Summer is finally here and so there seems no better time to talk about the sunshine vitamin – vitamin D! Here are some facts you might not know about this important vitamin.
1. It is essential for bone health
Vitamin D is essential to help our bodies absorb and regulate calcium. It also regulates phosphate levels – an essential nutrient for keeping our bones, teeth and muscles healthy.
Not getting enough vitamin D can lead to bone tenderness and pain, muscle weakness and in children, conditions such as rickets, skeletal deformities, anaemia and susceptibility to respiratory infections. It is, therefore, vital that we get enough from our younger years into adulthood.
2. How to get vitamin D from sunshine
The sunshine vitamin is so-called because our bodies make it when our skin is exposed to ultraviolet B rays or UVB radiation from the sun. This means that in the UK from April until September, or in countries which are sunny all year round, you can get enough vitamin D naturally by exposing your face, arms and legs for five to 30 minutes two or three times a week or nine minutes a day. But you must be careful not to burn, so take care not to overdo it as prolonged exposure increases the risk of skin cancer. Remember – minutes not hours!
3. Certain factors limit absorption
Certain factors can limit your absorption of vitamin D from the sun such as wearing sunscreen, or covering your skin. The darker your skin, the more exposure you need. This is because melanin, which causes skin pigmentation, lowers the skin’s ability to make vitamin D in response to sunlight exposure. Sunscreen blocks vitamin D synthesis, as does glass, and sunbeds are not recommended as alongside UVB, sunbeds emit UVA which can cause skin cancer and does not contribute to vitamin D production.
4. Should we supplement over the autumn and winter?
In the UK the weak winter sunlight does not provide enough UVB for us to make sufficient vitamin D. This is why Public Health England advises that everyone in the UK consider taking a supplement between October and early March. People who cover up or stay indoors most of the time should consider taking a supplement all year round.
For adults, 10 micrograms (400 IU) per day is enough and you shouldn’t go above 25 micrograms (1,000 IU). Vegan vitamin D supplements in the form of tablets and sprays are widely available in health shops and online.
5. Vitamin D is found in some foods but in small quantities
Some plant foods provide vitamin D, but not usually in high enough quantities for us to rely on as the only source. The best plant sources are:
- Vitamin D mushrooms: These are mushrooms that have been exposed to UV light so that they produce their own vitamin D. On average they contain around 10 micrograms per 100g – 100 per cent of your daily requirement.
- Vitamin D-fortified plant milks: Most fortified vegan plant-milks will contain vitamin D, for example, a 200ml glass of Alpro original soya milk contains 1.5 micrograms.
- Fortified margarines
- Breakfast cereals
6. Deficiency is not uncommon
Overall, 60-70 per cent of the UK population is thought to have low vitamin D levels.
In 2016 the National Diet and Nutrition Survey found that around a fifth of adults had low blood levels of vitamin D. For children, the situation was even worse, now affecting one in four over the whole year.
Since such a large proportion of the population suffer from low levels, it seems that deficiency has far more to do with lack of sunshine than diet.
7. There are two types of vitamin D
There are two types of vitamin D – D2 (ergocalciferol), and D3 (cholecalciferol). Although they are both used in the same way by the body, they come from different sources. Vitamin D2 is always vegan, but vitamin D3 can be of animal origin.
Commercially produced D3, such as the type you would find added to most non-vegan cereals, is produced from lanolin in sheep’s wool. However, some D3 is now produced from mushrooms and lichen – this is suitable for vegans.
Some cereals (eg Weetabix Protein Crunch, Weetos and Ready Brek) now contain vitamin D2, which is suitable for vegans (there is a risk of cross contamination from other products made on the same production lines). This can change, and often does, so read the ingredients list on the packet when you buy cereal.
8. You can have too much
Even though it is important that we are getting enough vitamin D, it is also important to avoid getting too much. Too much vitamin D can cause your body to absorb too much calcium, leading to hypercalcaemia – high levels of calcium in the blood. Hypercalcaemia can weaken your bones and damage the kidneys and heart.
Government guidelines warn anyone over the age of 11 not to take more than 100 micrograms of vitamin D a day as it could be harmful. Children aged 1-10 years shouldn’t have more than 50 micrograms a day and infants under 12 months shouldn’t have more than 25 micrograms a day.
9. Vitamin D may help combat depression
The sunshine vitamin could also help you feel happier! Some research suggests that having sufficient vitamin D can help to reduce symptoms of depression.
There are a number of theories as to why this might be, including the amount of calcium in our cells contributing to the onset of depression, and vitamin D helping to reduce inflammation, and maintaining the synthesis of serotonin – the happiness hormone!
10. Vitamin D may reduce the risk of Covid-19 complications
Vitamin D is known to provide some protection against respiratory tract infections. There is some evidence that deficiency may be a risk factor for severe Covid-19.
Vitamin D plays an important part in regulating the immune system. Research suggests that vitamin D reduces survival and replication of the SARS-CoV-2 coronavirus and reduces the risk of a ‘cytokine storm’, where the body attacks its own cells rather than just fighting against the virus.
The research on this has produced mixed results, but ensuring you get enough vitamin D is a good idea anyway! What we do know is that a healthy plant-based diet may reduce the risk of severe covid-19.
Enjoy the sunshine this summer but take care not to burn!