**Background:** Vitamin D deficiency (VDD) affects approximately one billion people globally. Despite India being a tropical country with adequate sunshine, 70–100% of both rural and urban Indian populations are reported to have VDD. The Kashmir valley (latitude 32°44'N, longitude 74°54'E, altitude 1574–5425 feet) has an average UV index of seven, requiring only 15–20 minutes of sunlight exposure for adequate vitamin D synthesis, yet VDD prevalence is 83% in healthy adults, 88.6% in adolescent girls, and 74% in pregnant women. Tribals constitute 11.9% of Jammu and Kashmir's population but experience considerable health disparities due to cultural practices, limited sun exposure from heavy clothing, lack of food fortification, and limited awareness. No comprehensive study had previously assessed vitamin D status among the tribal population of Jammu and Kashmir.
**Methods:** This cross-sectional study was conducted from August 2015 to June 2018 as a sub-study of a larger NCD health survey. Five of 12 districts housing tribals (Gujjar and Bakarwal) were selected using multi-stage cluster sampling with probability proportional to size. From each district, one tehsil, one block, and two villages were selected. A total of 1,732 apparently healthy participants (786 males, 946 females) were enrolled. The modified WHO-STEPs questionnaire was administered face-to-face. Anthropometric measurements (weight, height, BMI, waist circumference) and blood pressure were recorded in triplicate. Fasting venous blood samples were collected for hemogram, calcium, phosphorus, glucose, lipids, liver and kidney function, and serum 25(OH)D. Serum 25(OH)D was measured using the ADVIA Centaur immunoassay system. VDD was classified per Endocrine Society recommendations: deficiency (<20 ng/mL), insufficiency (20–30 ng/mL), and sufficiency (>30 ng/mL). Data were analyzed using SPSS version 22; baseline mean vitamin D levels were compared using one-way ANOVA, and Pearson correlation assessed relationships between demographic and environmental factors. Two-sided P<0.05 was considered significant.
**Key Results:** The mean age of male participants was 43.79±18.47 years (range 10–80) with mean BMI 20.50±7.53 kg/m²; female participants had mean age 35.47±14.92 years (range 10–80) with mean BMI 22.24±4.73 kg/m². Using Endocrine Society criteria, 1,143 of 1,732 (66%) subjects had VDD, 254 (14.71%) had insufficiency, and 334 (19.3%) had sufficient serum 25(OH)D levels. Using IOM/SACN guidelines (<20 ng/mL), the prevalence was 44.4%. The mean serum 25(OH)D level was 24.92±22.97 ng/mL. VDD was equally prevalent in males and females (P=0.972). Serum 25(OH)D levels improved significantly with increasing age (P≤0.01), with the highest prevalence of VDD in those <20 years. Serum 25(OH)D correlated positively with serum calcium (r=0.065, P=0.056) and phosphorus (r=0.07, P=0.02), and negatively with alkaline phosphatase (r=−0.063, P=0.04), hs-CRP (r=−0.176, P=0.01), and insulin (r=−0.079, P=0.01). VDD was lower in those with higher education (P=0.03). Among underweight individuals (BMI <18.5 kg/m²), 75.4% of males and 68.4% of females had VDD. Sun exposure (<2 h/day) marginally decreased VDD risk. Smoking increased risk, while physical activity had no significant effect. Altitude, food habits, and dairy consumption did not show significant associations with VDD.
**Clinical Implications:** This is the first comprehensive study of vitamin D status in the Kashmiri tribal population. The 66% VDD prevalence, while high, is notably lower than the 83% reported in the general Kashmiri population, suggesting that the tribal population's outdoor occupational activities (farming, wood cutting, herding) and higher dairy consumption may confer relative protection. The inverse correlation of 25(OH)D with hs-CRP and insulin suggests potential links between VDD and inflammation or metabolic dysfunction. The lack of association between sun exposure duration and vitamin D status may reflect cultural practices of heavy clothing and the high latitude's seasonal UV-B limitations. Given the skeletal and extra-skeletal consequences of VDD, these preliminary data highlight the need for well-controlled interventional studies to guide supplementation strategies in this underserved population. Limitations include the absence of serum PTH and detailed dietary data, and low response rate (74%) in the 0–20 year age group.