In the usual course of nutrition research, discoveries are first tested on animals and then applied to man. Already the anti-gray hair vitamins have proved their potency in restoring color to the graying fur of foxes, dogs and rats. The next step is to try them on human beings.

No scientist will at this writing promise that vitamins will bring back the color to your gray hair or prevent its turning gray. They merely say they don't know. Nevertheless, though cagily noncommittal in public, scientists shed their caution when they're alone among their test tubes. Plenty of scientists are gray-haired, if not venerable, and a number of them are human enough to have taken their own gray hair medicine. Scattered reports have drifted out of the cloisters indicating that certain vitamin concentrates have succeeded in darkening the color of prematurely graying human hair.

There is still some dissension as to the exact vitamin that works these miracles, but it is certain that it is one or perhaps several factors of the miraculous B complex. The important thing is that, even though not specifically identified, the food sources of the factor are well known and easily available to anyone.

One of the first reports on the gray hair vitamins came out of the laboratories of Dr. Agnes Fay Morgan of the University of California just a few months ago. A strain of black-coated rats was fed a diet that included liberal amounts of four purified B vitamins: thiamin, riboflavin, nicotinic acid, and pyridoxine. In six to eight weeks the black hair of the rats began to turn gray. They ceased to grow and died within six to eight months. Their personal appearance was most unhappy; they looked like emaciated centenarians with loose, baggy skin and sparse gray hair.

This was exciting to all concerned except the rats. The animals didn't know what they were missing and neither did the scientists, but obviously it wasn't the four B vitamins. These had been obtained in the customary way by shaking water solutions of yeast, liver or rice bran with Fuller's earth.

The filtrate that remained after this process of separation obviously contained another vitamin or vitamins. This was satisfactorily proved when the rats showed immediate improvement and were quickly restored to full health by feeding concentrated extracts of the filtrate factor. Miraculously, the gray patches in their fur grew out with normal black color.

A six-week-old cocker spaniel with long, coal black, curly hair was put on a filtrate-deficient diet. Soon his hair lost pigment at the roots and within three months his coat was gray. Fed a filtrate made from yeast, his coat, too, resumed its glossy black hue.

Piebald rats in the care of Dr. Conrad Elvehjem of the University of Wisconsin turned gray on certain diets. He succeeded in restoring normal hair color by feeding them liver extract. A similar observation and cure was reported by Dr. Gulbrand Lunde and Dr. Hans Kringstad, two Norwegians who are credited with the first report on the antigray hair vitamin. In still another experiment, black-haired rats fed on a milk diet became anemic and their hair turned a silvery gray. In this case the color was restored by adding iron and copper to the diet.

Many investigators believe that pantothenic acid, one of the newer B vitamins, is the essential factor in preventing and restoring gray hair. Concentrated dosage of pure pantothenic acid has cured gray-haired rats; other investigators have failed to restore hair color with pantothenic acid alone. Dr. Morgan is convinced that pantothenic acid is concerned in the phenomenon of graying hair but that other factors are probably important also.

That one, perhaps the most essential, of these factors is a well-known chemical out of which novocain is made is indicated by the work of Dr. S. Ansbacher of the Squibb Institute for Medical Research. The substance, a B vitamin bearing the formidable name of para-aminobenzoic acid, has restored hair color to rats where pantothenic acid alone has failed.