While a vegetarian diet is among the healthiest ways to eat, certain nutrients can be lacking on a diet that contains no animal products at all. In particular, many people are concerned that vegans may not get enough protein, calcium and iron from plant-based foods. This is because most people think of eating dairy products for calcium and meats for iron and protein. But it is possible to consume adequate amounts of these nutrients on vegetarian diet. It just takes bit of effort and knowledge about plant-based sources the nutrients.
Iron is an important mineral because it plays a vital role in transporting oxygen through the bloodstream. People who do not have adequate iron intake can suffer from iron deficiency anemia, a condition characterized by extreme fatigue and weakness. Adult men and post-menopausal women need about 10 mg of iron per day, while women of child-bearing age need about 15 mg per day. There are two types of iron heme iron (from meat) and non-heme iron (from plant sources). Though non-heme iron is generally not as easily absorbed as heme iron, the incidence of iron deficiency anemia is no higher in vegans than in the general population. Dried beans and dark leafy green vegetables can provide adequate amounts of dietary iron if consumed on a regular basis. To boost absorption of iron, iron-rich plant foods should be consumed with vitamin C supplements or foods rich in vitamin C. Since vegans diets tend to be high in vitamin C naturally, iron consumption is really not as much of a problem for most vegans as might be expected. In fact, some foods, like broccoli and bok choy, are high in both iron and vitamin C. These foods are often eaten with other iron and vitamin C-rich foods, such as beans and tomato sauce.
Another important nutrient for vegetarians to consider is calcium. Adults need about 1000 mg of calcium per day. Most people think of dairy products when they think of calcium, which important for strong bones and teeth. But vegans can get plenty of calcium from dark greens, tofu processed with calcium sulfate, and other foods or from calcium supplements. Soymilk and rice milk are often fortified with calcium as well. Other good sources of calcium for vegans include blackstrap molasses, fortified orange juice, tahini and almonds. It is important to note that a compound known as oxalic acid, found in vegetables like spinach, rhubarb, chard, and beet greens, can bind with calcium and prevent it from being well absorbed. Therefore, greens like broccoli and collards are better sources of calcium for vegans.
Though there is much concern about vegetarians getting enough protein, the need for protein is often overrated. The average diet contains far more protein needed for health. In fact, excess protein can damage the kidneys and contribute to the development of osteoporosis. The recommended daily allowance of protein is 8/10ths of a gram for every kilogram of body weight or about 10-15% of total calories. Foods like soy, rice and beans, and nuts and nut butters can provide adequate amounts of protein for vegans. In contrast, animal foods are so high in protein that non-vegetarians can easily exceed the upper limit recommended for protein intake, which is 4.5 grams of protein per 100 calories of food.
Protein is comprised of amino acids, which are often called protein building blocks. The body needs nine different amino acids from foods. Because the body cannot make these nine amino acids, they are known as essential amino acids. Foods that contain all nine essential amino acids are considered “complete protein” foods. Non-vegan vegetarians can easily get all nine amino acids from eggs and dairy products. For vegans, soy protein, which is a complete protein, is often considered the best source. The nine essential amino acids can also be obtained by combining whole grain rice and beans. Other vegan sources of high quality protein include the grain quinoa and spinach. Eating a variety of legumes, grains, nuts, and seeds daily ensures that vegans consume all of the protein they need.