"We always tell women to take calcium and vitamin D," said Dr Michele Curtis, a women's health researcher from the University of Texas Health Science Center at Houston. "At the end of the day what this study really says is, what you thought was a good thing to do really is a good thing to do."
Because of the known risks of hormone therapy, one of the study's authors said women should not take it solely to ward off fractures – but if they're taking hormones for other reasons, it might be a good idea to add calcium.
Although many women take calcium and vitamin D for bone health, evidence has been mixed on how much supplements really help over and above what women get through their diets. In February, the government-backed US Preventive Services Task Force said there were no benefits but some risk for post-menopausal women taking low-dose vitamin D and calcium.
The group recommended against supplement use to prevent broken bones. For the new study, Jean Wactawski-Wende from the University at Buffalo and her colleagues compared seven years' worth of fracture data for women in their 50s, 60s and 70s participating in the Women's Health Initiative (WHI) study.
In one arm of the trial, participants were randomly assigned to take either hormone therapy or a drug-free placebo. In another, they took 1 000 milligrams of calcium and 400 IU of vitamin D or placebo tablets each day. About 16 000 women were part of both the hormone and vitamin trials, including 4 000 randomised to both hormone therapy – either oestrogen alone or oestrogen and progesterone – and calcium and vitamin D.
Fractures dropped by 50%
In total, 214 women had a hip fracture during the study. The researchers found that women assigned to both the hormone therapy and vitamin groups were about half as likely to have a fracture as those in the placebo groups. During an average one-year period, they calculated that 11 out of 10 000 women taking both hormones and calcium and vitamin D would suffer a hip fracture, compared to 22 per 10 000 using neither.
However, the combination treatment had no effect on women's bone mineral density – a reflection of osteoporosis and fracture risk, Wactawski-Wende and her team reported in the journal Menopause. Some previous studies have suggested that vitamin D may protect against fractures less by strengthening bones than by improving muscle strength and thereby reducing falls, but others have not found the same effect.
Hormone therapy has become less common since WHI data linked hormone use to heart disease, stroke and breast cancer, though it's still considered the most effective treatment for some symptoms of menopause, such as hot flashes. Curtis, who wasn't involved in the new research, said she thinks the pendulum initially swung too far away from hormone therapy, and that doctors are coming to realise it may still help some women.
"I think ultimately people have become aware that maybe it's
not the placebo for getting older that some may have perceived it was being
marketed as, but that maybe there are benefits for it," she told Reuters
Health. Because of the risks, women shouldn't take hormone therapy just to
prevent fractures," Wactawski-Wende said.
"The major indication for taking hormone therapy is for management of moderate to severe menopausal symptoms," she told Reuters Health. "However, those women who are on hormone therapy for vasomotor symptoms, who may also get the benefit of prevention of fractures, should consider supplementing with calcium at the same time to get the best benefit," she said.