Degree Type

Thesis

Date of Award

2013

Degree Name

Master of Science

Department

Food Science and Human Nutrition

First Advisor

Rick L. Sharp

Abstract

Background. One explanation for the relationship between vitamin D and cardiovascular disease (CVD) mortality could be related to altered serum lipids. This study aimed to determine the association between 25OHD and serum lipid concentrations in healthy, older adults.

Methods. Serum lipid panels and 25OHD concentrations were obtained on 190 adults (median age 67 years) after a 12-hour overnight fast. 25OHD was measured by the DiaSorin Liason system. Subjects were stratified by 25OHD concentrations: <20.0 ng/mL, 20.0-29.9 ng/mL, 30.0-39.9 ng/mL and ≥40 ng/mL. One-way ANOVA was used to observe unadjusted differences and Student's t-tests were used to determine differences between groups. Multiple regression analyses were performed to determine the ability of 25OHD to predict serum lipid concentrations when accounting for BMI, sex, age, and statin use. Stepwise regression analyses were used to establish the best prediction model for each outcome.

Results. There was a significant relationship between 25OHD and BMI (p<0.001), glucose (p=0.042), TG (p=0.020), TC (p<0.001), LDL (p<0.001) and the TC:HDL ratio (p<0.001), but not for blood pressure, HDL, or TG:HDL ratio. When comparing subjects with 25OHD ≥40.0 ng/mL to those with <20 ng/mL, those in the highest group had a significantly lower BMI (26.1 0.7 and 29.9 0.8 kg/m2), TG (100.9 7.8 and 130.4 9.5 mg/dL), TC (182.7 5.2 and 217.4 6.3 mg/dL), LDL (100.3 4.5 and 131.2 5.4 mg/dL), and calcium (9.67 0.05 and 9.50 0.06 mg/dL) concentrations, and had significantly lower TC:HDL (3.09 0.15 and 4.15 0.08) and TG:HDL (1.79 0.22 and 2.56 0.27) ratios.

When adjusting for confounders, the relationship between 25OHD and TC (p<0.001) and LDL (p<0.001) remained significant, but that between TC:HDL and TG:HDL did not. When a stepwise regression analysis was performed to determine the best model for predicting serum lipid parameters, each 10 ng/mL increase in 25OHD predicted a statistically significant 6.72 mg/dL decline in TC (p<0.001) and 5.55 mg/dL decline in LDL (p<0.001).

Conclusions. 25OHD status is associated with favorable concentrations of TG, TC, LDL and lipid ratios in older adults. When adjusting for confounders, this relationship remains for TC and LDL. Altered lipid metabolism may help explain the association between vitamin D and CVD mortality.

Copyright Owner

Felicia L. Steger

Language

en

File Format

application/pdf

File Size

84 pages

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