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March is the ideal time of year for those of us in the UK (and Northern Hemisphere) to test our Vitamin D levels. Vitamin D is made by the body on exposure to sunlight on the skin. This nutrient, sometimes referred to as a hormone, is stored in the body and in theory the sun exposure from the summer should produce enough Vitamin D to last us until spring. By the end of an English winter, (unless you have been supplementing or jetting off to the Caribbean) it should be at its lowest. Testing your Vitamin D levels is useful even if you are supplementing. Vitamin D needs to converted to the active form by the body so it is important to test to see how well your body is doing this. If you are going to supplement with Vitamin D it is wise to test before you do so.
Optimal Vitamin D levels have been shown to have a vital role in many aspects of health and immunity. Studies have shown that many of are deficient. Low or deficient Vitamin D has been associated with hypertension, diabetes, cancer, depression and arthritis1. Without Vitamin D, calcium and phosphorus are not able to enter the bone tissue, resulting in weak bones and teeth and potentially putting us at risk of rickets or osteoporosis. For good bone density later in life it is essential that bone strength is established during childhood.
Although some foods (oily fish, egg yolks, whole milk) contain small quantities of Vitamin D, it is mostly produced through sun exposure from late March in the UK through to the end of September. To produce Vitamin D in the body, skin should be exposed without sunscreen to sun between 11am and 3pm2. Individuals will have to assess their skin type and susceptibility to burning to decide on how long this should be (probably about 10-15 minutes) and sensible sun exposure is still advised. It is recommended that children aged 1-4 years and people that are outside very little should supplement with 10µg of Vitamin D3 daily. Further advice on supplementation, including that for babies and children can be found on the NHS Choices website.
Vitamin D is a fat soluble Vitamin. This means that it is only absorbed in the presence of fat. This means that is you follow a low-fat diet (or have done), it is likely that your Vitamin D status could be low. Fat is an essential nutrient in the diet and must never be cut out unless advised by a professional. Good fat levels in the diet are also necessary for the absorption of Vitamins A, E and K and a variety of sources of fat are recommended. Sources of fat include oily fish, grass-fed meat, dairy produce, goat or sheep cheese, olive oil, avocado, coconut oil, coconut milk, nuts and seeds.
If you would like to test your Vitamin D levels, you can ask your GP or private tests are available cheaply which you can carry out at home. For further information about Vitamin D testing or supplementation you can make an appointment with a registered Nutritional Therapist.
References
1. https://www.nhs.uk/Livewell/Summerhealth/Pages/vitamin-D-sunlight.aspx2. https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-9-65