Why do we need Vitamin D?
Vitamin D is made in our skin via direct exposure to sunlight. Our liver and kidneys then convert it into a form we can use. Vitamin D is extremely important for strong bones and teeth, as it helps us absorb the calcium we eat and it also controls the amount of calcium in our blood. It’s really important that our vitamin D levels aren’t low or our body won’t absorb the calcium we eat.
There aren't any visual signs of vitamin D deficiency. If our levels are very low and we are severely deficient, we are at risk of developing weaker bones which is a condition known as
osteomalacia. Severe deficiency in children may result in soft skull or leg bones and their legs may look curved or bow-legged, which is a condition called
rickets. As low levels are common in the UK, it's worth getting tested if you're concerned. Ask your GP for a blood test.
Vitamin D levels explained
| Vitamin D blood ranges | Classification |
| Under 25nmol/L | Deficient |
| 25 - 50nmol/L | Insufficient |
| 50-75nmol/L | Sufficient |
| Over 75nmol/L | Optimal |
How much sun do we need?
During the summer months, approximately 20-30 minutes of direct sunlight two to three times a week should be enough for a fair skinned person to make the vitamin D they need. For the elderly and darker skinned people, exposure time or frequency needs to be increased two to tenfold to get the same level of vitamin D synthesis as fair skinned individuals.
A word of caution though, too much sun exposure can be damaging due to the risk of developing skin cancer. Only spend a small amount of time in the sun without sunscreen either early in the morning or late in the afternoon and the rest of the time be sure to cover up and avoid any chance of sunburn.
Amount of sun required to compensate for 49 days of no exposure
| Skin type | Minutes of July sun required |
| Fair | 10 - 12 mins |
| Asian | 30 mins |
| African/ Afro-Caribbean | 120 mins |
What affects our Vitamin D levels?
Several different factors can affect our vitamin D levels such as skin pigmentation, age, season, clothing and use of high factor sunscreens. As elderly people have thinner skin they are unable to make as much of the vitamin as younger people. Also, the position of the UK means that 90% of it lies above the latitude that permits exposure to the sun rays necessary for vitamin D synthesis. The southern part of the country is marginally better positioned for vitamin D synthesis (the closer you are to the equator the better). All of these factors will have an effect on our levels.
Approximately 60–70% of the UK adult population have insufficient levels of vitamin D in winter and spring and 16% are considered deficient. At the moment, there are no recommendations for daily intake. Whilst UK recommendations have not been set for the general population, some groups are at higher risk for developing deficiencies. These include:
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Pregnant and breastfeeding women
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People who have darker skin, such as those of South Asian, African or Afro-Caribbean descent
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Men and women who are over 65 years of age
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Babies and children aged six months to five years
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Adults who stay out of the sun or cover up when outside
Vitamin D in our diet
Foods that naturally contain vitamin D include oily fish such as mackerel, sardines, tinned salmon, herring and kippers. Some foods are fortified with small amounts of vitamin D, including breakfast cereals, infant formula and margarine. There are smaller amounts found in eggs and some red meats, such as duck, goose, pheasant and venison however, the exact amount is unknown. Breast milk also contains vitamin D and mums should make sure they aren’t deficient as this will affect the levels in their milk.
Vitamin D-rich foods
| Food per portion | Vitamin D content |
| Kipper (140g) | 35µg |
| Herring (140g) | 31.5µg |
| Mackerel (140g) | 24.5µg |
| Tinned salmon (140g) | 17.5µg |
| Sardines (140g) | 10.5µg |
| Duck eggs (2) | 3.75µg |
| Hen eggs (2) | 2.5µg |
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