TUESDAY, Dec. 23 (HealthDay News) -- Doing weight-bearing exercise during adolescence may help women maintain their bone strength in old age, a new study says.

Published online Dec. 22 in the British Journal of Sports Medicine, the Japanese study drew its conclusions by looking at the teenage exercise habits of 46 postmenopausal women, now aged 52 or older.

Those who had participated in low-impact, weight-bearing exercise, such as swimming, while younger had significantly greater bone mineral content in both the spine and the thigh bone. The other women in the study had either played more high-impact sports in their youth that involved running or jumping, such as volleyball or tennis, or no sports at all.

Those in the weight-bearing group also had larger outer femoral bone area, which would help protect them more from fracture during pressure from movements, such as bending.

As none of the women with the strongest bones were taking part in any weight-bearing exercise programs at the time of the bone density study, the Suzuka University of Medical Science authors suggest their exercising in their youth helped them more than 40 years later.

More information

The U.S. Department of Health & Human Services has more about preventing osteoporosis.

FRIDAY, Dec. 19 (HealthDay News) -- Restricting the availability of unhealthy snacks in elementary schools led to a small increase in fruit and vegetable consumption among fifth-graders, a new study found.

The roughly 3 percent increase in fruit and vegetable intake among those children in schools that restricted the availability of snacks was still significant, said study co-author Edward A. Frongillo, chairman of the University of South Carolina's department of health promotion, education and behavior.

When school policies limit the availability of high-fat and high-sugar snack foods, even a small percentage increase in fruit and vegetable consumption among fifth-graders means the policy may affect a fairly large number of children throughout the school, Frongillo said.

The findings were published in the January 2009 issue of The Journal of Nutrition.

The study surveyed 10,285 fifth-graders at 2,065 elementary schools nationwide. School administrators reported on snack-restriction policies and snack availability from vending machines, school stores, snack bars and cafeterias.

The children themselves reported on their fruit and vegetable consumption for the entire day, not just during school hours and not just snacks.

"What the data are saying is that children's experience in one part of their day is having an impact on the whole of the day," Frongillo said. "The implication isn't that there are bad ways to provide food to children. The real issue is, are we modeling in the foods we make available to children what they should be eating?"

Lona Sandon, a spokeswoman for the American Dietetic Association, challenged that theory about children's eating habits.

"In elementary school, they really model [follow] what their parents are doing. Once they get into junior high, they may begin to make a little bit more choices on their own," she said.

If parents don't eat fruits and vegetables at home, their children "are probably not going to start eating them in school," added Sandon, who is a registered dietitian and an assistant professor at the University of Texas Southwestern Medical Center at Dallas.

"Snack policies are not intended to make them eat more fruits and vegetables. They're intended to cut down on added sugar and calories that lead to childhood obesity," she said.

Sandon also said school cafeteria services get an "awfully bad rap. The kids are only eating one meal at school, and they are only at school one third of their day."

Snack policies have become part of the national debate on childhood obesity. A recent Temple University study showed that three-quarters of middle schools in their nationwide sample of 42 schools have vending machines that dispense snacks and sugared drinks.

Another study earlier this year by Mathematica Policy Research in Cambridge, Mass., found that only about 17 percent of elementary schools have vending machines, while 82 percent of middle schools and 97 percent of high schools have them.

School breakfasts and lunches that receive federal subsidies have to meet federal nutrition guidelines, said Sonya Jones, a co-author of the new study and an assistant professor at the University of South Carolina department of health promotion, education and behavior.

"Elementary school meals sort of reflect what we think a healthy lunch or breakfast looks like, and children are developing those habits as part of their development," she said.

More information

The U.S. Centers for Disease Control and Prevention has more on childhood obesity.

MONDAY, Dec. 15 (HealthDay News) -- Certain people just may be destined to be obese, based on the discovery of six additional genetic variants tied to people with higher body mass index, a new study says.

The study by an international consortium, published online Dec. 14 in Nature Genetics, adds to previous research that linked two other genetic variants to obesity.

"One of the interesting things is that the genes near these variants are all active in the central nervous system, suggesting that inherited variation in appetite regulation may have something to do with people's predisposition to obesity," study leader Dr. Joel Hirschhorn of Children's Hospital Boston and the Broad Institute of Harvard and MIT, said in a news release issued by some of the consortium participants.

The study, by the Genetic Investigation of Anthropometric Traits (GIANT) consortium, concluded that each individual known variant had a small but cumulative effect on a person's BMI, a ratio of weight to height. In all, it added up to an average of 10 pounds in those with most of the variants, compared to those with the fewest. However, Hirschhorn said the researchers may have found only a handful of possibly hundreds of genetic regions that made such small contributions to one's weight, and more studies would be needed to uncover them all.

"As we learn more about what some of the genes in these regions do, we hope that these discoveries might suggest routes to new therapies for obesity," joint first author of the study, Dr. Elizabeth Speliotes of Massachusetts General Hospital, said in the news release.

Previous studies in families or twins have found that genetics account for up to 70 percent of BMI variation in the general population.

The World Health Association estimates that more than 1 billion adults worldwide are overweight, with at least 300 million of them classified as obese (having a BMI of 30 or above).

More information

The American Heart Association has more about body mass index.

FRIDAY, Nov. 14 (HealthDay News) -- Eating peanuts early in life may help prevent development of peanut allergy, according to a study that casts doubt on government health recommendations that infants and new mothers shouldn't eat peanuts.

The researchers examined the incidence of peanut allergy in 8,600 Jewish school-age children in the United Kingdom and in Israel. They then compared the results with data on peanut consumption by infants ages four to 24 months.

The prevalence of peanut allergy was 1.85 percent among the U.K. students and 0.17 percent among the Israeli children, said the study, which also found that 69 percent of Israeli children were eating peanuts at nine months of age, compared to only 10 percent of the British children.

"The most obvious difference in the diet of infants in both populations occurs in the introduction of peanut," wrote lead author Dr. George Du Toit and colleagues. But they cautioned that more research is needed before the U.K. and other countries change their guidelines that advise avoidance of peanut consumption during pregnancy, breast-feeding and infancy.

The study was published in the November issue of The Journal of Allergy and Clinical Immunology.

While these findings are promising, they shouldn't prompt any immediate changes, cautioned the American Academy of Allergy, Asthma & Immunology (AAAAI). There are a number of other factors that may explain the differences in peanut allergy prevalence between Israel and the U.K.

"While this study's findings provide optimism for prevention of peanut allergy in the future, randomized, controlled trials are needed to verify that early introduction of peanut is indeed effective," Dr. Jacqueline A. Pongracic, vice chair of the AAAAI's Adverse Reaction to Food Committee, said in an academy news release.

More information

The Nemours Foundation has more about nut and peanut allergy.