DEAR DR. DONOHUE: I have noticed that many packaged cookies, doughnuts, cakes, candy, crackers and whipped-cream toppings contain palm oil, palm kernel oil or coconut oil. Where do these oils come from? What effect do they have on our health? — R.C.

ANSWER: Those “tropical” oils come from various parts of the palm tree. Palm oil is added to foods like peanut butter to prevent the ingredients from separating. It’s called an emulsifier. I suppose that’s why it’s in whipped cream. Palm oil is high in saturated fat, the kind of fat that raises a person’s cholesterol. Palm kernel oil comes from the seeds of the palm tree fruit. It, too, has a high concentration of saturated fat. Coconut oil, from the coconut palm tree, has the highest amount of saturated fat. Some years back, these tropical oils were widely used in baked goods. They took the place of butter, margarine and other such cooking materials, as they were cheaper and kept the finished products from going stale quickly.

The tropical oils were supplanted by fats called trans fats, fats that are now considered even greater boosters of blood cholesterol. Since this information became known, the tropical oils have made a comeback. One of the reasons for their revival is newer evidence that palmitic acid, the main ingredient in tropical oils, appears to have not as great an effect on cholesterol as was once thought.

Even though these oils have been partially exonerated, experts still say to use them sparingly. Vegetable oils — olive oil, canola oil and safflower oil — don’t have any effect on cholesterol and are preferable for use in baking and cooking when they can be used.

DEAR DR. DONOHUE: What can I do to relieve dry, itchy scalp? I have tried many different shampoos with only limited success. — R.M.

ANSWER: Purchase Head and Shoulders shampoo (the kind that says on the container “itchy scalp care”) or Selsun Blue shampoo. Use either product three times a week for two weeks. To use the shampoos correctly, you need to massage them into the scalp and leave them on the head for five minutes before washing them off. If, after two weeks, the itching has lessened, you can use them less frequently.

While you’re at the store, buy Scalpicin. You’ll find it in the same section as the shampoos. It’s a liquid that contains cortisone. It can be applied to the scalp three or four times a day to curtail the itch. It’s most helpful in the early days of your treatment.

If, after two weeks, you notice little improvement, switch to Nizoral A-D, a shampoo that contains an antifungal medicine called ketoconazole. The fungus Malassezia is partly responsible for the itchiness.

If Nizoral fails, then you’ll have to see your family doctor for prescription medicines. Remember, other conditions like psoriasis and head lice cause itching, too.

DEAR DR. DONOHUE: I have been on statins for several years. When my cholesterol reached 282 mg/dL (7.3 mmol/L), I changed my diet and exercised more, but it did not get below 230. (Normal is 200 mg, 5.2 mmol.) My doctor insisted on my taking Crestor. It brought down my cholesterol, but I did not feel good after I started taking it. When I complained, the doctor changed me to Lipitor, which kept my cholesterol in check but made me feel bad, with no energy and easily tired. I stopped taking the medicine. My doctor was really upset. I went back on Crestor. Now I have to stop during my walk because I am tired and my legs ache. Why do you have to take these medicines for life? What should I do?

ANSWER: When diet, exercise and weight loss fail to lower cholesterol, then the only option is medicine. The statin drugs such as Crestor and Lipitor are the most reliable cholesterol-lowering medicines we have. They generally have to be taken for life, since they don’t enable the body to dispose of cholesterol on its own.

Making your diet almost a vegetarian diet — lots of vegetables, fruits and whole grains, and little red meats or whole dairy products — might budge your cholesterol. If it doesn’t, then medicines such as Questran, Colestid and Welchol can be tried. They are not related to the statin drugs.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.