Q. I need to follow a low-cholesterol diet, but I'm confused by some conflicting information on this subject. I've always heard that shrimp are high in cholesterol, but I recently read that they have a relatively low cholesterol content, about 90 milligrams per three-ounce serving. I also just read an article that said fatty fish have a greater amount of HDL than the traditionally favored leaner fish.

I think all of us who are carefully following a low-cholesterol diet would profit from some guidance on this topic.

A. Keeping your blood cholesterol level low helps prevent hardening of the arteries, heart attacks and premature death. But the cholesterol content of foods is only one part of the dietary battle against high blood cholesterol.

Depending on which of six types of high blood cholesterol you have, dietary treatment is slightly different. General guidelines for most people on low-cholesterol diets include:

Losing weight if overweight.

Cutting down on your total and saturated (as opposed to unsaturated) fats, which is actually more important than reducing your cholesterol intake.

Eating less than 250 to 300 milligrams of cholesterol a day.

Drinking no alcohol, or less than one ounce a day.

Eating a diet high in fiber.

A handful of foods are especially high in cholesterol. These are egg yolks (252 milligrams of cholesterol per yolk), organ meats (hearts, liver, sweetbreads, kidneys and brains, which contain from 233 to 1,700 milligrams per three-ounce serving), sardines (119 milligrams per three ounces) and shrimp (128 milligrams per three ounces). Beef, by comparison, contains 80 milligrams of cholesterol in three ounces.

Relatively speaking, most other foods -- including other shellfish -- are low in cholesterol, although they may have a cholesterol-raising effect because of their high saturated fat content.

Keep in mind that only foods of animal origin -- meat, fish, and fowl -- contain cholesterol. Fruits and vegetables are safe, the main exception being foods made with coconut oil or palm oil, which are high in saturated fat.

There's not much difference in the cholesterol content of fatty versus leaner fish (trout, 47 milligrams per three-ounce serving, and salmon, 40 milligrams, versus flounder, 43 milligrams). In fish, the amount of HDL cholesterol -- the type of cholesterol associated with a lower risk of heart disease -- doesn't matter, because eating foods with high HDL levels doesn't raise your own HDL level. But fatty fish have more of a substance known as EPA, which seems to slow the hardening of arteries.

I agree that planning a low-cholesterol diet can sometimes be difficult. That's why I recommend that people starting out on a major, lifelong change in their eating habits get professional advice from their physician or dietician. For a list of local dietitians trained in the dietary treatment of high cholesterol levels, call Barbara Hass, R.D., of the D.C. Dietetic Association at 589-3634. I also recommend that you get a book about low-fat diets that lists the cholesterol content of foods and tells you how to avoid saturated fats.

Lastly, since high cholesterol levels tend to run in families, I recommend that your children be tested in case they need dietary treatment as well.

Q. For about three years I've had several small, red, flaky spots on my face. Recently I had a biopsy done and the diagnosis was flat warts. I was told there was no treatment and that they would eventually go away on their own.

Can you please tell me what flat warts are, what causes them, how they are different from regular warts, and what treatments there are for them?

A. Flat warts do tend to go away on their own, but if they've lasted this long, there are a few things you can have done to treat them.

There are several kinds of warts, which are abnormal skin growths caused by the papilloma virus:

*Common warts, the best known variety, which most often grow on the hands.

*Filiform warts, narrow, needle-like growths occurring mainly on the neck and face.

*Flat warts, small, flesh-colored spots usually appearing on the face, neck, back of the arms and hands.

*Plantar warts, often mistakenly called "planter's warts," so named because they occur on the plantar surface of the foot, from the Latin word for sole. These are usually the toughest to get rid of.

*Venereal warts, or condyloma acuminata ("pointed knobs"). These grow in the genital area and have been linked with cancer of the cervix in women.

Depending on their type and location, there are many ways to treat warts. But even without treatment, half of warts will go away by themselves in one year, and two thirds within two.

Treatments include freezing with liquid nitrogen, burning with electrical current, minor surgery to cut them out, and topical medicines.

Topical medications range from acids, such as salicylic acid, lactic acid and dichloroacetic acid, to cantharidin, a blister-forming agent, and podophyllin, which is most often used on genital warts.

Compound W and Wart-Off are some over-the-counter wart medicines containing salicylic acid. I'd recommend getting your doctor's okay before using these products.

Flat warts usually respond well to liquid nitrogen freezing. Salicylic acid applications also work, but I don't recommend these for the face or genital area.

Although not approved for this use, Retin-A, a prescription acne medicine, may also clear flat warts.