With the days getting shorter, my thoughts have gone to daylight. How much do we need and what are the impacts of reduced light on our bone health, mental health and vitamin D levels? And what about all the artificial light we are exposed to. Does this affect our sleep and wellbeing?
In the depths of Tasmanian winter we have only 9 hours of daylight at best. For many of these hours, the healing light of the sun is hidden behind cloud or mountains. With many people around the world suffering with low Vitamin D (you might be one of them!) it is important to know what impact this has on our body.
What is Vitamin D?
Vitamin D is a fat soluble vitamin. The two main forms of Vitamin D are D3 (cholecalciferol) and D2 (ergocalsciferol). D3 is the one that is formed when our skin is exposed to sunlight. However, we only make a pre-curser to active vitamin D at this stage. The process of making active D relies on our liver and kidneys to activate it. Eating foods rich in vitamin D relies on the health of our gut lining and gut function.
How do we get Vitamin D?
The key source of Vitamin D is from sunlight. Specifically, the UVB rays. The sun gives off the entire spectrum of visible light in every colour of the rainbow. And this type of light makes us feel good. We are able to synthesise the pre-cursor to vitamin D when the light hits our skin. The darker the skin, the harder it is to make vitamin D.
How does D deficiency affect us?
We need adequate Vitamin D for many health reasons. The main reasons are:
· It maintains calcium and bone health. Think osteoporosis risk and bone density
· Immune health
· Cancer prevention. Adequate D levels protect against many types of cancer including bowel and breast
· It lowers diabetes risk. Maybe even more than reducing obesity does
· It lowers depression risk
· It may reduce period cramps and PCOS inflammatory symptoms
What to do?
Get out into the sun with 10-30% of body exposed when the sun is high in the sky. Without sunscreen.
Eat sunlight-exposed mushrooms. Shitake are the best, with dried varieties having even higher concentrations of D2.
Foods such as fatty fish (salmon, sardines, mackerel), egg yolk, and cod liver oil may be worth increasing in the winter months.
Ask about testing your blood levels and finding a supplement to suit you.
PART TWO – COMING SOON! We look at the impact of artificial light and how you can get a better night sleep.