Vitamin D - the link with cholesterol
Vitamin D is often linked to cholesterol because cholesterol is required to make vitamin D in the skin from the action of sunlight.
Ultra violet (UV) rays from the sun are needed to convert 7-hydrocholesterol in the skin to vitamin D (cholecalciferol). Because the UK lies at a very northern latitude there is only enough of the right type of UV rays during the spring and summer months. About 90% of our vitamin D is made in the upper layers of the skins because this is where the light penetrates the skin. But this is not the active form of the vitamin. Vitamin D from the skin and small amounts of vitamin D from the diet pass via the blood to the liver and kidneys where they undergo the first of two conversions – the first to 25 hydroxyvitamin D and the second to 1, 25 dihydroxyvitamin D. 1,25 dihydroxyvitamin D is the active form of vitamin D
25 hydroxyvitamin D, often shortened to 25(OH)D, is the major circulating form of vitamin D. It’s what doctors and nurses measure to decide if someone has enough vitamin D or not. Levels below 25nmol/L are considered inadequate.
What is the safe level of vitamin D intake?
Back in 2003 an expert UK group was commissioned to look at safe intakes of all vitamins and minerals. They agreed an upper safe level of vitamin D intake of 25mcg per day for adults. More recently this was reviewed by the European Food Safety Authority (EFSA) and set at 100mcg/d for adults. An upper limit of 50 mcg per day was set for children aged 1-10y to take account of their smaller body size and for infants 25 mcg per day.
You can never get too much vitamin D from over exposure to sunlight. This is because when vitamin D levels are adequate, pre vitamin D is converted into biologically inactive compounds which can be reactivated once vitamin D stores become depleted.
Do statins lower vitamin D?
Statins are a class of drug prescribed to help lower cholesterol levels. Most cholesterol is produced in the liver by a multi-step process. Statins work by partially blocking one of the steps in this process. Because cholesterol is needed for vitamin D production questions have been asked about the effect on vitamin D status. Statin intolerance is often linked to a generalised muscle ache. Some of the effects of vitamin D deficiency are muscle weakness and bone tenderness which are not dissimilar.
With estimates of vitamin D deficiency being as high as 2 in every 5 adults it is possible that:
- many people taking statins are vitamin D deficient, especially towards the end of the winter months when vitamin D stores are exhausted
- vitamin D deficiency symptoms are easily mistaken for statin related muscle pain
It is very simple for your doctor to test your vitamin D status if your doctor suspects, just by doing a simple blood test.
Public health guidance on vitamin D intakes was issued in 2016 and aimed at helping ensure those most at risk get an adequate supply of vitamin D. However some think this is not enough and that there should be routine fortification of foods with vitamin D. You can visit the advice given by the department of health here
Find out more about vitamin D and how to ensure you are getting enough.
All the public health advice is informed by the Scientific Advisory Committee on Nutrition (SACN) Report on vitamin D.