I have been adding studies on a vegan diet’s effect on common diseases to my disease postings, and found I was rejecting some, and I want to talk a little about why, because I think it gets to the heart of why we are so confused about diet. Many of these ideas I was introduced to in The China Study, by Dr. T. Colin Campbell. I’m just a reader, not a doctor.
Reason number one for rejecting a study is that they lump vegetarians all together. To outsiders, we may all seem the same, but the diet of a regular lacto-ovo vegetarian is usually quite cheesy and eggy. Just take a look at any commercial specialty vegetarian products or the vegetarian menu in a typical restaurant – unless they’re going out of their way to be vegan, it will have cheese in it just as a matter of habit. A study that just asks people, “Do you eat meat?” is not getting to the heart of the problem. The study really needs to look at overall animal product consumption, and any macro-nutrients such as saturated fat need to be broken into plant and animal sources. Even independent of animal product intake, different types of vegetarians can have vastly different diets that I would expect to have an impact on disease as well. A vegetarian eating lots of refined grains, french fries, soda, cookies and cakes, etc., is going to have different health from someone who is eating whole grains and lots of fruits and vegetables. Even whole grains don’t really have many antioxidants – eat your veggies! I’d still be interested to know what the impact of less animal products is, but a study that combines us is ignoring the very large protective effect of the healthy foods that a good vegan or semi-vegan diet is based on. A study that lumps us together and concludes that eating less meat doesn’t improve health much (ignoring what is eaten more of), is not that helpful. What we really need to see is what is the effect of eating less animal products (down to zero) and, independently, what is the effect of eating more whole grains, fruits and veggies (from zero up to lots).
Even if a study with this problem does find an improvement for vegetarians, it just isn’t what I’m looking for. I think we all know that eating less meat and eating more plants is good for our health. I don’t need to waste your or my time repeating that. I am interested in studies that show what happens when you reduce total animal products towards zero.
This brings me to the second type of study I’m not interested in. Studies like the famous Nurse’s Study, referenced ubiquitously as the gold standard of nutritional studies, and yet not very helpful because it compares women who eat way too much meat to women who eat way, way, way too much meat. Their average protein intake is 19% of calories, compared with the U.S. average of 15-16% and the U.S. RDA of 9-10% [p.274]. More importantly, 78-86% of the nurses’ high level of protein comes from animals, compared to 70% for the U.S. (and 10% in China); even those nurses eating the lowest amount of total protein get 79% of it from animals[*]. It is not particularly surprising if not much benefit is to be had by merely eating poorly instead of very poorly, so I don’t put much stock in studies based on nurse’s data (or similar poor western diets) that draw conclusions that cutting back on meat doesn’t reduce risk of this or that disease. I don’t want to indulge in circular reasoning, but if these studies don’t show improvement with eating less meat and more plants, which I believe is fairly well established, perhaps instead of disproving any correlation, they just prove that once you’re eating that poorly, you might as well go all out. What would be more useful would be to put a random group of those nurses on a diet with much lower animal product intake.
I’m also not particularly interested in studies that follow one particular food, such as soy (or even worse, a micro-nutrient such as selenium) against one particular disease. I don’t want to live the kind of life where I am constantly trying to remember the chemical components of the individual whole foods I eat. I’m vegan for ethical reasons, so I eliminate animal products based on that; other than that, I just go for a variety. If you read my blog a lot, you know I do not spend time in postings telling you how this meal is really high in calcium or folic acid or something. I just find that confusing and boring. I stick with the level of food groups over the course of the day – did I get in my legumes today? How many servings of veggies did I work in? I’m aware of the foods that are higher in calcium, and I make a point to choose them, and I eat lots of greens because they’re super healthy (and I like them), but that’s about it. I guess I see those types of nutrient-disease studies as looking for a shortcut. “Let’s isolate a chemical in this plant that prevents this disease,” they seem to say, “and then we can put it in a pill or powder so people can continue to eat junk, but they’ll die of some other preventable disease instead of this one.” I just don’t see the point and I’d rather think about something else.
I’d like to take a moment here to express another point that Dr. Campbell made in his book. I couldn’t find it in the index, but he said something to the effect that there could be 19 studies showing that a certain diet reduces disease, but if there is one study that shows no correlation, the whole issue is often called “controversial.” It’s not that that one study said the diet increased disease, just that it seemed to have no effect. I think a reasonable person would feel that one study was suspect, and that probably the 19 studies were right, but labeling it controversial, while not entirely truthful, is helpful to someone with an agenda. Sometimes the agenda is business, and sometimes it is just keeping the status quo. So that is another thing to look out for when you’re looking into diet and disease.
Speaking of agendas, we have to be careful not to throw out the truth with any perceived bias. I hope that readers will not dismiss my words just because I would like everyone to be vegan. That would be an ad hominem fallacy. Ignore who I am, and just look at what I say. Is it the truth?