To Your Health

Q: When I picked up a prescription a few days ago, my pharmacist advised me not to use grapefruit juice while I was taking the medication. Why would that make any difference?

A: Grapefruit juice is a unique source of a bioflavonoid known as naringin. Other citrus fruits do not contain significant amounts. Naringin is known to impair a specific liver enzyme that our bodies use to destroy foreign chemicals that make their way into our bodies. Ordinarily this is exactly what we would want, but sometimes a physician needs to know rather precisely how much medicine to use. Reduced activity of this enzyme, which results from drinking grapefruit juice, makes it more difficult to estimate the amount you need. Refraining from grapefruit juice consumption for a couple of weeks reduces this uncertainty and enables the physician to judge the correct dose more accurately.

Interestingly, about a pint per day of grapefruit juice is sometimes recommended to prolong the activity of certain expensive drugs. Taking advantage of the ability of naringen to interfere with the destruction of these expensive drugs allows smaller (and thus less expensive) amounts to be used.

Grapefruit juice can be included in a varied diet in more moderate amounts without changing the ability of your liver to function properly. A glass of grapefruit juice at breakfast 3-4 times a week can be a pleasant alternative to orange juice and will have only benefits. Naringin is one of the bioflavonoids that help protect us against cancer (breast cancer in particular), so any time you are not taking a prescription medicine there is no harm in enjoying grapefruit juice.

Q: I plan to have LASIK eye surgery to correct my vision. Is there anything I should do, nutritionally, beforehand?

A: LASIK surgery (Laser-Assisted In Situ Keratomileusis) is one of two popular laser techniques used to correct the shape of the cornea. (PRK, or PhotoReactive Keratectomy, is the other.) Both procedures have a high success rate. However, surgery of any sort is inevitably damaging to surrounding tissues and it pays to be prepared. Since anesthesia is not used, you should concentrate on using the nutrients involved in healing the injured tissues, which include vitamin C and zinc. Supplements of vitamin C in the range of 2,000-3,000 milligrams (mg) per day and zinc in the range of 40-60 mg per day would be safe. Use both these nutrients for a few weeks before and a few months after the surgery.

The laser used in the surgery, although it doesn't generate the heat that other lasers do, does generate free radicals. Free radicals are damaging to all tissues and antioxidants protect us against free radicals from any source. Vitamin C is a good antioxidant, but it alone is not sufficient to protect against these free radicals. Recent research reports that vitamin A (25,000 IU/day) and vitamin E (230 mg/day) improved the outcome of PRK surgery would be likely to also do so for LASIK surgery. In this experiment, the healing of the cornea was significantly faster among those who took the vitamin combination, compared to those who took a placebo (a dummy pill). The appearance of a haze on the cornea, a common side effect of this surgery, was also significantly reduced among the vitamin takers. Participants who took the vitamins also saw more clearly; this benefit was most dramatic among those whose vision problems were the most severe.

You can anticipate improvement in vision from LASIK surgery with fewer complications if you invest in some nutritional preparation for surgery in the form of vitamin C, vitamin E, vitamin A, and zinc supplements.