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Vitamin

Vitamin D

Vitamin D is a fat-soluble vitamin that the skin makes in sunlight and that also comes from a few foods. Its two main forms are D2 and D3.

Bone & Joint

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Bone densityBone & JointNot rated–No linked study
Every rating with its studiesGrouped by health goal, with the publications behind each rating

Overview

A fat-soluble vitamin; D2 and D3 are distinct forms. Both help supply vitamin D.

Sources

  1. NIH ODS · Vitamin D

Further reading

Illustration for Vitamin D.GuideCan low vitamin D levels contribute to depression or low mood?Low vitamin D levels are seen more often in people with depression. That does not tell us whether the deficiency causes the symptoms. Supplements might ease depressive symptoms when a deficiency exists, but the studies do not agree. In…Read the article Illustration for Vitamin D.GuideLiquid vitamin D: absorption, dosing and blood levelsHow vitamin D drops and capsules differ, what role meals and blood levels play, and where the limits on dosing and benefit lie.Read the article Illustration for Vitamin D.GuideWhy vitamin D alone may not be enough when magnesium is lowHow magnesium is linked to vitamin D metabolism, which study findings are described, and what remains open on doses, blood tests and other cofactors.Read the article Illustration for Vitamin D.GuideDoes vitamin D make you tired? Deficiency, supplements and sleep in contextVitamin D does not act like a sleeping pill. What tiredness may mean with deficiency or high doses, and how solid the data on timing are.Read the article Illustration for Vitamin D.GuideVitamin D (25-OH): blood level, cutoff ranges and follow-up testsWhat the 25-OH vitamin D level tells you, why cutoffs vary, and how season, kidney function, medications and lab method change how a result is read.Read the article Illustration for Vitamin D.GuideVitamin D deficiency: understanding and interpreting your blood testsVitamin D deficiency can weaken bones and muscles. This article explains what 25-hydroxyvitamin D, calcium and other blood values say about your vitamin D status, which symptoms can occur, and what limits apply to interpreting results…Read the article Illustration for Vitamin D.GuideHow much vitamin D do you need during pregnancy?How much vitamin D do you need during pregnancy? The basics, how to read the findings, and frequently asked questions.Read the article