Episode 4: COVID19 and Vitamin D — Answering your questions.
Episode Summary by Francesca Jacklin
In this week’s episode, Dr Bahijja Raimi-Abraham answered some of your questions about COVID-19 and vitamin D. Dr Bahijja takes the opportunity in this episode to investigate two interesting questions in detail, by exploring some exciting new scientific literature.
Question 1: “Approximately how long do vitamins last in the body once you have taken them as a supplement?” — Temi, Surrey
Vitamins are essential nutrients that our body requires in small amounts to develop and function properly. Because we can’t make most of them, we have to get them externally, either from varied diets or supplements. Vitamins can be split into two groups: fat-soluble vitamins, and water-soluble vitamins. Fat-soluble vitamins, such as vitamins A, D, E and K, are stored in our fat cells, and they require emulsification with fatty acids in order to be absorbed. In contrast, water-soluble vitamins, (including the vitamins Bs, Cs, and more) are not necessarily stored in the body and need to be replenished frequently. Your body takes in vitamins from the diet and any extra supplementations, and excretes any excess as waste.
To answer Temi’s question, vitamins last in the body for varying amounts of time depending whether they are fat- or water-soluble and other factors. Water-soluble vitamins tend to last in the body for less than 48 hours, while fat-soluble vitamins can be stored in the body for up to 6 months! This also depends on the requirements of the individual. For example, while vitamin D supplements can last in the body of adequately nourished individuals for around three months, in deficient individuals, the supplements could last only four weeks. Other factors affecting how long vitamins last for include the dosage of a particular supplement, the absorption rate, and indeed the quality of the supplement. We assume that when we take supplements, we are getting 100% of the described dose (e.g. 1000mg of vitamin C), but this isn’t always the case.
Question 2: “Do you think there is any link between the lack of vitamin D in people and those people dying from coronavirus?” — Lee, Norfolk
Vitamin D is a very interesting vitamin. It’s uniqueness arises not only from the fact that it acts as a steroid hormone, but it can also be produced in the skin by exposure to UV sunlight. Despite the body’s ability to produce it internally, an estimated 40–75% of individuals are deficient in the vitamin. Vitamin D has a well understood role in bone health, and several studies have highlighted additional roles in infectious diseases, heart disease, cancer, fertility, depression, diabetes, and Parkinson’s disease. In order to answer Lee’s question, we need to unpick the risk factors for vitamin D deficiency, and its role in respiratory and viral infections, specifically in COVID-19.
Common risk factors for vitamin D deficiency:
- Individuals with darker skin tones are at increased risk of vitamin D deficiency owing to higher levels of melanin in their skin (melanin is a pigment that decreases the skin’s ability to procure vitamin D from sunlight).
- Inadequate sunlight exposure, for example for individuals that tend to stay indoors, or live in countries with low light levels.
- Inadequate dietary intake of vitamin D-containing foods like fish or dairy.
- Individuals who are obese have higher risk of vitamin D getting trapped in fat tissues instead of getting released into circulation.
Low vitamin D status has been associated to increased vunerability to infectious diseases, specifically respiratory infections. However, whether low vitamin D levels are a cause or a consequence of disease is still a point of debate in scientific communities and is being actively investigated. There are a few research articles that have been published in the last couple of months that have investigated the relationship between vitamin D and COVID-19 mortality, which we will summarise here to shed some light on the possible connection.
Study 1: Vitamin D and SARS-Cov-2 Virus/COVID-19 Disease
A short report by researchers in the UK found that vitamin D appeared to inhibit pulmonary inflammatory processes, while enhancing the immune system against respiratory pathogens. They noted a population-based study that showed positive associations between vitamin D levels and lung function. Interestingly, they suggest that low vitamin D status may be exacerbated during COVID-19 crisis due to increased indoor living (reduced sun exposure), and individuals living in areas of low sunlight may benefit from vitamin D supplementation.
Study 2: Vitamin D and Inflammation: Potential Implications for Severity of COVID-19
The group analysed European adult population studies completed since 1999 which measured vitamin D levels, and compared these vitamin D levels with death rates from COVID-19. They found that countries at a lower latitude (typically sunny countries) had low concentrations of vitamin D, which corresponded to high levels of infection and death rates from COVID-19 in Europe. Surprisingly, northern latitude countries including Norway, Finland, and Sweden, had higher vitamin D levels despite having lower UV exposure, presumably as they use more supplementation and fortification in food products. These countries also have lower levels of COVID-19 infection, and the authors concluded that the correlation between low vitamin D levels and COVID-19 mortality was statistically significant (this means that the relationship is likely not to have arisen due to chance). They also suggested that optimising vitamin D levels is likely to reduce complications from COVID-19, due to its role in regulation and suppression of inflammatory responses. This raises some interesting questions surrounding whether people would benefit from regular vitamin D supplementation.
Researchers conducted a statistical analysis of data from hospitals and clinics across 10 countries affected by COVID-19. They noticed that patients from countries with high COVID-19 mortality rates (at the time of their analysis) such as Italy, Spain, and the UK, had lower levels of vitamin D compared to countries not as severely affected. They discovered a strong correlation between vitamin D levels and a phenomenon called cytokine storm, a hyperinflammatory condition that has strong links to mortality in COVID-19 patients. They also found a correlation between vitamin D deficiency and mortality.
Although there is currently limited data available, the few studies investigate a possible relationship between vitamin D levels and COVID-19 have demonstrated clear links between low vitamin D levels and increased vulnerability to the disease. This doesn’t necessarily mean that everyone should start hoarding vitamin D supplements, but it is important to be aware of the emerging understanding of COVID-19, as we are constantly learning more about the disease and ways that we can protect ourselves.
Thank you for your questions Temi and Lee! If you have any questions you’d like to be answered by Dr Bahijja, feel free to send them in via the website chat, or email MondayScience2020@gmail.com. You can also send us your questions as a voice message via https://anchor.fm/mondayscience/message. We love to hear your thoughts!
