly double theirs. Whoopsie! And if you're wondering, they eat slightly more total fat than us too, 158 grams to 157.

Discussion and Conclusions

Even if you still want to cling idea that eating saturated fat causes heart disease, you have to admit that in Europe the consumption of saturated fat is AT BEST a secondary cause of heart disease. A more direct conclusion would be that saturated fat doesn't cause heart disease there. Keep in mind that although correlation does not imply causation, a lack of correlation casts serious doubts onto causation.

Eastern Europeans suffer from far less heart disease than Western Europeans despite eating far less saturated fat. There is not a single country in Europe in the top quartile of both saturated fat consumption and heart disease rates nor is there a country in the lowest quartile of both. Conversely, France, Belgium, The Netherlands and Switzerland are in the top quartile of saturated fat consumption but in the lowest quartile of heart disease deaths. Armenia, Georgia, Kazakstan, Krgyzstan, Russia, The Ukraine and Uzbekistan are in the lowest quartile of fat consumption but the highest quartile of heart disease.

You may think that it's unfair to compare heart disease rates between Eastern and Western Europe due to different socioeconomic factors in the two areas, but actually that is exactly the point. For too long, heart disease has been considered a "disease of affluence". Google it, you'll see. The idea is that as we become more affluent we get lazy and fat. We can afford more luxury items like steak and cheese. Then we die of heart attacks. This graph shows that that theory is exactly wrong, methinks. Furthermore, although there is no trend amongst Western European countries, among Eastern European countries there is a clear trend that the ones that eat the least animal fat have the most heart attacks.

There is no French Paradox. France follows the general European trend of wealthy countries eating more animal products and having less heart disease. If there is a paradox here, all of the European countries stand together, united and unyielding in the "Axis of Paradox".