Month: December 2010

Hot Off the Press: A New “China Study” Links Wheat with Weight Gain

You’re going to hate me. This isn’t the wheat post, which means I’ve broken my “wheat is next” promise for the 80th time and should never be trusted with anything again ever. But during my nightly Pub(Med) crawl, I saw this nearly-new gem of a study glimmering in the dust and said to myself, “Wow. Wow! Wow.” By the third wow, a blog post was inevitable. So here it is. I promise this is truly interesting (not that me promising things matters anymore).

But first, some background.

A few years ago, a study hit the stands with the audacious title Vegetable-rich food pattern is related to obesity in China. The paper showed that among four diet patterns—“macho” (meat and alcohol), “sweet tooth” (sugary drinks and cake), “traditional” (rice, vegetables, pork, and fish), and “vegetable-rich” (vegetables, wheat, whole grains, and fruit)—only one had any relationship to obesity: the vegetable-rich pattern.

The study didn’t exactly receive a lot of press, probably because no one wants to think vegetables make people fat (including the researchers, who hummed and hawed their way to a half-baked conclusion—check out this post by Michael Eades). And as Stephan Guyenet explained, the study really showed a trend between wheat intake and weight gain, with the pounds rising as wheat replaced rice as a staple.

I mention this because the new study is actually a follow-up to the old one. It tracked changes in the participants’ weight over the span of five years, using the same method of divvying up food consumption into distinct diet patterns. In fact, here’s the table with their “factor loading” system, showing how various foods were weighted to determine adherence to each diet pattern. (Go ahead, click on it. You know you want to.)

I’m going to explain this study point-by-point before getting to the good stuff, because it’s a little complicated (but totally worth understanding).

Note that only two patterns use wheat as a factor: the “traditional” and “vegetable-rich” diets. The traditional pattern loaded inversely on wheat flour and positively on rice, whereas the vegetable-rich pattern loaded inversely on rice and positively on wheat. In simpler terms, that means the “traditional” pattern is rice based and the “vegetable-rich” pattern is wheat based. These two patterns are polar opposites in terms of their staple grain. The “macho” and “sweet tooth” patterns don’t take grain consumption into account.

After the researchers schemed up these diet patterns, they divided everyone into quartiles of adherence. Folks in the first quartile of any pattern had the lowest adherence to it, whereas folks in the fourth quartile ate diets most in line with that particular pattern. The paper only gives a detailed breakdown of the “traditional” diet quartiles and smaller summaries of the other three, but you can still see how food intake changes from quartile to quartile:

From the paper:

A clear increasing trend of the intake of fat was seen across quartiles of the ‘traditional’ pattern from low to high. Participants in the first quartile of this pattern had the highest intake of wheat flour and dietary fibre compared with the other groups. … There was a significant negative association between the ‘traditional’ pattern and energy density.

Darn right. The first quartile boasts an average wheat intake of 298 grams per day, versus only 21 grams in the fourth quartile. And fat intake rises from 75 to 87 grams per day from the first to fourth quartile. Energy density (calories per gram of food) also drops, although the researchers don’t mention that total energy intake (calories) is actually highest in the fourth quartile.

The researchers also note that “across quartiles of the ‘vegetable-rich’ pattern, the intake of energy, wheat flour and vegetable oil increased.” Most of that info didn’t make it into any tables, so we’ll just have to take their word for it.

Now here’s where it gets interesting.

The following table shows the five-year weight change for the different quartiles of each diet pattern. Remember that the “traditional” and “vegetable-rich” diets are the only ones defined—at least in part—by wheat consumption (or lack thereof). (A) is the traditional pattern, (B) is the macho pattern, (C) is the sweet-tooth pattern, and (D) is the vegetable-rich pattern.

What stands out here? How about this:

After adjustment for age, sex and baseline weight, the ‘traditional’ dietary pattern was inversely associated with weight gain, while the ‘vegetable-rich’ pattern was positively associated with weight gain. … No significant associations of the ‘macho’ and ‘sweet tooth’ patterns with weight gain were found.

