[mikekchar]

I ate a vegan diet for many years. Zinc was one of the things I was very conscious of (I tracked my diet fairly carefully). One of the things I noticed was that if I ate a traditional (i.e. from a culture that ate that way historically) vegan diet, that getting the nutrients I needed was not nearly as difficult. I think a lot of people simply cut out animal products from a traditional meat based diet and end up with problems. Potato chips are usually vegan, but a diet consisting of only potato chips is not healthy ;-)

My own personal take on this kind of thing is that there traditional diets where people have eaten a certain way for hundreds of years. While we may not have good studies on these diets, there is a kind of evolutionary effect. As people get a lot more choice in how they eat, we're running into problems where people think they can design a healthy diet. Sometimes they get it quite wrong.

I've also spent a good part of my free time over the last 20 years reading papers on nutrition. Another big thing that I notice is that a huge proportion of these papers are terrible - poor sampling techniques, inadequate reporting of conditions, insanely small trial sizes (sometime less than 10 people!!!), statistics that are plain wrong, etc. People with particular agendas often push their point of view, backing up impressive arguments with mountains of really poor research. It is hard/impossible for the average person to adequately judge the validity of the arguments and they end up making poor dietary choices as a result. Even with the amount of time I spend, I have no idea if my current biases are reasonable or not.

Diet is hard :-( Usually I suggest that people pick a traditional diet that appeals to them, study it carefully and try to adopt it. Then they should track their health carefully and make sure to get frequent health checks.