Vitamin D is created in the body by direct exposure to sunlight, and from about late March/early April to the end of September, most people should be able to get all the vitamin D they need from sunlight.
As the nights draw in, however, people may not get enough of the vitamin from sunlight, which can impact the body in a number of ways.
Vitamin D helps regulate the amount of calcium and phosphate in the body – nutrients that are needed to keep bones, teeth and muscles healthy.
As a result, having a vitamin D deficiency can cause a number of bone problems, and evidence points to two issues in particular.
Bone and lower back pain may signal a person is lacking the sunshine vitamin, according to several large observational studies, which found an association between a deficiency and chronic lower back pain.
One study examined the association between vitamin D levels and back pain in more than 9,000 older women.
The researchers found that those with a deficiency were more likely to have back pain, including severe back pain that limited their daily activities.
Furthermore, in one controlled study, people with vitamin D deficiency were nearly twice as likely to experience bone pain in their legs, ribs or joints compared to those with blood levels in the normal range.
Vitamin D deficiency: One controlled study linked the vitamin to bone pain
Vitamin D supports calcium absorption and bone metabolism – a process that plays a key role in both growth.
Evidence suggests a vitamin D deficiency can lead to bone loss, which in turn can hike the risk of developing osteoporosis.
As the NHS explains, osteoporosis is a health condition that weakens bones, making them fragile and more likely to break.
In a large observational study in more than 1,100 middle-aged women in menopause or postmenopause, researchers found a strong link between low vitamin D levels and low bone mineral density.
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How to treat a vitamin D deficiency
While direct exposure to sunlight provides the best source of the vitamin, the nutrient is also found in a small number of foods, although people will not get enough of the vitamin from foods alone.
- Oily fish – such as salmon, sardines, herring and mackerel
- Red meat
- Egg yolks
- Fortified foods – such as most fat spreads and some breakfast cereals
According to the NHS: “In the UK, cows’ milk is generally not a good source of vitamin D because it isn’t fortified, as it is in some other countries.”
People who run the risk of having vitamin D deficiency are advised to take vitamin D supplementation to keep the risks at bay.
The Department of Health recommends you take a daily supplement containing 10 micrograms of vitamin D throughout the year if you:
- Aren’t often outdoors – for example, if you’re frail or housebound
- Are in an institution like a care home
- Usually wear clothes that cover up most of your skin when outdoors
Vitamin D deficiency: If you have dark skin you may also not get enough vitamin D from sunlight
It added: “If you have dark skin – for example you have an African, African-Caribbean or south Asian background – you may also not get enough vitamin D from sunlight.
“You should consider taking a daily supplement containing 10 micrograms of vitamin D throughout the year.”
The NHS warns against exceeding the recommended dosage of vitamin D, however, as taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body.
Taking more than 100 micrograms of vitamin D could be harmful, and this applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years, says the health site.
Children aged one to 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, says the health body.
As the NHS points out, the recommended dosage may not be suitable for people with certain medical conditions, and, if in doubt, you should consult your doctor first.
According to the health site, if your doctor has recommended you take a different amount of vitamin D, you should follow their advice.
While you cannot overdose on vitamin D by exposure to sunlight, you should always remember to cover up or protect your skin if you’re out in the sun for long periods to reduce the risk of skin damage and skin cancer.