“Longer indoor activities plus poor nutrition status has driven an increased risk of vitamin D deficiency amongst the population in the past two decades”.
Vitamin D is the most potent fat-soluble vitamin which is important for proper growth and development. Unlike other vitamins, this vitamin can be synthesised from a non-economical source (sunlight) but you can also obtain this from food sources including fortified products, milk, egg and fish. The main principle role of vitamin D is to support calcium metabolism. It aids the body to absorb calcium and phosphorus from food to promote healthy bone formation.
Hossein-nezhad and Holick (2013), stated that Vitamin D deficiency (VDD) has been reported worldwide which is a universal health problem that not only influences muscular-skeletal health but also affects a wide range of acute and chronic diseases. In India, regardless of the tropical country which receives sunlight throughout the year, VDD has been documented ubiquitously to be in a range of 50-90% among all age groups (Mehlawat et al, 2014). VDD or low level of vitamin D can be related to certain conditions, namely, cardiovascular diseases, cancer, diabetes, depression and infectious diseases.
Apart from this, vitamin D synthesis in the body is directly correlated to multiple factors such as latitude, atmospheric pollution, skin pigmentation, clothing and duration, exposure to sunlight and cultural practices (Aparna et al, 2018). Therefore, it is very important to create an awareness among the public and healthcare centres about the significance of vitamin D and the outcome of deficiency. However, our Indian diets usually do not meet the daily requirement of vitamin D for a normal adult. Due to which food industries have already come up with innovative ideas just to overcome this deficiency. The government has also taken certain initiatives like food fortification (vitamin D fortified milk and milk products).
Fig. 1: Biosynthesis and functions of vitamin D (Brown et al, 2012).
As mentioned above, VDD can be combated either by sufficient sun exposure, fortified foods or through supplementation. Vitamin D supplementation is present either in the form of calcitriol or cholecalciferol. The former one is the activated form of vitamin D while latter one is the pre-activated form. Vitamin D3 supplements are widely accessible in the market which is converted into its activated form (i.e., calcitriol) in the kidney. Then, it helps in the absorption of calcium and phosphorus from the intestine and aids in bone health. Health benefits of vitamin D are not confined to bone health. There are various other functions of vitamin D in the body which are outlined below:-
Fig.2: Functions of Vitamin D
Status of vitamin D relative to 25-Hydroxyvitamin D level
Serum 25(OH) D is important to support both skeletal and extraskeletal physiological effects. According to the US Endocrine Society classification, less than 20 ng/mL of serum 25 (OH) D with a subsequent and consistent increase of parathyroid hormone (PTH) while a decrease in intestinal calcium absorption is observed as vitamin D deficiency (Holick et al, 2011).
Table 1 showed the diagnostic cut-offs of levels of serum vitamin D.
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TABLE 1: DIAGNOSTIC CUT-OFFS OF LEVEL OF SERUM VITAMIN D |
|
|
Vitamin D status |
The serum level of vitamin D in ng/ml |
|
Deficiency |
<20 |
|
Insufficiency |
21-29 |
|
Sufficiency |
>30 |
|
Toxicity |
>150 |
30-100 ng/mL of serum 25(OH)D level would be considered desirable and safe because at that level intestinal calcium absorption attains its peak whereas PTH levels persistently fall till this level of 25 (OH) D is achieved (Holick, 2007).
Indian diets are almost devoid or low in vitamin D rich foods. Majority of the Indian population lives in an areas where they get sufficient exposure to sunlight throughout the year and are expected to have enough vitamin D level. But this is not the case, in India prevalence of VDD is high. Withal, vitamin D 3 supplementation is one of the easiest to accomplish the daily vitamin D requirements.
References
1. Aparna, P., Muthathal, S., Nongkynrih, B., Gupta, S.K. (2018). Vitamin D deficiency in India. J Family Med Prim Care, 7, 324-30.
2. Brown, S.D., Calvert, H.H., Fitzpatrick, A.M. (2012). Vitamin D and asthma. Dermato-Endocrinol, 4,137–145.
3. Hossein-nezhad A, Holick MF (2013). Vitamin D for health: A global perspective. Mayo Clin Proc, 88, 720–55.
4. Holick, M.F., Binkley, N.C., Bischoff‐Ferrari, H.A., Gordon, C.M., Hanley, D.A., Heaney, R.P. et al. (2011). Evaluation, treatment, and prevention of Vitamin D deficiency: An endocrine society clinical practice guideline. J Clin Endocrinol Metab, 96,1911‐30.
5. Holick, M.F. (2007). Vitamin D deficiency. N Engl J Med, 357, 266‐81.
6. Mehlawat, U., Singh, P., Pande, S. (2014). Current status of Vitamin-D deficiency in India. Innovations in Pharmaceuticals and Pharmacotherapy, 2(2), 328-335.