[odshoifsdhfs]

From memory, protein, B12 vitamin and iron. Again all these can be avoided with a good understanding of what you are eating while on a vegan diet (buying fortified foods to get B12 for example, or mixing protein sources).

The other thing which I believe (but no idea if scientifically true) is that different people (due to genetics or whatnot) respond to diets a bit differently. A high carb diet for me is a no-no. I get joint pains, tired all the time, break up in acne all over my scalp (and no, I don't eat grains. I eat rice or pasta maybe once a month, most/all is from veggies and fruit). If I go over 100-150g of carbs I have these effects.

My ex-wife had issues with a high protein diet that exarcebated her anxiety and panic attacks.