Claims that breast-feeing reduces risk for childhood obesity may go too far

Breast-feeding is widely encouraged for its many positive health effects, but the claim that it reduces the risk for childhood obesity may be going too far. A randomized trial following children through age 11 has found that even long-term exclusive breast-feeding has no effect on obesity or stature in childhood.

Researchers studied more than 13,000 breast-feeding mother-infant pairs in 31 maternity hospitals in Belarus in 1996 and 1997. About half the mothers were assigned to a breast-feeding promotion program developed by the World Health Organization, while the rest received usual care. At three months, 43 percent of the women in the WHO program were still exclusively breast-feeding, compared with 6 percent in the control group; by six months, the figures were 7.8 percent for those in the program and 0.6 percent for the controls.

The study, published in the Journal of the American Medical Association, found no significant effect on either the weight or height of the children. The senior author, Dr. Emily Oken, an associate professor at Harvard, stressed, "There are lots of good reasons to breast-feed."

Researchers report that a woman's regular use of aspirin may decrease her risk for melanoma, the most serious kind of skin cancer. The study, published online last week in the journal Cancer, included 59,806 women ages 50 to 79. There were 548 incidents of melanoma during the 12-year period. The researchers found that women who reported using aspirin had an average 21 percent lower risk of melanoma compared with nonusers, and the longer they used aspirin, the lower their risk. The reasons for the effect are unclear, but the authors — led by Dr. Jean Y. Tang, an assistant professor at Stanford — suggest that aspirin's known effect in promoting cell death and activating tumor suppressor genes may be factors.

There is more cautionary news for the world's most advanced malaria vaccine. A new study in Kenyan children shows that its protection wanes over time, dropping to near zero after four years. The results, published in the New England Journal of Medicine, are another strike against the chances that the vaccine — called RTS,S — will be widely used in its current form. But the news is not all dim. Because so many children get malaria in the region and many get it multiple times, the researchers calculated that for every 100 children vaccinated, 65 cases of malaria were prevented.