Vitamin D deficiency

Are you getting enough vitamin D?
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02.Preventing deficiency

How much sun?


It’s recommended you get 5-15 minutes of sunlight to your unprotected face, hands and arms 4-6 times a week outside the hours of 10am-2pm (11am-3pm daylight savings time). 

However, this also depends on where you live, your skin colour, age and other factors. 

The map above provides recommendations based on location – people with dark skin may need 3-4 times as long.

Too much sunscreen?

One of the main reasons offered for widespread vitamin D deficiency is overzealous use of sunscreen and other sun protection – in other words, we’ve taken up advice to slip, slop and slap too well. 

Some have rejected this suggestion: one study from 1995 found that people using a placebo (non-protective) cream had similar levels of vitamin D to people using a SPF 17 sunscreen every day over summer – possibly because they didn’t use enough or reapply as often as necessary. 

But sunscreens these days tend to have a higher SPF (30+ is the norm) and besides this, people are likely spending more time indoors, particularly recreation time.

Good morning, sunshine!

When you go out for your daily dose of vitamin D, you might like to consider taking a morning, rather than afternoon, stroll. A study in mice has found that propensity to skin cancer fluctuates according to circadian rhythms. Mice are more likely to get skin cancer when exposed to UV radiation in the morning, thanks to low levels of an enzyme which repairs UV damage. 

Researchers have hypothesised that humans likely have higher levels of the enzyme in the morning (the opposite of mice, which are nocturnal) and may be less susceptible to cancer from UV damage in the morning than the afternoon. Further research is planned.

Pills and potions

If you’re at risk of vitamin D deficiency you could consider taking a supplement, with experts recommending a minimum of 400IU, and preferably 800IU per day. 

Vitamin D supplements are cheap, at around 10-16 cents per day, and usually come in a dose of 1000IU.

Many multi-vitamins contain vitamin D, but not in the amount required for preventing or treating deficiency. Also, vitamin D2 is considered less potent than vitamin D3. 

For people with a diagnosed deficiency greater amounts will be needed, possibly in conjunction with calcium – your doctor or other health professional will advise you.

A safe upper maximum for adolescents and adults is 4000IU per day. Long-term amounts over 10,000IU per day have been associated with kidney damage.

CHOICE verdict

It’s definitely a good idea to get enough vitamin D for bone health, whether through exposure to sun or supplements, and this may confer additional preventative health benefits. 

But too much sun poses its own risks, and taking vitamin D supplements other than to avoid deficiency is not going to make you healthier.

More information

The National Prescribing Service has an information sheet on vitamin D deficiency aimed at health professionals.


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