Many of us don’t realise we need to boost our intake, especially during the winter months

Sunlight

Sunlight is the main source of vitamin D © iStock

Vitamin D is essential for healthy bones and teeth, but it’s becoming clear that it does many other jobs, too, and that deficiency may be linked to breast and other cancers, diabetes, neurological and metabolic disorders, and susceptibility to infections or heart disease.

Recent research has suggested that supplements for older people could even pay for themselves by boosting muscle strength, and reducing falls and their consequences (long-term care and/or death).

Where to get it

Our main source is sunlight, which stimulates vitamin D production in our skin; but the further north we live (and the more sunblock we use to protect against skin cancers), the less we make.

Sunshine daily for 15 minutes on your unprotected face, arms and neck may suffice during sunnier months, but from mid-October to April, sunlight doesn’t contain enough of the right ultraviolet rays.

So we need to eat a good diet as well – eggs, fortified cereals, margarine, cod-liver oil and oily fish, including salmon, sardines, mackerel and fresh tuna.

However, NICE (the National Institute for Health and Care Excellence) recommends that many adults should take a daily 10-microgram vitamin-D supplement (see tips box), while under-fives need age-appropriate drops (from pharmacies or free under the Healthy Start scheme).

But don’t overdo it – too much vitamin D can ‘drain’ your bones of calcium and weaken them, or lead to damaging calcium deposits in your kidneys.

Are you at risk?

Up to half of us may have vitamin D levels below the normal range (although we may not have any symptoms), and some of us become severely deficient during the winter months, especially if we live in the north or Scotland.

People whose skin doesn’t get a lot of sunlight are particularly at risk, year-round, as are people who are housebound, or over 65 years of age.

Children, pregnant women, and exclusively breastfed babies (especially after the age
of six months) may not get enough vitamin D. Poverty or being obese, vegetarian or alcohol-dependent may reduce dietary intake, too.

The symptoms

Vitamin D affects the way we absorb and use calcium and phosphate, two vital ingredients for bones, teeth and muscles.

In children, deficiency can affect bone development and lead to rickets (bow legs), poor growth and damaged teeth, and (if severe), affects other organs as well.

Adults may feel tired, have muscle aching and weakness (for example, when getting up from a chair – severe forms are called osteomalacia), have tender bones or even osteoporosis (honeycomb-like thinning that makes bones weaker and more likely to break).

NHS blood tests for vitamin D deficiency are restricted in many areas to people who have certain bone diseases or medical conditions that affect vitamin D levels (such as poor food absorption or low levels as a result of taking steroids or some epilepsy medications).

But supplements can be prescribed without tests in situations where deficiency is likely, or combined with calcium supplements for people taking medication such as bisphosphonates for osteoporosis or anti-oestrogens for breast cancer.

5 groups who should take Vitamin D

1 Pregnant and breastfeeding women, especially teenagers and young women.

2 Babies over six months (and some breastfed babies from the age of one month) and children aged under five years.

3 People who have dark skin and/or cover their bodies or faces for cultural reasons, especially people of African, African-Caribbean or South-Asian origin.

4 People who are over the age of 65 years.

5 People who are housebound, (or almost housebound, for example living in a care home).

Cod-liver oil

Taking cod-liver oil tablets can be beneficial © iStock