WHI study not waste of money, says women's health group
media outlets as questioning the link between calcium and bone
health has led to an exercise in damage limitation; women's health
experts convened this week to discuss the results, and to reassure
policy makers that funding such studies is money well spent.
The Women's Health initiative calcium and vitamin D supplement trial was published in the New England Journal of Medicine (February 16 2006, 354;7). It showed a "small but significant" benefit in hip bone density in healthy postmenopausal women, no significant reduction in hip fracture, and increased risk of kidney stones.
However these conclusions, reported in the abstract, were seen across the 36,282-strong study population (women aged 50 to 79 years) as a whole. In the body of the paper the researchers reported a 21 reduction in hip fracture risk in women over 60, and a 29 percent decrease in hip fracture risk amongst all the women who actually complied with supplementation as directed by the study (more than 80 percent of supplements taken).
The WHI study also suggested that there should be no changes to the recommended daily intake of calcium and vitamin D - 1,200mg and 800 IU per day respectively.
Phyllis Greenberger, president and CEO of the Society of Women's Health Research, which convened experts on Capitol Hill on Monday, told attendees that the $725m government funding for the WHI study - which also covered other aspects of women's health - was "a wise investment".
"We have gained a tremendous amount of information, much of which is still being analysed. We need to build upon the WHI research that further pinpoints the keys to preventing, diagnosing and treating conditions such as heart disease, fractures, and breast and colorectal cancer, which increase substantially in women as they reach their menopausal and post menopausal years."
The gulf between the actual findings and the way in which they were reported was seen to be a classic example of poor standards in science journalism, where time-pressed journalists may not look beyond the original communication or abstract.
The society said that this led to confusion amongst both doctors and consumers.
"It is important to remember that this was a tremendously complex research study," said Greenberger. "Unfortunately science does not work in sound-bites. Headlines that grab attention rarely tell a story completely or accurately."
Other members of the scientific community also reacted to the negative reports of the study's findings.
In an interview with NutraIngredients.com Roger Francis, professor of geriatric medicine at the University of Newcastle, said that the study "shows that vitamin D and calcium supplementation would not work as a public health measure, because vitamin D - calcium trials have notoriously poor adherence."
Professor Francis pointed out however that an earlier French study (Scand J Rheumatol Supp. 1996 Vol. 103, pp. 75-78) reported that calcium and vitamin D supplements given to elderly women significantly reduced the risk of hip fracture. This sample population was much older than the WHI population.
The US 2005 dietary guidelines recommend consumption of three cups of milk products a day. Individuals who are unable to get enough calcium and vitamin D through foods are advised to speak with their doctors about supplementation.
Osteoporosis is estimated to affect about 75 million people in Europe, the USA and Japan. According to the International Osteoporosis Foundation, the total direct cost of osteoporotic fractures is € 31.7 billion in Europe, and $17.5 billion in the US (2002 figure).
