Effects of vitamin D3, omega-3 fatty acids and a simple home exercise program on change in physical activity among generally healthy and active older adults: The 3-year DO-HEALTH trial

Abstract

Objectives

Physical function and physical activity (PA) are key drivers of health and autonomy at older age. We examined the effects of supplemental vitamin D3, supplemental marine omega-3 fatty acids (omega-3s), and a simple home exercise program (SHEP), alone or in combination, on change in physical function and PA among generally healthy older adults.

Design

Multi-center, 2 × 2 × 2 factorial design, randomized controlled trial, follow-up of three years

Methods

Self-reported PA and physical function were pre-defined outcomes of the DO-HEALTH trial, which included older adults (≥70 years) free of major comorbidities. The interventions were vitamin D3 (2000 IU/d), marine omega-3s (1 g/d), and a SHEP (3 × 30 min/wk), applied alone or in combination in eight treatment arms. The outcomes were change in PA (self-reported total PA, metabolic equivalent [MET] h/wk) and physical function (five times sit-to-stand test, hand grip strength, gait speed) from baseline to 12, 24 and 36 months. Mixed effect models were used and adjusted for age, sex, BMI, prior fall, time and baseline level of the outcome.

Results

All 2157 DO-HEALTH participants (mean age 75 years; 83% physically active; 59% vitamin D3 replete) were included. Baseline PA was 75 MET h/wk. Participants receiving omega-3s versus no omega-3s and randomized to SHEP versus control exercise did not differ in PA change over 3 years. However, participants receiving vitamin D3 compared to those receiving no vitamin D3 (Δadjusted means: −7.1 [95% CI −12.7, −1.5] MET h/wk, P = 0.01) showed a decline in PA. Results did not differ in subgroups by sex and age (70−74 yrs, ≥75 yrs). Vitamin D3, omega-3s or SHEP did not improve physical function.

Conclusion

Among generally healthy, active, and largely vitamin D3 replete adults aged 70 years and older, vitamin D3, omega-3s and SHEP, individually and in combination had no benefits on self-reported PA and objectively measured physical function. The detrimental effect of vitamin D supplementation on PA change needs further examination.