Association between vitamin D status and physical function in the severely obese

Area of Science:

• Obesity and Metabolism
• Nutritional Science
• Physical Medicine and Rehabilitation

Background:

• Severe obesity (BMI > 40 kg/m2) is associated with an 85% higher mortality rate, potentially due to poor physical function.
• Hypovitaminosis D (vitamin D deficiency) is prevalent in obese individuals and linked to physical dysfunction, particularly in the elderly.

Purpose of the Study:

• To investigate the relationship between vitamin D status and physical function in severely obese individuals.
• To determine if vitamin D levels correlate with physical activity and performance metrics in this population.

Main Methods:

• A cross-sectional study involving 252 severely obese subjects (BMI 50.7 ± 9.7 kg/m2).
• Participants were categorized into three groups based on Institute of Medicine (IOM) vitamin D status.
• Physical function was assessed by self-reported activity levels, 500-m walk time, and step-up/step-down test performance.

Main Results:

• 109 participants (43%) had 25-hydroxyvitamin D (25OHD) levels below 30 nmol/L.
• Subjects with 25OHD > 50 nmol/L reported higher weekly activity (3.1 ± 3.4 h/wk) and had faster 500-m walk times (6.2 ± 1.1 min) compared to those with 25OHD < 30 nmol/L.
• Serum 25OHD showed a positive association with activity levels (r=0.19, P=.008) and a negative association with 500-m walk time (r=-0.343, P<.001).

Conclusions:

• Vitamin D status significantly correlates with physical activity and function in severely obese individuals.
• Low physical activity may exacerbate hypovitaminosis D due to reduced outdoor exposure.
• Further research on vitamin D supplementation efficacy in this population is recommended.