Essentials of Nutrition for Sports

depigmented hair and skin, pressure sores, and depressed immune function.

Amino Acids For Disease Treatment

A few amino acids have been studied as therapeutic agents.

Tryptophan

Adults require about 250 milligrams

daily for protein synthesis.

Doses greater than 1 gram daily (four times the daily

requirement) induce sleep.

Tryptophan as a pharmacological agent has been associated with

toxic effects, probably due to supplement contaminants. Branched-Chain Amino Acids (Leucine, Isoleucine, Valine)

Intravenous solutions are used to improve nitrogen retention in

septic and uncomplicated postoperative patients.

Branched-chain amino acids along with lowered amounts of the

aromatic amino acids may be help

ful in hepatic encephalopathy.

Arginine

Arginine stimulates the release of hormones including growth

hormone and insulin.

Arginine, in doses as high as 30 grams per day, reduces nitrogen

loss in surgical patients with moderate trauma and improves lymphocyte function in healthy subjects. Glutamine

Glutamine is conditionally essential in critically ill patients. It is a preferential energy source for the intestinal mucosa and is

used extensively for energy by lymphocytes when they are stimulated to proliferate.

It has been tested in doses to 40 grams per day.

Other Health Claims Weight Control

In short-term studies, a diet that includes more protein and less

carbohydrate may be more effective for losing weight or keeping weight steady than a high-carbohydrate diet. This is due, in part, to loss of storage glycogen, which binds about three times its weight in water.

Long-term effects are less certain.

Cardiovascular Disease

One large, prospective study has investigated the association

between dietary protein and heart disease or stroke.

In the Nurses’ Health Study, over a 14-year period, women who

ate the most protein (about 110 grams per day) were 25 percent less likely to have a heart attack or to die from heart disease than women who ate the least (about 68 grams per day). Cancer

There is no evidence that a little or a lot of protein influences

cancer risk.

Toxicity

The average American consumes about 100 grams of protein per

day—almost twice the recommended daily allowance (RDA) of 50 grams for women and 63 grams for men.

Dietary protein consumed in excess of requirements is not

stored.

It is deaminated (nitrogen is removed) followed by either:

1.^

Oxidation (use as energy) of the carbon skeleton through pathways of glucose or fat metabolism, or

2.^

Stored as glycogen or fat, depending upon the specific amino acid and the energy balance at the time.

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