Commonly known as the “Sunshine Vitamin” Vitamin D is actually a hormone, produced in the body when sunlight hits the skins. It has had widespread press recently after several studies have shown that deficiency of this vitamin is widespread and can have an important impact on our health.
According to the National Diet and Nutrition Survey (1), 90% of the general population in the UK have insufficient blood levels of Vitamin D and 5-20% of the population are severely deficient. This indicates that the majority of us do not have enough of this essential vitamin.
Deficiency of Vitamin D has been linked to a variety of disorders (2):
- Rickets, Osteoporosis, Brittle Bone Disease
- Increased incidences of infections; Colds and Flu, Urinary Tract Infections and Respiratory Infections
- Atopic Disorders including Eczema and Asthma
- Auto-immune disorders such as MS, Type 1 Diabetes, Crohn’s Disease, Rheumatoid Arthritis and Psoriasis
- Dental disease
- High Blood Pressure and Heart Disease
Sunshine is our main source of Vitamin D. Full body exposure during summer months for 10-15mins in an adult produces between 10,000 – 20,000IU of Vitamin D3 within 24 hours (4). It is not possible to overdose on Vitamin D from sunlight (which it is from supplements), however it is possible to burn so safe sun exposure is key. It’s hardly surprising that in the UK the majority of us are likely to be deficient due to our long dark winters, and inability to get enough sunlight on our skins.
The recommended daily requirement for Vitamin D is currently 600IU for an adult, with daily optimal levels of 1500IU-2000IU (5). Unfortunately very few foods naturally contain Vitamin D and fortified foods are often inadequate to satisfy either a child’s or adult’s vitamin D requirement (1), and are not enough to correct a deficiency.
Food source of Vitamin D include oily fish (trout, salmon, mackerel, herring, sardines, fresh tuna), cold liver oil, egg yolk, butter, fortified cereals and milk (3). It is difficult to achieve optimal daily levels (2,000IU) of Vitamin D through diet. Wild Salmon for example, provides 500-1000IU per 100g therefore you would need to eat 2-4 servings per day, and to correct a deficiency you would need 10-20 servings per day! Therefore safe sun exposure during the summer months is necessary, and supplementation to maintain an optimal level or correct a deficiency during winter months is advisable.
Vitamin D levels can be tested through a simple blood test or finger prick test. Supplementation should be monitored by a qualified practitioner to avoid the risk of toxicity through excessive supplementation. I do see clients who have been taking high doses of vitamin D long term and without checking their levels. my rule with vitamin D is always test, don’t guess! You can ideally check your levels every 6 months, or every 3 months if you have been working to increase levels based on a test result.
If you would like to work me to assess your vitamin D levels – please fill out the short client intake form via the contact page.
(1) Nutr Rev. 2008 Oct; 66 (10 Suppl 2):S153-64
(2) Am J Clin Nutr. 2008 Apr; 87(4): 1080S-6S
(3) BMJ. 2010 Jan 11;340:b5664
(4) Pediatrics. 2008 Nov; 122:5
(5) J Clin Endocrinol Metab. 2011 Jul; 96(7): 1911-30