Rickets, a disease caused by vitamin D deficiency, is rarely diagnosed by the practicing physician today. At the beginning of the twentieth century, rickets was prevalent among poor children living in polluted and industrialized cities. The discovery of vitamin D and its anti-rachitic properties soon brought about the fortification of milk with vitamin D and the near elimination of rickets in the 1930s (1). Since then, the major health problems resulting from vitamin D deficiency have thought to have been resolved. However, rickets represents an extreme form of vitamin D deficiency. Overall, it is estimated that nearly one billion people worldwide are either deficient in or have insufficient amounts of Vitamin D, making this a global health problem that needs to be addressed (2).
The majority of vitamin D in humans is obtained from exposure to sunlight, while the rest comes from a person’s diet. Few foods naturally contain vitamin D, and those that do, such as fatty fish and beef liver, are generally not eaten every day. The absorption of solar UVB radiation by the skin leads to the synthesis of vitamin D; therefore anything that interferes with this affects the synthesis of vitamin D. Both melanin, which increases skin pigmentation, and sunscreen are extremely efficient in absorbing UVB radiation and, consequently, reduce vitamin D synthesis in humans by as much as ninety-nine percent (3). Additionally, other factors such as old age, obesity, season, latitude and time of day can all affect vitamin D synthesis. Above approximately thirty-five degrees north latitude, which includes St. Louis, little or no vitamin D can be produced from exposure to sunlight from the months of November to February (3). Combining the aforementioned components with the omnipresence of technology, increased urbanization and more indoor jobs, it is no surprise that society today spends less time outdoors than in the past. With less time spent outdoors, less vitamin D is synthesized. As a result of this, vitamin D deficiency is of greater concern and can affect nearly anyone.
But what does all of this mean? What are the effects of being vitamin D deficient? Vitamin D is responsible for regulating the function of over two-hundred genes and is crucial for growth and development (4). It is also necessary for the absorption of calcium and phosphorus, both of which are essential to bone strength and development. Vitamin D deficiency in adults has long been known to cause and exacerbate bone diseases such as osteopenia and osteoporosis, increase the risk of fractures and increase the risk of muscle weakness (5). Of great interest, however, is its recently recognized association with increasing the risk of several chronic illnesses, including multiple types of cancers, cardiovascular disease and type I diabetes, all of which are leading causes of death. It is because of these risks that the vitamin-D-deficiency pandemic is starting to generate considerable concern among scientists. In fact, several retrospective and prospective studies support this idea that vitamin D deficiency increases the risk of developing cancer. Adults who were followed for up to nineteen years “had a thirty- to fifty-percent increased risk of developing colorectal, breast, prostate, and many other cancers (6).” How vitamin D causes this increased risk is thought to originate from the genes that vitamin D regulates, many of which may control cell growth and cellular differentiation. Although more research is needed on the topic, the associated effects cannot go ignored.
In a study analyzing data collected through the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2012, it was found that among the four-thousand- nine-hundred-sixty-two participants, one-thousand-nine-hundred-eighty-one (39.92%) were vitamin D deficient. The results were consistent with a NHANES study conducted from 2005 to 2006, where forty percent of the population was found to be vitamin D deficient (7). Such results are surprising and warrant attention to the prevalence of vitamin D deficiency, especially when thinking in terms of conducting future large-scale studies. As of now, no governmental body or international health organization has formally addressed this global health issue or discussed the urgent need of reaching sufficient vitamin D levels.
In the absence of an informed general public, vitamin D deficiency will continue to be overlooked. The fact that this deficiency is generally asymptomatic, meaning it presents no observable symptoms, makes it even more likely to go unnoticed until other problems begin to arise. Long term strategies to address this problem should include vitamin D supplementation, public education regarding risks and prevalence of vitamin D deficiency and national policies to implement screening in order to detect vitamin D deficiency. It is important to note that vitamin D supplementation is most effective when serum levels of vitamin D are low or in high-risk individuals. The newly recognized risks of vitamin D deficiency and its increasing prevalence should be enough to create an impetus for ensuring sufficient levels of vitamin D in order to reduce these associated risks early on.
Edited by: Katie Church
Illustrated by: Lily Xu