New guidelines aren’t just aimed at the one in six of us who may develop a severe deficiency before summer

Vitamin D is so important for your health

Up to half of us in the UK have lowish vitamin D levels (scientists are still debating what’s ‘normal’), although we may not actually have deficiency symptoms. But our lack of winter sunlight makes us particularly vulnerable, especially if we live further north, or have other risk factors (see box, right).

Where does it come from?

Most of it’s made in our skin, in response to the sun’s ultraviolet B rays; we need 15 to 30 minutes’ daily outdoor sun exposure on faces and arms – more difficult in winter or if we cover up when we go out. We get much less from our diets, but UK law says infant milks and margarines must be fortified with vitamin D.

Other sources include oily fish, liver, egg yolks, red meat and fortified breakfast cereals.

Where does it come from?

Most of it’s made in our skin, in response to the sun’s ultraviolet B rays; we need 15 to 30 minutes’ daily outdoor sun exposure on faces and arms – more difficult in winter or if we cover up when we go out. We get much less from our diets, but UK law says infant milks and margarines must be fortified with vitamin D.

Other sources include oily fish, liver, egg yolks, red meat and fortified breakfast cereals.

How much do we need?

This has been surprisingly difficult to establish from research, particularly as so many of us seem to manage with ‘low’ blood levels, while others run into problems at higher levels, so blood tests are rarely recommended. There’s also concern about taking too much; our skin safely regulates its own production, but it’s hard to know how much vitamin D we get individually from our diets.

Scientists say more research should be carried out, including on whether our needs are affected by our weight, body fat, age, ethnic group or actual blood level.

In 2012, the government produced vitamin D guidelines for people in at-risk groups, but these were strengthened by Public Health England (PHE) at the end of last year, following a new report from the Scientific Advisory Committee on Nutrition (SACN).

The new SACN guidelines

These say that almost all of us, aged four years and upwards, need an average of at least 10 micrograms (400 international units/IU) of vitamin D daily to keep us above ‘population-protective levels’. But it’s hard to keep track of whether we’re getting enough individually, especially from weak winter sunshine, or if we’re in an at-risk group (see box).

So PHE has said anyone over the age of one year may benefit from a daily 10 microgram supplement, particularly from October to March, and especially if they are in an at-risk group.

Under-fours should take supplements all year round; under-ones should have a daily 8.5 to 10 microgram supplement, unless they’re drinking more than 500ml (just less than a pint) of vitamin D-fortified infant formula milk daily (breast milk and cow’s milk don’t contain enough).

Adults can buy vitamins from the pharmacy or supermarket. Ask your health visitor about supplements for babies and children (they may be free under the Healthy Start scheme).

4 Groups at higher risk

1. People with dark skin (especially those of African-Caribbean, South Asian or Middle Eastern origin).

2. People who are housebound, or rarely go out without putting on sunblock or covering skin with clothing.

3. Babies, children, pregnant/breastfeeding women and elderly people.

4. People with restricted diets or conditions that affect nutrient absorption, such as vegetarians, people who eat non-fortified breads, or with chronic liver/kidney or bowel disease, or alcoholism.