Research
Micronutrients & recovery
Daily supplementation with Vitamin D (2000 IU/day) reduces the risk of acute respiratory tract infections, with the greatest benefit observed in individuals with baseline deficiency (<25 nmol/L).
Take 2000 IU of Vitamin D daily. Do not take it in large, infrequent 'bolus' doses, as this appears ineffective for infection prevention. This is especially critical if you have low baseline levels, where the protection is strongest.
GoodSupportsHIGH confidence
A daily intake of 2000 IU (50 µg) is recommended... They found a 19% reduction in individuals taking a daily or weekly dose without bolus doses... and a 70% reduction for those with baseline levels <25 nmol/L
Why this rating
Based on a large individual participant data meta-analysis (n=10,933) of randomized controlled trials.
Source
Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections
Philip C. Calder et al. · Nutrients · 2020
DOI 10.3390/nu12041181
narrative_reviewCited 919×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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