Nutrition still has its secrets," says Dr. Jean Mayer, who taught nutrition at Harvard before moving on to become president of Tufts. "If the story of the development of our science is a dependable guide, there may be nutrients performing significant duties for ust that we have not yet identified."

On this point, those who believe that if a little Vitamin E is good, a lot of Vitamin E is better, agree with Mayer. On what to do about it, they part company. If there are important nutrients which we haven't identified yet, Mayer says, "we are getting them from the varied diet we enjoy and consume."

Food supplement pill poppers don't agree. So they take megadoses of Vitamin E, supplement their diet with lecithin and zinc, consume enormous quantities of yogurt, bran and black strap molasses, even when they don't like the taste.

These are some of the reasons why.

Vitamin E

According to Tom Zeibarth, an attorney with the fraud division of the U.S. Post Office who has presecuted many companies for making false claims about food supplements, "E has been touted as an aphrodisiac or sexual restorative based on early studies which show that the total absence of E in rats destroyed their reproductive ability. From this people jumped the hurdle, and many mix Vitamine E with ginseng on the basis if one is good, two are better.

"One ad," according to Zeibarth, "said cattlemen gave E to their bulls before mating. A USDA official, who specialized in ruminant nutrition allowed as how this is udder nonsense."

Other claims for Vitamin E, which occurs naturally in whole grains, oils, butter, wheat germ and eggs, include an ability to cure diabetes, leg cramps and aching feet. In past years the Food and Drug Administration has taken action against E products promoted for treating sterility, muscular dystrophy and heart disease.

Says Dr. Mark Hegsted, administrator of the Department of Agriculture's Human Nutrition Center, "The evidence doesn't support all the claims made for it although we'd have to admit we don't know the optimum requirement of man. The Recommended Daily Allowance is as good an estimate as we have. The evidence is fairly good in animals on greater need for E if you are eating more polyunsaturated fats."

Mayer agrees with Hegsted, but he says the requirements is "not three to 12 times as much as the RDA of 15 units per day," which some people take.

Hegsted also says burn patients may need therapeutic doses of E because they lose so much through their burns. "It's safe to assume their nutritional needs are elevated - maybe two or three times, not a hundred times."

Dr. Johanna Dwyer, director of the Frances Stern Nutrition Center at Tufts, suggests that if you eat a normal diet of lightly processed foods, you'll get all the E you need.

A Montgomery County physician, who treats patients with vitamin thereapy, says "people who take Vitamin E should have medical supervision."

Lecithin

People in search of a magic formula to lower their cholesterol may have explored the lecithin theory along the way. There may be some suggestive evidence that lecithin, an emulsifier, breaks up and disperses cholesterol. But nutrition expert Dr. Eleanor Williams says there have been no "controlled studies which indicate that lecithin lowers blood cholesterol."

Hegsted, however, acknowledges that "lecithin is a little peculiar right now in view of the work at MIT that choline (of which lecithin is a good source) may affect some neurological diseases." But Hegsted adds, "There is no evidence of widespread deficiency of choline. If you get into disease states you ought to talk to your doctor, not go to health food stores."

Vitamin C

Vitamin C, ascorbic acid, hovers between the world of fad and respectability. Whether or not it cures the common cold or prevents cancer (claims made long ago by Nobel Prize winner, Lunus Pauling), more and more physicians and establishment scientists acknowlege that large does of Vitamin C do reduce the severity and symptoms of the common cold by acting as an antihistamine. General Mills recently published a paper by a scientist who acknowledged the value of Vitamin C in the treatment of cold symptoms. Pharmacist Joe Graedon, in his book "The People's Pharamcy," recommends large doses of Vitamin C for the same reason.

Megadoses of Vitamin C on a daily basis - three, four, five or more grams - can cause "rebound" scurvy and kidney stones. But Dr. Gabe Mirkin, a specialist in sports medicine, says taking it during a cold won't cause a problem.

Ascorbic acid may be partially effective as a block against cancer-causing agents. Experts in carcinogenicity of sodium nitrite often suggest that people who insist on eating bacon cured with nitrite and smoking cigarettes, drink orange juice to help offset the combined carcinogenic effects of the bacon and cigarette smoke.

Yogurt

One of the few food fads enjoying respectability among both food supplement aficionados and establishment physicians is yogurt. Not, however, for any curative powers; or for its ability to help you live past 100, as one yogurt commercial hints. Nor has it been proven that yogurt lowers blood cholesterol levels or aids digestion, though for people who have severe lactose intolerance, doctors sometimes recommend yogurt as a source of calcium.

Turks believe it cured insomnia, possibly because milk contains the amino acid tryptophan which has shown some evidence as a sleep inducer. Persian women used yogurt to banish wrinkles. Doctors recommend yogurt, with live bacteria cultures will replace the friendly intestinal flora killed by the antibiotics.

