Vitamin D – the sunshine vitamin

I was recently invited to dicuss vitamin on RTE’s The Afternoon Show and thought it woudl be a good idea to share some of this inoformation….

Vitamin D is a fat-soluble vitamin that is naturally present in a few foods, added to others, and available as a dietary supplement. Vitamin D plays an essential role in the absorption and use of calcium and phosphorus, so it is imperative for the formation and health of bones, teeth and cartilage. Without sufficient vitamin D bones can become thin, brittle, or misshapen. Prolonged vitamin D deficiency can cause rickets in children and osteomalacia (softening of the bones) in adults. More marginal vitamin D deficiency is likely to be a significant contributing factor to osteoporosis risk. A good dietary intake of calcium and vitamin D can help protect against osteoporosis.

High risk groups for vitamin D deficiency include elderly people who do not get sufficient skin exposure to sun along with a poor dietary intake, those who cover themselves for religious or cultural reasons, those with malabsorption conditions and those with kidney disease. Also certain medications may interfere with the body’s conversion of vitamin D.

According to a recent study undertaken at UCC it was found that Nearly 75 per cent of adults in Ireland have an average daily intake of Vitamin D that is less than half of what is recommended, while 88 per cent of primary schoolchildren don’t meet recommended Vitamin D levels.

In the UK and Ireland, the recommended daily allowance (RDA) for vitamin D is 0-10µg/ day depending on how much sunlight you obtain. For those aged over 51 years the RDA is 10µg/ day. The absorption of vitamin D from sunlight can vary at different times of the day and year. Very little if any vitamin D is absorbed through sunlight from October to end of March. During the summer months we absorb vitamin D from the sun especially between the hours of 11am and 3pm.1 Therefore extra care needs to be taken with dietary sources of vitamin D in wintertime. Sunscreen can also reduce vitamin D absorption from the sun as ultraviolet rays are prevented from penetrating the skin. With both our climate and safe sun protection practises possible factors in affecting our vitamin D status, a good dietary intake, supplements and food fortification are important to help prevent low vitamin D status.

Good dietary sources of vitamin D include;

Oily fish e.g. herring, salmon, tuna, sardines, pilchards and mackerel, fish liver oils and egg yolks are among the best sources. There are also fortified foods available including; dairy produce e.g. supermilk, breakfast cereals and margarines.

When are supplements necessary?
Supplements are necessary among certain vulnerable groups;
1. The FSAI now recommend that all babies aged from 0-12months in Ireland are supplemented with
vitamin D. It is particularly important for exclusively breast fed babies. We know that breast is the best
start for a baby and is recommended for at least the first six months of life. Breast milk is nutritionally
complete and contains immunological agents that promote the development of a baby’s immune system.
However breast milk is a poor source of vitamin D, especially if the mother herself has a low vitamin D
status. Supplementation is recommended in;
a. All exclusively breast fed babies (particularly those with dark skin). They should receive a vitamin
D supplement daily from birth to 12 months. This provides 5µg of vitamin D.
b. Partially breast fed babies should also be supplemented with vitamin D particularly if they do not
receive more than 500mls of formula per day.2
c. All babies no matter how they are fed would benefit from having extra vitamin D as foods
containing vitamin D are rarely included in weaning diets.
d. There are vitamin D drops available from your pharmacy that are suitable for babies
2.Those who are confined to indoors may benefit from a vitamin D supplement.
3. Elderly adults may benefit from supplements for two reasons. One is that negligible absorption of vitamin
D occurs between October and the end of March but the second factor is that skin syntheses of vitamin
D can decrease with age. A daily intake of 10 µg is recommended for adults aged 51-70 years. However
recent Irish research has shown that 89% of 51-64 year olds do not achieve the 10µg/day
recommendation, with mean daily intakes (MDI) of vitamin D from food sources being 4.01 µg in men and
3.39 µg in women.3 Results like this show us that we need to concentrate on good dietary sources in
the diet and supplementation should be promoted amongst our older population.

References;
1. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom, 1996
2. Vitamin D – new recommendations from the food safety authority o f Ireland, www.fsai.ie
3. UCC vitamin D research group; www.ucc.ie/en/vitamind