In a world-first bone density study, a group of children between the ages of three and 10 years, who had avoided cows' milk for a period of four months or more, were examined. The research found that almost 50 per cent of the group had already suffered one or more fractures.
Postgraduate human nutrition student Ruth Black, under the direction of Professorial Research Fellow Ailsa Goulding, carried out the study which was funded by the Health Research Council and New Zealand Milk.
"We were surprised by the severity of the low density in the children we studied, by the high number of young children we saw who had already broken bones – and by the fact that many were short and overweight, says Professor Goulding."
The short stature of the group was an unexpected finding. Several earlier studies have noted that milk supplementation is associated with height gain, while calcium deprivation may retard growth, says Professor Goulding. "Milk does contain active peptides which favour bone gain, so it may be a property of milk-avoidance, not just calcium deprivation, which contributes to the shorter stature and small bones of children who avoid milk."
The study is the first to measure bone density throughout the skeleton of a group of young children who have avoided cows' milk. Low density was found throughout the skeleton (forearm, hip, spine and total body) and many of the children had already broken bones after trivial falls, though the average age of the group was only six years.
Only eight per cent of the group met the daily guidelines for recommended calcium intake.
The study was unique in that any child who avoided milk was accepted, regardless of the reasons why. Half of the children studied reported suffering from allergy-like symptoms after ingesting milk while the other half abstained from drinking milk because they disliked the taste or their families did not provide milk at home.
Although 97 per cent of the parents of the children recognised that cows' milk was an important nutritional food for growing children, few sought advice on possible supplements from health professionals.
"It is essential that the diet should supply sufficient calcium for the needs of the growing skeleton", says Professor Goulding. "If children don't drink milk, they do need to step-up their calcium intakes from other sources. Children also need Vitamin D to efficiently absorb the calcium they consume."
Other authors of the study are Sheila Williams (Preventive & Social Medicine) and Ianthe Jones (Medicine). The research is being published in the American Journal of Clinical Nutrition this week.
For more information, please contact:
Professor Ailsa Goulding
Medical & Surgical Sciences
University of Otago
Ph: +64 3 474 0999 (ext. 8511)
Email: ailsa.goulding@stonebow.otago.ac.nz
Serena Gill
Media Specialist
University of Otago
Ph: +64 3 479 5415
Mobile: +64 3 27 279 7223
Email: serena.gill@stonebow.otago.ac.nz
Journal
American Journal of Clinical Nutrition