Vitamin D deficiency
Vitamin D is essential for healthy bones. We get some of it from food, but most comes from sunlight.
Between October and March, the sunlight in Britain is not strong enough to make enough vitamin D, and up to a quarter of the population has low levels of vitamin D in their blood.
Vitamin D is also found in oily fish, such as salmon, mackerel and sardines, eggs, fortified fat spreads, fortified breakfast cereals and powdered milk. However, it is hard to get enough vitamin D just from food.
Symptoms of vitamin D deficiency
Vitamin D deficiency can put people at risk of:
- Rickets bone problems in children
- Osteomalacia bone problems in adults
Some research suggests that not getting enough vitamin D may also be linked to:
Vitamin D deficiency at-risk groups
The Chief Medical Officers of the UK say these groups are at particular risk of vitamin D deficiency:
- Pregnant and breastfeeding women, especially teenagers and young women.
- Infants and children under 5 years of age.
- People 65 and over.
- People who have little or no exposure to the sun. This includes covering-up for cultural reasons, people who are housebound or who stay indoors for long periods of time.
- People with darker skin, such as African, African-Caribbean and South Asian origin. These groups are not able to make as much vitamin D as those with paler skin.
Blood test for vitamin D deficiency
The most accurate way to measure how much vitamin D is in your body is a blood test to measure 25-hydroxy vitamin D in your bloodstream. This is a form of vitamin D produced in the liver. In the kidney, 25-hydroxy vitamin D is converted into an active form of the vitamin for use by the body to help control calcium and phosphate levels.
Safe sun exposure
Around 10 to 15 minutes a day in the summer sun without sunscreen is enough to top up vitamin D levels for most people. Health officials don't give firm recommendations on the duration because the ideal amount of sun depends on people's skin type and how quickly they get sun burn. People with darker skin need longer in the sun than those with lighter skin.
The best time of day for making vitamin D from sunlight is 11am to 3pm, April to September.
It doesn’t require putting on a bikini or trunks, but the larger the area of the body uncovered, the more vitamin D the body makes.
Other than a daily vitamin D top-up, the usual sun protection measures should be taken, including using sun protection factor of at least SPF 15.
However this will not provide sufficient vitamin D during the winter months.