Metabolic Effects of a Traditional Asian High-carbohydrate Diet

A recent study supports the notion that an 'ancestral diet' focused around high-starch agricultural foods can cultivate leanness and metabolic health.

John McDougall gave Christopher Gardner a hard time at the McDougall Advanced Study Weekend.  Dr. Gardner conducts high-profile randomized controlled trials (RCTs) at Stanford to compare the effectiveness of a variety of diets for weight loss, cardiovascular and metabolic health.  The "A to Z Study", in which Atkins, Zone, Ornish, and LEARN diets were pitted against one another for one year, is one of his best-known trials (1).

Dr. McDougall asked a simple question: why haven't these trials evaluated the diet that has sustained the large majority of the world's population for the last several thousand years?  This is an agriculturalist or horticulturalist diet based around starchy foods such as grains, tubers, legumes, and plantains, and containing little fat or animal foods.  Researchers have studied a number of cultures eating this way, and have usually found them to be lean, with good cardiovascular and metabolic health.  Why not devote resources to studying this time-tested ancestral diet?  I think it's a fair question.

Read more »

Buckwheat Crepes Revisited

One of my most popular posts of all time was a recipe I published in 2010 for sourdough buckwheat crepes (1).  I developed this recipe to provide an easy, nutritious, and gluten-free alternative to flour-based crepes.  It requires no equipment besides a blender.  It's totally different from the traditional buckwheat crepes that are eaten in Brittany, in part because it's not really a crepe (I don't know what else to call it, maybe a savory pancake?).  I find these very satisfying, and they're incredibly easy to make.  They're especially delicious with fresh goat cheese, or scrambled eggs with vegetables, but they go with almost anything.  Chris Kresser also developed his own version of the recipe, which is fluffier than mine, and more like a traditional pancake (2).

Buckwheat is an exceptionally nutritious pseudograin that's rich in complete protein and minerals.  In contrast to most whole grains, which have low mineral availability due to phytic acid, buckwheat contains a high level of the phytic acid-degrading enzyme phytase.  This makes buckwheat an excellent source of easily absorbed minerals, as long as you prepare it correctly!  Phytase enzyme works best in an acidic environment, which may be part of the reason why so many cultures use sour fermentation to prepare grain foods.  My original recipe included a sour fermentation step.

But there's a problem here.  Buckwheat doesn't ferment very well.  Whether it's because it doesn't contain the right carbohydrates, or the right bacteria, I don't know, but it spoils rapidly if you ferment it more than a little bit (using a strong sourdough starter helps though).  Others have told me the same.  So here's my confession: I stopped fermenting my buckwheat batter about a year ago.  And it tastes better.

Read more »

Celiac and Fat-Soluble Vitamins

One of the things I've been thinking about lately is the possibility that intestinal damage due to gluten grains (primarily wheat) contributes to the diseases of civilization by inhibiting the absorption of fat-soluble vitamins. If it were a contributing factor, we would expect to see a higher incidence of the common chronic diseases in newly-diagnosed celiac patients, who are often deficient in fat-soluble vitamins. We might also see a resolution of chronic disease in celiac patients who have been adhering faithfully to a long-term, gluten-free diet.

One thing that definitely associates with celiac disease is bone and tooth problems. Celiac patients often present with osteoporosis, osteopenia (thin bones), cavities or tooth enamel abnormalities (thanks Peter).

An Italian study showed that among 642 heart transplant candidates, 1.9% had anti-endomyosal antibodies (a feature of celiac), compared with 0.35% of controls. That's more than a 5-fold enrichment! The majority of those patients were presumably unaware of their celiac disease, so they were not eating a gluten-free diet.

Interestingly, celiac doesn't seem to cause obesity; to the contrary. That's one facet of modern health problems that it definitely does not cause.

The relationship between cancer and celiac disease is very interesting. The largest study I came across was conducted in Sweden using retrospective data from 12,000 celiac patients. They found that adult celiac patients have a higher overall risk of cancer, but that the extra risk disappears with age. The drop in cancer incidence may reflect dropping gluten following a celiac diagnosis. Here's another study showing that the elevated cancer risk occurs mostly in the first year after diagnosis, suggesting that eliminating gluten solves the problem. Interestingly, celiac patients have a greatly elevated risk of lymphoma, but a lower risk of breast cancer.

There's a very strong link between celiac and type I diabetes. In a large study, 1 in 8 type I diabetic children had celiac disease. This doesn't necessarily tell us much since celiac and type I diabetes are both autoimmune disorders.

One last study to add a nail to the coffin. Up to this point, all the studies I've mentioned have been purely observational, not able to establish a causal relationship. I came across a small study recently which examined the effect of a high-fiber diet on vitamin D metabolism in healthy (presumably non-celiac) adults. They broke the cohort up into two groups, and fed one group 20g of bran in addition to their normal diet. The other group got nothing extra. The bran-fed group had a vitamin D elimination half-life of 19.5 days, compared to 27.5 for the control group. In other words, for whatever reason, the group eating extra bran was burning through their vitamin D reserves 30% faster than the control group.

Unfortunately, the paper doesn't say what kind of bran it was, but it was probably wheat or oat (**Update- it's wheat bran**). This is important because it would determine if gluten was involved. Either way, it shows that something in grains can interfere with fat-soluble vitamin status, which is consistent with the staggering negative effect of refined wheat products on healthy non-industrialized cultures.

Add to this the possibility that many people may have some degree of gluten sensitivity, and you start to see a big problem. All together, the data are consistent with gluten grains interfering with fat-soluble vitamin status in a subset of people. As I discussed earlier, this could contribute to the diseases of civilization. These data don't prove anything conclusively, but I do find them thought-provoking.

Thanks to Dudua for the CC photo