Calcium/vitamin D pills won't lower blood pressure

NEW YORK (Reuters Health) - A daily dietary supplement of calcium plus vitamin D taken for 7 years neither reduces blood pressure nor alters the risk of developing high blood pressure, also called hypertension, in older postmenopausal women, results of a randomized study indicate.

"Shortcuts with dietary supplements cannot be substituted for encouraging people to adopt dietary patterns that have been shown to lower blood pressure and decrease the risk of hypertension," concludes the study team, led by Dr. Karen L. Margolis, at HealthPartners Research Foundation in Minneapolis.

Epidemiologic evidence and small, short-duration clinical trials have suggested that calcium supplementation, with or without vitamin D, could exert a blood pressure-lowering effect, Margolis and colleagues point out in the journal Hypertension.

As part of the Women's Health Initiative, the research team studied the effects of 1000 milligrams calcium plus 400 international units vitamin D3, or placebo, in women 50 to 79 years of age. There were 18,000 women in each study group.

After an average follow-up of 7 years, there was no significant difference between groups in the change in blood pressure, or in the number of women who developed hypertension or prehypertension.

However, Dr. Johanna Marianna Geleijnse, from the Wageningen University in the Netherlands, maintains in a related editorial that the null findings from the current study do not represent the final answer on the benefits of calcium/vitamin D supplementation.

She points out that nearly half of the women already had high blood pressure prior to the study and close to a third were using blood pressure-lowering medication. She also suggests that longer term treatment, at younger ages, may be more effective.

Therefore, she thinks randomized controlled trials in untreated subjects, using a high dose of vitamin D "and focusing on blood pressure as the primary outcome, are still warranted to solve this issue."

SOURCE: Hypertension, November 2008.