Sheean P, et al. - This cross-sectional study was designed to ascertain the prevalence of low serum 25(OH)D in an exclusively African-American cohort of female breast cancer survivors with overweight/obesity. Furthermore, the researchers aimed to assess the role of ultraviolet (UV) light exposure, body composition, and dietary sources of vitamin D on serum 25(OH)D levels. Among these African-American breast cancer survivors, the prevalence of vitamin D deficiency was high, considering the number of women who endorsed the use of vitamin D supplementation. In order to improve the vitamin D status of this minority survivor population, vitamin D supplementation, sun behavior, and waist-to-hip ratio could serve as future points of intervention.

Methods

• The researchers recruited pre- and postmenopausal African-American breast cancer survivors (n=244) from various neighborhoods in the city of Chicago, IL, between September 2011 and September 2014 for a larger weight loss trial.
• They collected demographic, clinical, anthropometric (body mass index [calculated as kg/m²], waist circumference, and hip circumference), blood specimen, dietary intake (food frequency questionnaire), and sun behavior data by trained study personnel before trial participation.
• To quantify adiposity (total, percentage, regional, visceral) and lean mass, dual-energy x-ray absorptiometry was used.
• They used serum 25(OH)D as the biomarker reflective of vitamin D status.

Results

• In this study, the average age of the participant was 57.4 years old (±10.0), 6.9 years (±5.2) from initial breast cancer diagnosis with a body mass index of 36.2 (±6.2).
• The majority of participants (60%) reported habitual oral vitamin D supplementation with mean intake of 327 IU (±169).
• When the cut points of the Endocrine Society (<30 ng/mL or <75 nmol/L) and the Institute of Medicine (<20 ng/mL or <50 nmol/L) were applied, vitamin D deficiency was prevalent in 81% and 43%, respectively.
• After adjusting for age, seasonality of blood draw, total energy intake, use of supplemental vitamin D, darker skin pigmentation, breast cancer stage, and waist-to-hip ratio, a multivariate model was able to explain 28.8% of the observed variance in serum 25(OH)D concentrations.
• The researchers detected no significant associations for body mass index or any dual-energy x-ray absorptiometry measures of body composition.