What Does Vitamin D Actually Do and How Do Indians Get Enough
India receives some of the most abundant sunlight of any country on earth. And yet over 70 percent of urban Indians are Vitamin D deficient. This apparent contradiction is one of the more important nutritional stories in the country and one that most people have not fully understood.
What Vitamin D actually does
Vitamin D is technically a hormone precursor, not a vitamin in the conventional sense. It regulates calcium absorption for bone health, modulates immune system function, supports muscle protein synthesis, influences mood through serotonin pathways, and plays a role in insulin sensitivity and metabolic health.
When it is low, the downstream effects are wide-ranging: reduced bone density, weakened immunity, muscle weakness, fatigue, low mood, and impaired recovery from illness and exercise.
Why urban Indians are deficient despite the sun
Vitamin D synthesis requires UVB radiation to hit the skin directly. Several factors specific to urban Indian life systematically prevent this. Office jobs mean most daylight hours are spent indoors. Sunscreen, protective clothing, and covered skin block UVB. Glass windows filter out UVB entirely. Air pollution in Indian cities reduces UVB penetration. Darker skin requires longer sun exposure to synthesise the same amount of Vitamin D as lighter skin.
The result is a population living in abundant sunshine with almost no sun exposure that actually results in Vitamin D synthesis.
Food sources and their limitations
Very few foods contain meaningful Vitamin D. Fatty fish, egg yolks, and fortified foods are the primary sources. For most vegetarian Indians, dietary Vitamin D is negligible. Sun exposure remains the primary source, and supplementation is the most reliable alternative when sun exposure is inadequate.
What to do
Get a 25-hydroxyvitamin D blood test. Levels below 20 ng/mL are deficient. Levels between 20 and 30 are insufficient. Most urban Indians fall in one of these two categories. Supplementation with Vitamin D3 (cholecalciferol) alongside Vitamin K2 is the standard correction protocol. The K2 is important: it directs calcium to bones rather than soft tissue. Dose and duration should be guided by your test result and a doctor.