Vitamin D
The vitamin that the body produces when exposed to sunlight — levels of which are often low in winter, and which plays a key role in bone health, muscle function and immunity.
Benefits
- Helps maintain normal bones
- Contributes to normal muscle function
- Supports the normal functioning of the immune system
Precautions
Fat-soluble vitamin: prolonged excessive intake may be toxic. Do not exceed the recommended doses without a blood test or medical advice.
Recommended dosage
1,000 to 2,000 IU a day, particularly from October to April
Did you know?
Routine vitamin D supplementation, either on its own or in combination with calcium, does not reduce the risk of fractures in older adults living at home.
What the studies say
This meta-analysis shows that vitamin D supplementation can safely reduce the risk of acute respiratory tract infections. The benefits were more pronounced in those taking daily or weekly doses, rather than single (bolus) doses. People who were initially severely deficient in vitamin D (25-hydroxyvitamin D levels <25 nmol/L) derived the greatest benefit from supplementation.
Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, Dubnov-Raz G, Esposito S, Ganmaa D, Ginde AA, Goodall EC, Grant CC, Griffiths CJ, Janssens W, Laaksi I, Manaseki-Holland S, Mauger D, Murdoch DR, Neale R, Rees JR, Simpson S, Stelmach I, Kumar GT, Urashima M, Camargo CA. — BMJ (Clinical research ed.) (2017) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more