Vitamin D is a steroid hormone which you naturally generate through sun exposure. So it’s a good idea to get out in the summer sunshine as much as you can, showing as much skin as possible (around 80%).

If enough of you is exposed, you can produce between 10,000 to 25,000 IU from the time you bare your skin until just before it turns pink! Just make sure you do it without using sunscreen which inhibits the process. 

There are two types of vitamin D – D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D2 is found to be less effective at increasing vitamin D levels than D3. So D3 is the type to go for when it comes to optimising the vitamin D levels in your blood.