Vitamin D is important for bone, teeth and muscle health. It is an extremely important vitamin that has powerful effects on several systems throughout your body. Unlike other vitamins; vitamin D functions like a hormone, and every single cell in your body has a receptor for it.

Vitamin D modulates the response of our white blood cells – a key component of our immune system – by preventing them from releasing too many inflammatory cytokines. These are proteins we produce to fight an invading infection, but which also lead to the inflammatory symptoms we experience, such as fever.

SARS-CoV-2, the virus that causes Covid-19, is known to cause an excess of pro-inflammatory cytokines. The sickest patients suffer what is known as a ‘cytokine storm’ – a severe immune response to the infection that causes major inflammation.  Now there are mounting questions about whether vitamin D has a role to play in the fight against coronavirus.

The Scientific Advisory Commission on Nutrition (SACN) and the health watchdog the National Institute of Health and Care Excellence (NICE)² have done a rapid review of the evidence. The Scientific Advisory Committee on Nutrition (SACN) has reviewed studies on vitamin D for treating or preventing chest infections and say there is insufficient evidence to recommend the vitamin for this.

But can it stop coronavirus?

A review of research by NICE suggests there is no evidence to support taking vitamin D supplements to specifically prevent or treat COVID-19. But experts do think that it may have some broader health benefits during the pandemic.

How do I get Vitamin D?

Your body makes Vitamin D from cholesterol when your skin is exposed to sunlight.  Sunlight exposure is a major source of vitamin D for most people, with 20-60minutes of non-protected sun exposure skin being required daily to enable optimum levels of Vitamin D. It can also be obtained from the diet. It’s found in certain foods such as oily fish, eggs and mushrooms. Although eating a well-balanced diet can help ensure the normal functioning of the immune system, it’s difficult to get enough vitamin D from food alone. Eating a well-balanced diet is important for good health and is advisable even when people aren’t facing a pandemic disease outbreak. Some breakfast cereals, breads and dairy products are fortified with vitamin D in countries where sunlight exposure is limited.

Vitamin D is also available as a supplement in tablet, oral drop, capsules or spray forms.

Am I Vitamin D deficient?

Vitamin D deficiency has been associated with a variety of health problems: weak immune system, rickets, fatigue, bone fractures, osteoporosis and headaches.

NICE estimates that about one-quarter of the Irish & UK population is deficient in Vitamin D, rising to about one-third in winter months, owing to reduced sun exposure. This deficiency is also extremely common during autumn and winter in Northern and Central Europe, Canada and the northern half of the USA, and similarly some regions in the southern hemisphere.

Deficiency in Vitamin D is more commonly found in older individuals- as you get older your bodies ability to process Vitamin D decreases. It has also been highlighted that Vitamin D levels are below the optimum 100+ nmol/l serum blood levels in many of the younger population also. This is due to several factors which would include acquiring less sun exposure throughout the year compared to our equator counterparts along with and increased population living in more densely populated areas where high buildings are prominent causing more shaded areas. This coupled with the effects of populations being more ‘sun aware’ and hence blocking our skin with sun protection along with more being spent indoors than past generations may well be contributing to a sub optimum level of vitamin D.

What are the recommendations?

To protect bone and muscle health, at present Government health agencies advise that everyone needs vitamin D equivalent to an average daily intake of 10 micrograms (400 international units). They advise that all people should consider taking a daily supplement containing 10 micrograms vitamin D during autumn and winter months. They also advise that people whose skin has little to no exposure to sunlight and ethnic minority groups with dark skin, from African, Afro-Caribbean and South Asian backgrounds, should consider taking a vitamin D supplement all year round. This advice would also apply to people whose skin has little to no exposure to sunlight because they are indoors shielding, self-isolating, normally wear clothes that cover most of the skin or in a nursing home.

