Sir,
Serum 25-OH vitamin D (25OHD) includes both 25-OH vitamin D2 (25OHD2) and 25-OH vitamin D3 (25OHD3). Most of the vitamin D is synthesized in the skin and is in D3 form, whereas D2 form is derived from plant sources. Serum 25OHD2 contribution to serum 25OHD levels is low. However, there are no studies that report serum 25OHD2 among Indians. The aim of this study is to estimate vitamin D status in healthy adult volunteers from southern coastal Andhra Pradesh using liquid chromatography–tandem mass spectrometry (LC–MS/MS) method.
This is a community-based cross-sectional study conducted between January 2019 and July 2019 at Nellore, Andhra Pradesh, India. Apparently healthy adults were randomly selected. Pregnant and lactating women, individuals on calcium, vitamin D, or multivitamin supplements, and those with acute illness were excluded from the study. A fasting blood sample was collected from all the participants, and serum total vitamin D, vitamin D3, and vitamin D2 levels were estimated by LC–MS/MS method. The test was conducted at Thyrocare®, Mumbai. Vitamin D status was classified according to the guidelines by the Endocrine Society of US [1].
The study included 82 participants including 47 females. The mean age of the study population was 34.3 ± 7.9 years. Serum total vitamin D level was 17.9 ± 7.35 ng/ml. Only two individuals had vitamin D sufficiency (serum 25OHD: > 30 ng/ml), 31 patients had vitamin D insufficiency (serum 25OHD: 20–30 ng/ml), and 48 participants had vitamin D deficiency (serum 25OHD: < 20 ng/ml). Serum 25-hydroxy vitamin D2 level of the study population was 0.60 ± 0.62 ng/ml accounting for 4.31 ± 5.59% of total vitamin D levels. Serum 25OHD, 25OHD2 and 25OHD3 levels were not significantly different between males and females whereas percentage serum 25OHD2 level tended to be higher among females than males (5.24 ± 6.89 vs 2.74 ± 0.46, p = 0.053) (Table 1). Percentage serum 25OHD2 level inversely correlated with age (r = − 0.263, p = 0.017) and serum 25OHD level (r = − 0.406, p < 0.001).
Table 1.
Comparison of age and vitamin D levels among males and females
| Males (n = 35) | Females (n = 47) | p Value | |
|---|---|---|---|
| Age (years) | 35.7 ± 6.6 | 33.2 ± 8.6 | 0.134 |
| Serum 25-hydroxy vitamin D (ng/ml) | 18.6134 ± 5.8 | 17.4049 ± 8.3 | 0.443 |
| Serum 25-hydroxy vitamin D2 (ng/ml) | 0.5409 ± 0.49 | 0.6581 ± 0.71 | 0.381 |
| Serum 25-hydroxy vitamin D3 (ng/ml) | 18.08 ± 5.7 | 16.81 ± 8.3 | 0.416 |
| Serum 25-hydroxy vitamin D2 (%) | 3.06 ± 2.7 | 5.54 ± 6.8 | 0.045 |
Several studies have consistently reported low hypovitaminosis D among Indians [2–4]. The hypovitaminosis D is almost universal among the urban as well as rural population from Andhra Pradesh [4]. This is the first study to report vitamin D status from southern-costal Andhra Pradesh and found almost universal hypovitaminosis D, in accordance with the several published Indian studies [2–4].
A large, laboratory-based retrospective study has reported hypovitaminosis D using LC–MS/MS among Asian Indians [5]. Our study, although small, is the first study to report hypovitaminosis D by LC–MS/MS among Asian (south) Indians in a community-based study. The study also has the credit of being the first study to report serum 25OHD2 levels among Asian Indians. Unlike most of the Western countries, ergocalciferol preparations are not available in India and the measured D2 levels in our study population truly represent the naturally derived D2. Serum 25OHD2 levels accounted for less than 5% of serum 25OHD level suggesting the negligible contribution of the plant-based diet derived vitamin D2 to total vitamin D in south-Indian population. A negative correlation of 25OHD2 with 25OHD suggests lower absolute contribution of vitamin D2 to total vitamin D in those with higher serum 25OHD. This suggests a capping for the plant-based diet derived vitamin D in the study population.
To conclude, most of the adults from coastal southern Andhra Pradesh suffer from hypovitaminosis D. Serum 25OHD2 levels were negligible and accounted for less than 5% of serum 25OHD level.
Funding
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Conflict of interest
The authors declare that they have no conflict of interest.
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References
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