Dairy has little benefit on children's bone health?
promote children's bone health, claim researchers in a review of
almost 40 studies investigating milk's benefit to bones.
Their findings conflict with current government recommendations in the US and UK to raise intake of dietary calcium by eating more dairy products in order to protect against osteoporosis.
Osteoporosis is second only to cardiovascular disease in terms of leading global health care problems, according to the World Health Organisation, and governments are preparing for rapidly rising cases of the condition as populations age and become increasingly heavier.
However the meta-analysis of research on calcium and bone health suggests that dairy products may not be the most effective way to stave off this disease.
In a review of 37 studies examining the impact of calcium consumption on bone strength in children older than seven, the team found 27 did not support drinking more milk to boost calcium.
"A clear majority of the studies we examined for this review found no relationship between dairy or dietary calcium intake and measures of bone health. In the remaining reports, the evidence was sketchy," said lead author Dr Amy Lanou, nutrition director for the non-profit organisation Physicians Committee for Responsible Medicine (PCRM).
The US-based group is known to be pro-vegetarian.
"In some, the effects on bone health were small, and in others, the results were confounded by vitamin D intake from milk fortified with vitamin D," added Dr Lanou.
The level of dairy product consumption in the United States is among the highest in the world but osteoporosis and fracture rates are also among the highest, noted the authors.
They believe that exercise and other calcium sources such as tofu and green vegetables could be better methods for protecting bone health among children. Previous studies have showed exercise to be more important than calcium intake.
The review also included 10 randomized, controlled trials of supplemental calcium, nine of which showed modest positive benefits on bone mineralization in children and adolescents.
"We found no evidence to support the notion that milk is a preferred source of calcium," write the authors in the March issue of Pediatrics (vol 115, issue 3, pp736-43).
In an accompanying commentary, Frank Greer, a pediatrician at the University of Wisconsin in Madison, said children should exercise and consume up to 1,300 milligrams a day of calcium. The easiest way to get that calcium is from low-fat dairy products, which also contain valuable nutrients such as vitamin D, generally not available from other dietary sources.
In an interview with WebMD, he pointed out that researchers still do not know if calcium intake during childhood and adolescence has a long-term impact on bone health and osteoporosis protection.
Hereditary factors also play a role in osteoporosis onset.