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Tuesday, September 19, 2006

Veganism Cures Diabetes?

Originally posted 8-26-2006

A study came out recently touting the benefits of a low-fat vegan diet over the diet promoted by the American Diabetes Association. I love the headline: “Vegan diet best for diabetes” [emphasis added], as if it has been compared to every diet out there. This vegan diet was a plant-based diet, void of animal products, and low in fat and sugar. The ADA diet is a grain-based diet, which allows some animal products (4-6oz per day), some fat (~30% of calories), and some sugar. Food choices on the ADA diet are relatively unrestricted other than sticking to the pyramid. A few other headlines reporting this same study are:
- Vegan diet offers diabetics a carb bonanza (talk about hyperbole)
- Vegan diet reverses diabetes symptoms, study finds
- Vegan diet found to markedly improve health of diabetes patients

The vegan diet study is being promoted by the Physician’s Committee for Responsible Medicine, which some say is a front for PETA. Regardless of whether PCRM is PETA or just has a lot of ties to PETA, if a group with any ties to the beef or pork industry put out a study showing a diet high in beef or pork to be better than any other diet, it would be attacked and scrutinized. However, since it is politically correct to talk about vegetarians and vegans as being the healthiest humans on earth and showing us gluttonous meat-eaters to be on the fast-track to a heart attack, this study raises no eyebrows. Pointing out the ties between PCRM and PETA probably amounts to an ad hominem logical fallacy, but oh well. The point remains that ties to a group with a certain agenda automatically weakens your stance.

So where should we begin? First, the ADA diet is identical to the old Food Guide Pyramid with a focus on carbohydrates, especially processed carbohydrates such as bread, pasta, and other grains. Since diabetes is a disease where the body doesn’t properly process carbohydrates, it seems rather odd to prescribe a diet that is based on carbohydrates, especially one based on high glycemic load carbohydrates such as breads, pastas, and starchy vegetables. The point is that one diet (the vegan diet) is based on low glycemic fruits, vegetables, and whole grains and provides a great load of vitamins and minerals, while the other is based on processed grains, with a small amount of fruits, vegetables, meat, and other vitamin-containing foods.

Participants also said that the vegan diet was easier to follow, which means that compliance was quite likely higher. Considering that the vegan dieters were less likely to eat high-sugar, trans fatty junk foods, it should come as little surprise that these diabetics exhibited better glucose control. However, let’s take a quick look at a result that was glossed over: “43 percent of those on the vegan diet and 26 percent of those on the standard diet were either able to stop taking some of their drugs such as insulin or glucose-control medications, or were able to control their condition with lower doses.” So apparently to be considered a good diet, it doesn’t even need to improve the condition of half of the test population. Let’s consider that again; the vegan diet that is being touted as “best for diabetes” doesn’t even allow 50% of the people following it to lower their medication dosage.

There is no denying that a vegan diet is better than the diet of a great majority of America, in terms of nutrient content and quality of foods consumed. Anytime you eliminate the bulk of processed foods that most people call dinner, you will see a prodigious improvement in health. However, it appears that the study authors and the media are setting up a false dichotomy whereby the two choices are “vegan” or “not vegan” and choosing a poor candidate for “not vegan”. To truly test the effectiveness of the vegan diet, we need to see studies pitting it against a well-designed omnivorous diet based on grass-fed meats, nutrient-dense vegetables and fruits, nuts and seeds, and no sugar. My car is fast if I compare it to a Yugo or even a Honda Civic, but the real test of whether my car is fast is to compare it to a Corvette or some other truly fast car.

Regina Wilshire points out that other markers of glucose control fall short of the National Institutes of Health standards, such as fasting glucose and HbA1c. Both groups had fasting glucose above the diabetic threshold. HbA1c, a marker of glucose control over time that is considered the critical marker of diabetes control, and both groups came in above the 7% standard, denoting “poor glucose control.” Basically, to paraphrase Ms. Wilshire, one diet that produced substandard results is being touted over another diet that produced substandard results. My car sure is fast when compared to a Yugo.

One has to wonder why there was no media blitz when a study of equal length (22 months) showed even greater improvements from a low-carbohydrate diet. Subjects following a 20% carbohydrate diet had HbA1c of 6.6%, 7.0%, and 6.9% at 6, 12, and 22 months, respectively. All three readings are within the standard of glucose control, yet we heard nothing of this study. Even more interesting, seven of the subjects in the low-fat group saw the results that the low-carb group was achieving and switched to the low-carb diet! The ADA says that they won’t promote the low-carb diet because “patients find it restrictive,” yet they readily acknowledge that the diet helps patients control their blood glucose. So the ADA is making decisions that should best be left to the patient, that of what lifestyle one finds most beneficial. While some would certainly prefer to take drugs over changing their lifestyle, there are surely some diabetics motivated enough be the promise of health to follow a low-carb diet, were it offered as an option by their doctors.

We can also examine the drawbacks of a strict vegan diet. Because of shunning all animal products, the vegan diet is markedly void of certain vitamins and minerals only found in meat, such as vitamin B12, conjugated linoleic acid, and long-chain omega-3 fatty acids. B12 deficiency is linked to Alzheimer’s and nervous system disorders. The low-fat and low-protein nature of the diet means that vitamins A, D, E, and K, the fat-soluble vitamins, are poorly absorbed. Further, vitamin D intake is necessary for uptake of calcium, phosphorus, and magnesium. Vegan literature will tell you that protein needs can be met from vegetable sources, such as soy, but those have their own issues, from poor protein quality to numerous antinutrients. Also, many people turn to flax seeds and oil to increase their omega-3 intake, but the omega-3 fatty acids in flax are short-chain acids which must be converted to long-chain acids, a process which is highly inefficient, converting generally less than 5% of the alpha-linolenic acid (ALA) to the long-chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Basically, yet again, the evidence doesn’t support what is commonly shown to be “the way to health.” The ADA refuses to provide its patients with the materials that they can use to decide what avenues they should pursue to regain their health. The ADA continues to promote a diet based on carbohydrates for people that cannot effectively process carbohydrates, while promoting a low fat and protein intake, the two nutrients that slow the rate of absorption of carbohydrates. And once again, we’re told how great a vegan or vegetarian diet is for us, when studies show a low-carb, meat-eating diet to produce even better results. I’m off to find a Yugo to race.