Your body need vitamins for a variety of human organism functions. Vitamins are a substance essential in very small quantities for your healthy nutrition. Since your body does not make enough vitamins naturally, your primary source for these substances should be food.
Vitamin deficiency (extremely low levels) and even poor intake of some vitamin can negatively affect natural body self-protection against infections, increase risk for birth defects and diseases such as cancer, heart disease, and osteoporosis (thinning of the bones). On the other hand too much of certain vitamins especially A and D, can results in toxicity, which causes negative effects such as headache, nausea, and diarrhea. You might get to much of them if using vitamin supplements without doctors advice. Unless you really know what your body vitamin needs are.
But in health food concentration of vitamins is lower than in chemically made pills. This way you can not overdose them, either you will not suffer any diseases appeared from vitamin deficiency. Various health food eaten regularly (every day) will supply you with a whole variety of vitamins. Variety is essential for your body being vital and healthy as a whole. This way you will get different and equally important kind of vitamins.
Ways to get all necessary vitamins is from whole foods - fruits and vegetables are your the best friends revitalizing your body. Also grains, dairy products and lean meat contains some vitamins. Whatever food you choose for your healthy wellbeing just make sure to keep the quality and the variety.