We make vitamin D in our skin but only when the UV index is greater than 3. In the UK, this is usually only in Spring and Summer
As many people have been self-isolating at home during Spring 2020 and not getting their usual sun exposure, Public Health England recently extended its previous advice to take vitamin D supplements during autumn and winter to recommend that adults continue to take vitamin D throughout the year.i
Dr Sarah Brewer, Healthspan Medical Director said: “Vitamin D supplements are especially important for older people who have been, or are still cocooning indoors and are at high risk of vitamin D deficiency due to lack of sun exposure. Even before the current pandemic, the national diet and nutrition surveys revealed that around 27% of adults over the age of 70 years old are deficient in vitamin D, and that 1 in 8 adults over the age of 50 years old is deficient in vitamin D the whole year-round.”
Using sunscreens to protect against skin cancer also makes vitamin D supplements advisable. Used properly, even a sunscreen with a sun protection factor of SPF8 reduces vitamin D production in the skin by 95%, while SPF15 reduces vitamin D3 production by 99%.
Vitamin D and COVID-19
Researchers from Trinity College Dublin have found there are high rates of vitamin D deficiency in some sunny countries, such as Spain and Northern Italy, which experienced high coronavirus infection and death rates. In contrast, people living in Norway, Finland and Sweden had good vitamin D levels (due to oily fish intake and supplementation rather than sun exposure) and were less severely affected by COVID-19.ii
Doctors have also highlighted that the risk of being admitted to an Intensive Care Unit with COVID-19 is 20-fold higher in people who are vitamin D deficient compared with those who are not.iii
Previous research shows that taking a vitamin D3 supplement can reduce the risk of experiencing a respiratory tract infection (including the common cold, influenza and pneumonia) by a third compared with placebo.iv The benefits are even greater in people with an existing vitamin D deficiency.
Vitamin D and immunity
Our immune cells, including B and T lymphocytes, all carry specific vitamin D receptors that help to regulate their activity.v Vitamin D helps to activate macrophages – our hunter-killer immune cells that engulf and destroy viruses and bacteria, and stimulates the production of antibiotic-like proteins (definsins) within the lining of the respiratory tract. Vitamin D also increases our production of natural antimicrobial factors.vi
During Victorian times respiratory infections were treated with cod liver oil and exposure to UV rich sunlight, both of which are now known to help boost circulating levels of vitamin D.
Studies involving over 19,000 adults show that people with the lowest levels of vitamin D are 36% more likely develop a common cold than those with high levels, for example.vii
Other research shows that taking a vitamin D3 supplement can reduce the risk of experiencing a respiratory tract infection (including the common cold, influenza and pneumonia) by a third compared with placebo.viii The benefits are even greater in people with an existing vitamin D deficiency.
By protecting against the viruses that cause colds and bronchitis, vitamin D also helps to reduce the risk of a flare-up in people with asthma. Taking a vitamin D supplement can reduce the risk of a severe asthma attack that needs emergency treatment by as much as 61%. In fact, the association between low vitamin D level and respiratory infections is greatest in people with asthma (5.6-fold increased risk) or chronic obstructive pulmonary disease (2.2-fold increased risk).ix
Taking vitamin D safely
Vitamin D is only found in useful amounts in oily fish, liver products, eggs, butter or fortified foods. Public Health England therefore recommends that we all take a daily 10mcg vitamin D supplement during the colder months of the year.
Older people may benefit from a higher dose as the ability to make vitamin D in the skin at least halves between the ages of 20 to 80 years – often more. In one study, researchers found that people aged 62 to 80 years synthesised four times less natural vitamin D than those aged 20 to 30 years.x I recommend 25mcg vitamin D3 for adults aged up to 50 years, and 50mcg per day thereafter.
Available in various formats now besides Healthspan Super Strength Vitamin D3 Supplements, 60 tablets £3.95 such as gummies and sprays.
Or it is available in a sachet format with A.Vogel’s Balance Drink that also contains other important minerals and works like an electrolyte drink www.avogel.co.uk (7x 5.5g) £6.99.
Excess vitamin D can cause side effects due to disturbances in calcium metabolism such as headache, loss of appetite, nausea, vomiting, diarrhoea or constipation, palpitations and fatigue. An upper safe intake level of 100mcg per day (4000 IU) is therefore recommended by the EU.xi
iv Bergman P et al. PloS ONE 8(6):e65835
v http://www.ncbi.nlm.nih.gov/pubmed/22259647 Youssef DA et al. Dermatoendocrol 2011 3(4):220-229
viii Bergman P et al. PloS ONE 8(6):e65835