What we all need to know about vitamin D

According to an answer to a recent Parliamentary question, more than 75,500 people who were admitted to hospital in 2017 had a primary or secondary diagnosis of vitamin D deficiency. Six years earlier that number had been just 10,000.

Vitamin D is essential for healthy bones because without it our bodies cannot absorb and use calcium and phosphate from our diet. Vitamin D deficiency can cause bones to become soft and weak, which can lead to bone deformities.

In children a lack of vitamin D can lead to rickets, while in adults it can lead to bone pain and tenderness caused by a condition called osteomalacia. Studies have also linked a lack of vitamin D to low mood, weight gain and sleeplessness.

Government figures show that up to a quarter of people have low levels of vitamin D in their blood. In 2012, following rising concerns about vitamin D deficiency, the UK’s four chief medical officers wrote to health professionals reminding them about this issue.

They highlighted a number of groups at risk, including those pregnant and breastfeeding, children under five and adults over 65, those who have low or no exposure to the sun (for example those who cover their skin for cultural reasons) and people of African, African-Caribbean and South Asian origin, because their bodies are not able to make as much vitamin D.

One source of vitamin D is sunshine, but in Britain our opportunities to benefit are limited – there is just too little of the right type of sunshine between October and early March. This is a situation that may be worsening. According to a new study from the University of Toronto, Britain’s increasing cloudiness during the summer could be an important reason for the mysterious increase in vitamin D deficiency.

The researchers found that median incidences of rickets, which had been declining since the 1960s, almost doubled between 1997 and 2011, going from 0.56 cases per 100,000 British children to 1.01 cases.

In the UK, health experts have determined that six hours a month of sunshine are needed to produce enough vitamin D in people’s skin. But since the mid-1990s, increasing cloud cover has deprived the British Isles of about four hours of sunshine per month in the summer. Since the mid-1990s, the U.K. has received only an average of 183 hours of sunshine per summer month.

Dr Asim Hasan, Care UK’s regional medical director for primary care in London, said: “This is an interesting study and may give some indication of what has caused the increase of a condition many of us associate more with Victorian poverty than with modern Britain. The good news is there is plenty we can do to ensure our vitamin D levels are at an optimal level.”

Dr Hasan’s four ways to get vitamin D in your life:

  1. Incorporate it into your diet. Although vitamin D only appears in a small amount of foods, they are healthy and easily incorporated into a family meal plan. They include oily fish such as salmon, mackerel, herring and sardines, as well as red meat, liver and eggs.
  2. Look out for foods that are fortified with vitamin D, such as some breakfast cereals, fat spreads and non-dairy milk alternatives.
  3. Consider taking supplements from a recognised provider, rather than online, particularly in the autumn and winter months or if you spend the majority of the day indoors, such as those living in a care home, or those with a restrictive diet such as vegans. For anyone over five years old, a daily supplement containing 10 micrograms (mcg) of vitamin D is suitable.
  4. Don’t take more than 100mcg of vitamin D a day, from all formats (including food, supplements and sunshine) as it could be harmful. This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years. Children aged one to 10 years should have no more than 50mcg a day in total; infants under 12 months should have no more than 25mcg a day. Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart.

Seven British health organisations, including the British Association of Dermatologists, Cancer Research UK, Diabetes UK, the Multiple Sclerosis Society and the National Osteoporosis Society, have issued a consensus statement of their unified views on getting a small amount of unprotected sunshine in spring and summer.

They advise short bursts of less than the time needed to redden or burn the skin. Regularly going outside for a few minutes around the middle of the day without sunscreen is suggested as best and that the more skin exposed the greater the chance of producing sufficient vitamin D before burning. Importantly, this advice applies in the UK, and not in hotter climates.