This article reviews the roles of vitamin D in reducing the risk of respiratory tract infections, knowledge about the epidemiology (cause and prevention ) of influenza, and COVID-19.
The world is facing serious lockdown and shutdown due to the COVID-19 pandemic. The government of India is taking all necessary steps to ensure that we all are prepared well to face the challenge and threat posed by the growing pandemic of COVID-19 the novel coronavirus.
What is Vitamin D
We all are not from a science background but yet we still know the importance of vitamins for our health but knowing more about it will help in developing better relationships with our food and health.
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, and available as a dietary supplement.
Exposure to the sun helps the body to make vitamin D, that’s why it is also known as Vitamin Sun.
Vitamin D obtained from sun exposure, food, and supplements is biologically inert (not useful) and must undergo activation in the body. vitamin D3 is manufactured by chemical conversion of cholesterol.
Why we need vitamin-D
Vitamin D promotes calcium absorption in the gut and maintains calcium and phosphate concentrations to enable normal mineralization of bone and to prevent low blood calcium. It is also needed for bone growth and bone remodeling. Without sufficient vitamin D, bones can become thin, brittle, and that may lead to misshapen.
Vitamin D sufficiency prevents rickets in children and osteomalacia in adults. Together with calcium, vitamin D also helps protect older adults from osteoporosis.
Vitamin D has other roles in the body, including modulation of cell growth, neuromuscular and immune function, and reduction of inflammation.
Research indicates vitamin D deficiency plays a role in causing seventeen varieties of different cancers as well as heart disease, stroke, auto-immune diseases, birth defects, and periodontal disease.
How to get our daily dose
There are very few foods in nature contain vitamin D and Calcium .
The flesh of fatty fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. Small amounts of vitamin D are found in beef liver, cheese, and egg yolks. Some mushrooms provide vitamin D2 in variable amounts.
Vitamin D in these foods is primarily in the form of vitamin D3
Most people meet at least some of their vitamin D needs through exposure to sunlight. Ultraviolet penetrates uncovered skin and converts to pre-vitamin D3, which in turn becomes vitamin D3
In supplements and fortified foods, vitamin D is available in the form of D2 (ergocalciferol) and D3 (cholecalciferol)
How much is Recommended
RDA (recommended daily allowance) of 600-800 IU is recommended to maintain adequate levels of vitamin D.
In our country, the Indian Council of Medical Research (ICMR) recommends a daily supplement of 400 IU/day of vitamin D for Indians under situations of minimal exposure to sunlight.
The ignored Pandemic of Vitamin D deficiency
Over a billion people worldwide are vitamin D deficient or insufficient. Nutrient deficiencies are usually the result of dietary inadequacy, impaired absorption, and use, increased requirement, or increased excretion.
A vitamin D deficiency can occur extensive use of sunscreens and placement of children in daycare programs, where they often have less outdoor activity and sun exposure.
Rickets and osteomalacia are classical vitamin D deficiency diseases. In children, vitamin D deficiency causes rickets
Groups that are at Risk
Breastfed infants: Vitamin D requirements cannot ordinarily be met by human milk alone, mothers who supplement with high doses of vitamin D may have correspondingly high levels of this nutrient in their milk.
Older adults: Older adults are at increased risk of developing vitamin D insufficiency in part because, as they age, skin cannot make vitamin D as efficiently, they are likely to spend more time indoors, and they may have inadequate intakes of the vitamin People with limited sun exposure:
Home-bound individuals: Women who wear long robes and head coverings for religious reasons, and people with occupations that limit sun exposure are unlikely to obtain adequate vitamin D from sunlight.
Obese people: People who are obese may need larger than usual intakes of vitamin D to achieve D levels comparable to those of normal weight
Vitamin D in relation to Covid-19
According to research, vitamin D can reduce the risk of infections through several mechanisms,
Those mechanisms include inducing cathelicidins and defensins that can lower viral replication rates and reducing concentrations of pro-inflammatory cytokines that produce the inflammation that injures the lining of the lungs, leading to pneumonia, as well as increasing concentrations of anti-inflammatory cytokines.
That vitamin D deficiency has been found to contribute to acute respiratory distress syndrome; and that case-fatality rates increase with age and with chronic disease comorbidity, both of which are associated with a lower concentration of Vitamin D.
To reduce the risk of infection, it is recommended that people at risk of influenza and or COVID-19 consider taking 10,000 IU per day of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations,
Research also shows that vitamin D plays a role in reducing lung damage. On the contrary, chronic hypovitaminosis D induces pulmonary fibrosis.
It has been suggested by some vitamin D researchers, that approximately 5–30 minutes of sun exposure between 8 AM and 11 AM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient vitamin D synthesis.
Individuals with limited sun exposure need to include good sources of vitamin D in their diet or take a supplement to achieve recommended levels of intake.
UV radiation is a carcinogen responsible for most skin cancers and deaths due to metastatic melanoma that occurs annually all over the world. We Indians are more resistant due to darker skin (high Melanin) still it’s better to avoid direct sunlight and try to get RDA dose from food and safe supplements.
For the treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful. Randomized controlled trials and large population studies should be conducted to evaluate these recommendations.
It is important to interpret evidence like this as part of a bigger scientific conversation, meaning it would be premature to make any recommendations and certainly way too premature to hit the supplement aisle before further evidence arrives. Rather taking vitamin D from the natural source is recommended
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