{"id":35749,"date":"2020-04-01T15:00:47","date_gmt":"2020-04-01T13:00:47","guid":{"rendered":"https:\/\/getindya.com\/?p=35749"},"modified":"2026-11-03T17:31:25","modified_gmt":"2026-11-03T16:31:25","slug":"vitamin-d-sunlight","status":"publish","type":"post","link":"https:\/\/getindya.com\/en\/vitamin-d-sunlight\/","title":{"rendered":"Vitamin D and sunlight"},"content":{"rendered":"

Vitamin D: more than we once thought<\/b><\/h2>\n


\nVitamin D was once discussed mainly for its role in bone health. Advances in research have improved our understanding of its endocrine system and wider biological importance.<\/span><\/p>\n

Vitamin D receptors and molecular targets have been identified in bone, immune cells, the cardiovascular system and skeletal muscle, showing that its functions extend beyond the skeleton.<\/span><\/p>\n

Several of these functions matter for <\/span>sporting performance<\/b>, including normal muscle function, bone health and immune function.<\/span><\/p>\n

Vitamin D should be viewed as a biological requirement rather than an automatic performance enhancer. Individual circumstances should be assessed before supplementation.<\/span><\/p>\n

\"Sunlight<\/p>\n

What is vitamin D deficiency?<\/b><\/h2>\n


\nLow vitamin D status occurs in the general population and among athletes. Spending much of the day indoors can contribute, as can season, latitude, skin pigmentation and other factors.<\/span><\/p>\n

Panel C of the historical image below uses 100\u2013150 nmol\/L as a proposed athlete range. This is not a universal target: NIH guidance considers 50 nmol\/L or more adequate for most people, and levels above 125 nmol\/L may have adverse effects.<\/span><\/p>\n

The image\u2019s proposed 40\u201360 ng\/mL range should therefore not be treated as a routine supplementation goal.<\/i><\/strong><\/p>\n

For context, NIH categorises less than 12 ng\/mL as a risk of deficiency, 12\u201320 as potentially inadequate, and 20 or more as adequate for most people. Higher is not always better. The old thresholds of 5 and 72 in the source are not universal diagnostic or toxicity cut-offs.<\/span><\/i><\/p>\n

Blood concentrations must not be converted into international units (IU), which describe an amount of vitamin D, not a serum concentration.<\/strong><\/span><\/i><\/p>\n

The source listed 500, 500\u20131200, 1200\u20132000, above 2000 and above 7200 as if they were equivalent blood-status ranges in IU. That conversion is invalid and should not guide dosing.<\/span><\/i><\/p>\n

Why does sunlight matter?<\/strong><\/h2>\n


\nThe skin can synthesise vitamin D following exposure to ultraviolet B radiation (UVB).<\/b> UVB acts on 7-dehydrocholesterol in the skin to produce previtamin D3, which becomes cholecalciferol, or vitamin D3.<\/span><\/p>\n

Food and supplements can supply vitamin D3 or vitamin D2, depending on the source.<\/span><\/p>\n

Vitamin D undergoes two hydroxylation steps to form its active hormone: mainly in the liver and then the kidneys, with some local activation in other tissues.<\/span><\/p>\n

Active 1,25(OH)2D3 binds to its receptor and influences gene expression and proteins involved in several regulatory processes.<\/span><\/p>\n

\"Vitamin<\/p>\n

Dietary vitamin D absorption varies with the food, supplement and individual; the original article\u2019s figure of around 50% is not a universal rule. Sun exposure can contribute, but it is not a risk-free or precisely controllable vitamin D dose.<\/strong> The amount produced depends on skin type, latitude, season and time of day. Avoid sunburn and follow sun-protection advice.<\/p>\n

Foods that provide vitamin D<\/strong> include:<\/span><\/p>\n