Amino Acid Requirements

There are definitely specific requirements for proteins, though the exact amount is somewhat questionable. The Recommended Daily Allowance (RDA) of protein according to U.S. government standards is 0.8 gram per kilogram (1 kilogram equals 2.2 pounds) of ideal body weight for the adult. Ideal body weight is used in the calculation because amino acids are not needed by fat cells, only by the lean body mass. So an adult male who should weigh about 154 pounds, or 70 kilograms, requires 56 grams of protein daily. A female whose best weight is 110 pounds, or 50 kilograms, needs 40 grams a day. The RDA increases by 30 grams per day during pregnancy and 20 grams per day during lactation. During growth, different amounts are needed. For example, 2.2 grams of protein are needed per kilogram of body weight each day in the first six months of life, and 2.0 grams per kilogram for the next six months.

Daily Protein Requirements

Age RDA*
0–6 months2.2
6 months–1 year2.0
1–3 years1.8
4–6 years1.5
7–10 years1.2
11–14 years1.0
15–18 years0.9
19 years and older 0.8

*(in grams per kilogram [2.2 pounds] of body weight)

These requirements are based on maintaining a positive nitrogen balance in children and an even to positive nitrogen balance in adults. Protein is the nitrogen-containing nutrient. As it is broken down for excretion, it must be replaced by dietary nitrogen so protein formation can continue. In the healthy adult, nitrogen equilibrium, or zero balance, is the ideal, while a positive nitrogen balance is needed during times of illness and healing. In children, when growth is occurring regularly, a positive nitrogen balance is necessary, as it is in pregnancy.

As discussed in the previous section, Food Complementarity, the protein requirements are also based on the protein quality, as measured by the biological value (BV). Protein is also measured by the way it supports growth; this measurement, called the protein efficiency ratio (PER), is determined by feeding an animal a particular protein food and measuring its growth.

The reference protein for determining the biological value of foods is that of eggs (ovalbumin), the food with the highest BV at 94 percent (although mother’s milk is valued at 100 percent). Next are fish at 75–90 percent, rice at 86 percent, legumes at 70–80 percent, and meats and poultry at 75–85 percent. Corn, an incomplete protein, has approximately 40 percent biological value.

Protein Excess

There is definite concern that the developed countries are overconsuming protein, especially from meat and dairy foods. Since nearly 700 million people in the world are protein deficient, it seems ludicrous that Americans and people in other well-to-do countries consume so much. But we could be paying the price!

The RDA protein standards may be highly overestimated; and grams of protein daily. The World Health Organization more conservatively puts our protein needs at about half of the U.S. government minimum levels, or 0.45 grams of protein per kilogram of ideal body weight.

The Western world definitely has less deficiency disease than parts of the Third World, such as Africa, the Near and Far East, and Central and South America. But we also have far more chronic and degenerative diseases, such as arthritis, diabetes, cardiovascular disease, and cancer. All of these problems have dietary correlations, some of which are shown in specific studies, but many that, in my opinion, will be discovered in future years with research into the nutritional components of disease. Eventually, through knowledge and behavior, we need to find the right balance in our diet.

Protein Deficiency

With all the worldly and space technology and the wealth of resources we possess, much of the world’s population is yet impoverished and near starvation. Thousands of children and adults die daily from lack of nourishing food, and protein is of key importance. In areas where meats and milk products are not plentiful and where often only one or two food sources are available, such as rice, wheat, corn, or potatoes, people are not getting the complete balance of amino acids and protein needed to sustain the body. They go into negative nitrogen balance and begin to experience weight loss, fluid retention, weakness, hair loss, and the inability to heal wounds.

The name for protein deficiency disease is kwashiorkor, a Ghanian word for “the evil spirit that infects the child.” Protein deficiency is a wasting disease that in its severe state leads to death. It is curable, of course, with consumption of complete protein foods or supplements. Marasmus, another protein deficiency disease associated with calorie or food deficiency, comes from a starvation diet and results in complete loss of energy and tissue wasting. Also called “protein-calorie malnutrition” (PCM), it is the world’s most widespread and correctable malnutrition problem, killing millions yearly.

The Western world’s example of protein deficiency is mirrored in the alcoholic, who obtains a large portion of his or her calorie intake from carbohydrates in the form of ethyl alcohol. Food and protein consumption may be minimal. Malnutrition and fat accumulation in the liver lead to rapidly advancing demise unless alcohol is reduced and nutrition is increased. Cirrhosis, scarring, and malnutrition of the liver is one of the top ten degenerative diseases leading to death in the United States.

Recently there has been worldwide concern over hunger, malnutrition, and starvation. It certainly seems that a primary part of our responsibility on this planet is to feed all the people adequately. After all, on an individual or family level, food, shelter, and clothing come before fancy cars, exclusive restaurants, and trips to the Caribbean. Donations to hunger projects, attending fundraising music concerts, and helping to raise money ourselves are short-term ways to feed some hungry people, but there are other approaches too. Currently, on a global level, higher precedence is given to using land for grazing meat-rendering animals than for growing grain for direct human consumption. Many acres of grain and plant proteins are used to feed a small number of cattle and still more grain is used to feed poultry. This grain could feed many more people than can the meat of dead chickens! A reduction in animal meat production and an increased emphasis on vegetable and grain foods would help feed the impoverished everywhere. Yet perhaps the most important contibution we can make towards reducing hunger and starvation in the world is by helping and teaching people to plant and harvest their own food sources.

Elson M. Haas MD Written by Elson M. Haas MD

We Humbly Recommend