Vitamin D, also known as the ‘sunshine vitamin’, is a hot topic at the moment and has been hitting the headlines due to speculation that it is linked with COVID-19. Whilst there is no definite evidence that shows vitamin D can prevent or cure COVID-19, making sure you get enough vitamin D is still very important, especially at this time of year.
Vitamin D plays an important role in helping our body to absorb calcium. It contributes to the development and maintenance of normal healthy bones, teeth and muscle, in addition to ensuring normal immune functions. It helps to prevent rickets in children and osteomalacia in adults (characterised by bone pain and muscle weakness), as well as reducing the likelihood of falls. Within the UK, 19% of children aged 4 to 10 years, 37% aged 11 to 18 years and 29% of adults have low vitamin D levels which would suggest risk of deficiency. Small cases of rickets are still evident across the UK which is considered unacceptable as it is easily preventable. We reach our peak bone mass during our 20’s, meaning we make deposits of important bone tissue up until that stage. Therefore, it is essential that children and teenagers get enough vitamin D to help calcium in establishing their maximum bone skeleton.
Humans are able to create vitamin D when our skin is exposed to UVB rays from direct sunlight. This is our body’s main and preferred source of vitamin D. However, where we live, age, skin tone, sunscreen use, air pollution and indoor lifestyles can all affect how much vitamin D we are able to create from sun exposure. A simple way to measure whether or not the sun is strong enough to produce vitamin D is by looking at your shadow. If your shadow is shorter than your height, then your body can make vitamin D from that sunlight.
Vitamin D can also be found in foods such as oily fish (salmon, sardines, trout, pilchards, herring and mackerel), egg yolk, liver, meat, mushrooms and some fortified products such as breakfast cereals, yoghurts and spreads. However, it can be difficult to achieve the recommended intake of 10 micrograms from diet alone as there are not a lot of sources. Usually food companies will advertise if they have added vitamin D to their product. Check the nutrition information on the label at the back of the packaging if you're not sure.
Whilst supplements are not generally needed as a well-balanced, varied diet is likely to ensure you reach nutritional recommendations, vitamin D is the exception. Unfortunately, within Northern Ireland, the sunlight isn't strong enough from the end of September until late March and therefore the NHS recommends that everyone aged one and older should consider taking a daily 10 microgram vitamin D supplement during winter months. This may be shown as 10µg, 10mcg or 400IU on the label. Capsules, gummies, drops or spray supplements all work the same so do not be worrying about spending a fortune. There are two main forms of vitamin D; vitamin D3 and vitamin D2. Studies have shown that vitamin D3 is more effective and generally this is the form within supplements. However, if you follow a vegan diet, be careful when choosing a supplement as vitamin D3 is often made from animal sources, whereas vitamin D2 is suitable for vegans. The advice for babies varies depending on whether they are breastfed or are given infant formula. Breastfed babies should have a daily vitamin D supplement containing 8.5-10 micrograms from birth. If formula-fed babies are having more than 500mls then they do not require a supplement as infant formulas are fortified with vitamin D. Taking a vitamin D supplement is particularly important this year as, due to lockdown restrictions, the majority of us spent the summer months indoors which is the period when we would usually make most of our vitamin D from the sunlight. Whilst you may be tempted to take a megadose supplement, be careful not to fall prey to scaremongering as vitamin D is fat-soluble. This means our body can store it and we do not flush it out in our urine; therefore, it is possible to take excessive amounts.
Please note that the guidance within this article are general recommendations and should not replace medical advice. Always consult a healthcare professional if you have particular concerns about your vitamin D status.
Written by guest PhD student Holly Neil for Nutrition4kids