When President Clinton went (almost) vegan several months ago, my reaction to the news wasn’t quite as enthusiastic as it might have been. Seeing high-profile people (or anyone for that matter) go vegan for health reasons makes me nervous. First, President Clinton referred to his diet as “strict,” which is not an especially enticing word when it comes to food choices. He also suggested that it was an “experiment,” noting that 82 percent of those who go on low-fat almost-vegan diets see their heart disease reverse. The implication was that, if he turns out to be among the 18 percent who aren’t so lucky, the experiment will be over. That is, his diet is a treatment, not a commitment to an animal-free lifestyle.  
For the record, I expect that President Clinton will see benefits because he’s lost so much weight, and this alone has a powerful effect on heart disease risk. But despite that, I think the health argument fails veganism and animals for several reasons.   
~People who adopt vegan diets for health reasons never seem to be satisfied with just being vegan. They’re inclined to pile on more restrictions like no added oils or no cooked foods, or only whole plant foods, or even no nuts and seeds. If any of those restrictions had actual benefits, it would be one thing of course. But they don’t, and they can actually work against good health for vegans.
I’d love to know where the evidence is that vegans who eat only whole foods are healthier than those who consume some fortified orange juice, calcium-set tofu, olive oil and a little Coconut Bliss now and then. I’ve certainly never seen any. I think people who adopt more restrictive forms of veganism are more likely to run into health problems, not less. For example, the World Health Organization (WHO) advises women to eat a diet that provides at least 15 percent fat—yet some vegan women strive for 10 percent fat or less by shunning all added fats and limiting other high-fat foods.
Researchers with the WHO are also taking a new look at protein needs—and some believe that these needs may be higher than previously believed. That’s not a big deal for the average omnivore, and probably not for the average vegan, either. But for those vegans who eat a raw foods diet or a super-low-fat diet that minimizes higher-protein foods, it could be.
~The ethical argument for veganism pertains to everyone, but health arguments target a very specific population. In a trailer for the book The Engine 2 Diet, one person who went through “the program,” is no longer on it, because “she doesn’t need to be.” That is—like many omnivores—she is in good health and sees absolutely no reason why she should be vegan.
~The health argument is not foolproof. Per my comments about President Clinton above, if people don’t get the intended benefit—reduced cholesterol or weight loss—they don’t have much reason to stick with a vegan diet. In contrast, the ethical argument for veganism always delivers on its promise. It is always the most compassionate choice and it always promotes an ethic of justice for animals.
~The health argument isn’t unique. People who are focused only on the health aspects of a vegan diet are more likely to be enticed by other dietary philosophies that make promises about improved health. For ethical vegans, there is no comparable or alternative way of eating and living.
The counter-argument to all of this, of course, is that getting people to go vegan for any reason is a good thing. It reduces animal use and it helps shift paradigms about food choices—which can eventually open minds to the issue of animal liberation. I’m in favor of most efforts and campaigns that do those things. But here is the problem with using the health argument in this way—it’s that there isn’t any health argument for veganism.
There is, of course, a pretty good argument for eating more plants (lots more plants) and less animal food, but no one has shown that you must eat a 100 percent plant diet in order to be healthy. So to make an argument for a 100% vegan diet based on health benefits alone, we have no choice but to stretch the truth. We have to overstate the benefits of vegan diets, and sometimes minimize or dismiss the risks. And as soon as we stray from the actual facts, our advocacy is on shaky ground.
There is a reason why I recommend only a handful of resources on vegan nutrition, such as  Vegan Health, and the Vegetarian Resource Group. It’s because these are reliable resources that never overstate the benefits of veganism or ignore potential pitfalls. And guess what? They come from health professionals who are ethical vegans.