The study published in JAMA Pediatrics, examined the association between remembered teenage milk consumption and risk of hip fracture at older ages in a study of more than 96,000 men and women with a follow-up of more than 22 years.
Led by Diane Feskanich of Brigham and Women's Hospital and Harvard University, the authors noted that while drinking milk during adolescence is recommended to achieve peak bone mass, the role of milk consumption in reducing the risk of hip fractures later in life has not been established.
Indeed, the team that drinking more milk is associated with attaining greater height, which is a risk factor for hip fracture.
Feskanich and her colleagues reported finding that teenage milk consumption (between the ages of 13-18 years) was associated with an increased risk of hip fractures in men, with each additional glass of milk per day as a teenager associated with a 9 percent higher risk.
"We did not see an increased risk of hip fracture with teenage milk consumption in women as we did in men," said the authors. "One explanation may be the competing benefit of an increase in bone mass with an adverse effect of greater height."
"Women are at higher risk for osteoporosis than men, hence the benefit of greater bone mass balanced the increased risk related to height," they suggested.
Study details
Feskanich and her team assessed the frequency of milk consumption along with consumptio nof other foods during ages 13 to 18 years, which along with height were reported at baseline.
During the 22 year follow up, current diet, weight, smoking, physical activity, medication use, and other risk factors for hip fractures were reported on biennial questionnaires.
During the follow-up, 1,226 hip fractures were reported by women and 490 by men.
Analysis of the data suggested that milk consumption was not associated with hip fractures in women, but that an association between drinking milk and hip fractures in men was partially influenced by height.
Cheese intake during teenage years was not associated with the risk of hip fracture in either men or women.
Gender differences?
In a related editorial, Dr Connie Weaver of Purdue University commented that a main tenet of Feskanich and colleagues is that milk consumption in teens may have led to an increase in height as an adult - noting that it is not clear why this would be true in men but not women, "especially given that men experience about one-fourth the hip fractures that women do."
"The investigators could have tested the contribution of other dietary protein sources (eggs, meat) to height and subsequent fracture risk to help confirm the impact of dietary protein more generally," Weaver added.
"Practically speaking, does the study by Feskanich and colleagues offer a solution to osteoporosis? Without dairy, dietary quality is compromised. If milk intake in teens contributes to height, and therefore fracture risk in older men, who among men aspire to be shorter?" she concluded.
Source: JAMA Pediatrics
Published online ahead of print, doi:10.1001/jamapediatrics.2013.3821
"Milk Consumption During Teenage Years and Risk of Hip Fractures in Older Adults"
Authors: Diane Feskanich, Heike A. Bischoff-Ferrari, et al