SANTIAGO – The role of vitamin D in preventing coronavirus mortality has been suggested by several research studies worldwide. An observation study that used data from 20 European countries affected by Covid-19 was published in the journal Aging Clinical and Experimental Research Apr. 15, 2020. The average vitamin D level was found to be closely related to both the number of cases and deaths due to the infection.
The high risk group for Covid-19 are the elderly, observed to have lower vitamin D in countries like Spain, Italy, and Switzerland – the same countries with a reported high death rate. A comparatively lower death rate was found in the northern part of Europe where people have higher average vitamin D levels thanks to the consumption of cod liver oil, supplements, fortified milk, and possibly less sun avoidance. This has been linked to vitamin D’s possible protective effects vis-à-vis the infection.
Vitamin D has already been shown to protect against acute respiratory infections. Its role in elevating immune response during flu and previous coronaviruses has been studied and proved. According to a paper published in The Lancet (Apr. 10, 2020), the role of vitamin D in immunity regulation by reducing the cytokine storm may avoid the complications caused by a cytokine storm frequently observed in elderly Covid-19 patients.
Cytokine storm indicates the production of higher levels of cytokines by the overactivated adaptive immune system when the innate immune system fails after coronavirus infection. This has been observed in elderly Covid-19 patients leading to fatal complications such as pneumonia, heart, or kidney failure. The paper analyzed the potential impact of vitamin D supplementation in controlling cytokine storms and suggested this may reduce the severe cases.
Why Is Vitamin D So Important?
Vitamin D helps in absorbing calcium in the gut and maintaining its sufficient levels along with phosphate. This, in turn, results in the normal mineralization of our bones. It is also required for bone growth and bone remodeling. When vitamin D is insufficient, our bones can become thin, brittle, and lose strength. Vitamin D sufficiency prevents rickets in children and, together with calcium, helps protect older adults from osteoporosis. Other essential roles in the body include modulation of cell growth, neuromuscular and immune function, reduction of inflammation, strengthening the immune system, preventing and combating obesity, and decreasing the production of cancer cells.
Vitamin D enters our body in two ways: dietary sources and sun exposure. It is formed beneath the skin by ultraviolet rays of sunlight (sunshine vitamin). It is naturally present in very few food items such as oily fish (salmon, tuna, mackerel), fish liver oil, and, to a lesser extent, in egg yolk, beef liver, and some wild mushrooms.
Despite the importance of sunlight for producing vitamin D, it is nevertheless recommended that people limit skin exposure to sunlight and UV radiation from tanning beds, because UV radiation is responsible for most of the estimated 1.5 million skin cancers globally. Avoiding sun exposure and using sun protection, however, puts people at higher risk for vitamin D deficiency.
As people age, they also become increasingly homebound and get less sun exposure. Proper diet and supplements are therefore key for many. Fortified foods have become common in the United States, Canada, and Finland, where daily food items like milk, cheese, yogurt, and orange juice, are fortified with vitamin D either by law or voluntarily.
Why Chileans Need To Worry
Winter and decreased sun exposure might further complicate the Covid-19 situation in Chile. There has been vitamin D deficiency or insufficiency in both men and women of all ages throughout the country and it is more noticeable in wintertime.
Chile has recorded the lowest intake of vitamin D among Latin American nations. The Chilean population barely reaches 25 percent of the recommended daily vitamin D intake. For example, only 17 percent of Chileans surveyed met the recommendation to consume fatty fish twice a week, which is touted as the best dietary source of Vitamin D.
The inhabitants of extreme latitudes are particularly at high risk due to low sun exposure, e.g., Aysén and Magallanes. The distribution of solar rays being dependent on the unique geographical shape of Chile, solar radiation may not be sufficient from Concepción south, in the autumn and winter.
An alternate route of providing vitamin D is being investigated under the Nutrition and Dietetics Program at Pontificia Universidad Católica, Santiago. Nutritionists from the university’s faculty of medicine are studying a list of foods to fortify that Chileans typically eat. For example, items like bread, oil, milk, and flour are commonly consumed in Chile and readily available to a larger part of the population at a low cost compared to oily fishes.
The Path Forward?
It might be useful to check vitamin D levels in elderly people (≥ age 70) throughout the country and those with bone or muscle diseases such as osteoporosis and osteoporotic fractures, those who use medications that interfere with vitamin D metabolism, and those who suffer from liver or kidney damage. This data will be useful in managing in Covid-19 cases throughout the country as it is an emerging, rapidly evolving situation.
Given that over 85 percent of Chile’s population is urban and that Santiago is the epicenter of ongoing coronavirus infection, residents’ lifestyle should be a concern for the public health system. Average vitamin D levels should be surveyed and the extent of sun avoidance, the use of sunscreen due to fear of UV-induced skin cancer, daily proportion of vitamin D rich diet and supplements, and the use of fortified food should all be studied.
The link between severe Covid-19 cases and vitamin D deficiency, however, has mainly been established by observational studies to date since the pandemic began. This should be taken with a grain of salt and hence cannot be used to inform public policy as there is no clinical data.
Dr. Mahesh Balwant Khot is working as a postdoctoral scientist at Biotechnology Centre of University of Concepcion at Concepcion campus of Chile. Dr. Mahesh is handling a FONDECYT, Goverment of Chile funded project, on biodiesel production from a newly isolated yeast obtained from Valdivian temperate forest ecosystem of southern Chile. He obtained his Ph.D. in microbiology from Shivaji University, Kolhapur and University of Pune in India.