Protein in the vegetarian diet
Vegetarians must be sure to eat protein, the source of amino acids.

Fueling a car is simple. When you get too close to empty, you go to the gas station and fill up. Occasionally, you might pour some fuel injector cleaner or anti-freezing solution in there for some added oomph. Unfortunately, fueling the human body is a bit more complex. Some people forego meats and even dairy products because they feel that humans shouldn't consume animal products. But eating only foods that grow from the earth can come with its own set of problems, no matter how healthy it is overall. One of those problems is protein deficiency.

You see, the human body needs amino acids to function in a proper and healthy manner. There are more than 20 different amino acids in nature, 10 of which are required in various amounts by the human body. Because proteins are made up of amino acids, human beings have a real need for protein. The best source of proteins is often animal products. Therefore, a vegetarian who doesn't plan his or her meals right may end up suffering from low levels of one or more essential amino acids.

That's a problem, because all the tissues in your body, from your skin down to your muscles and internal organs, require proteins and the amino acids that comprise them. Also, many of the chemicals your body produces to keep things running properly, such as hormones and enzymes, are made up of proteins, so the body needs a protein source to make them. Serious protein deficiencies can lead to a process called catabolism, in which the body essentially cannibalizes its own tissues to obtain the proteins it needs. This, obviously, is not a good long-term solution and can lead to a decline in overall health.

It is possible, though, to obtain the amino acids one needs to maintain optimal health, even on a strict vegan diet that precludes dairy products. You need the right combinations of foods and, if absolutely necessary, nutritional supplements.

People who eat meat, dairy and egg products don't have to give the process as much thought, because animal-based foods contain all the amino acids that humans, who also are animals, require. Those are "complete" proteins. Plants have proteins, too, but they often lack one or more amino acids that humans require to function. They are, therefore, usually "incomplete" proteins from the human perspective. This is why you may have heard of combining certain rices and beans, for example, to get a complete protein. Whole grains like wheat, rye, barley and oats lack the amino acid lysine, for example, while legumes like beans, peas and lentils are rich in lysine even though they are low in another amino acid, methionine.

You don't need to get your complete proteins all in the same meal. Simply make sure you eat a variety of protein sources throughout the day, from nuts to seeds, to rice and grains.

Another great option is to get some soy into your diet because it offers a complete protein. You could do this by eating soy-based foods or by adding a soy protein supplement to something like a fruit smoothie. If you're not a huge soy fan or if you want to mix things up a bit, you can go for a grain called quinoa, which also offers a complete protein and which can be cooked and served in much the same way as rice.

Protein supplement products aren't necessary with proper meal planning. But, if you doubt your ability to plan your vegetarian meals around sufficient protein, you can consider supplements. Consult a registered dietician for further information.