Do You Live in the City? Stock Up on Vitamin D Supplements
If you are one of the billions of people living in the urban centers of the world, you may not be getting enough vitamin D. As you may know, the best way for your body to get vitamin D is through the skin’s exposure to sunlight. However, most of the major city centers in the world are located well north or south of the equatorial regions. As a result, modern humans are exposed to significantly less sunlight than their ancestors in equatorial Africa. And that means that they have a greater risk of being deficient in vitamin D.
The need for vitamin D shaped human evolution
Nina Jablonski, a renowned professor of anthropology at Penn State gave a lecture at a conference in Boston sponsored by the American Association for the Advancement of Science outlining how a pigment in our skin helped our ancestors regulate the production of vitamin D. Melanin is the chemical in the body’s outer tissue covering that gives it color. Since early humans evolved in areas near the equator, their skin developed high levels of melanin to protect them from the intense rays of the sun that destroys folate, which is responsible for controlling cell division. The uncontrolled division of cells is what leads to cancer.
As early humans began to migrate to the northern latitudes, they did not need the same degree of protection from the sun since the ultraviolet radiation there is not as intense. At the same time, they needed to become more efficient in synthesizing vitamin D from weaker sunlight. As an adaption, the level of melanin in people’s skin gradually declined and the pigmentation of their skin became lighter. This explains why people in northern Europe developed pale skin, while people close to the equator retained their dark skin. Although they had common ancestors, northern europeans had to lose the melanin in their skin in order to be able to survive in environmental conditions which made it difficult to produce vitamin D.
In addition, when the industrial revolution arrived, it became more common for people to work in factories where they had even less exposure to the sunlight.1 During the late 19th to early 20th century, the signs of vitamin D deficiency became evident as rickets started to affect people. Rickets is a condition where bones and teeth become soft and misshapen because of not having enough vitamin D in their system.2 Medical science soon discovered that vitamin D supplements could cure rickets.
Migration to the cities means more people are at risk of vitamin D deficiency
Even among populations living at the same latitude, people living in urban areas get far less exposure to sunlight than people living in rural areas. Big city features such as shopping malls, office buildings, and underground transportation, make it possible for urban dwellers to spend their whole day outside without any meaningful exposure to sunlight.
According to Organization for Economic Cooperation and Development (OECD), urban areas have experience an average annual rate of growth of one percent and 53 percent of the populations in OECD countries live in cities. Some areas, such as Phoenix, Toronto, and Atlanta have experienced more than twice this rate of growth.3 When you consider that only 30 percent of the world’s population lived in urbanized settings during the 1950s as compared to forecasts projecting that 60 percent of people in the world will live in cities, it is easy to see the reason that vitamin D deficiency is on the rise.
If you live in a city or spend most of your time working indoors, make sure you take vitamin D supplements to avoid becoming deficient in this essential nutrient.
1Penn State. Mismatch Between Sun Exposure In Modern Life And Skin Pigmentation. Medical News Today. MediLexicon Intl. 2013.
2United States National Library of Medicine. Rickets.2012. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001384/
3OECD. Trends in Urbanization and Urban Policies in OECD Countries. n.d. Retrieved from http://www.oecd.org/urban/roundtable/45159707.pdf