Most of the body's vitamin D comes from making it in your skin on exposure to sunlight when the UV index is greater than 3. During the winter months maintaining adequate vitamin D levels is difficult because the UV index is too low for synthesis to occur as a result of the shorter days, rainier climate and weaker strength of the UV rays.
Vitamin D is vital for the absorption of calcium and phosphorus from the diet, making it essential for healthy bones and teeth. Vitamin D is increasingly believed to be a helping hand for your immune system and is also linked with muscle strength and risk of falls in older people. Mood changes, such as seasonal affective disorder (SAD), are also believed to be linked to lack of vitamin D. If you think you're deficient, try the following techniques to manage your intake.
Taking a vitamin D supplement during winter is a great way of providing the necessary levels of vitamin D. There are two types available; vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). It's recommended that you take supplement that contains vitamin D3 which is the same form made by the body when it's exposed to sunlight, and is more effective in maintaining blood vitamin D levels than D2, which is the form used by plants. There is also a vegan vitamin D3 available to ensure you're taking the best form of vitamin D.
Eating eggs is a great way to get vitamin D into your diet. Make sure to eat the whole egg and not just the whites. The yolks are the bit that's packed with vitamin D3. Oily fish (salmon, mackerel, herring and sardines); dairy products and fortified margarines; and meat (liver and kidney) are also rich in vitamin D3. Sunshine, not food, is the main source that's why it's advised that a supplement is taken during the winter, together with a balanced diet, to ensure you get an adequate amount of vitamin D.
Light box therapy
Light therapy can be useful if you suffer from SAD. These boxes used to mimic outside light to increase the body's intake of vitamin D. They should emit as little UV rays as possible to avoid skin damage. When you buy your light box make sure yours is designed to treat SAD so it doesn't produce unnecessary UV light, which can be damaging to your skin. Before you buy one chat your GP so they can talk through all the options available.