Produced in the skin after exposure to sunlight, vitamin D is known as the “sunshine vitamin”. But unfortunately it's not quite as simple as that! The production of vitamin D in our bodies can be affected by factors such as the season, weather, latitude, time of day, use of sunscreen, colour of skin, age and lifestyle. Indeed, many of us are low or deficient in this vital nutrient which can only be obtained in small amounts through our diet – so much so that Public Health England now advise everyone to take a daily vitamin D supplement. The benefits of vitamin D3 are well documented for maintaining healthy bones and teeth, but it is also needed for healthy muscles and the normal function of the immune system. It is especially important for the normal growth and development of bones in children.