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6 1.1 Nutritional Requirements
Vitamin A are outside in daylight. The action of UV
(ultraviolet) radiation of wavelength 290–310 nm
Vitamin A comes in two forms: retinol in some converts 7-dehydrocholesterol to vitamin D3 (via
animal foods (full-fat milk, butter, margarine, egg its precursor). Skin synthesis is affected by many
yolks and liver) and carotene in fruits and factors, including the following:
vegetables. Carotene is the orange colour in fruits
and vegetables and it is also present in dark green ●● Latitude: The intensity of the sunlight decreases
vegetables such as spinach and broccoli. with increasing distance from the equator. In
the UK vitamin D is only made in the skin
Vitamin A is very important for growth and during the summer months from April to
development as well as vision. As an antioxidant it September. Hence in summer a store of vitamin
is part of the immune system helping to prevent D must be built up to last through the winter.
infections and illness. Young children do not
always get enough vitamin A in their diet, which is ●● Climate: Cloud cover decreases the intensity of
why the Department of Health recommends a daily the sunlight.
supplement for all under-fives. In the developing
world, many children have impaired vision due to ●● Air pollution: This reduces the critical UV light
a deficiency of vitamin A. Fortunately this waves available for skin synthesis.
deficiency is not seen in the UK.
●● Skin type: Synthesis is higher in white populations
Excess vitamin A taken in the form of too many than in darker pigmented skins of children of
supplements could be a problem for children as Asian, African and Middle Eastern origin.
excess amounts are stored in the body. Liver is very
high in vitamin A now that animal feed is enriched ●● Lifestyle habits with regard to time spent
with it. The Food Standards Agency recommends outside or clothing. People who cover most of
that children and adults should only consume liver their skin when outside have limited
once per week. synthesis and are more likely to be deficient
in vitamin D.
B vitamins
●● Sunscreen use, as sunscreens prevent skin
The B vitamins are thiamin, folic acid, niacin synthesis. Although it is important not to let
(nicotinamide), riboflavin, pyridoxine, biotin, children’s skin burn in the sunshine, it is also
pantothenic acid and vitamin B12. These are all important for them to spend time outside
important for growth and development of a healthy everyday in summer in order to make plenty of
nervous system, and are needed to convert food vitamin D and build up a good store. Sunscreens
into energy. Vitamin B12 and folate are important should only be used to prevent sunburn when
for preventing types of anaemia. Good sources of B children are outside for extended periods in the
vitamins include meat, milk products, fish, eggs, middle of the day. If sunburn is unlikely then
cereals, seeds and vegetables. Dark green children should be encouraged to play outside
vegetables, liver and pulses are high in folate. without sunscreen.
Vitamin C Very few foods contain vitamin D – oily fish is the
best source. In the UK, margarines, formula milks
Vitamin C, also known as ascorbic acid, is essential and some breakfast cereals are fortified with
for increasing the iron absorption from plant vitamin D. Meat and egg yolks contain tiny
foods, protecting cells from damage and for amounts.
maintaining blood vessels, cartilage, muscle and
bone. Vitamin C is also involved in wound healing. The liver enzyme 25-hydroxylase converts
A severe deficiency causes scurvy. endogenously synthesized vitamin D3 and
diet-derived D2 and D3 to 25 hydroxyvitamin D. In
Vitamin D the kidney, 25 hydroxyvitamin D can be converted to
1,25-dihydroxyvitamin D, the active hormone which
Vitamin D is sometimes called the ‘sunshine has several roles in the body:
vitamin’ as most is made in exposed skin when we
