Our bodies convert sunlight to vitamin D but from October to March, the sun in the UK doesn't contain enough UVB radiation for our skin to produce adequate amounts.
Many people are deficient during the colder months of the year. Older people are particularly at risk because our bodies become less efficient at producing the vitamin as we age.
Vitamin D is essential for healthy bones, and low levels have been linked to heart disease, multiple sclerosis, type-2 diabetes and depression, not to mention several types of cancer, so getting enough of the sunshine vitamin all year round is super-important. Here are 10 ways you can top up your reserves.
Learn more about vitamin D and the role it plays in your health
Take a supplement
The latest official advice is clear: everyone over the age of five should take a daily supplement containing 10 micrograms (400 IU) of vitamin D, especially during the colder months of the year. There are actually five types of vitamin D, but vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) are the most prevalent.
Studies show sunlight and animal-derived vitamin D3 is more effective than plant-sourced vitamin D2, so unless you follow a vegan diet, look for vitamin D3 supplements at the chemist or health food shop.
Consider a mouth spray
If you're not a fan of popping pills or just don't enjoy swallowing tablets, you can opt for a vitamin D3 mouth spray. Higher Nature's spray delivers the recommended daily intake (RDI) of 10 micrograms (400 IU) per spray, while Better You's MultiVit spray provides 10 micrograms (400 IU) of vitamin D3 per dose, along with other essential micronutrients like vitamin A, calcium and folic acid.
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Stock up on salmon
Oily fish such as salmon are the best dietary sources of vitamin D3, the more potent form of the vitamin. A small 100g fillet contains around 10 micrograms (400 IU) of vitamin D3, 100% of your RDI, so if you like fatty fish, it's worth increasing your intake during the winter months. If you can afford it, opt for wild salmon. Several studies indicate that wild-caught fish tend to have higher levels of vitamin D3 than farmed.
Visit our salmon recipe hub
Eat more oysters
Shellfish may be an acquired taste for many people, but if you're partial to oysters, you're in luck. A mere three of these delicious bivalves provides 100% of your daily vitamin D needs. Oysters are also rich in nutrients many of us may be deficient in, from vitamin B12, to minerals like copper and selenium – all the more reason to up your intake.
Trust in tinned tuna
If salmon isn't your thing and shellfish makes you feel squeamish, dependable tinned tuna is your next best bet. A 160g can of tuna contains 100% of the RDI of vitamin D – that's about enough for a generous tuna mayo sandwich filling, a one-portion tuna bake or a medium-sized Niçoise salad. Red meat is another excellent source of vitamin D3 but given its saturated fat content, it's best to keep consumption to a minimum and stick to alternative sources of the vitamin.
Try our tuna recipes
Try vitamin D mushrooms
Vitamin D mushrooms are special shrooms that are grown in ultra-violet light, which stimulates production of vitamin D2. While vitamin D2 isn't as potent and bio-available as vitamin D3, these mushrooms offer a decent source of the vitamin for vegans as dietary vitamin D3 is animal-derived and D3 supplements are extracted from sheep's wool.
M&S has stocked vitamin D mushrooms for a few years now and Tesco has just started to sell them. Powdered vitamin D mushrooms are also available and can be stirred through almost anything to add an umami taste as well as D2. Munching three of these shrooms should provide all your daily vitamin D requirements.
No access to vitamin D mushrooms? Research found that taking your mushrooms out of the wrapper and leaving them outside in the sun or under a UV lamp for 15 to 120 minutes gives them a big boost of vitamin D.
Mushrooms – the new superfood?
Don't forget fortified dairy
Fresh pasteurised milk doesn't tend to be fortified in the UK, but many long-life products contain added vitamin D2. Evaporated milk is a good source but condensed milk isn't. Yoghurt and fromage frais marketed at children also tend to contain vitamin D2, albeit in rather small amounts. Some brands of processed cheese and long-life whole, skimmed and semi-skimmed milk have added vitamin D2 too. If in doubt, check the ingredients labels.
The foods engineered for health
Drink non-dairy milks
If you prefer to avoid dairy products, non-dairy milks are more often than not fortified with vitamin D2. Again, it's a good idea to check the ingredients labels but most of the major brands of soya, rice, oat and almond milk contain the vegan form of the vitamin. A medium-sized glass of fortified non-dairy milk should provide around a third of your daily vitamin D requirement.
How to make nut milks
Enjoy your egg yolks
The average egg yolk contains 80 IU of vitamin D3, about a fifth of your RDI. Farmers are increasingly fortifying chicken feed, so some eggs can contain even higher levels.
Choose free range if you can. A 2009 study found that eggs laid by chickens that are free to roam and forage in the sunshine contain more vitamin D3 than eggs laid by factory-farmed hens that receive little natural light.
Try these quick and easy egg recipes
Start the day with fortified cereal
As well as mushrooms and non-dairy milks, fortified cereal is good source of vitamin D, with some brands containing D3 and others containing D2. Again, it's worth checking the labels, but many branded and supermarket own-label breakfast cereals contain decent amounts of vitamin D, but nothing to write home about. A small bowl will only provide around a tenth of your RDI, but you can of course bolster your brekkie with fortified milk to help get your daily requirement.
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