Consumer reporter Sidney Margolius says yogurt "is a highly nutritious food with usually much the same nutrients as whole or low fat milks," depending on the brand. Yogurt also costs more than milk, and when it's fruit-flavored, it has a lot of calories. Still, Hegsted thinks fruit-flavored yogurts are a fine substitute for ice cream.

Black Strap Molasses

The sweetener with the strong flavor, black strap molasses, fares a bit better than honey among food fad debunkers. Writing in "Health Foods, Facts and Fakes," Margolius says: "Disregarding claims that blackstrap is food for inducing sleep, correcting nervousness and restoring gray hair to its natural color, molasses otherwise is a useful food in a limited way. It is a concentrated sugar food with a high content of iron and calcium (much more than honey) especially the darker kinds, the U.S. Department of Agriculture pointed out.But in normal usage in small amounts, it does not make an important contribution to the ordinary diet."

As Dwyer suggests, the trace elements it contains can be found elsewhere, in foods with far fewer calories and a lot more of other essential nutrients. If you need potassium, try grapefruit juice and bananas; if you want more iron, try liver; if you want calcium, try milk.

One of the original food faddists, Gaylord Hauser, promoted blackstrap molasses for longevity.His claims for life-extending powers concerned FDA, which feared people suffering from undiagnosed disease might be persuaded that they were simply suffering from malnutrition and not seek medical advice.

At the time, Jimmy Durante cracked that blackstrap molasses doesn't really make you live longer, it just seems longer.

Wheat Germ And Brewer's Yeast

Even cynic Margolius syas wheat germ and brewer's yeast "are worthwhile supplements to any diet." Both are food sources of the B vitamins: both have protein.

Wheat germ's protein, compared to other grains, is high, but it hasn't as much protein as dry peas, soybeans or nonfat milk powder. Unfortunately wheat germ is refined out when wheat is processed to make white flour. Thus, the most nutritious part of the wheat is discarded, or sold separtely for a lot more money.

As both Dwyer and Margolius point out, ordinary protein foods and whole grain products have plenty of B vitamins. But if the price is reasonable, brewer's yeast is a useful supplement to diets low in animal protein. And for lower quality cereals, wheat germ is a useful supplement, again, if the price is rational.

Or, as Dwyer says, "If people want to use these things, let them, but they don't have any special curative powers."

Dwyer likes wheat germ in her cookies.

Bran

Bran is so popular right now it has made its way out of the health food stores onto the supermarket shelves - at a considerably higher cost!

There seems to be little disagreement that bran, one of the many forms of fiber, changes the quality of the stool, and most experts agree that change is for the better because the stool passes through the system more quickly.

There is some evidence that diets low in fiber cause some of the diseases of the Western world, such as diverticulitis. But "In terms of preventing cancer or appendicitis," says, "the evidence isn't in yet."

Most experts acknowledge that the diet of our grandparents was far higher in all forms of fiber than it is today and that additional amounts of the form of bran cereal or unprocessed bran might be useful. Says Hegsted: "Americans should be advised to consume more dietary fiber and bran contains dietary fiber, but so do a lot of other things."

If there is so little evidence that these food supplements are essential in megadoses, why do some people insist they feel better with them than without them?

Tom Zeibarth calls it "the self-fullfilling prophecy." Others describe it as the placebo effect. Scientists have been aware of it for years. If you think you are taking something to make you feel better, it will.

According to Hegsted, 30 percent of the population are "placebo reactors." That means if you give 100 people sugar pills (placebos) 30 of them will respond. Says Mirkin, the only way to test the efficacy of a substance is through double blind study. And even that is subject to "placebo reactors."

Where, then, does this lack of hard scientific evidence lead those who want to improve their diets and health?

To whole foods, which are more likely to provide all the nutrients needed for sound health than the typical American diet of hightly processed foods.

The Montgomery County physician who prescribes vitamin and mineral therapy says, "Most people might do fine on a lightly processed diet, but for some the needs may be much greater." But he said, "You still have to do a body chemistry, a trace mineral analysis of hair," to find out if someone is deficient.

Deficiencies can occur if you are on special medication. Or, if you eat hot dogs, soda, potato chips, bleached white flour, french fries, Danish pastry to the exclusion of other foods that form a balanced diet, you may need a double supply of special nutritional supplements. Increased consumption of that kind of food has nutritionists worried.

Says Mayer in "A Diet for Living": "The trend toward constantly increased use of refined flour, sugar, isolated single protiens and purified oils and fats may be beyond our capability to know what nutrients to replace by enrichment and fortification. The only safe course is to continue to make sure that a large portion of our diet consists of a VARIETY of wholegrain products, fruits and vegetables, animal products..."

Even the authors of "A Dictionary of Food Supplements," Annette Dickinson and Lee Fryer, prefer the real food route. "Excellent nutrition is cheaper when you include many whole foods in your regular dies: whole grain bread, whole seeds and nuts, whole grain breakfast cereals, liver, fish, eggs, milk, cheese and lightly processed food oils. These all provide good supplies of many vitamins and minerals in sound biological assortments..." CAPTION: Illustration, no caption, By Robert Barkin - The Washington Post