By now, everyone should know about the hazards of undertaking the so-called protein-sparing fasting diet without close medical supervision. This semi-starvation approach to weight loss is fraught with dangers.

However, dieters are not the only people buying the many types of protein supplements. These concoctions also are being promoted for athletes, the elderly and others who fear they are not eating a balanced diet.

Who really needs these protein supplements? The answer is "nobody!"

Americans have a mystique about Protein. In the minds of many, eating protein is synonymous with good nutrition. While it's true that we all need this essential nutrient, it is simply not true that excessive amounts will make you thin as a snake, or strong as a weight lifter, or lively as a cricket. What's more, the typical American diet contains more than ample amounts of protein. Indeed, surveys show that many people regularly consume double the recommended dietary allowance, and even persons with very low incomes get enough protein.

How much protein you actually need depends upon several things. Proportionally, infants and growing children need more than adults. Pregnant and nursing women need more than other women. The quality of protein is also a factor. The human body requires thousands of different proteins for growth and maintenance. These proteins are formed from the protein in our foods, which are first broken down in the body into 29 building blocks called amino acids.

Eight, and possibly nine, of the 20 amino acids cannot be manufactured in the body. Thus it is essential that we get them from the foods we eat. The remaining 11 or 12, however, can be made out of combinations of the other eight or nine essential amino acids. Obviously, if one or more of the essential amino acids is in short supply, protein formations will be inhibited. Cereals, for instance, are how in lysine, one of the eight essential amino acids. If a child ate only cereals, he would have trouble eating enough to avoid a protein deficiency. However, milk is rich in lysine, so by pouring half a cup of milk on a cup of oatmeal for breakfast, the child starts his day with nearly 10 grams of high-quality protein. That's a third of the recommended allowance for a 4-year-old child, a fourth of the 46-gram allowance for a nonpregnant woman, and a fifth of the 56 grams needed by an adult male.

What makes a protein high quality? In general, milk and other animal proteins closely resemble the proportions of essential amino acids in our own bodies, so we say they are of "high biological value," or quality. Breast milk tops the list with a perfect score of 100, followed by whole egg protein at 94, and milk, meats and fish with scores between 75 and the high 80s.

But some vegetable proteins rate almost as high. Soybean protein scores 70 and dried peas and beans rate 40 to 60. Although potatoes do not contain large amounts of protein, what they do have scores a high 78. Since animal protein tends to be expensive, you can easily obtain all the essential amino acids by mixing some of the incomplete but good quality protein found in vegetables with small amounts of animal protein.

Or you can get more than enough protein from readily available animal sources. For example, the recommended daily amount for a lactating woman is 70 grams the highest of any category. This can easily be obtained from one egg (6 grams), four cups of milk (36 grams), a cup of yogurt (7 grams) and a 3-ounce piece of chicken (21 grams).

But, you may aks, what about special situations, such as the professional athlete or the elderly? Do these people ever need protein supplements? In a word, no. Contrary to popular belief, athletes need no more protein than anyone else. Indeed, athletes who compete in endurance events, such as running the marathon, do better on a high-carbodydrate diet, rather than one that is high in protein.

If an older person's diet is so restricted that it is inadequate in protein, it is also undoubtedly inadequate in other nutrients as well. In these instances, a physician's advice and a dietitian's guidance is needed in planning a good diet, even on a restricted income. Don't put your money into expensive and ineffective protein supplements.

Getting enough natural protein need not cost a fortune. In addition to sources already mentioned, consider that a peanut butter sandwich provides 12 grams of protein, a slice of bread 2 grams, a corn muffin 3 grams. A cup and a half of macaroni with cheese provides a whopping 26 grams. In short, the very best protein "supplements" are found throughout the supermarket. Our ordinary daily foods not only provide more than enough protein, but also, contribute the other essential nutrients as well.