Public Health England is recommending people consider taking daily vitamin D supplements throughout the spring and summer as the coronavirus lockdown continues.
Normally, many of us get enough of it by spending time outdoors. Our skin makes it when exposed to the sun.
The sunshine vitamin, along with others, can help our body stay fit to ward off illness and infections - important during a pandemic.
So who might need supplements?
Vitamin D supplements are recommended by public health officials during the lockdown. Getty Images
What is the advice?
People in the UK are already advised to consider taking a supplement of 10 micrograms a day during the winter months (from October to March), and all year round if we aren't spending much time outdoors.
Public Health England is concerned that people could be missing out on the vitamin during the coronavirus pandemic when we are being advised to stay at home more.
It recommends vitamin D throughout the year if:
- you are not often outdoors - if you are housebound because you are shielding, for example
- you live in a care home
- you usually wear clothes that cover up most of your skin when outdoors
People with dark skin may also not be getting enough even if they spend time outdoors.
Scottish and Welsh governments have issued the same advice.
Sara Stanner of the British Nutrition Foundation said: "Unfortunately, as the effects of coronavirus continue, many of us are limited in the time we can spend outdoors. Correctly abiding by government rules and staying at home is immensely important and, while many of us have limited access to sunlight, this means we need to take a little extra care to keep our vitamin D levels healthy."
Some cereals are fortified with vitamin D. Getty Images
Why do we need vitamin D?
Vitamin D is important for healthy bones, teeth and muscles. A lack of it can lead to a bone deformity illness called rickets in children and a similar bone weakness condition called osteomalacia in adults.
Some studies suggest avoiding deficiency helps our resilience to common colds and flu, although there is no evidence that vitamin D boosts the immune system.
Should I take lots of it?
No. Although vitamin D supplements are very safe, taking more than the recommended amount every day can be dangerous in the long run.
If you choose to take vitamin D supplements:
- Children aged 1-10 should not have more than 50 micrograms a day
- Infants (under 12 months) should not have more than 25 micrograms a day
- Adults should not have more than 100 micrograms a day and if they are going to take supplements the recommended amount is 10 micrograms a day
Higher doses may sometimes be recommended by a doctor for patients with proven vitamin D deficiency.
Some people with certain medical conditions, such as kidney problems, cannot safely take vitamin D.
Can it stop coronavirus?
No. There is no evidence that it reduces the risk of catching or getting ill with coronavirus.
But experts do think that it may have benefits during the pandemic.
Vitamin D supplements will improve the health of people who are deficient.
Some researchers have suggested that vitamin D deficiency might be linked with poorer outcomes if someone catches coronavirus. But other underlying risk factors, such as heart disease, are common in these patients too, making it hard to draw conclusions.
Spanish and French researchers are doing clinical trials to see if vitamin D helps coronavirus patients.
Prof Jon Rhodes, emeritus professor of medicine in the UK, says vitamin D has anti-inflammatory effects and there is some research that suggests it may dampen down the body's immune response to viruses. This could be relevant in very ill coronavirus patients where severe lung damage can result from an inflammatory "cytokine storm" in response to the virus, although much more research is needed to explore this, he says.
Where can I buy it?
Vitamin D supplements are widely available from supermarkets and chemists. They may be just vitamin D or part of a multivitamin tablet.
Do not buy more than you need to help keep supplies of supplements available for everyone, say experts.
The ingredient listed on the label of most Vitamin D supplements is D3.
Vitamin D2 is produced by plants, and Vitamin D3 is the one made by your skin.
Vitamin drops are available for babies.
What about diet?
Although eating a well-balanced diet can help ensure the normal functioning of the immune system, no individual nutrient, food or supplement is going to "boost" it beyond normal levels.
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.
It can include vitamin D rich foods such as oily fish and eggs. Some breakfast cereals, margarines and yoghurts are fortified with vitamin D.
Vitamin D has anti-inflammatory effects and capsules are available in supermarkets. Getty Images
Should I sunbathe?
Although you cannot overdose on vitamin D through exposure to sunlight, strong sun burns skin so you need to balance making vitamin D with being safe in the sun. Take care to cover up or protect your skin with sunscreen to prevent burning and damage.
What about children, babies and pregnant women?
The advice is:
- breastfed babies from birth to 1 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 1 to 4 should be given a daily supplement of 10 micrograms
The dose for adults (10 micrograms a day) applies to pregnant and breastfeeding women.