With less sunshine, how else can we boost Vitamin D?
As we leave summer behind and look ahead to the darkening shorter days of winter, there is one vitamin that deserves our attention: Vitamin D. Vitamins typically are not made in the body – we get them from food. However vitamin D isn’t actually a vitamin – it’s a hormone and it is made in the skin from exposing a form of cholesterol to UV sunlight. Our bodies can also store it, so we can draw on these reserves when sunlight is not available. But when these reserves are insufficient, especially as we get into the deeper winter months, exogenous sources are required. While there may be sunny days during the winter, this sunlight contains insufficient UV radiation for vitamin D synthesis.
There are few dietary sources of vitamin D – oily fish are the richest source ie salmon, mackerel, anchovies, sardines, herring (SMASH). Other sources include liver, eggs, butter, fortified milk and mushrooms. But we can’t get enough Vitamin D from these.
Why is vitamin D important?
The main function of Vitamin D is to control the level of calcium in your body, especially your bones, and maintain optimal bone density. This is important at any age, but especially to help prevent osteoporosis with ageing.
Vitamin D is crucial for the immune system: it boosts your innate immunity to help fight against infection and it also inhibits the development of autoimmunity, particularly multiple sclerosis and inflammatory bowel disease. Vitamin D also reduces inflammation and improves your gut health.
How much vitamin D do we need?
There is much debate regarding the optimal level of Vitamin D. It is always best to check your current level with a blood test first. Most GPs will include this as part of a standard full blood count or you can get a quick finger prick test done. You definitely want your level to be above 50 nmol/L and above 75 nmol/L is optimal.
Can you have too much Vitamin D?
You will never make too much vitamin D from sunlight exposure because your body inherently regulates this. Some people recommend taking very high supplemental levels. While they have to be extremely high to achieve toxicity, excessively high doses are unlikely to achieve corresponding additional health benefits. You should not take more than 4000iu a day. The basic supplement dose for adults is 1000iu and this is quite safe.
Who is at greater risk of Vitamin D deficiency?
Certain groups of people are at higher risk of deficiency and are likely to need supplementation either all year round and/or at higher doses.
As we age, the ability of our skin to synthesise vitamin D declines - institutionalized elderly patients are almost all deficient.
Those living in temperate climates such as the UK may not get enough sun exposure especially if they do not spend enough time outdoors.
Fairer skins synthesise vitamin D more effectively than darker skins. Those who keep their skin covered with clothing will not be producing enough vitamin D as the skin needs direct sun exposure.
Individuals with a history of liver or kidney disease, or with poor fat absorption (because Vitamin D is absorbed with the help of fat), may also be at risk of deficiency.
Now is a good time of year to get your levels tested to guide you (or with the help of a nutritional therapist) as to the correct supplement dose through the winter months.
by Olivia Smart, MA Cantab, dipCNM, mANP, mGNC
Registered Naturopath and Nutritional Therapist