Vitamin D plays an important part in maintaining health in the following ways:
- Calcium absorbtion and forming strong bones
- Joint, heart and brain health
- Immune system
- Appears to reduce risk of developing type 2 diabetes and some types of cancer
It is formed by the action of UVB rays from the sun on the skin when the UV index is greater than 3, so exposure to the sun is an easy way to keep levels up. However, the required UV index levels are only reached in the UK in the spring and summer, so supplements may be needed in autumn and winter. Vitamin D is found in small amounts in some foods.
- Oily fish, fish liver oils, animal liver.
- Fortified margerine, eggs, butter and fortified milk.
- Avocado is a good source, and can be used in salads, sandwiches and mashed on toast.
- Mushrooms are able to make vitamin D when exposed to sunlight; leave
them in good sunlight for 15 minutes, gill side upwards to expose the
greatest surface area. Flat mushrooms can make more vitamin D than
button mushrooms.
Supplements
- Supplements of vitamin D3 are more effective in maintaining blood vitamin D levels than vitamin D2.
- The EU recommended daily allowance if 5mcg (200 IU) per day; however a daily intake of 25mcg (1000 IU) is usually recommended during winter months.
- Vitamin D supplements are best taken with fatty foods (e.g. milk or yoghurt) for more effective absorption as it is a fat soluble vitamin.
- Excess can lead to side effects associated with high calcium levels, such as demineralisation of bone, kidney stones, headache and weakness.
From Healthspan magazine
Lifespan, winter 2013 issue and
Trust Me, I'm a Doctor, BBC2 February 2017.
