CASE STUDY: BRAIN GUM.

Active Ingredient: Phosphatidyl serine (PS), a fat-like substance extracted from soybeans that is also found naturally in brain cells, where it may help the flow of nerve impulses.

The Promise: Chewing Brain Gum will help most adults, especially "mature" ones, remember names, faces, phone numbers, information, and where they put their eyeglasses or keys.

Does It Work? Research suggests that PS extracted from cow brains or soybeans may help--but not cure--people who have greater than average memory loss for their age. Since age-related memory loss doesn't strike everyone, and since not everyone with age-related memory loss responds to PS, the company's claim that most adults would benefit from chewing Brain Gum is bunk.

The Fine Print: In the successful studies, volunteers took 300 mg a day of PS for at least a month (see "Fear of Forgetting," May 1997, p. 3). Brain Gum's manufacturer, KR Research Inc. of Reno, Nevada, recommends starting with 250 mg a day--six pieces of gum--for three weeks, then dropping to a "maintenance" dose of 85 mg--two pieces--a day. The bill: $60 the first month and $25 every month after. Unfortunately, no good studies have looked to see what minimum dose of PS is effective.

Is It Safe?: PS is found naturally in the body and in food (though in much smaller quantities). No long-term safety studies have been done, but researchers haven't seen side effects when people take it as a supplement.

The Bottom Line: The evidence for PS is better than the evidence for any other "memory-boosting" dietary supplement. But it's only been tested on people who have greater than average memory loss (not on just anybody who wants to think more sharply), it doesn't help everyone with that condition, and it's not cheap.