"Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet." - Albert Einstein
Most vegetarian diets are low in animal products. They are also usually lower than non vegetarian diets in total fat, saturated fat and cholesterol. Many studies have shown that vegetarians seem to have a lower risk of obesity, coronary heart disease (which causes heart attack), high blood pressure, diabetes mellitus and some forms of cancer.
Vegetarian diets can be healthful and nutritionally sound if they are carefully planned to include essential nutrients. However, a vegetarian diet can be unhealthy if it contains too many calories and not enough important nutrients.
Protein: You don't need to eat foods from animals to have enough protein in your diet. Plant proteins alone can provide enough of the essential and non-essential amino acids, as long as sources of dietary protein are varied and caloric intake is high enough to meet energy needs. Whole grains, legumes, vegetables, seeds and nuts all contain both essential and non-essential amino acids. Soy protein has been shown to be equal to proteins of animal origin.
Iron: Vegetarians may have a greater risk of iron deficiency than non vegetarians. The richest sources of iron are red meat, liver and egg yolk, all high in cholesterol. However, dried beans, spinach, enriched products, brewer's yeast and dried fruits are all good plant sources of iron.
Vitamin B-12: This comes naturally only from animal sources. Vegans need a reliable source of vitamin B-12. It can be found in some fortified (not enriched) breakfast cereals, fortified soy beverages, some brands of nutritional yeast and other foods, as well as vitamin supplements.
Vitamin D: Vegans should have a reliable source of vitamin D. Vegans who don't get much sunlight may need a supplement.
Calcium: Studies show that vegetarians absorb and retain more calcium from foods than non vegetarians do. Vegetable greens such as spinach, kale and broccoli, and some legumes and soybean products are good sources of calcium from plants.
Zinc: Zinc is needed for growth and development. Good plant sources include grains, nuts and legumes. Shellfish are an excellent source of zinc. Take care to select supplements containing no more than 15-18 mg zinc. Supplements containing 50 mg or more may lower HDL ("good") cholesterol in some people.