Pure Pamplemousse Is grapefruit bad for postmenopausal women? We don't want to jump to hasty conclusions, but here's how one theory goes: A component of grapefruit may inhibit the action of a type of protein that plays a role in estrogen metabolism. When estrogen is improperly metabolized, the resulting increase in estrogen could raise breast cancer risk in certain women. In a recent study from the University of Southern California that followed the dietary habits and medical records of more than 50,000 postmenopausal women, researchers found a link between daily grapefruit consumption and a 30 percent increase in breast cancer risk. If you're a postmenopausal woman with elevated estrogen, and if grapefruit is part of your daily diet, you might want to talk to your doctor about this study. But keep in mind that it's only one study, and it's not a clinical study, so even the USC researchers caution that it's far too early to assume a link between a daily grapefruit and breast cancer risk. Now - that said - I'll tell you about a study that puts grapefruit in a very different light. The leading cause of tooth loss in adults is gum disease - also known as periodontitis. As we've seen in previous research, gum disease has been linked to increased heart disease risk. In addition, aggressive treatment for advanced gum disease has been shown to significantly reduce C-reactive protein levels and other important heart disease markers. According to a study from Germany's Friedrich Schiller University, a couple of grapefruits each day might provide some assistance to aggressive treatment of periodontitis. Schiller researchers compared vitamin C plasma levels in nearly 60 subjects with chronic periodontitis and 22 healthy subjects. Levels were measured before the test period, and again after a two-week intervention in which each of the periodontitis patients ate two grapefruits daily. Results showed, first of all, that the periodontitis subjects had "significantly reduced plasma vitamin C levels" compared to the healthy subjects before the test period. And predictably, C levels were higher among the gum disease subjects after the test period. These subjects also had considerably less bleeding from the gums. In a statement about this study, Dr. Gordon Watson of the British Dental Association made this additional point for BBC News: "It reinforces the message that if you have enough vitamin C in your diet then it tends to promote healing." The Schiller study also offers insight into the unhealthy effect that cigarette smoking has on the gums. Researchers found that among the smokers who had periodontitis, vitamin C levels were about 30 percent lower compared to non-smokers with the disease. Smokers increased their C levels on the two-week grapefruit diet, but the levels were still much lower compared to non-smokers. Scientists don't know why smoking is linked to low levels of vitamin C. The explanation may be biological - smoking could impair C metabolism. Another theory is that smokers as a group may tend to have unhealthy diets. In either case we can chalk up "healthy gums" as yet another excellent reason to quit smoking. Sources:
"Prospective Study of Grapefruit Intake and Risk of Breast Cancer in Postmenopausal Women: The Multiethnic Cohort Study" British Journal of Cancer, Vo. 97, No. 3, 7/31/07, nature.com/bjc
"Grapefruit Consumption Improves Vitamin C Status in Periodontitis Patients" British Dental Journal, Vol. 199, No. 4, 2005, nature.com/bdj
"Grapefruit 'May Cut Gum Disease'" BBC News / Health, 12/25/05, news.bbc.co.uk National Cancer Institute, Vol. 96, No. 22, 11/17/04, jncicancerspectrum.oupjournals.org | 
