Vitamin D


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Summary

All Essential Benefits/Effects/Facts & Information

In Progress


This page on Vitamin D is currently marked as in-progress. We are still compiling research.



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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects vitamin d has on your body, and how strong these effects are.

Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
Risk of Falls Notable Moderate See all 4 studies
The risk of falls in the elderly (and subsequently, rate of bone fractures) appears to be significantly reduced with Vitamin D supplementation at 700 IU or greater, with most research in the 700-1000 IU range. Lower doses do not appear effective, and a greater protective effect appears to exist alongside calcium supplementation (and possibly Vitamin K supplementation)
Cardiovascular Disease Risk Minor Moderate See all 4 studies
There appears to be less risk of cardiovascular disease and related cardiovascular complications with supplementation of 1,000 IU of Vitamin D or higher serum levels of Vitamin D, although studies using less have had null results. The degree of prevention found in positive trials is of borderline clinical significance.
Parathyroid Hormone Strong Very High See all 4 studies
Vitamin D supplementation is the reference drug for reductions in parathyroid hormone due to directly negatively regulating its secretion
Colorectal Cancer Risk Notable - See study
The association between serum Vitamin D at 37ng/mL and colorectal cancer is is approximately a halving of risk according to one meta-analysis, which is a notable risk reduction
Blood Pressure Minor Very High See all 3 studies
Some correlational and intervention studies note that higher serum vitamin D is associated with mildly lower blood pressure, although the evidence is somewhat conflicted and effects that have been found are rather small.
Bone Fracture Risk Minor - See study
A decrease in bone fracture risk (nonvetebral and hip) appears to exist when supplemental doses of Vitamin D3 are taken above 800 IU, with this protective effect being highly correlated with the improvement in functionality and fall reduction risk
Fat Mass Minor Low See all 3 studies
Mixed effects on overweight/obese persons, but it appears that normalizing a deficiency may aid fat loss in persons of higher body weight. Insufficient evidence to suggest the role of Vitamin D in lean persons
Functionality in Elderly or Injured Notable - See study
An improvement in muscular and neural functionality in the elderly is thought to underlie the reductions of fall risk and reduced bone fracture rate seen in elderly cohorts
All-Cause Mortality Minor Very High See 2 studies
Cohorts of people with higher serum Vitamin D appear to die less frequently than cohorts with less serum Vitamin D; this may be heavily influenced by reducing falls in the elderly (reduction of falls and subsequent hospitalizations reducing death rates)
Asthma Minor - See study
Appears to be somewhat effective at reducing the occurrence of asthma attacks in youth
Height Minor - See study
A higher vitamin D level in serum during growth spurts in children is associated with greater heights during adulthood; currently no evidence to support the role of Vitamin D in inducing height growth in adults
Influenza Minor Very High See 2 studies
May reduce the risk of catching the flu
Insulin Secretion Minor Very High See all 3 studies
An improvement in insulin secretion is noted in diabetics (type II mostly) and in persons at risk for diabetes, which is thought to be secondary to protective effects at the level of the pancreas.
Insulin Sensitivity Minor Moderate See all 4 studies
Improvements in insulin sensitivity can occur secondary to increasing pancreatic insulin secretion
Interleukin 5 Minor - See study
An increase in IL-5 has been noted with Vitamin D supplementation
LDL-C Minor Very High See 2 studies
Either no significant influence on LDL cholesterol or a slight increase (around 5%) has been noted; practical significance of this information unknown
Lean Mass
Minor
- See 2 studies
An increase in lean mass has been noted in dieting obese women relative to control (2,000IU) and a trend to reduce lean mass relative to control has been noted in exercising healthy persons (4,000IU); there appears to be potential for both effects with Vitamin D supplementation, but there is insufficient evidence to draw conclusions
Symptoms of Systemic Lupus Erythematosus Minor - See study
Inflammatory symptoms associated with Lupus appear to be reduced with Vitamin D ingestion
Symptoms of Tubercolosis Minor - See study
A decrease in symptoms associated with tuberculosis are noted with Vitamin D
TNF-Alpha Minor - See study
A decrease has been noted over time relative to placebo, of relatively minor magnitude
Testosterone Minor - See study
An increase in testosterone has been noted in men with 3,332 IU of Vitamin D over the course of a year
Triglycerides Minor - See study
The decrease in triglycerides is present after long term ingestion of Vitamin D, although it isn't to a highly significant degree
Blood Glucose - - See study
No significant influence on fasting blood glucose levels
Bone Mineral Density - - See study
Calcium Absorption - - See study
Superloading Vitamin D (rather than staying sufficient) does not appear to further increase absorption rates of calcium, although normalizing a deficiency can aid in absorption which is hindered.
Collagen Content - - See study
Endothelial Function - - See study
No significant influence on endothelial function
Food Intake - - See study
No significant alterations in food intake noted with Vitamin D supplementation
HbA1c - Very High See 2 studies
The decrease in HbA1c is statistically insignificant and very small in magnitude, likely not a concern.
Hip Fracture Risk - - See study
Inflammation - - See study
No significant influence on select inflammatory cytokines
Insulin - Very High See 2 studies
No significant influence on fasting insulin levels
Metabolic Rate - - See study
No detectable influence on metabolic rate over time
Pain - - See study
Power Output - Very High See 2 studies
Although a trend to increase power output has been noted, most research suggest no benefit, although recovery times may improve.
Symptoms of Osteoarthritis - - See study
Upper Respiratory Tract Infection Risk - - See study
Lack of efficacy in reducing rate of sickness
Weight - Very High See 2 studies
No significant alterations noted in weight, even when fat mass is lost, in obese persons
Risk of Multiple Sclerosis Notable - See study
The risk of developing MS is significantly reduced by both sunlight, latitude, and supplemental Vitamin D
Arthralgia Minor Very High See 2 studies
May reduce symptoms of athralgia
Breast Cancer Risk Minor Very High See 2 studies
There is less risk of breast cancer associated with Vitamin D supplementation
Hematocrit Minor - See study
Small drops in hematocrit were noted in vitamin D-insufficient healthy people supplemented with 800 IU over 12 weeks.
Hemoglobin Minor - See study
Small drops in hemoglobin were noted in vitamin D-insufficient healthy people supplemented with 800 IU over 12 weeks.
Incidence of Type 1 Diabetes Minor - See study
May reduce the incidence of type 1 diabetes in offspring and adults when supplemented (for the former, but the mothers)
Pancreatic Cancer Risk Minor - See study
Appears to be associated with less risk of pancreatic cancer
Red Blood Cell Count Minor - See study
Small drops in red blood cell count were noted in vitamin D-insufficient healthy people supplemented with 800 IU over 12 weeks.
Symptoms of Multiple Sclerosis Minor - See study
There appears to be a lower relapse rate in multiple sclerosis patients when Vitamin D is present at higher concentrations
Depression - See study
Glycemic Control / Insulin Sensitivity - See study
HDL-C - - See study
No change in HDL-C was seen in vitamin D-insufficient healthy people supplemented with 800 IU over 12 weeks.

Studies Excluded from Consideration

  • Used injections of the active hormone[1]


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