Vitamin D

Of 6,943 Vitamin D results Loop ran on urban working professionals in the latest 12-month window, 81.4% sit below 30 ng/mL — the threshold for insufficiency — and a clear 60.1% sit below 20 ng/mL, the deficiency line. The Indian Council of Medical Research's national review puts adult Vitamin D deficiency between 70% and 90% across most regional studies, urban and rural alike (Aparna et al., Journal of Family Medicine and Primary Care, 2018). Loop's professional cohort — younger, better-paid, more likely to test and to supplement than the national average — lands squarely inside that band. Income, education, and health awareness do not buy a higher blood Vitamin D level in this population.

The distribution:

The population mean is 20.93 ng/mL — below the insufficiency threshold, not near it. A sufficient population would centre above 30. What's depressed here is the whole distribution, not a long tail dragging an otherwise healthy median down.

Insufficiency is near-universal, but the floor — severe deficiency — is where the population splits#

Insufficiency below 30 ng/mL is so common in this dataset that it barely discriminates between groups: every age band, both sexes, and all five metros sit between 69% and 87%. The signal that separates the workforce is the severe band below 10 ng/mL, where a fifth of the population sits and where the spread between groups is real.

Below 10 ng/mL is not a borderline reading. It is the level at which calcium absorption is meaningfully impaired and at which clinical guidelines call for therapeutic correction rather than maintenance dosing. More than one in five of the working professionals Loop tested is there.

The deficit runs backwards on age — the youngest workforce is the worst off#

Almost every biomarker in this report gets worse with age. Vitamin D is the exception. Severe deficiency is 2.5 times more common in the 20s than in the 60+ band (30.5% vs 12.3%), and insufficiency falls steadily across every decade of working life. The under-20 sliver (n=71) sits worst of all at 32.4% severe.

The gradient is behavioural, not biological. The 20-something professional works the longest indoor hours, commutes in the dark at both ends of winter, and is least likely to have been told by a doctor to start a maintenance dose. The 60-year-old has more daytime hours outside the office, a longer history of clinical contact, and is more likely to already be on supervised supplementation for bone health. Age, in this dataset, is a proxy for sunlight and for medical attention — and the youngest workforce has the least of both.

The reversal also explains why the population mean climbs with each decade: 17.99 ng/mL in the 20s, 20.73 in the 30s, 24.05 in the 50s, 26.08 by 60. The trajectory is the opposite of glucose, lipids, and liver markers, all of which deteriorate as a working life accumulates. Vitamin D is the one panel line on which a 25-year-old in this cohort would do well to envy their parents — and the clearest case of the "the curves don't align" pattern the Age & Generation page draws out across the report.

The clinical reading is uncomfortable. Vitamin D's payoff is cumulative — bone mineral density laid down in the 20s and 30s sets the ceiling a person draws down from for the rest of their life (Weaver et al., Osteoporosis International, 2016). The band running the deepest deficits is the band whose skeleton is still being built. A deficiency corrected at 60 protects against the next fracture; a deficiency corrected at 25 protects against the next forty years.

Women are less insufficient than men — but more severely deficient#

The headline gender gap reads in women's favour. It reverses at the floor.

At the 30 and 20 ng/mL cut-offs, men are worse. At the 10 ng/mL cut-off — the clinically urgent one — women pull ahead, and the gap is widest among the young. Women in their 20s are severely deficient at 37.0%, against 25.3% of men the same age — the single worst cell in the entire dataset.

The city map inverts the glucose map#

The ordering is the reverse of the blood-sugar one. On glucose, Mumbai leads the metros for dysfunction and Bengaluru is cleanest; on Vitamin D, Bengaluru and Pune are the worst and Delhi NCR is the best. The cities whose workforces look metabolically healthiest are the ones running lowest on Vitamin D.

The likely driver is the same indoor-work signal that shows up on age. Bengaluru and Pune are the report's densest IT and engineering hubs — air-conditioned campuses, long screen hours, the least midday sun exposure of any metro workforce. The Bengaluru reading pairs with the city's worst-in-the-dataset B12 deficiency (78.8%, the vegetarian-diet signal flagged in the WHI 2026 city work): the same office population is short on the two micronutrients hardest to get without sunlight and without animal protein. Delhi NCR's "advantage" is narrower than it looks — the city still runs 72.9% insufficient — and Delhi's polluted winter sky should, in theory, suppress UV-B synthesis. That it doesn't show up here suggests outdoor exposure patterns and supplementation contact matter more than ambient air quality for this marker.

Self and dependent both run deficient, with the employee marginally worse#

Across most of WHI 2026, dependents test worse than employees — on glucose the gap is 20 points. Vitamin D breaks that pattern. The employee is marginally worse here, and the reason is the age inversion: the employee layer skews younger and works indoors, while the dependent layer carries the older parents whose Vitamin D, perversely, runs higher. The 4-point employee disadvantage is small, but it is the right direction given everything else on this page. The deficit is an office problem before it is a family one.

Supplement uptake fell; the deficit did not#

Two-thirds of the survey audience take no supplement of any kind, and only one in five takes Vitamin D specifically — down from 26.2% in WHI 2025. Self-reported supplementation fell over the year while biomarker insufficiency held at four in five. The Supplementation page makes the same point across micronutrients: uptake runs roughly four times short of the deficiency burden it would need to close. The two datasets are not linked at the person level, so this is not evidence that supplements failed in the people taking them. It is the audience-level shape of the problem: a population overwhelmingly below the line, of whom a shrinking minority is doing anything about it.