There is plenty of evidence showing vegetarian and vegan diets are beneficial to health. However, it’s easy for a vegetarian or vegan diet to be harmful to your health if all necessary nutrients aren’t met.

One reason vegetarian and vegan diets are healthy

One benefit to vegetarian and vegan diets is the elimination of meat as a protein source. In fact, there is a protein myth that is especially prevelant in the United States, according to the Physicians Committee for Responsible Medicine. Protein’s primary functions are to build muscles, and to maintain healthy skin, bones, muscles and organs. In the past it was believed that there was no such thing as too much protein, and in the early 1900s, Americans were told to eat well over 100 grams of protein a day. Whereas it was once believed that athletes needed twice the amount of protien as others, it’s now known that athletes only need slightly more protein; and vegetarian or vegan diets are ideal for athletes. In the 1950s it was considered healthy to boost protein intake, and some current diet books recommend high-protein diets for weight loss – even though Americans generally eat twice the amount of protein than they need. Even without consciously trying to increase protein levels, the average American diet contains too much protein because of meat and dairy portions. High-protein diets may show short-term success in losing weight, but there are considerable health risks from high-protein diets. Excess protein is linked with osteoporosis, kidney disease, calcium stones in the urinary tract and some forms of cancer. Even if you remain an omnivore and keep meat and dairy in your diet, protein levels should definitely be reduced.

How to meet nutritional needs with a vegetarian or vegan diet    
Protein is not only derived from meat and dairy foods, but also from beans, lentils, grains and vegetables. It is actually amino acids that are needed to produce protein, and these food sources are all full of amino acids, as well as zinc. Protein needs can be met by consuming a variety of plant-based protein sources over the entire day, according to the American Dietetic Association. It is also important to eat enough calories to meet you energy needs, which is based upon your weight and physical activity level. The Mayo Clinic advises all of the following for a healthy vegetarian or vegan diet:

Ensure your calcium needs are met by incorporating dark green vegetables, such as turnip and collard greens, kale, broccoli and calcium-enriched and fortified products like juices, cereals, soy milk, soy yogurt and tofu.

Iodine is necessary for metabolism, and the growth and function of the brain, heart, kidney and thyroid; so be sure to include ¼ teaspoon of iodized salt a day.

Dried beans and peas, lentils, enriched cereals, whole grain products, dark leafy green vegetables and dried fruits provide protein and iron. However, vegetarians are recommended to double the advised iron intake because iron is not as easily absorbed from plant sources. To help your body absorb iron, eat foods like strawberries, citrus fruits, tomatoes, cabbage, and broccoli that are rich in vitamin C while you are eating iron-containing foods to make absorption easier.

The biggest nutrient needs that a vegan or vegetarian diet lacks is the same thing lacking in the average omnivore diet - omega-3 fatty acids, which are crucial for cardiovascular health, eye and brain development, and B-12. Fish and eggs are good sources of both B-12 and omega-3 fatty acids, but if they are eliminated from your diet be sure to use fortified products or take supplements.

Lastly, consider taking a D-2 supplement if you are not using soy or rice milk, cereal or margarines fortified with vitamin D.