veganism: some don't eat good things so they lack calcium,protein and iron.|||Veganism may or may not have a negative impact on health. It depends on how the diet is planned, and what foods are eaten in what quantities, the same as any other diet. There will be people who eat better and worse vegan diets, and a few might struggle. But the scientific data so far says that vegan diets, well planned, appear to appropriate at any stage of life, and can actually have significant health benefits over conventional ones.|||If the diet is balanced there really should be no problems Vegans do have to be careful with vitamin B12 because this is only found naturally in animal products - meat, eggs, milk B12 deficincy can lead to anemia and nervous system damage However it is only needed in very small amounts and as long as they are getting plenty of the fortified foods (where the B12 is made from bacteria)- fortified soya milks, cereals, marmite etc then there really should be no problem at all Vegan society has some info:http://www.vegansociety.com/food/nutriti鈥?/a>|||A proper vegan diet has no negative impact on health. A diet lacking in sufficient nutrients and minerals will affect the body in many ways; whether the diet is vegan, vegetarian, or omnivorous.|||There aren't any, as long as you eat a BALANCED DIET and get all of your nutrients. There isn't anything in milk or meat that you can't find in vegan food. Except blood and high concentrations of fat and cholesterol.