Substances in the atmosphere that contribute to air pollution are not only bad for our lungs but may also affect vitamin D levels, a new study published in the journal Scientific Reports reveals.
Vitamin D is an essential fat-soluble micronutrient responsible for the maintenance of bone and immune health, among many other bodily functions.* Vitamin D deficiency is a growing issue that affects an estimated one billion people globally—including 29% of American adults—which means air pollution could have profound long-term effects on our health and well-being in more ways than one.*
Converting sunshine to vitamin D.
Before we dive into the study and why it’s so important, let’s review the science. Though the process of receiving essential nutrients from the sun’s rays may seem better suited for plants than humans, we’ve been using the sun to produce vitamin D for millions of years. If this sounds like a magical human version of photosynthesis to you, you’re not entirely wrong!
During exposure to sunlight, a chemical in the skin called 7-dehydrocholesterol absorbs ultraviolet B (UVB) rays. This compound is then quickly converted to previtamin D3 and finally, through a process called thermal isomerization (i.e., a heat-driven reaction), previtamin D3 is further converted into bioavailable vitamin D3. Vitamin D3 is the body’s preferred form of the vitamin because it is the most bioactive and stable version of the nutrient.*
The link between air pollution and vitamin D synthesis.
Researchers have been studying the correlation between vitamin D levels and exposure to chemicals and pollutants for some time now. A 2018 review published in Environment International investigated how vitamin D synthesis, metabolism, and the entire vitamin D endocrine system (VDES) may be affected by exposure to environmental chemicals, air pollution, and smoking. It found there was significant evidence suggesting that exposure to these compounds can interfere with the VDES and directly contribute to vitamin D deficiency.
While the latest study published in Scientific Reports isn’t the first of its kind, it does provide additional information on how specific pollutants may affect vitamin D absorption in a particular geography and population (in this case, Kuwait). In the study, researchers reviewed four years of weather data in Kuwait to investigate the association of various pollutants with UVB intensity on the ground. They found a distinct correlation between increased air pollutants and decreased UVB intensity—particularly ozone, sulfur dioxide, nitric oxide, benzene, and ethyl-benzene.
Benzene and nitric oxide levels were found to be higher in the morning and evening hours, which is when sun exposure is highest in the region due to high midday temperatures. The decreased UVB levels (i.e., less sunshine hitting the skin) during these times could be a key factor explaining why vitamin D deficiencies are so prevalent in Kuwait, where only 20% of adults and 4% of adolescents have sufficient levels of vitamin D despite the use of fortified foods (which contain very modest vitamin D content, in Kuwait and the U.S., mind you).
While research to more intimately understand the link between air pollutants and vitamin D deficiency is ongoing, the results of this study show that air pollution may have a profound effect on vitamin D levels and sufficiency throughout a population.
If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
