Protein intake is vital to good health at any age

[In my last column, I discussed high-protein diets. Today's column is about the role of protein.]

Proteins are extremely complex substances that are essential parts of all living cells. They make up about 15 percent of the average person’s body weight. We need protein from the foods we eat to maintain bones, muscles and skin. We get proteins in our diet from meat, dairy products, nuts, and some grains and beans.

Proteins from meat and other animal products are complete proteins. This means they supply all of the amino acids the body can't make on its own. Plant proteins are incomplete. You must combine them to get all of the amino acids your body needs.

Amino acids play central roles as intermediates in metabolism, the chemical processes by which cells produce the substances and energy needed to sustain life.

So, it is important to get enough dietary protein. You need to eat protein every day, because your body doesn't store it the way it stores fats or carbohydrates. The average person needs 50 to 65 grams of protein each day. This is the amount in four ounces of meat plus a cup of cottage cheese.

However, most Americans already eat more protein than their bodies need. And eating too much protein can increase health risks.

High-protein animal foods are usually also high in saturated fat. Eating large amounts of high-fat foods for a sustained period raises the risk of coronary heart disease, diabetes, stroke and several types of cancer. People who can't use excess protein effectively may be at higher risk of kidney and liver disorders, and osteoporosis.

Older adults and vegetarians have to pay special attention to the protein in their diets.

A recent National Institutes of Health study of men and women in their 70s found that those who ate the least protein lost significantly more muscle than those who ate the most protein.

Maintaining muscle is important as you age. Older adults who lose muscle in their legs and hips are more likely to fall and injure themselves.

Animal proteins have all the essential amino acids, but plant-based proteins can have low amounts of some. So, vegetarians have to eat protein from several different sources to get all the different amino acids they need. Vegetarian food combinations that give you complete protein include rice and beans or peanut butter and bread.