Soy Benefits May Have Age Cutoff
Health Protection Escape Women When Supplements Started After Age 60
No Change After 1 Year continued...
"By the time you reach 60, so much of that estrogen-related bone loss has already occurred that I'm not convinced you can get it back -- with soy or anything else," Messina tells WebMD. "The effect soy might have on cognitive function [such as thinking and memory] is questionable anyway, so I wouldn't expect to see much there. And despite some early studies, more recent research shows that soy's benefit on cholesterol is modest, and it usually seen mostly in those with high cholesterol."
Like Kreijkamp-Kaspers, Messina, who writes a soy newsletter distributed to 70,000 dieticians, suggests that timing could play a role in how much benefit women get from soy-rich foods or supplementation.
"Giving the preliminary data that is encouraging but certainly not definitive, I have no problem telling women that when they hit menopause, they should definitely consider adding some soy or other sources of isoflavones in their diet -- especially if they're concerned about their bones," he says.
What We Know About Soy
Past studies show that regular consumption of soy can reduce hot flushes by as much as 50%. And following menopause, daily soy consumption in the 25-gram per day range has been shown to improve cholesterol levels by about 8%, enough to prompt both the FDA and American Heart Association to tout soy as being heart-healthy. In one study last year, regular soy consumption benefited people with high cholesterol as well as aided their prescription cholesterol-lowering statin drugs. But many critics have said that these studies included only a small number of people and their findings cannot be generalized to the population. Others have said that these studies are of poor quality.
Meanwhile, other studies show that soy supplements at similar amounts in Kreijkamp-Kaspers' study, can keep bones strong -- even after menopause -- and one study even showed that a soy-rich diet could halve a woman's risk of breast cancer following menopause, when it typically skyrockets.
However, Kreijkamp-Kaspers tells WebMD that many of those studies also included premenopausal women, as well as men, or tracked postmenopausal women who may have started taking soy before they reached menopause. "There is very little data that looks at starting soy supplementation only on women after they have already gone through menopause," she says.
But despite her findings, even she isn't suggesting that women shelve the notion that soy can help them. "I certainly wouldn't recommend that women begin taking soy postmenopause," she says. "But if they have started it before menopause and seem to get some benefit from it, there certainly can continue because soy poses no harm that we know of. However, as it relates to preventing several aspects related to aging, the timing of when you start taking soy does seem to play a role."