A recent study found that milk consumption during one's teenage years may have little or even negative impact (for men) on the risk of future hip fractures, U.S. Health News reported. The results, which haven't established a causal relationship and thus are being explained mostly by hypothesis (according to lead study author Diane Feskanich), were published Nov. 18 in the latest issue of the online journal JAMA Pediatrics.

Feskanich, an assistant professor in the department of medicine at Brigham and Women's Hospital and Harvard Medical School, admitted she didn't "consider this to be a definitive finding that would change the public-health message concerning milk at this point." Still, she contends that her study was unique and a starting point for future research.

"Even though we're very focused on milk in this country, we don't really have studies that have documented how people drink milk as kids and then have waited 50 to 60 years to see what happens to their bones," Feskanich pointed out.

Her work didn't suffer from lack of participants and dedication. Feskanich and colleagues polled nearly 100,000 white men and women, middle aged or older, on their teenage milk drinking habits, according to U.S. Health News. They found that men drank approximately 2.1 cups of milk per day to women's 1.6 during their respective teenage years. They subsequently tracked them for 22 years, documenting 490 hip fractures among men and 1,200 among women.

"What we found was a little surprising," Feskanich said, given that 95 percent of adult bone mineral content is accrued during adolescence, according to the study. "Teen milk consumption was associated with a higher fracture risk among men, but not women."

Controlling for related factors like diet, weight, smoking history, exercise patterns, and current milk-consumption habits, the researchers found that for every glass of milk drunk per day above average (above 2.1) a man's risk for future hip fracture increased by nine percent, indicating a two-glass sweet during one's teenage years, Medical News Today reported.

Milk spurs growth, which could explain why men, who tend to grow taller than women, were more at risk for future hip fractures than women - hip fractures being more common in taller people, according to Feskanich.

"The gender difference might be explained by several things," Feskanich said. "Difference in when women attain full height and maturity, or the fact that bone density is a bigger issue for men than women -- perhaps more of an issue than height. But at this point we're just hypothesizing."

Even if Feskanich's research isn't definitive enought to declare a causal relationship between excessive milk during one's teenage years and a greater risk for future hip fractures, the finding is interesting by the fact that it didn't find the expected result: that more milk early is a natural defense against later hip problems -- and makes that finding less likely to be true.