Vitamin D deficiency is a major health problem in the UK.
During late Winter and Spring, up to 90% of the UK population are vitamin D deficient and these are the prime causes:
- Most people spend a great deal of time indoors and this is especially true of adolescents.
- Sun protection creams, which are good to protect high sun exposure, reduce vitamin D synthesis from the sun’s UV rays. A factor 30 suncream reduces vitamin D generation by 95%. It is however very important to protect skin from sun burn to reduce skin damage, ageing and cancers. See link http://www.bad.org.uk/for-the-public/skin-cancer/vitamin-d
- Between October and April the sun’s UV rays are insufficient to generate much if any vitamin D and many UK summers have high cloud cover.
- Ageing affects the skins ability to synthesise adequate vitamin D.
- High body fat and particularly a BMI of greater than 30 reduces available vitamin D
- Digestive conditions of fat malabsorption and bariatric surgery affect absorption of vitamin D.
- Dark skin pigmentation reduces vitamin D production in the skin
- Some prescription medications particularly corticosteroids, Cholestyramine, anti-convulsive medications etc. can reduce vitamin D metabolism.
- Some vitamin D can be obtained from eggs and oily fish however it is very difficult to obtain a significant amount from foods.
Safe sun exposure
There are a number of factors therefore to consider for healthy vitamin D generation. Current guidelines suggest regular sun exposure from April to October, of no more than 15 mins, between the hours of 11am to 3 pm, (or half the time it takes for skin to become pink in the sun) with forearms, hands or lower legs uncovered, is adequate to safely generate vitamin D stores. There are however many influencing factors as mentioned above. Also see link http://www.nhs.uk/Livewell/Summerhealth/Pages/vitamin-D-sunlight.aspx
Low Vitamin D and Health Conditions
Vitamin D deficiency results in abnormalities in calcium and phosphorus absorption and research has shown that without vitamin D only 10-15% of dietary calcium and 60% of phosphorus is absorbed. Low vitamin D therefore significantly impacts on bone health.
Current research shows:
Cancers; vitamin D decreases abnormal cell growth and has significant anti-inflammatory benefits. Many studies have suggested a link between low vitamin D levels and an increased risk of cancer, with the strongest evidence for colorectal cancer.
Heart disease; vitamin D offers a protective benefit and suppression of inflammation. Low vitamin D status has shown a 60% increase in heart disease and hypertension.
Type 2 diabetes; vitamin D sufficiency has been correlated with improved insulin management and a reduction in fasting glucose.
Depression; an increase in vitamin D status has shown an improvement in depression symptoms.
Fractures and falls; low vitamin D increases fracture risk in the elderly
Auto immune disorders; and particularly MS, type 1 diabetes, rheumatoid arthritis and auto-immune thyroid disease have all been correlated with low vitamin D.
Other conditions where improved vitamin D status is beneficial are; improved immunity, reduction in bacterial vaginosis, pelvic floor disorders and early age development of age related macular degeneration.
Laboratory Testing and Reference Ranges
Vitamin D status tests are available through the NHS or privately. Liquid chromatography mass spectrometry is the standard testing method and home kits for blood spot testing can be obtained from www.cityassays.org.uk http://www.vitamindtest.org.uk/ at a current price of £28 per test.
The current reference range from the Institute of Medicine for serum vitamin D is:
<30 nmol/L shows deficiency
30-50 nmol/L is inadequate
>50 nmol/L is sufficient
>75 nmol/L is ideal
Supplemental vitamin D
To know your vitamin D status is well worth the £28 test cost because supplementing (and careful sun exposure) can then be tailored to restore your levels to ideal for preventative health as well as disease reduction.
The ideal supplemental dosage should then be established from the test results and this is best done with the support of a Nutritionist or clinician. It will take several months to restore low levels to acceptable reference targets and then a maintenance dosage is ideal to ensure sufficient levels are maintained.
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