Not a diet. Veganism is a belief system. Countries don't tend to agree on much but plant based diets (assuming you meant that) is heavily studied and proven to be fine. These national organizations all agree (including for pregnant and "all life stages"): 1. Academy of Nutrition and Dietetics and Dietitians of Canada 2. Australian National Health and Medical Research Council 3. British Dietetic Association 4. British National Health Service 5. German Society for Nutrition ...and more