Therefore, advice during the COVID‑19 pandemic is that everyone should consider taking , at a very minimum, 10 micrograms (400iu) of vitamin D a day because they might not be getting enough from sunlight if they’re indoors most of the day. For most people, 10 micrograms of vitamin D a day will be enough and people should not take more than 100 micrograms a day because it could be harmful. However our experience at Pharmhealth would suggest that a daily intake somewhere in the region of 1000iu and 2500iu daily, partiticularly during the months of October to February may be necessary to have an optimum level of Vitamin D in your blood serum levels. Vitamin D which can be bought without prescription ranges from 10 microgams (400iu) to 40 micrograms (4000iu). However it is always best to ask for advise from us first to discuss your own particular individual needs or requirements.  If people take higher therapeutic doses of vitamin D (usually greater than 100 micrograms daily), monitoring is recommended.

It is important to note that people with proven vitamin D deficiency, or specific medical conditions such as malabsorption or kidney failure, may need higher doses or specific vitamin D preparations to ensure they have adequate levels of vitamin D.

The 2 major forms of vitamin D, vitamin D3 (colecalciferol) and vitamin D2 (ergocalciferol), are licensed for the prevention and treatment of vitamin D deficiency. Vitamin D supplements are not specifically licensed for preventing or treating any infection, including the novel coronavirus infection that causes COVID‑19.

There are many different brands and formulations of vitamin D supplements, often combined with other supplements (such as calcium), with different dosing regimens. This can make deciding which supplement to take, if any, difficult without health professional advice.

There are two forms of Vitamin D available – Vit D3 and Vit D2. Vitamin D3 is thought to be more easily absorbed into the blood stream and therefore requires less to obtain the same result.

There are also formulations available in liquid form which may make dosage adjustment easier over a 3 month period.

It is recommended if your blood result comes back as being deficient to take a Vitamin D supplement on a daily basis for at least 3 months and recheck your blood levels again then. Vitamin D, due to the fact that is a fat soluble vitamin takes time to build up in your system and thus a long term approach to taking this vitamin is better than a short one. Also, most of our Vitamin D is gained throughout the summer months, when sun is at its most prominent. The excess Vitamin D that may be gained during this period is stored for use when needed later on. However, most of Vitamin D acquired from sunlight during these summer months for up to 50% of the populations is not sufficient for these months alone not to mention periods when sunlight is at its lowest (winter).

What about children, babies and pregnant women?

The current advice is:

• breastfed babies from birth to one year of age should be given a daily supplement of 8.5 to 10 micrograms of vitamin D to make sure they get enough
• formula-fed babies should not be given a supplement until they are having less than 500ml (about a pint) of infant formula a day because formula contains vitamin D
• children aged one to four should be given a daily supplement of 10 micrograms
• The dose for adults (10 micrograms a day) applies to pregnant and breastfeeding women.

Where do we go from here?

 It would appear that more collaborative research worldwide needs to be carried out on how vitamin D is measured and also taking into account individual’s different circumstances, in order to see if vitamin D recommendations are enough for current circumstances and if it has a positive effect on Covid-19.

There have been many reports that vitamin D may be more beneficial than harmful whilst waiting for the evidence; Professor Rose Anne Kenny from Trinity College Dublin  said:

“In England, Scotland and Wales, public health bodies have revised recommendations since the COVID-19 outbreak. Recommendations now state that all adults should take at least 400 IU vitamin D daily. Whereas there are currently no results from randomised controlled trials to conclusively prove that vitamin D beneficially affects COVID-19 outcomes, there is strong circumstantial evidence of associations between vitamin D and the severity of COVID-19 responses, including death.” ³

Dr Eamon Laird added:

“Here we see observational evidence of a link of vitamin D with mortality. Optimising vitamin D intake to public health guidelines will certainly have benefits for overall health and support immune function. Research like this is still exploratory and we need further trials to have concrete evidence on the level of vitamin D that is needed for optimal immune function. However, studies like this also remind us how low our vitamin D status is in the population (even in sunny countries) and adds further weight to some sort of mandatory vitamin D fortification policy. If the Nordic countries are allowed to do this, there is no reason Ireland, the UK or rest of Europe can’t either.”³

¹ Rapid review: Vitamin D and acute respiratory tract infections June 2020

² COVID-19 rapid evidence summary: vitamin D for COVID-19 (www.nice.org.uk/guidance/es28)

³ E. Laird, J. Rhodes, R.A. Kenny. Vitamin D and Inflammation: Potential Implications for Severity of Covid-19. Irish Medical Journal, 2020; 113 (5): P81 [abstract]