By Steven Bratman, M.D.
For the last several years, natural treatments with good evidence behind
them have been the subject of major media exposure. St. John's wort,
ginkgo, and saw palmetto are among the most well known. The evidence
that these treatments really work has become so strong that even
mainstream medicine now takes them seriously.
Sooner or later, the media will run out of proven natural treatments to
write stories about at least until further research identifies others.
But there is one dietary supplement with great evidence behind it that
still remains to be popularized: ipriflavone. The science behind this
treatment for osteoporosis is truly impressive. However, most people
haven't heard of it yet.
Ipriflavone is related to substances found in soybeans called
phytoestrogens. These chemicals act somewhat like estrogen. Ipriflavone
also acts like estrogen, but only in one specific way: it keeps bones
strong. Unlike estrogen, ipriflavone does not appear to affect breast
and uterine tissue.
This is ipriflavone's significant potential advantage over estrogen.
Estrogen increases the risk of uterine and breast cancer, however,
ipriflavone probably does not.
Numerous double-blind placebo-controlled studies involving a total of
more than 1,300 participants show that ipriflavone can slow the
progression of osteoporosis, and perhaps even reverse it to some extent.
For example, a 2-year double-blind study followed 198 postmenopausal
women who showed evidence of bone loss. At the end of the study, there
was a gain in bone density in the ipriflavone group, while people in the
placebo group lost bone mass. Numerous other studies have found similar
A recently published study shows that ipriflavone is even effective
during the first couple of years following menopause, the period of most
rapid bone loss for women. In this double-blind trial of 60 women in
early menopause, treatment with ipriflavone substantially prevented loss
of bone in the spine, as compared to treatment with calcium supplements.
(Calcium supplements can help slow bone loss, but not effectively enough
to protect the spine during the first few years after menopause.)
In addition, this study provides evidence on how ipriflavone works to
prevent osteoporosis. The body is always remodeling bone, simultaneously
building it up and breaking it down. It appears that ipriflavone mainly
works by slowing down the bone breakdown part of this equation (as does
estrogen and most medical therapies for osteoporosis). The net result is
preservation of bone mass against the forces leading to osteoporosis.
Dosage and Safety
The usual dose of ipriflavone is 200 mg 3 times daily, or 300 mg twice
Thousands of people have used ipriflavone in clinical studies, with no
more side effects than the participants taking placebo. However, there
are some potential risks with this generally safe supplement.
Ipriflavone can interfere with certain drugs by affecting the way they
are processed in the liver. For example, it could raise blood levels of
the asthma drug theophylline. It could also raise levels of caffeine and
theobromine (a chemical in chocolate). This means that if you drink
coffee or eat chocolate while taking the supplement, you might feel
stronger effects than you expect. Ipriflavone might also interact with
oral diabetes medications.
Additionally, ipriflavone could interact with phenytoin (used for
epilepsy) and warfarin (a blood thinner). This is a worrisome issue
since phenytoin and warfarin cause osteoporosis, and some people on
those drugs might be tempted to take ipriflavone at the same time to
protect their bones, leading to potentially dangerous effects.
Finally, because ipriflavone is metabolized by the kidneys, individuals
with severe kidney disease should have their ipriflavone dosage
monitored by a physician
What about Bodybuilding?
Ipriflavone is sometimes marketed for bodybuilding and other sports
uses, but there is no evidence at all that it works for these purposes.
For more information, see Ipriflavone and Osteoporosis.
Agnusdei D, Crepaldi G, Isaia G, et al. A double-blind,
placebo-controlled trial of ipriflavone for prevention of postmenopausal
spinal bone loss. Calcif Tissue Int. 1997;61:142,147.
Ohta H, Komukai S, Makita K, et al. Effects of 1-year ipriflavone
treatment on lumbar bone mineral density and bone metabolic markers in
postmenopausal women with low bone mass. Horm Res. 1999;51(4):178,183.
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