What interests me is that the largest change in weight out of any of the graphs—1.4 kilograms—occurs between the first and second quartile in the “traditional” pattern. This corresponds with a drop in average wheat intake from 298 to 40 grams per day. (Without knowing the actual per-quartile numbers for the “vegetable-rich” pattern, it’s impossible to say how changes in wheat consumption match up with that graph, although the researchers already stated that wheat consumption rises throughout the quartiles.)

The inverse relationship between the “traditional” pattern and weight (and therefore wheat and weight) doesn’t seem to be confounded by other factors, either:

In the stratified multivariate analyses, an inverse association between the ‘traditional’ dietary pattern and weight gain was present in subjects aged < 40 years and ≥ 40 years, in non-smokers and smokers, in overweight and normal-weight subjects, in alcohol drinkers and non-drinkers, and in men and women. There were no significant interactions between any of the above factors and the ‘traditional’ dietary pattern with weight gain.

The connection between wheat and weight was so prominent in this study that the researchers (who carefully tiptoed around the subject in their 2008 writeup) couldn’t beat around the bush any longer. They slammed the “discussion” section with a giant wall of wheat text. Since I’m not sure how long the study will be available for free, I’ll quote the relevant parts right here (interspersed with some commentary):

A large difference in the intake of rice and wheat flour was found across quartiles of the ‘traditional’ dietary pattern. It represented two different sub-patterns with two different staple foods in inverse proportions, i.e. rice and wheat.

(No quibbles there. But the next part is where they try painfully hard to rationalize the wheat-weight connection.)

Rice is a low-energy food that contributes to the bulk of the traditional diet. Compared with wheat, rice absorbs more water when cooked. In addition, different cooking methods are used in preparing these two staple foods. For instance, steamed rice contains twice the amount of water and half of the energy compared with steamed bread(17). Thus, the energy density of the rice staple diet is usually lower than the one based on wheat.

(Regardless of energy density, the fourth quartile for both diet patterns show that the rice-based pattern had a higher average calorie intake than the wheat-based pattern, yet lower five-year weight gain—0.0 kilograms versus 1.6 kilograms.)

Since the content of wheat was only predominant in the first quartile of this dietary pattern, this may partly explain the negative association between the ‘traditional’ pattern and weight gain in the present study.

(Ding, ding, ding. But is it because wheat has lower water content, as they suggest, or does our favorite grain somehow wreak metabolic havoc? The weight changes in the “traditional” pattern echo wheat consumption more consistently than total energy intake.)

Also, this association could not be explained by fat intake, since a higher intake of the ‘traditional’ pattern was associated with a higher intake of fat. Intake of fibre was the highest among people in the first quartile of the ‘traditional’ pattern. Thus, the benefit of weight maintenance of the traditional dietary pattern was not related to dietary fibre.

(Blasphemy! How did such nonsense pass peer-review?)

The reason I find this so fascinating is that it perfectly corresponds with the patterns in the Oxford-Cornell China Study, which showed that wheat was the single biggest contributor to BMI out of any diet variable. Calories didn’t matter. Fat didn’t matter. Weight followed the wheat.

I recommend reading the full study before the Powers That Be shove it behind a pay wall (or before the wheat industry files a lawsuit). And I’d say my real wheat/heart disease post is coming up next, but I don’t want to jinx myself. It’s on the way, though. I promise (?).


An “I Promise I’m Not Dead” Update

As much as I hate posting entries that aren’t twelve pages long and jazzed up with graphs, I’m becoming plagued with blog-related nightmares about my chronic lack of updates—so here’s a peek at what to expect really soon. All may seem calm on the Raw Food SOS front, but three things are brewing behind the recent curtain of silence:

1. The “is wheat going to give you a heart attack?” post. I’m sure my delay-apologies are bordering on parody at this point, but here’s another one anyway: Sorry it’s taking so long! I’ve been trying to get in touch with some researchers who’ve done relevant wheat/gluten/WGA work, but it seems many of them take even longer to respond to emails than I do. (I have tasted my own medicine, and it is bitter.) Nonetheless, expect to see this sucker finally up by next weekend—I’ll post whatever I’ve finished, even if it needs to become a two-parter.

