Doctors keep promoting osteoporosis treatments that aren't working and corporate sponsorship might be the cause, new research says.
In a study published in the British Medical Journal, University of Auckland researchers have found calcium and vitamin D supplements - often prescribed to treat or prevent the medical condition - do not seem to help with reducing bone breakages.
The study looked at 38 clinical trials on the supplements from between 2002 and 2010, and found 32 of them reported no benefits - with some reporting harm.
"Despite this, many practice guidelines continue to recommend increasing calcium intake and/or the use of vitamin D supplements for managing osteoporosis," Professor Andrew Grey, one of the study's authors, said.
The researchers also looked at why the treatments were promoted and found several industries, including the dairy industry, were sponsors of prominent osteoporosis advocacy organisations around the world.
"Such companies also sponsor medical societies and groups of academic experts in the osteoporosis field. These conflicts of interest are often not declared," Dr Grey said.
The study calls for greater transparency around payments from the supplement industry to medical practitioners and academics.
Osteoporosis is a condition that causes bone-brittleness and is often caused by calcium and vitamin-D deficiency or hormonal issues.
Global annual sales of calcium supplements in 2013 amounted to about $6 billion, the study found.