Children's bones weaker; diet to blame?

An increase in children's consumption of soft drinks together with a decline in that of milk may be the cause behind a marked increase in forearm fractures in adolescents, suggests a new study.

Forearm fractures are on the rise among both adolescent boys and girls, according to a Mayo Clinic​ study published in the 17 September issue of the Journal of the American Medical Association​ (JAMA).

During childhood, the incidence of distal forearm fractures - those located near the wrist - typically peaks around age 12 in girls and 14 in boys. Previous studies have documented that most of these fractures occur around the time of the growth spurt during puberty.

"Our study examined whether these fracture rates have changed over time, and the data would indicate that there has been a substantial increase in these fractures,"​ said a concerned Dr Sundeep Khosla, a Mayo Clinic endocrinologist and the study's primary investigator.

Experts have theorized that forearm fractures that occur during adolescence are related to the fact that bones become more porous during growth spurts. However, Khosla says the fracture rate increase documented by her team paints a picture that requires further study.

"Our study does not explain why these fracture rates increased, but the data raise concerns about whether bone-mass development in today's children may be impaired by other lifestyle and dietary factors such as increased soft drink consumption, decreased milk consumption or changing patterns of physical activity,"​ commented Khosla.

Supported by the National Institute on Aging, the researchers recorded the number of forearm fractures that occurred in people under age 35 who lived in Rochester, Minnesota, during four defined time periods. A previous study had published these data from 1969-1971. Dr Khosla's team re-examined these data and looked at the same population 10, 20 and 30 years later in 1979-1981, 1989-1991 and 1999-2001.

The most significant finding according to Khosla was that the forearm fracture rate among young people increased by 42 per cent, from 263 per 100,000 people annually in 1969-1971, to 373 per 100,000 in 1999-2001. Mostly due to increased fractures among people under age 20.

From 1999-2001, girls between eight and 11 and boys between 11 and 14 had higher fracture rates than all other age groups studied. And 12-year-old boys had the highest fracture rate of all at 1.5 per cent per year.

The researchers also grouped the fractures by categories, including those caused by disease, serious trauma, or moderate trauma - such as a minor fall. The incidence of fractures associated with recreational activities almost doubled.

Adequate bone-mass development during childhood is critical to preventing osteoporosis and the related bone fractures that can occur later in life.

"Increasing rates for forearm fractures in children could mean we will see a dramatic increase in the risk for hip fractures and other more serious fractures when these children become older adults,"​ explained L. Joseph Melton, a co-investigator in the study and an expert on the epidemiology of osteoporosis.

This research follows findings revealed​ in August which suggested that the incidence of rickets - a disease usually attributed to a lack of vitamin D or insufficient exposure to sunlight - was on the rise in North American children, due to a lack of calcium in children's diets, also believed to be caused in part by the replacement of milk by other soft drinks.

Earlier this week Michael Jacobson, executive director of the Centre for Science in the Public Interest called for sodas in school vending machines to be replaced by healthier alternatives such as fruit juices or low fat milk.