If you're a strict vegetarian or vegan, you want to make sure you're getting enough vitamin B-12. The reason is vitamin B-12 comes mainly from animal food sources including fish, meat, eggs, and dairy products. If you're a strict vegetarian or vegan and are experiencing symptoms like low energy, brittle nails, brittle hair, depression, chronic fatigue, these are all signs of a vitamin B-12 deficiency. So, you want to make sure you get your vitamin B-12 serum levels checked regularly, and you may need to take a vitamin B-12 supplement. Another good vitamin for strict vegetarians or vegans is vitamin D. The only food source that you can get vitamin D from are fatty fish, cod liver oil, and eggs. So, for strict vegetarians and vegans, taking a vitamin D supplement can be a really good idea.