VITAMIN D DEFICIENCY-THE NEXT PANDEMIC?
Dr.Dinesh Eshwar Mummareddi, MBBS
Over the last decade, Vitamin D Deficiency (VDD) has unfolded globally, swaying extra-skeletal health (infections, auto-immune disorders, cancers, psychological health) besides skeletal health. Well, the dwellers of a tropical nation like India where the sunlight is in plentitude, should not in the least suffer from the sunshine vitamin insufficiency. Yet the prevalence figures of VDD are irreconcilable. (14-24% VDD reported in 0- 19 years of age by Comprehensive National Nutrition survey by Ministry of Health and Family welfare).
Read on to get enlightened!
VDD is the most under-diagnosed and under-treated nutritional deficiency in the world. VDD is omnipresent in individuals no matter what their age, gender, ethnicity, geographical location may be. Vitamin D is photosynthesized in the skin on exposure to UVB rays. Exposure to daylight itself ought to serve the demands of Vitamin D. Despite plentiful sunshine, VDD is widely prevalent in India.
Recent literature has implicated the significance of VDD in skeletal and extra-skeletal disease. By virtue of its multifarious associations with ill- health, VDD deficiency epidemic in India contributes to a humongous burden on the healthcare system of India.
Endogenous cutaneous conversion of 7 dehydrocholesterols into cholecalciferol under the influence of UV-B marks the central source (90%) of Vitamin D for usual physiological functioning. Though this bioconversion seems undemanding, in actual is knotted with/limited by varied host and environmental factors.
Sunlight and exposure
A whole lot of the population in the urban areas are captivated in glass/cozy shelters in the course of work. The intensity of UV irradiance which is in chief element for the cutaneous biosynthesis is filtered through the surfaces we planted for protection and comfort. The UV light should be received unfiltered directly on to the skin for Vitamin D production efficiently. A minor proportion of the population though working outdoors, still manifest with deficiency due to Sub Optimal exposed Body Surface Area. A daily sunlight exposure of 30-45 mins over 15-40% BSA is recommended for at least 5 times a week during noon across different regions and seasons help in preventing VDD. The feasibility of this recommendation is still questionable due to urban lifestyle.
BSA exposed to sunlight is weighted the highest limiting factor for cutaneous synthesis of Vitamin D. Socioreligious and cultural practices which often dictate clothing practices do not facilitate adequate sun exposure.
Studies demonstrated that topical sunscreen/creams application lessens the sunlight penetration thereby causing serum Vitamin D decline. But the likelihood of developing skin related complaints shoot up if the use of the latter is not advocated. This is addressed by frequent small sub erythemal UVB dosing (MED = 40- 60mJ/cm2), proven to be more efficacious than single, prolonged bouts of exposures excluding the odds of skin damage.
7-dehydrocholesterol, an irreplaceable substrate for the vitamin D production declines as we move towards the old age. Fitzgerald Skin types, single nucleotide polymorphisms and lifestyle also invariably affect Vitamin D synthesis.
Eat to meet Vitamin D RDA??
Dietary contribution to the pool of plasma Vitamin D is less than 10%. Though negligible, dietary intake of Vitamin D needs to be pondered upon for the reason that it is workable as compared to sunlight exposure. Animal sources like fish, cod liver oil and plant sources like mushrooms which are rich in Vitamin D, are often consumed by the population. The CNNS report depicted VDD to be more prevalent in vegetarians than non-vegetarians (Major chunk of Indian population are vegetarians). Thus Vegetarianism certainly limits vitamin D rich dietary options.
Alternatively, dairy products, regardless of its minimal Vitamin D content, are rampantly used. Skimmed milk or low-fat milk (principally used in the urban sector to limit the calorie intake and to prevent obesity) has low levels Vitamin D compared to full cream and toned milk. So, fortification of Dairy products can be the key strategy to address this public health concern.
Planning to improve serum cholecalciferol levels in the population using Vitamin rich foods is ineffective due to its unavailability, cost effectiveness and dietary practices (Vegetarian and Non-Vegetarian food).
After comprehending sunlight and dietary recommendations to increase serum Vitamin D levels, which are unachievable in an urban context, what more can be done? Can an artificial source suffice the requirement? – The rise in serum 25(OH)D was less with the use of artificial UVB source than natural sunlight.
Can vitamin D supplementation provide a solution?
Studies on adult subjects have shown that vitamin D supplementation provides a higher and more predictable outcome compared to sunlight exposure. Though widely available, cost of these supplements is essentially prohibitive to the majority. Most Indians are not aware that they need additional vitamin D.
But for children the evidence to prove inferiority or superiority of using Vitamin D supplementation over sunlight is inadequate.
Pregnancy & Vitamin D
The cut off for VDD in pregnancy is higher (<20ng/ml) than that for adults(<12ng/mL) in view of its physiological role in conception and fertility. However, there is not enough evidence to endorse the higher cut offs for VDD in pregnancy. >30% pregnancies are associated with VDD. This soaring prevalence can be accounted to the lofty cut offs values. WHO provides comments only on dietary interventions & sunlight exposure for improving pregnancy outcomes, but does not debate over routine Vitamin D supplementation in pregnancy. Therefore, the clinical benefits of antenatal Vitamin D supplementation need to be investigated to provide evidence to practice.
What can we do to prevent Vitamin D deficiency??
- Addition of Vitamin D rich foods into routine diet (egg yolk, mushrooms, dairy products, cod liver oil, fish like salmon mackerel, tuna)
- Adequate exposure to sunlight
- Screening in case of high-risk individuals
l Fortification of staple foods with vitamin D is the most viable population-based strategy to achieve vitamin D sufficiency.
Conditions requiring routine Vitamin D supplementation
l Bed ridden patients for prolonged periods
- Chronic disease
- Long term glucocorticoid, anti-epileptic drugs, ketoconazole use
- Chronic Alcoholism
- Disorders with extensive cutaneous involvement
- Gupta P, Dabas A, Seth A, Bhatia VL, Khadgawat R, Kumar P, Balasubramanian S, Khadilkar V, Mallikarjuna HB, Godbole T, Krishnamurthy S, Goyal JP, Bhakhri BK, Ahmad A, Angadi K, Basavaraj GV, Parekh BJ, Kurpad A, Marwaha RK, Shah D, Munns C, Sachdev HPS. Indian Academy of Pediatrics Revised (2021) Guidelines on Prevention and Treatment of Vitamin D Deficiency and Rickets. Indian Pediatr. 2022 Feb 15;59(2):142-158. Epub 2021 Dec 29. PMID: 34969941.