2. A ridiculously huge review of every single vegan study in existence (or close to it). Even though some prominent vegan nutritionists concede that “no one has shown that you must eat a 100 percent plant diet in order to be healthy,” the vegan-versus-omnivore debate is probably never going to die. (Which is kind of a good thing—what else would we have to argue about?) So I’m compiling an analysis of all the current vegan research, including reviews of study design and evaluations of how well confounders were accounted for. I think this is a worthwhile project because:

  • As Harriet Hall of Science-Based Medicine recently pointed out, some of the oft-cited studies supporting veganism for disease reversal are either uncontrolled (like Esselstyn) or tangled up with variables like exercise and stress reduction (like Ornish). And other studies sometimes credit veganism for health improvements despite having eliminated more than just animal foods—such as this one that concludes a “vegan diet had beneficial effects on fibromyalgia symptoms,” even though the diet in question was also devoid of grains, sugar, seed oils, and processed fare.
  • I want to see whether most vegan research is really looking at the effects of diet or if it’s reflecting other (unadjusted for) health behaviors. For instance, a recent Polish study took a hard look at the lifestyle differences between vegans, vegetarians, and omnivores, and the (not surprising) conclusion was that meat-avoiders “present a higher level of caring about their health” than standard omnivores—a reality that makes it difficult to separate the effects of diet versus other pro-health behaviors in research focused on vegans or vegetarians. According to this study, 75% of vegans abstain from alcohol (versus 8% of those on a traditional diet), and only 6% of vegans use tobacco products (versus 33% for standard omnis). Vegans and vegetarians are also significantly more likely to exercise and engage in other health-promoting behaviors than typical meat eaters—resulting in a multifaceted lifestyle shift that’s hard, if not impossible, to account for in diet studies.
  • This one’s my main impetus for this endeavor. As proof of the healthfulness of veganism, many folks are citing the opening paragraph of the conservative American Dietetic Association‘s most recent vegetarian position paper, which says:

It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes.

That sounds pretty great. But if you trudge beyond the first paragraph and actually read the whole paper (available for download here), you’ll find a less-than-glowing description of the vegan literature—including sections indicating that vegans have higher homocysteine levels, lower DHA in their breast milk, more  frequent bone fractures, higher rates of vitamin D and iodine deficiency, and pregnancies that haven’t been studied enough to draw any conclusions. I already have some other issues with the ADA, but I probably don’t need to explain how I feel when data and the conclusions drawn from it don’t match up.

3. Top Secret China-Study-Related Mystery Thing: I’d love to spill the beans on this one, but they’re not done soaking and I’d hate to flood you guys with lectins. So for now, I’ll just say that I’m working on a thing with a person, and the person and I have the goal of getting the thing published in a well-known other thing, and if all goes as planned, the published thing should help combat the “but the China Study re-analysis isn’t peer reviewed!” argument. As soon as I can say more about the thing, you’ll be the first to know.

Last but not least, Mercola has a brand new interview up with the original China Study obliterator Chris Masterjohn—and it’s a must-listen for anyone still following “The China Study” debacle. Chris does a stellar job of explaining the most important gaps and distortions in Campbell’s best-selling book, including the problems with his casein research. If you had trouble trudging through my shamelessly verbose critique or didn’t have time to read articles addressing other misleading parts of “The China Study,” this interview will get you caught up to speed. (One warning: The date on Mercola’s article is December 11, 2010—currently six days into the future. Will linking to it right now destabilize the universe? I guess we’ll find out.)

More coming soon!