Women who took vitamin D and calcium supplements had the same number of menopausal symptoms as women who did not take the supplements, according to a study published today in Maturitas, the official journal of the European Menopause and Andropause Society.

The study, which involved 34,157 women ages 50-79, is part of the Women's Health Initiative, one of the largest clinical trials ever undertaken to address the most common causes of death, disability and impaired quality of life in menopausal women.

"Our study suggests that women should not rely on vitamin D and calcium supplements to relieve menopausal symptoms, but there are important caveats," said Erin S. LeBlanc, MD, MPH, lead author and investigator with the Kaiser Permanente Center for Health Research in Portland, Oregon. "The average age of the women at the start of our study was 64, but the average age of menopause is 51, and it's around that time that the most severe symptoms usually occur.

"If we want to understand vitamin D's effects on the most severe symptoms of menopause, we need to do a study in younger women," added LeBlanc.

For this study, researchers followed the women for an average of 5.7 years, from the mid-1990s to 2005, and asked them about more than 20 menopausal symptoms, including hot flashes, emotional well-being, fatigue and sleep disturbances. All women in the study were menopausal, which is defined as not having had a period for over a year. While symptoms tend to be most acute in a woman's early 50's, they can last for more than a decade.

Study participants were enrolled via 40 clinical trial sites throughout the United States where they had yearly office visits and filled out extensive health questionnaires at the beginning and end of the study.

Half of the women took daily calcium/vitamin D supplements; the other half received placebo pills. Over the course of the study, women in the intervention experienced an average of 6.26 menopausal symptoms compared to an average of 6.32 symptoms for women who received the placebo pills. There were also no differences on overall measures of emotional well-being, fatigue and sleep disturbances between the two groups.

This study builds on earlier work by Dr. LeBlanc which found no significant connection between menopausal symptoms and low levels of vitamin D in women's blood. That study was published in Menopause in 2014.

Dr. LeBlanc has conducted extensive research on vitamin D, including a study that found the potency of over-the-counter vitamin D can vary widely, and an evidence review for the US Preventive Services Task Force that examined screening for vitamin D deficiency.