# 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

## TL;DR

A 3-year study found that vitamin D3, omega-3s, and a home exercise program did not improve physical activity or function in older adults, and vitamin D3 may even reduce activity.

## Contribution

This study is the first to show that high-dose vitamin D3 may negatively affect physical activity in older adults.

## Key findings

- Vitamin D3 supplementation was linked to a decline in physical activity over three years.
- Omega-3s and the home exercise program had no significant effect on physical activity or function.
- The combination of vitamin D3 and omega-3s reduced gait speed.

## Abstract

•High-dose vitamin D3 supplementation (2000 IU/d) may have detrimental effects on physical activity.•Vitamin D3 supplementation had no beneficial effects on physical function.•Omega-3s supplementation (1 g/d) had no effect on physical function or physical activity.•The combination of vitamin D and omega-3s, had negative effects on gait speed.•The simple home exercise program (SHEP) did not improve physical activity or physical function.

High-dose vitamin D3 supplementation (2000 IU/d) may have detrimental effects on physical activity.

Vitamin D3 supplementation had no beneficial effects on physical function.

Omega-3s supplementation (1 g/d) had no effect on physical function or physical activity.

The combination of vitamin D and omega-3s, had negative effects on gait speed.

The simple home exercise program (SHEP) did not improve physical activity or physical function.

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.

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

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.

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.

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.