Heart, bone damage from low vitamin D levels amplified by estrogen shortage

Published: Monday, November 16, 2009, 10:49 [IST]
 

Washington, Nov 16 (ANI): Johns Hopkins researchers have found that heart and bone damage caused by lack of vitamin D is amplified by declines in sex hormones.

They found that long-term ill effects of vitamin D deficiency were tied to lower levels of the key sex hormone estrogen, but not testosterone.

The new findings build on previous studies showing that deficiencies in vitamin D and low levels of estrogen, found naturally in differing amounts in men and women, were independent risk factors for hardened and narrowed arteries and weakened bones

"Our results confirm a long-suspected link and suggest that vitamin D supplements, which are already prescribed to treat osteoporosis, may also be useful in preventing heart disease," said lead study investigator and cardiologist Dr Erin Michos."All three steroid hormones - vitamin D, estrogen and testosterone - are produced from cholesterol, whose blood levels are known to influence arterial and bone health.

"Our study gives us a much better understanding of how the three work in concert to affect cardiovascular and bone health," Michos added.

In the new study, researchers analysed the blood samples of a subset of men participating in a study on cancer.

The men in the study had their hormone levels measured for both chemical forms of testosterone and estrogen found in blood, when each is either unattached or circulating freely, and when each is attached to a separate protein, known as sex hormone binding globulin, or SHBG for short.

Initially, the research team found no link between vitamin D deficiency and depressed blood levels of either hormone.

And despite finding a harmful relationship between depressed testosterone levels and rates of heart disease, stroke, and high blood pressure, as well as osteopenia in men, researchers found that it was independent of deficiencies in vitamin D.

However, when researchers compared ratios of estrogen to SHBG levels, they found that rates of both diseases, especially osteopenia, the early stage of osteoporosis, were higher when both estrogen and vitamin D levels were depressed.

For every single unit decrease in ratios of estrogen to SHBG, men low in vitamin D showed an 89 percent increase in osteopenia, but men with sufficient vitamin D levels had a less worrisome 64 percent jump.

Using the same measure of estrogen levels, men low in vitamin D were also at heightened risk of cardiovascular diseases, at 12 percent.

"These results reinforce the message of how important proper quantities of vitamin D are to good bone health, and that a man's risk of developing osteoporosis and heart disease is heavily weighted on the complex and combined interaction of how any such vitamin deficits interact with both their sex hormones, in particular, estrogen," Michos said.

The study was presented at the American Heart Association's (AHA) annual Scientific Sessions in Orlando. (ANI)


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