Fish oil supplements continue to be sold in the market in spite of the fact that there is no use for them. In its campaign against quackery, the U.S. Food and Drug Administration (FDA) has prohibited products from saying that they can prevent and/or treat diseases since "there is inadequate scientific evidence to support any health claims on fish oils.

Among the many unfounded claims of fish oil supplements is that they can cure psoriasis. This myth was sparked by a double-blind study which showed that patients who took 1.8 grams daily of EPA (eicosapentanoic acid), one of the two omega-3 fatty acids in fish oils, were better off than those who didn't take fish oil at all.

While all that may sound promising, a single study is not enough to prove the use of fish oils in psoriasis. The FDA has reviewed scores of materials regarding the possible uses of fish oils and found that none of them hold water. Public health officials recommend eating more fish instead.

"The best way to get your fish oils is the way nature packaged them in fish," according to Dr. Sheldon Saul Hendler in "The Doctors' Vitamin and Mineral Encyclopedia." That means eating a lot of herring, salmon, tuna and shrimps daily which can cut your risk of a heart attack by as much as 50 percent.

Those who continue to swallow fish oil supplements - whether for psoriasis or other reasons - may actually increase their blood cholesterol level. But that's not all: pill poppers can also suffer from loose stools, belching and abdominal discomfort as well.

"Other potential risks of taking fish oil pills: blood that becomes too 'thin' to clot in the case of an accident, and higher blood sugar levels for people with diabetes," warned Lawrence Lindner in American Health magazine.

Psoriasis sufferers may turn to lecithin for relief. What's the verdict on this fatty substance found in marga¬rine, ice cream, chocolate and mayonnaise? Again, there is no evidence that it works.

What we do know about lecithin is that too much can cause certain problems. The psoriatic patient who wastes money on lecithin supplements may end up fat - a condition that may trigger flare-ups. This is because lecithin has as many calories like other fats and contributes to obesity.

"Our bodies make as much lecithin as we need and any extra simply serves as a source of calories - and rather expensive ones at that. Extra lecithin is of no benefit whatsoever," said Arnold Bender, vice president of the International Union of Food Science and Technology in "Health or Hoax?"

"An intake of over 10 grams a day will cause severe stomachache, sweating, drooling and loss of appetite," added dietitians Annette Natow and Jo-Ann Heslin in "Megadoses: Vitamins as Drugs."

What about zinc supplements? Can they treat psoriasis? A zinc deficiency (which usually occurs during pregnancy) can result in dermatitis (skin inflammation) of the face and limbs which may resemble psoriasis. Gorging on zinc tablets, however, has no effect on the disease itself.

Taking as much as 500 milligrams can cause nausea, vomiting and diarrhea. Other side effects are dehydration, stomach pain, poor muscle coordination, tiredness and kidney failure, according to Drs. Harold M. Silverman, Joseph A. Romano, and Gary Elmer in "The Vitamin Book: A No-Nonsense Consumer Guide."

"One group reported that in young men large doses of zinc (150 milligrams of zinc daily) depress high-density lipoprotein (HDL) cholesterol levels. This is undesirable, because high-density lipoprotein cholesterol is thought to protect against coronary heart disease," Hendler said. (Next: Treating psoriasis.)