Text and Photos by Henrylito D. Tacio
Aside from vitamin C and zinc, doctors recommend that those who are infected with SARS-CoV-2 should also take vitamin D, a fat-soluble vitamin. Nicknamed the “sunshine vitamin” due to its ability to be absorbed by the body through sunlight, it is especially important for immune system health.
“The immune system defends the body against foreign organisms such as bacteria, viruses, and parasites,” writes Sherry Christiansen for verywellhealth.com. “Not only does the immune system kill foreign invaders, but it also develops a protective ability (acquired immunity) to prevent future infections.”
Some research shows that having healthy levels of vitamin D can help the immune system be healthy and may protect against respiratory illnesses in general. In fact, a recent study that appeared in the peer-reviewed journal PloS One indicated that patients hospitalized with coronavirus disease 2019 (C0VID-19) who had sufficient vitamin D levels had a decreased risk for adverse outcomes and death.
“Vitamin D is necessary for the proper functioning of your immune system – which is your body’s first line of defense against infection and disease,” explains healthline.com’s Katherine Marengo, a clinical registered dietitian. “This vitamin plays a critical role in promoting immune response. It has both anti-inflammatory and immunoregulatory properties, and is crucial for the activation of immune system defenses.”
Vitamin D is so important for an immune function that low levels of it have been associated with increased susceptibility to infection, disease, and immune-related disorders. Low vitamin D levels, some studies found, are associated with an increased risk of respiratory diseases, including tuberculosis, asthma, and chronic obstructive pulmonary disease.
More importantly, vitamin D deficiency has been linked to decreased lung function. This is one of the reasons why doctors recommend taking vitamin D as COVID-19 can cause lung complications such as pneumonia and, in the most severe cases, acute respiratory distress syndrome.
Egg yolks 
Fortified milk
Right now, there is still no cure or treatment available for COVID-19. Only a few studies have investigated the effect of vitamin D supplements or vitamin D deficiency on the risk of contracting the dreaded coronavirus that causes COVID-19.
In her feature, Marengo reported on a study that analyzed hospital data of 235 patients with COVID-19. “In patients older than 40, those who had adequate levels of vitamin D were 51.5% less likely to have adverse outcomes, including becoming unconscious, hypoxia, and death, as compared to vitamin D-deficient patients.”
Other studies have shown that vitamin D supplements can enhance immune response and protect against respiratory infections overall. There are also studies that indicate that vitamin D deficiency may harm immune function and increase a person’s risk of developing respiratory illnesses.
“Vitamin D supplements have also been shown to reduce mortality in older adults, who are most at risk of developing respiratory illnesses like COVID-19,” Marengo writes. “What’s more, vitamin D deficiency is known to enhance a process known as the ‘cytokine storm.’”
Cytokines are small glycoproteins produced by various types of cells throughout the body. “During a cytokine storm,” explains Benedette Cuffari of New Medical Life Sciences, “various inflammatory cytokines are produced at a much higher rate than normal. This overproduction of cytokines causes positive feedback on other immune cells to occur, which allows for more immune cells to be recruited to the site of injury that can lead to organ damage.”
Despite its name, vitamin D is actually not a vitamin but a prohormone or precursor of a hormone. A human body produces it as a response to sun exposure. “The body creates vitamin D from direct sunlight on the skin when outdoors,” says the National Health Service (NHS) of Great Britain.
People who are infected with the COVID-19 virus are advised to have sunshine exposure for 20-30 minutes, either in the early morning or late afternoon.
“You cannot overdose on vitamin D through exposure to sunlight,” the NHS says. “But always remember to cover up or protect your skin if you’re out in the sun for long periods to reduce the risk of skin damage and skin cancer.”
Vitamin D is also found in a small number of foods. Sources include oily fish (such as salmon, sardines, herring, and mackerel), fortified milk, cheese, red meat, beef liver, egg yolks, mushrooms, and fortified foods (like some fat spreads and breakfast cereals).
Another source of vitamin D is dietary supplements. “Although people can take vitamin D supplements, it is best to obtain any vitamins or minerals through natural sources wherever possible,” urges Medical News Today’s, Megan Ware.
Although the body can create vitamin D, a deficiency can occur in some instances. According to Ware, vitamin D deficiency symptoms may include regular sickness or infection, fatigue, bone and back pain, low mood, impaired wound healing, hair loss, and muscle pain.
“If vitamin D deficiency continues for long periods, it may result in complications such as cardiovascular conditions, autoimmune problems, neurological diseases, infections, pregnancy complications, and certain cancers (especially breast, prostate, and colon),” Ware says.
A study which came out in The American Journal of Sports Medicine showed that about one billion people worldwide are either vitamin D insufficient or deficient.
In the Philippines, a study conducted by the Department of Science and Technology (DOST) showed one in 10 Filipino children – 6 to 12 years old – lacks vitamin D.
One in 10 or 10.3 percent (%) of Filipino children 6 to 12 years old coming from selected provinces and cities in the country is vitamin D deficient.
According to the 2018 Expanded National Nutrition Survey (ENNS) of the DOST’s Food and Nutrition Research Institute (FNRI), a significantly higher proportion of vitamin D insufficiency is observed in girls, 6 in 10 (57.6%) than among boys, 4 in 10 (43%), aged six to12 years old. A vitamin D concentration of 50 to less than 75 nanomoles (nmol) per liter (L) is considered insufficient (50- <75 nmol/L).
The survey also found out that there are more children in urban areas (59%) who have insufficient vitamin D compared to their rural counterparts (45.4%). Likewise, around 4 to 5 in 10 of Filipino children, six to12 years old across islands (NCR: 57.9%, Luzon: 45.8%, Visayas: 47.7%, and Mindanao: 51.2%) have insufficient levels of vitamin D.
The survey added that older children 11-12 years old have a higher likelihood of having vitamin D deficiency than younger children. In addition, girls are 1.5 times more likely to be vitamin D deficient than boys.
The probability of having vitamin D deficiency is 5.4 times higher in children living in urban areas, the survey concluded.
“Vitamin D deficiency has links to high blood pressure in children,” Ware says, citing a 2018 study that found a possible connection between low vitamin D levels and stiffness in the arterial walls of children.
The US National Institute of Health (NIH) Admits that obtaining sufficient vitamin D from natural (non-fortified) food sources alone is difficult. Some doctors advise taking supplements. But don’t take too much of it. Remember, vitamin D is a micronutrient that helps increase mineral absorption like calcium which is necessary for bone health and development.
“Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body,” the NHS says. “This can weaken the bones and damage the kidneys and the heart.”
If you choose to take vitamin D supplements, ten micrograms a day will be enough for most people. “Do not take more than 100 micrograms (4,000 IU) of vitamin D a day as it could be harmful,” NHS warns. “This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years.”
Children aged 1 to 10 years should not have more than 50 micrograms (2,000 IU) a day, the NHS says. Infants under 12 months should not have more than 25 micrograms (1,000 IU) a day.
There are people who have medical conditions, which mean they may not be able to safely take as much. Vitamin D supplements may also interact with several types of medications. “If in doubt, you should consult your doctor,” the NHS advises.
Now, if your doctor has recommended you take a different amount of vitamin D, you should follow his advice.