Seasonal effects on vitamin D status influence outcomes of lifestyle intervention in overweight and obese women with polycystic ovary syndrome

Capsule:
Overweight and obese women with polycystic ovary syndrome who increased their serum 25-hydroxyvitamin D levels more during lifestyle intervention achieved greater improvement in waist circumference and cholesterol.

Authors:
Rebecca L. Thomson, Ph.D., Simon Spedding, M.A.E., Grant D. Brinkworth, Ph.D., Manny Noakes, Ph.D., Jonathan D. Buckley, Ph.D.

Volume 99, Issue 6, Pages 1779-1785, May 2013

Abstract:

Objective:
To investigate the effect of undertaking lifestyle interventions during periods of seasonal change on vitamin D status and health outcomes in overweight/obese women with polycystic ovary syndrome (PCOS).

Design:
Retrospective, unplanned secondary analysis of two cohorts during different seasons.

Setting:
Outpatient, clinical research unit.

Patients:
Fifty overweight/obese women with PCOS.

Interventions:
Twenty-week lifestyle modification program (Clinical Trials Registration Number: ACTRN12606000198527); one cohort started in winter and finished in summer and one started in summer and finished in winter.

Main Outcome(s):
25-hydroxy vitamin D (25OHD), weight, waist circumference (WC), body composition, cardiovascular disease (CVD) risk factors, and menstrual cycle length.

Results:
Baseline 25OHD levels were 27.6±9.0 nmol/L. The winter cohort had lower 25OHD levels at baseline which increased over 20 weeks, whilst the summer cohort started with higher levels which decreased. Changes in 25OHD were inversely correlated with changes in WC (r=-0.48) and cholesterol (r=-0.36) when controlling for baseline values, such that increases in 25OHD were associated with greater reductions in WC and cholesterol.

Conclusion:
Obesity and CVD risk profiles improved in vitamin D deficient women with PCOS following a 20 week lifestyle intervention during which vitamin D status improved with seasonal change.

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