Our guide to vitamin D, the essential nutrient for health and immunity
In 2016, Public Health England (PHE) published new advice recommending everyone to take a daily supplement containing 10 micrograms of vitamin D from October to April, and for children to take one all-year round.
This year, the NHS issued new guidance, following lockdown restrictions which meant we were all isolating at home. Due to us all spending a lot more time indoors, the NHS recommended everyone to take 10 micrograms every single day – even through the summer season.
PHE recommends vitamin D throughout the year if:
- you are not often outdoors
- you live in a care home
- you usually wear clothes that cover up most of your skin when outside
People with dark skin may also not be getting enough, even if they spend time outdoors, and should consider an all-year-round supplement.
Why is vitamin D so important?
Nutritionist Rose Holmes, education and training manager at Rio Health, answers: “Vitamin D has important roles in the skeletal health, immunity, brain function, mood regulation and many other aspects of whole-body health. Each of these aspects of health – especially important during periods of growth during childhood – may be impacted by deficiency of this essential vitamin.
“The main functions of vitamin D are: to regulate serum calcium and phosphorus in the body, to improve calcium absorption and build strong bones and teeth, to assist in suppressing cholesterol uptake in the arteries, to act as an inflammatory mediator and to regulate immune activity.”
Many studies have found links between vitamin D deficiency and poor immunity. Keeley Berry, nutritional expert and product developer at BetterYou, comments: “The nutrient – often hailed ‘the sunshine vitamin’ – is vital for optimal performance of the killer cells within the immune system (the T-cells) and without sufficient vitamin D, these cells will not be able to react and fight off serious infections within the body.”
Vitamin D deficiency
So, what happens when your vitamin D levels are low? Joanna Dziedzic, nutritional therapist at Pure Encapsulations, says: “Suboptimal levels of vitamin D are still very common and associated symptoms can vary from person to person. The key and most common ones are fatigue, muscle weakness and aches, bone pain, low mood and depression and lowered immunity. Although these are the key signs it’s recommended to check vitamin D status with a blood test, especially in people with diabetes, some types of cancers and autoimmunity.”
Increase your levels
The body makes around 90 percent of the vitamin D it needs, but this process can only happen when unprotected skin (bare skin, without clothing or SPF protection) is exposed to direct UV light from the sun. This means that, for those living in the UK and other parts of the northern hemisphere, it can be difficult to ensure our recommended levels are met.
“The best way to ensure adequate vitamin D levels is via exposure to sunlight,” explains Holmes. “Use of sunscreen blocks the production of vitamin D by the skin so even the summer months may not provide sufficient exposure to sunlight to produce enough vitamin D needed for bones, teeth and immune health. Between the months of November and March, sunlight in the UK is insufficient to allow natural production by the body of vitamin D, and supplementation may be the best means to obtain sufficient levels of this important vitamin.
“A daily intake of 400 IU/day of vitamin D is recommended for everyone over the age of one year, especially during the fall and winter months. Higher dosages are often recommended for adults, especially during the winter months.”
The government recommends everyone to take a daily vitamin D supplement of 10 micrograms a day, particularly during the months of October to April when sunlight is limited.
“When it comes to vitamin D requirements, there’s no one-size-fits-all and many factors including medical conditions, lifestyle, diet, age, weight, and skin colour can all affect our ability to absorb this essential nutrient or ensure adequate intake,” explains Berry. “A healthy lifestyle, with time spent outdoors in the sunshine and a varied, vitamin D-rich diet, combined with daily vitamin D supplementation, is a sensible way to maintain your levels all year round.”
Focus on nutrition
Whilst the Scientific Advisory Commission on Nutrition has concluded that it’s difficult to obtain adequate levels of vitamin D from food sources, you can still add vitamin D-rich foods to your diet.
“Fatty fish such as salmon, halibut and mackerel provide meaningful sources of vitamin D, along with fortified foods such as cereals and yoghurts,” comments Berry. “Meat products and milk also contain small amounts of the nutrient, in varying levels depending on the season. Egg yolks also provide a great source – but only when sourced from hens that are fed vitamin D.”
“Food sources of this important vitamin include mackerel, sardines, halibut, salmon and other fish, raw milk, eggs and some mushrooms,” adds Holmes. “Whilst raw milk is thought to contain some natural vitamin D, synthetic vitamin D is added to some pasteurised milks including cow’s milk and soy milk.”