Vitamin D is one many fat-soluble vitamins that the body requires to function correctly. We make this essential vitamin from the skin's unprotected exposure to sunlight, but it can also be found in certain foods such as eggs, cereal and fatty fish.
Despite being vital for healthy bones and a robust immune system, our more sedentary lifestyles have meant that exposure to the sun has dropped dramatically and our processed and specialist diets has meant that supplementation is needed to maintain a healthy level of vitamin D.