Vitamin D
Vitamin D, also called calciferol, is a fat-soluble vitamin that the body can get from some foods, fortified products, and supplements. The body can also make vitamin D when sunlight hits the skin. It helps the body absorb calcium, supports bone health, and plays a role in the immune system.
Is this used to correct a deficiency or achieve supramaximal levels?
Deficiency
Is it taken for life span or health span?
Mainly lifespan by reducing the impact of falls
Is it targeting a specific disease? Or general health?
Targets bone related diseases or damage as well as general health
Any genetic involvement?
N/A
Is there a biomarker to track its effects?
25-hydroxy vitamin D
MOA of supplement
Vitamin D acts as a hormone and plays a key role in bone health by increasing calcium absorption in the gut and activating osteoblasts, cells that build and strengthen bones by laying down new mineral. It also helps regulate parathyroid hormone (PTH), which keeps calcium levels balanced. Vitamin D has receptors on many immune cells and influences genes involved in immunity
Risk vs reward
+ No major side effects
+ May play a role in reducing cancer mortality
+ Improves bone strength
- Risk of excess levels which may cause hypercalcemia. Vitamin D is fat soluble so it is hard to eliminate excess levels and cam become toxic overtime
- The dose should be changed in different seasons of the year to account for differences in sun exposure
- Hard to assess the effects of vitamin D due to the contribution from sunlight
Evidence for it?
RTC This study investigated impact of daily vitamin D supplementation (200–800 IU) on fall risk in elderly nursing home residents over 5 months. Among the 124 participants (average age 89), only the group receiving 800 IU daily showed a significant reduction in falls, with a 72% lower fall rate compared to placebo. Lower doses (200–600 IU) showed no benefit. This suggests that adequate daily supplementation with 800 IU of vitamin D may help reduce falls in elderly populations.
Observational study This study of 235 hospitalised COVID-19 patients found that those with sufficient vitamin D levels (≥30 ng/mL) had significantly lower disease severity, mortality, and inflammation (CRP), and higher lymphocyte counts. Only 9.7% of vitamin D–sufficient patients over 40 died compared to 20% with lower levels. The findings suggest vitamin D may improve immune response and reduce the risk of severe COVID-19 outcomes.
Evidence against it?
VITAL trial , a large study of over 25,000 adults in the U.S. testing whether daily vitamin D (2000 IU) could prevent cancer or cardiovascular disease. Over 5 years, results showed no significant reduction in cancer, heart attacks, strokes, or death. While there was a slight, non-significant trend toward fewer cancer deaths, overall, vitamin D supplements did not reduce the risk of cancer or heart disease in healthy older adults.
Meta analysis of RTCs Vitamin D supplementation did not reduce overall cancer incidence, but did lower cancer mortality by up to 16%, especially with daily dosing rather than large, infrequent doses.
Systematic review and meta analysis This review looked at 35 trials with 43,407 people to see if vitamin D3 supplements help with blood sugar control or prevent diabetes. The results showed that vitamin D had no noticeable effect on insulin levels, blood sugar, or the risk of developing diabetes. Even though some studies link low vitamin D to higher diabetes risk, vitamin D supplements had no effect in these trials. The results might be influenced by differences between trials and short follow-up times. *In vit D trials, not possible for placebo group to have no exposure (can’d control exposure from sunlight) which is an issue. Research is actually comparing higher and lower doses of Vit D.
Best bioavailable form?
Capsule or liquid
Advice on taking it?
40-60 ng/mL