Type of dietary fat is associated with the 25-hydroxyvitamin D3 increment in response to vitamin D supplementation

CONTEXT Mono- and polyunsaturated fats may have opposing effects on vitamin D absorption.
OBJECTIVE The purpose of this study was to determine whether intakes of different dietary fats are associated with the increase in serum 25-hydroxyvitamin D (25OHD) after supplementation with vitamin D(3).
DESIGN, SETTING, AND PARTICIPANTS This analysis was conducted in the active treatment arm of a randomized, double-blind, placebo-controlled trial of vitamin D and calcium supplementation to prevent bone loss and fracture. Subjects included 152 healthy men and women age 65 and older who were assigned to 700 IU/d vitamin D(3) and 500 mg/d calcium. Intakes of monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and saturated fatty acids (SFA) were estimated by food frequency questionnaire.
MAIN OUTCOME MEASURE The change in plasma 25OHD during 2 yr vitamin D and calcium supplementation was assessed.
RESULTS The change in plasma 25OHD (nanograms per milliliter) during vitamin D supplementation was positively associated with MUFA, (β = 0.94; P = 0.016), negatively associated with PUFA, (β = -0.93; P = 0.038), and positively associated with the MUFA/PUFA ratio (β = 6.46; P = 0.014).
CONCLUSION The fat composition of the diet may influence the 25OHD response to supplemental vitamin D(3). Diets rich in MUFA may improve and those rich in PUFA may reduce the effectiveness of vitamin D(3) supplements in healthy older adults. More studies are needed to confirm these findings.