Vitamin D
What is Vitamin D and why is it needed?
- Fat soluble vitamin that is needed for optimal health to maintain strong bones as well as muscle function
- 2 different forms: D2 (ergocalciferol) and D3 (cholecalciferol); D3 is preferable and is converted to ‘active’ Vitamin D in the liver and kidney
- Main source is from exposure to ultraviolet B (UVB) radiation from sunlight
- Small amounts are found in foods such as oily fish (salmon, tuna mackerel) egg yolks and some fortified foods such as milk, cereals and margarine
- Food alone does not provide enough vitamin D
Risks and prevalence of deficiency
- Deficiency can lead to several health issues such as increased risk of bone injuries, chronic musculoskeletal pain and viral respiratory tract infections.
- Recent studies have shown low levels among athletes
- Defined serum 25(OH) Vitamin D levels are:\r\n
- deficiency: serum levels <20ng/ml (50nmol/L)
- insufficiency: serum levels <32ng/ml (75nmol/L)
- sufficiency: serum levels >32ng/ml (75nmol/L)
- Higher levels may be preferred for athletes to allow a larger safety margin and optimize performance
Which athletes are most at risk?
- Those with low exposure to sun in training environment
- Dark skin pigmentation
- Wearing clothing that covers most or all of their body
- Regularly use sunscreen or avoid the sun
- Missing limbs ( ie. athletes with a disability)
- GI malasbsorption (celiac disease or fat malabsorption)
- Family history of bone injury, disorders or Vitamin D deficiency
Athletic performance benefits of vitamin D supplementation if athletes have sub-optimal levels
- Strength
- Power
- Reaction time
- Balance
How much is recommended? (these are based on no or limited sunlight exposure)
- Recommended dietary intake = 600IU/day
- Upper level intake = 4000IU/day
Can I take too much Vitamin D?
- Yes, too much vitamin D can be harmful; toxicity is generally caused by supplement overuse
- The safe upper limit for vitamin D is 4000IU/day for an adult