Placebo response may be at work on reader's leg cramps

Dr. Keith Roach M.D.

DEAR DR. ROACH: I was a bit surprised that in your response to a question about coping with nighttime leg cramps some time ago, you made no mention of vitamin E. I was troubled with these painful cramps increasingly often and tried both calcium and magnesium supplements without evident improvement. I then saw mention of using vitamin E (a long time ago so I don't recall where), and tried 400 IU at bedtime with some improvement, then 800 IU, which soon resulted in complete cessation of the cramps. This has continued now for several years. I mentioned this to my doctor, who said that many of his patients benefit from using vitamin E for cramps. Vitamin E is so benign that I hope you will consider mentioning this in your column. -- E.H.

      ANSWER: A well-done trial back in the 1990s showed no benefit in using vitamin E to reduce leg cramp frequency, severity or sleep disturbance, despite a benefit having been seen in a trial from the 1970s. Still, you saw improvement, and your doctor has said he has also. 

       There may be two possibilities for this. The first, I have often discussed: the placebo response. Placebos are very powerful at improving symptoms. Up to a third of people in many trials across many types of medical problems will have improvement when taking a placebo tablet, and strangely, placebos can also work even if the person knows they are taking a placebo. Physicians benefit from the placebo response every day. We prescribe a medication to help relieve a symptom, our patients (sometimes) get better and we take the credit. Sometimes, the apparent benefit is a placebo response, and our patient would have gotten better with an inactive pill.

       Another possibility is that vitamin E helps some people, but not enough to show a benefit in a medical trial. In that case, identifying who would be likely to benefit is the key to successful prescribing. Two trials showed benefit in people on hemodialysis, for example. Of course, even a well-done trial may be inadequate to show a relatively small benefit.

       While vitamin E is mostly benign, it does increase the risk of prostate cancer, at least at an 800 IU per day dose. I recommend against high doses of vitamin E in men at risk for prostate cancer. Otherwise, vitamin E is certainly worth a try.

       The most effective preventive therapies for nocturnal leg cramps remain moderate exercise, daily stretching, proper foot gear and avoiding dehydration. Many people have written that keeping blankets and sheets untucked or loosely tucked has made a big difference.

      DR. ROACH WRITES: A recent column on dosing of over-the-counter drugs used aspirin as an example of dosing by weight and age. A pediatric nurse practitioner wrote with the concern that aspirin should be avoided in children under 16 due to the risk of Reye's syndrome. I would add that the risk of Reye's syndrome is highest in children and teens with influenza or chickenpox. I recommend against aspirin for children, except under orders of the child's pediatrician.