Supplements containing vitamin D helped women of varying race, ethnicity, socioeconomic status and education levels increase their long-term levels of 25-hydroxyvitamin D, according to research presented at the American Society for Bone and Mineral Research 2014 Annual Meeting.
“We studied a socially and ethnically diverse cohort of women in mid-life,” Deborah Mitchell, MD, of Massachusetts General Hospital, told Endocrine Today. “Over an approximately 11-year time span, the average 25-(OH)D level increased 6.5 ng/mL, which translated to a significant decline in vitamin D deficiency by the Institute of Medicine definition.”
Mitchell and colleagues investigated 25-(OH)D changes and predictors of the changes in the multicenter, racially and ethnically diverse cohort involved in the Study of Women’s Health Across the Nation (SWAN); 1,582 women had 25-(OH)D levels measured at baseline between 1998 and 2000 (at age 48 ± 3 years) and again at follow-up between 2009 and 2011 (at age 60 ± 3 years).
The researchers obtained measurements using liquid chromatography-tandem mass spectrometry in a single batch. Adjustments were made for age, BMI, menopausal status, study site and season of blood draw.
At end of study, mean 25-(OH)D level had increased from 21.5 ± 9.8 ng/mL to 28 ± 11.5 ng/mL (P<.001).
Although mean levels varied by race and ethnicity (14 ng/mL, black; 25.4 ng/mL, white; 19.8 ng/mL, Chinese; 18.3 ng/mL, Hispanic; and 24 ng/mL, Japanese; P<.001) at baseline, as expected, the magnitude of increase was similar among groups, ranging from 5.3 ng/mL in whites to 8.7 ng/mL in Chinese. The increases did not vary by socioeconomic status, education level or acculturation.
At follow-up, 49% of women reported taking a multivitamin or vitamin D supplement, and the adjusted 25-(OH)D increase was higher among this group (10.1 ng/mL vs. 3.2 ng/mL, P<.001).
Based on the Institute of Medicine definition of vitamin D deficiency, 25-(OH)D level <20 ng/mL, the proportion of women with deficiency decreased from 43% to 24% (P<.001). Among those who used supplements, the proportion decreased from 35% to 6% (P<.001) compared with 51% to 39% among nonusers (P<.001). Rates of 25-(OH)D levels <20 ng/mL were lower among supplement users of all racial and ethnic groups (P<.001 for all comparisons).
The findings cannot be generalized to women in other age groups or men, Mitchell said. However, she called the data “encouraging.”
“Health outcomes linked to vitamin D deficiency, including osteomalacia and fracture risk but possibly many others, could have a decreasing prevalence,” Mitchell said. “These findings should also promote efforts to better identify women who are not adopting vitamin supplementation in order to better target outreach and education efforts.” — by Allegra Tiver
For more information:
Mitchell D. Abstract #1075. Presented at: ASBMR 2014 Annual Meeting; Sept. 12-15, 2014; Houston.
Disclosure: Mitchell reports no relevant financial disclosures.