Vitamin D or better known as the "sunshine vitamin" is a hormone produced by the skin in the presence of sunlight. Exposing one's skin for a few minutes in the sun is enough for our Vitamin D stores to be increased. Therefore, now that summer is approaching, one does not need to sunbath for long hours without wearing any sunblock or sunscreen. It is important to note that the use of sunscreen with an 8 Sun Protection Factor can hypothetically inhibit more than 95% of Vitamin D skin production. In reality sunscreen is applied so as to not impact vitamin D status. One should also avoid peak hours between 10am and 4pm because during this time the sun's UV rays are the strongest, thus increasing the risk of skin cancer. On the other hand Vitamin D can also be found in small amounts in some foods such as oily fish including sardines and salmon, eggs, mushrooms, dairy products and margarine.
Who is at risk of developing Vitamin D deficiency?
Elderly people may have decreased sun exposure and decreased Vitamin D diet intake. Yet one of the most possible causes of Vitamin D deficiency in the elderly is decreased skin thickness which decreases the concentration of Vitamin D in the skin epidermis; reducing Vitamin D synthesis. On the other hand ageing also decreases calcium absorption by 10-15 years. It is also important to note that the lower fat percentage, the greater is the risk for Vitamin D deficiency. This can be seen in athletes who attempt to get as lean as can be. On the other hand, obese individuals have low levels of Vitamin D mainly due to decreased sunlight exposure because of limited mobility and excessive storage of Vitamin D in adipose tissue, that is, fat tissue. Rates of Vitamin D deficiency are also higher among people who have conditions such as Inflammatory Bowel Syndrome (IBS) and pancreatic insufficiency caused by cystic fibrosis which result in malabsorption. Celiac Disease due to low vitamin D levels can also result in calcium malabsorption. Also after gastric bypass, a surgical procedure which reduces intestinal absorption, vitamin deficiencies are common. Moreover, places far away from the equator such as the UK tend to have high seasonal variations leading to low Vitamin D levels to occur more in winter than summer. On the other hand people with darker skin have more melanin than people with lighter skin. Melanin causes the skin pigmentation which lowers the skin's ability to synthesize Vitamin D response to sunlight.
Why is Vitamin D important?
It helps to regulate calcium and phosphate levels in the body which are required to keep our bones, muscles and teeth strong. In fact if Vitamin D is deficient in our body it can lead to rickets and osteoporosis, increasing the risk for fractures. In Malta, despite our sunny climate, over 57% of patients who were tested for Vitamin D levels in 2017 had low or deficient levels, according to Health Minister Chris Fearne. On the other hand, high amounts of Vitamin D in the body can lead to calcium toxicity in the blood which is obviously harmful. Therefore, maintaining a balance in life is fundamental.
But can Vitamin D really cure or at least prevent COVID-19?
A study published this month in BMJ, Nutrition, Prevention and Health has unproven reports that Vitamin D doses higher than 4000IU/d could reduce the risk of being infected with COVID-19 and not only this but also treat patients infected with COVID-19. Although there is some evidence that low Vitamin D is associated with acute respiratory tract infections, there is currently insufficient evidence for Vitamin D as a treatment for COVID-19 and over-supplementing must be avoided as it could be harmful, scientists report. In fact the study findings published in the BMJ journal were based on data gathered from population groups in developing countries, which cannot be generalized to all humans.
It is important to keep in mind that high levels of Vitamin D can cause digestive distress, such as vomiting, nausea, stomach pain, fatigue, dizziness, confusion, excessive thirst, formation of kidney stones and frequent urination due to high calcium levels. Ironically high Vitamin D levels can also lead to bone loss and kidney failure. Therefore, it is fundamental that before taking any supplements you always consult your doctor.
Rebecca Caruana is a medical student