This fat-soluble nutrient is made in our body from sunlight and is only found in a few foods. It’s stored in the body and helps us absorb calcium and phosphorus, and regulates levels of calcium in the blood. This makes it a vital vitamin for developing bones and teeth in young children, and for keeping bones and teeth healthy and strong when we’re older. Vitamin D also helps to ensure our muscles and immune system work properly, and it’s needed for healthy inflammatory response.
What happens if you don’t get enough?
In babies and young children, a lack of vitamin D causes rickets (where bones become painful, soft and weak) and can lead to deformities of the skeleton such as bowed legs. In adults, a lack
of vitamin D results in osteomalacia,a condition that causes bone pain and tenderness.
Are low intakes a problem?
Yes! The Scientific Advisory Committee on Nutrition (SACN) – a group of independent health experts – estimates around a fifth of Brits have low blood levels of vitamin D, so may be deficient. The risk increases as we get older: 8% of 18-month to three-year-olds have low levels, rising to 14% of four to 10-year-olds, 22% of 11 to 18-year-olds, 23% of under-65s, and 38% of over-65s in institutions such as nursing homes.
Worryingly, the Royal College of Paediatrics and Child Health says there’s evidence that the incidence of rickets – a disease that had been practically eliminated – has quadrupled in the past 15 years.
The sunshine vitamin
One of the main reasons for our low intakes, experts believe, is the change in our outdoor habits. The main source of vitamin D is exposure to sunlight – we make it in our body in summer, when our skin is exposed to the sun’s rays. Covering up, staying in the shade, wearing sunscreen and spending more time inside mean our skin is shielded from the sunshine. This is all beneficial for helping to protect ourselves against skin cancer, but not for vitamin D production.
In the UK, from October to March the sun is too weak for the body to make vitamin D – even if we spend time outside on bright winter days, it won’t boost our levels of vitamin D. As a result, we rely on the amount we made and stored in the summer. That’s not to say we should start ignoring safe-sun advice and overexpose our skin to the sun’s harmful rays. Instead, we need to top up our levels with foods that contain good amounts of vitamin D and, in some cases, take a supplement.
The wider implications
Health experts believe consuming 20mcg vitamin D a day may reduce the risk of falling, and therefore fractured bones, in adults over the age of 60. Many scientific studies over the past decade also suggest it may protect us from heart disease, diabetes, certain cancers (especially bowel cancer), multiple sclerosis and rheumatoid arthritis, as well as depression and even obesity. More research needs to be carried out to confirm the role vitamin D may have in relation to these conditions.
How to boost your vitamin D intake
Because many of us don’t make enough vitamin D in summer, it’s vital to boost our intake of vitamin D-rich foods (and take a supplement if we’re in an at-risk group). The only foods that contain good amounts are oil-rich fish, eggs and fortified foods such as cereals and dairy products. Check our table, below, for foods that help you get more.
How much do I need?
The Scientific Advisory Committee on Nutrition (SACN) has recently reviewed all the evidence surrounding vitamin D and health. SACN concluded that it’s impossible to give a one-size-fits-all estimate as to how much vitamin D is made when skin is exposed to the sun as this varies from person to person depending on skin type, as well as being affected by external factors such as the time of day and year, and where you live in the UK, all of which affect the strength of the sun’s rays. As a result, SACN has set new recommendations on how much vitamin D we should have each day from our diet. Anyone over the age of four should have 10mcg daily. For babies and younger children, safe intakes are given: 8.5–10mcg for children under one and 10mcg for one to three-year-olds (safe intakes are used when there is insufficient evidence to make a clear recommendation).
Ultimately, everyone will need to rely on dietary sources of vitamin D during the autumn and winter but it’s very difficult to get 10mcg vitamin D alone from foods, even if we’re regularly eating oily fish, eggs and fortified foods. As a result, Public Health England say we should consider taking a 10mcg supplement of vitamin D during the autumn and winter months.
Meanwhile, people who have little exposure to the sun, such as those in care homes, or who always cover up their skin when outside, together with people from African, Afro-Caribbean and South Asian backgrounds, who have dark skin and so may not be able to make enough vitamin D, should consider taking a supplement year round.