Healthy bones need vitamin D to absorb calcium and phosphate from our diets.
These minerals are important for teeth and muscles as well. A vitamin D deficiency can make bones go soft, weak and leads to deformities. For example, in children it may trigger rickets and in adults it brings about osteomalacia or bone tenderness and pain.
The human body creates vitamin D from direct sunlight falling on the skin. In most parts of the Northern hemisphere, from the beginning of April/May to the end of September/October, we can get all the vitamin D that we need from sunlight. Being out in the sun during this time in short periods with forearms, hands or lower legs uncovered and without sunscreen, the body can make enough Vitamin D.
A number of factors such as geography, time of the day and/or year, skin color and how much skin is exposed determine the time needed to make enough vitamin D. It is also imperative to not burn in the sun by protecting the skin with sunscreen or to take cover before the skin starts to turn red. Usually people of African, African-Caribbean and south Asian origins need to spend longer time in the sun to produce equivalent amount of vitamin D as someone with lighter skin tone. Also, sitting by a window on a bright and sunny day is not enough to produce vitamin D because ultraviolet B (UVB) rays that the body needs to make vitamin D, cannot pass through the glass.
Summer is the ideal time for the body to produce vitamin D because the winter sunlight does not contain enough UVB radiation. The closer to mid day the skin is exposed to the sun, the higher is the amount vitamin D is produced because during the early and later parts of the day, rays from the sun enter earth at an angle and the atmosphere blocks the UVB radiation. A good rule of the thumb is if the shadow is longer than the body, then there is not enough vitamin D being manufactured.
About Taushik Mandal
Taushik Mandal is an Indian Photographer currently based in Paris, France. He specializes in portraiture photography and street photography. He has completed his European Master of Professional Photography from Spéos International Photo School, Paris. [Official Website]