With autumn fast approaching and holidaying to our favourite sunny destinations on hold, many of us won’t be having a couple of weeks of ‘guaranteed sunshine’ by the sea, opting instead for staycations within Scotland. Vitamin D is known as the ‘sunshine vitamin’ and has been in the news a lot during the COVID-19 pandemic, mainly due to concerns about time spent indoors during lockdown months. The Scottish Government recently issued revised guidance on vitamin D for all age groups, advising everyone (including children) to consider taking a daily supplement containing 10mcg of vitamin D. There is some confusion amongst the public with regard to vitamin D intakes, with evidence of Scots being unaware of the benefits of taking vitamin D supplements and uncertainty of which supplements to take.
We teamed up with Registered Nutritionist Dr Suzanne Zaremba to shed some light on vitamin D supplementation, sun exposure and scientific evidence surrounding disease prevention.
Q: Do I make more vitamin D if I expose more skin to the sun?
We definitely do not need to sunbathe to make vitamin D. The truth is, we need sun protection just as much as we need vitamin D – there is a place for both. In fact, being outside for only a short period of time with forearms, hands or lower legs uncovered is adequate. It’s difficult to advise individuals on how long they should spend in the sun for vitamin D synthesis – factors such as skin colour, cloud cover and skin surface area exposed to direct sunlight play a role in skin biosynthesis of vitamin D. But we know that 10-15 minutes of unprotected Scottish sun exposure is safe for all. The ‘more sun the better’ mind-set is potentially harmful for health and we should be mindful that UV rays are carcinogenic – we should always aim to use adequate sun protection. Because vitamin D can be acquired from the diet and supplementation, for those who are concerned about their vitamin D status I’d recommend individuals avoid excessive sun exposure and focus on oral intake.
Q: How can I get vitamin D from food, what should I eat?
Vitamin D is naturally present in only a small amount of foods. Vitamin D3 comes from animal-sourced foods, whereas D2 is a plant-based source. For those who eat fish, oily fish such as salmon, sardines and trout contain reasonable amounts of vitamin D3. Cod liver oil contains a large amount, so it’s important to be mindful of this if you take cod liver oil along with a vitamin D supplement. Depending on the season, milk provides a small amount of vitamin D3, along with meat and egg yolks. Some breakfast cereals, margarine and yoghurts have added vitamin D2. Vitamin D2 is a lot cheaper to produce, which is why D2 is commonly used in food fortification. Although eating a balanced diet will provide dietary sources of vitamin D, I’d suggest you also pick up vitamin D supplements from the supermarket or pharmacy to ensure adequate intake.
Q: What vitamin D supplements should I buy?
You’ll find vitamin D in two forms when reading supplement labels, vitamin D2 and D3. Both are absorbed by the gut but are metabolized differently. Evidence points to vitamin D3 being more effective for raising serum 25(OH)D concentrations than vitamin D2 does, so for that reason I’d opt for a supplement containing vitamin D3 (D3 is not suitable for vegans though). The important thing is that you take enough vitamin D, whether it be D2 or D3. According to Scottish Government advice, we should aim for 10 micrograms per day (this can be written as 10µg, 10mcg, or 400 IU on labels) which should be taken all year round, not just during the winter months. A study suggests that oral vitamin D mouth sprays (75mcg) appear to be as effective as oral capsules, however its important more research is carried out to investigate whether lower doses of sprays are also effective.
Q: Does vitamin D protect us against cancer?
There is evidence that suggests vitamin D (including supplemented vitamin D) may reduce the risk of colorectal cancer. Although evidence is limited, evidence for vitamin D and colorectal cancer risk is consistent – meta-analysis data reports significant decreased risk of cancer at this site. If we look at both macro- and micronutrients as being puzzle pieces, we need as many jig-saw pieces as possible to build a balanced diet to support health and prevent non-communicable disease, such as cancer.
Q: Do you have any tips for optimising our vitamin D intakes?
Vitamin D is a fat-soluble vitamin, meaning it doesn’t dissolve in water. Fat soluble vitamins are best absorbed when dietary fats are present, so I’d recommend taking your vitamin D supplement alongside a meal. Mushrooms are a source of dietary vitamin D2 – I like adding mushrooms to soups, pastas and pizzas (also counting towards my 5-A-Day). Setting an alarm on your phone or using a pillbox can be useful prompts for those who forget to take their vitamin D supplements. Eating a variety of foods will also provide you with more than vitamin D, including fibre, B vitamins, iron and calcium. Vitamin D is needed to absorb calcium.
Take away message: Vitamin D supplements, food sources and incidental, protected sun exposure will give you all the vitamin D you need, without putting your skin at risk of sun damage.