By Paula Mee, CORU Registered Dietician
Ever since COVID-19 landed on our shores, there has been a range of reports on immune boosting regimes, with the benefits of Vitamin D among them. Yet with the sheer amount of information available in the media and on social platforms, it can be hard to separate fact from fiction.
The lowdown on Vitamin D however is simple: Vitamin D is an essential nutrient for our general health, especially for our skeletal and immune health. It also plays a role in our mental health and in the management of depression.
Most timely is the discovery that Vitamin D might also be of benefit in the COVID-19 pandemic. One recent study from researchers at Trinity College Dublin found that Vitamin D plays a critical role in preventing respiratory infections, reducing antibiotic use, and improving the immune system’s response to infections. Researchers also found that 27% of ‘cocooning’ over 70’s are likely to be Vitamin D deficient, while one in eight adults over 55 are vitamin D deficient all year round, highlighting the need for an adequate level of vitamin D to help in the fight against acute respiratory infections and potentially COVID-19.
Why is Vitamin D so important?
Vitamin D helps the absorption of calcium from the gut and plays a key role in the prevention and treatment of falls and fractures. It also helps maintain bone and muscle health; Vitamin D deficiency causes bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults. Vitamin D is also used in the management of depressive symptoms. And notably, it helps with the normal function of the immune system, and helps prevent respiratory infections in people who have low Vitamin D levels.
How does Vitamin D work in the body?
Vitamin D helps our bodies absorb calcium and phosphorus for our bones and teeth. It also works in conjunction with calcium to help protect against the loss of bone mass and risk of fractures as we get older, and it helps muscles function and allows the brain and body to communicate through nerves.
But Vitamin D’s role does not end there. It also helps the immune system to function properly, reducing our risk of infection. Where there is an infection, Vitamin D can help regulate the inflammatory process. When needed, it helps produce more anti-inflammatory cytokines and less pro-inflammatory cytokines, which is particularly important in certain respiratory tract infections (such as COVID-19) where the body produces an overwhelming response in the form of a “cytokine storm”. As a result, it is thought Vitamin D may not only reduce the risk of COVID-19 infection but also the subsequent pneumonia that follows.
Where does Vitamin D come from?
There are three ways to get Vitamin D:
- from sunlight
- from natural or fortified foods and
- from supplements.
Vitamin D from sunlight
When sunlight falls on unprotected skin, your body converts certain UV rays into Vitamin D. While you only need ten to 15 minutes of sun exposure between 12noon and 4pm in the summer time, there is simply not enough of the type and amount of these UV rays to make sufficient levels of Vitamin D in Northern Europe during the winter months (October to March).
The summer months also present challenges to sunlight exposure due to Ireland’s cloudy and rainy weather. When it is sunny, we wear make-up and sunscreens with SPF protection to prevent skin damage and ageing. This means many of us make an insufficient amount of Vitamin D during the summer months too.
For these reasons, we need to focus on our dietary choices or supplements to ensure we get enough Vitamin D all year round.
Vitamin D in the diet
Naturally good sources of Vitamin D are found in very few foods. Oily fish such as salmon and mackerel are among the best sources of vitamin D while eggs, and mushrooms grown under UV lights, provide small amounts.
A daily fortified food can really help meet your needs. For example, Vitamin D-fortified milks are both an excellent source of calcium and other bone minerals.
Vitamin D in supplement form
Your GP can determine whether you are deficient in Vitamin D with a simple blood test. If you are recommended to take a Vitamin D supplement, they are available without prescription and safe to use at the recommended levels.
Who is most at risk of Vitamin D deficiency?
Certain people are more at risk of Vitamin D deficiency, including:
- babies up to 12 months old*
- people with darker skin from African, African-Caribbean or Asian backgrounds
- people who choose not to expose their skin for religious reasons
- people who are bedbound or house bound
- people who eat inadequate amounts of oily fish and Vitamin D-fortified foods
- people with liver disease, asthma, chronic lung disease, cystic fibrosis, coeliac disease and Crohn's disease
- people who are very overweight and physically inactive
- people who are severely malnourished
- people who have had gastric bypass surgery and
- older people over 70**.
Many Irish people may fall into one of these at-risk categories. It is important to discuss your own individual need for Vitamin D supplementation with your doctor or health care provider.
*Vitamin D supplements for babies
Doctors and health care providers now recommend all babies under 12 months of age take 5ug of vitamin D3 every day to prevent rickets, a childhood disease that causes bones to soften and break. The supplement applies to all babies whether they are formula or breast fed, given they are unlikely to acquire sufficient Vitamin D from their diets, and are recommended to avoid sunlight which can easily burn their new skin. Talk to your pharmacist about Vitamin D drops for your baby.
What amount of Vitamin D supplementation is generally recommended to prevent Vitamin D deficiency in older people?
- Adults: 10 ug (400 IU) is the minimum recommended daily during the wintertime (TILDA 2020).
- Adults at risk: Between 15 -20 ug (800-1,000 IU/day) is recommended for most at risk groups (TILDA 2020).
What are the most common food sources of Vitamin D?
By Paula Mee, CORU Registered Dietician