The Nutrient Series – VITAMIN D

The “sunshine vitamin” has had a lot of press recently, and for good reason! Vitamin D helps our bodies absorb calcium and phosphorous from the food that we eat, which are both essential nutrients for healthy bones, muscles and teeth. Even if you consume enough calcium, if you are deficient (don’t have enough in your body) in vitamin D, your body won’t be able to use the calcium where it’s needed. Children who are deficient in vitamin D can develop rickets (permanent bone deformities), whilst low vitamin D intake in adults can increase the risk of developing osteomalacia (bone pain and muscle weakness).

Where does vitamin D come from?

Most of the vitamin D that our body needs is made under the skin in response to daylight – that’s where its nickname comes from. You make more vitamin D in bright sunshine in the middle of the day than on a cloudy day. In the UK, the sun is strong enough for us to make vitamin D between April and September. The rest of the year your body uses vitamin D that has been stored in our bodies, or has comes from food or from supplements.

However, you don’t need to sunbathe for your body to be able to make vitamin D. It isn’t known yet how long is the optimum length of sun exposure due to many different factors affecting vitamin D production (such as skin colour or how much skin is exposed). The NHS suggest that a short period of sun exposure every day should be enough, but to make sure you take precautions not to get burnt.

Foods high in vitamin D

Oily fish such as salmon, mackerel and herring are relatively high in vitamin D, as is cod liver oil (don’t take this if you’re pregnant, though,  as it also contains very high levels of vitamin A which could harm your baby). Some foods are fortified with vitamin D such as margarine, some dairy-free alternatives, infant formula and yoghurt.

How much should we have?

The Scientific Advisory Committee on Nutrition (SACN) published a report in 2016 stating the importance of vitamin D in maintaining good muscle and bone health. They recommend taking a 10-microgram supplement daily, especially in the winter months, which can be found in most pharmacies. This is because in the UK we don’t have strong enough sunlight all year round to produce vitamin D, and because there are not a huge number of foods high in vitamin D.

Groups at risk of low vitamin D

There are some groups of the population who are at risk of low vitamin D, and who SACN suggest should consider taking a vitamin D supplement all year round.

  • Elderly – skin is not as efficient at making vitamin D in over 65’s
  • Those who are housebound, work in an office or shift workers – these people tend to spend less time outside during daylight
  • Pregnant women and breastfeeding mothers
  • People with dark skin tones living in the UK and northern countries where there is less sunlight
  • People who cover most of their skin when outside

 

Remember to contact your GP, a health visitor or a dietitian if you are worried about your vitamin D status.

 

Sources

BDA Food Facts – https://www.bda.uk.com/foodfacts/VitaminD.pdf

Essentials of Human Nutrition, Jim Mann & A. Stewart Truswell, 2012.

NHS Choices – http://www.nhs.uk/Livewell/Summerhealth/Pages/vitamin-D-sunlight.aspx

SACN vitamin D and health report – https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report

 

Photo: @lauraheck

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