DEAR DR. DONOHUE: I am 84, 5 feet 10 inches tall, and my weight ranges between 175 and 185. My calorie intake varies between 2,275 and 2,950. What are the acceptable limits of caffeine, cholesterol, sodium and sugar? I’m a label reader and am continually confused. How many grams are in 1 teaspoon? – F.S.

ANSWER: I take it you’ve managed to get 84 years under your belt without any great health problem. Whatever you’re doing, keep doing it. However, since you asked, I’ll answer.

Caffeine: two to four cups of coffee a day are acceptable.

Cholesterol: 300 mg a day. Most of blood cholesterol doesn’t come from cholesterol in food; it comes from our liver’s production of it. Saturated fats – the fat in red meat and in dairy products – jump-start the liver’s production of cholesterol, so those fats are the ones you have to limit. Only 7 percent to 10 percent of your total daily calories should come from saturated fat. For you, that translates into 20 to 28 grams. (Thirty grams is 1 ounce.) You have to watch out for trans fats, too. They’re the fats found in fried foods from many fast-food restaurants (although there’s a push to eliminate them) and in commercial baked goods. (The trans fat content is listed on labels.) Eliminate trans fats.

Sodium has different recommendations. The American Heart Association says the daily limit should be 2,400 mg (6,000 mg of salt, sodium chloride). One teaspoon of salt is 2,400 mg of sodium. The Institute of Medicine sets the limit at 1,500 mg, three-fifths of a teaspoon. The greatest source of sodium is salt in processed foods, commercial soups, frozen dinners and luncheon meats.

Sugar: Sugar has an undeserved bad name. In moderation, it’s fine. It promotes tooth decay and provides no nutrition other than calories. One teaspoon has 16 calories. A person whose total daily calories are 1,600 should consume only six teaspoons of sugar a day; one whose total calories are 2,800, 18 teaspoons. That sugar is sugar in all foods, not just the teaspoons of sugar added to coffee or tea or whatever. Many soft drinks contain nine to 12 teaspoons in 12 ounces, about a whole day’s limit in one can.

One teaspoon is the equivalent of 5 milliliters and 4 grams.

DEAR DR. DONOHUE: My mother had Alzheimer’s, and my wife is taking medicine for Alzheimer’s. I am told that there is no medicine cure but that medicine can slow the process down. I am concerned about my daughter and granddaughter inheriting it, and I asked our doctor if they should be taking the same medicine as my wife as a preventive measure. He said, “That’s a good question for Dr. Donohue.” – H.P.

ANSWER: It is a good question, but not a good idea. There are only a few instances where so-called prophylactic medicines work in preventing illness. No one has ever demonstrated that Alzheimer’s medicines prevent the illness in those who don’t have it but do have a family history of it. The slightly increased risk of coming down with Alzheimer’s doesn’t justify the risk of taking medicines whose prevention efficacy is unproved.

The Alzheimer’s booklet touches all aspects of this distressing illness. To order a copy, write to: Dr. Donohue – No. 903, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I developed a rapidly spreading rash on my chest, abdomen and back. It started with one large spot. A few weeks later, I broke out in a rash of smaller spots. The diagnosis was pityriasis rosea. I had never heard of it. The doctor said it would go away without treatment. What causes it? I’m 55. – D.B.

ANSWER: A virus causes it, and the ones usually stricken are older children and young adults. It begins with one large patch, the herald patch, which is followed in a week or two by an outbreak of smaller, oval, salmon-colored patches on the trunk, neck, thighs and groin. For most, it’s gone in three to eight weeks. It can be moderately itchy.

If it’s not bothersome, no treatment is needed. If it itches, cortisone lotions or creams curb the itchiness.

DEAR DR. DONOHUE: Please pass this information along to your readers who are myopic, so that they don’t have to endure the suffering I did. I had a retinal detachment two months ago. I am myopic, and my long eye stretched my retina beyond its limit, and it tore. Tell your myopic readers to have their eyes checked regularly for any signs of tearing. If it is repaired early, the repair usually is successful. – W.L.

ANSWER: About one in four adults have myopia, nearsightedness. Nearsighted people see blurry images in the distance but can see things up close well. They are sighted for near objects. They have elongated eyeballs, a genetic trait. Light that enters such eyes comes to focus in front of the retina. Clear vision demands focus directly on the retina. Glasses, contact lenses and lasers that reshape the cornea can focus incoming light correctly on the retina.

The retina is the light-sensitive layer that covers the back of the eye. A retinal detachment is a peeling away of that layer. It’s a bit like wallpaper coming off a wall. When the retina detaches, people see flashes of bright light, or they experience a shower of floaters – tiny black dots that dart around the field of vision. A shadow or curtain falls across what’s seen. These are signs that immediate attention is needed so that the eye doctor can tack the retina back in place with a laser.

Nearsighted people with elongated eyeballs are more apt to develop a retinal detachment than are people whose eyeballs are of normal length. I’m sure your warning will be appreciated by the millions of people who suffer with myopia.

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