User Post: Vegans, vegetarians, diets and health

I've stated in my short bio here that I've been a lifetime vegetarian, and many assume that vegetarianism is part of my "healthy lifestyle" philosophy. Well, it is and it isn't.

Let's start with a few common definitions--these definitions of course fall short of describing the full range of dietary practices of those who restrict animal products from their plate, and there are many variations not covered by these rather simplistic definitions.

Vegetarians exclude meat and fish from their diet but do eat dairy and eggs. Vegans exclude all animal products, including meat, fish, dairy and eggs. The terms "vegetarian" and "vegan" are not interchangeable from the nutritional science point of view; the two diets are quite dissimilar.

Vegetarians and vegans choose to abstain from animal products for a variety of diverse reasons, ranging from health advantages and environmental priorities, to ethical and cultural considerations. Vegetarians and vegans tend to consume more fruits, vegetables and whole grains than their meat- and fish-eating friends (although that's not always the case, and there are junk eaters among them too).

The American Journal of Clinical Nutrition is publishing a plethora of papers on vegetarian, vegan and plant-based diets and their effects on health as part of an upcoming supplement, so it's a good time to take a look at the latest research.

A paper by Professor of Nutrition Winston J Craig, summarizes the current knowledge of vegan diets and offers some practical dietary recommendation for vegans:

• Statistics: Vegans comprise 1.4 percent of the American population (by a Harris Interactive poll), and their numbers are growing.

• Cardiovascular disease: Vegans are thinner, have lower total LDL cholesterol (the "bad" cholesterol), and modestly lower blood pressure. In general, both vegetarians and vegans have a lower risk of cardiovascular disease.

• Cancer: Although some studies suggest that a vegan diet is associated with lower risk of several cancers, this article sums it up in:

• Bone health: Vegans typically fall short of recommended suggested daily intake of calcium (calcium sources for vegans are green leafy vegetables, tofu, tahini, etc., none of which is as abundant as dairy products), and some studies show that bone-mineral density in long term vegans is lower. On the other hand, for those vegans who do consume adequate calcium and have enough vitamin D, bone fracture rates are the same as for omnivores.

• Iron: Contrary to common belief, the risk of iron-deficiency anemia is no larger for vegans than it is for omnivores, and vegans' hemoglobin levels aren't any lower.

• Vitamin B12: This vitamin is present only in animal products, and is therefore lacking in an un-supplemented vegan diet. Vegans do have a higher prevalence of B12 deficiency, and vitamin B12 needs to be added to their diet regularly in fortified foods or supplements.

Craig calls for further research to study the effects of a vegan diet on diabetes, cancer and other chronic diseases, and concludes that on the basis of our current knowledge, a vegan diet has no significant advantage over a vegetarian one regarding chronic diseases.

I for one don't think the evidence is really there to convince a meat lover to change his habits for health reasons-although the evidence to support a diet rich in fruits and veggies and whole grains is convincing, there isn't great proof that consuming quality meat in moderation is harmful, and eating quality fish is healthy.

Sure, there are studies that show a correlation between vegetarian and vegan lifestyles and lower incidence of several chronic diseases, but the evidence is far from conclusive, and there are many confounders in the study of a self-selected group, such as vegetarians and vegans.

I believe that most traditional diets, based on mostly plant food have proven themselves over time to be healthful. Indeed, people can thrive on many different diet regimens. The one diet that's proving to be detrimental to health is our current Western diet of highly processed foods, fast foods and junk.

One hallmark of the American diet is very high consumption of animal products and especially meat (about half a pound of meat a day ). What's even worse is that most of those animal products come from animals raised in feedlots on a diet that's unnatural to them (grains and even animal by-products, instead of grass, in the case of cows) and regimens of antibiotics and hormones.

So what's my story?

My dad turned vegetarian when, as a kid, he saw a chicken slaughtered. When I was a teeny toddler my dad told me where meat comes from. He also told me that almost everyone eats meat, but he thinks animals do have a desire to live, show attachment to their young and do experience suffering.

I was convinced, and never tasted meat. I am concerned about animal welfare, and I think cruelty to animals-expressed in the extreme in feedlots and industrial slaughterhouses-has reached a point in which most people would be appalled if they actually saw where their meat comes from.

I admit it…for me it's easy. I have no desire to eat meat and don't even think of it as food, because I don't have a habit of eating it.

This is my anecdotal proof that what you feed your kids when they're young has a profound impact on their eating habits. I haven't gone any further than my dad did with animal welfare. I do eat cheese and eggs. I'll try to buy from producers that raise their animals in a humane and sustainable way, but I do realize that it's very difficult to give up foods you enjoy, were raised on and are part of your tradition. I don't think I'd likely give up dairy completely, even if there were evidence that abstaining from it might benefit my health somewhat. After all, there's risk everywhere; avoiding risk to the point of not enjoying yourself is risky too.

Every diet is characterized by what foods are eaten, not only by what's excluded. At this point I think there're plenty of reasons for everyone to eat more fruits and veggie-like the vegans do; it may turn out that the health benefits seen in vegans and vegetarians have more to do with what they eat, and not what they exclude.

There's much more to talk about concerning vegetarian and vegan lifestyles, and I haven't even touched on the environmental reasons against meat production , which are pretty compelling. But that's another post.

In the meantime I welcome your perspectives.

Dr. Ayala

Read more from Dr. Ayala at http://herbalwater.typepad.com/

Follow Dr. Ayala on Twitter