By: Natasha Duggan, MSPH
Minorities and African Americans in particular are disproportionately affected by various chronic diseases in comparison to their white counterparts. Diseases including obesity, diabetes, cancer and asthma are much more prevalent in the black community. The question is …why?
It is in part due to genetics. Some illnesses like diabetes have a genetic component, meaning risk of disease is passed down in your family through your DNA. However, genetics alone does not account for the disproportion of some diseases found only in certain populations or neighborhoods. These findings can be explained by epigenetics.
Epigenetics refers to the changes that occur in gene expression-turning genes on and off- without changing the actual DNA sequence.1 Epigenetic changes happen naturally but can be influenced by things like age, environmental exposures, and disease. In many instances epigenetic changes are reversible, but they are sometimes irreversible and affect a person for life.1 Exposure to different environmental factors can cause epigenetic changes which result in diseases like cancer, obesity, diabetes, and asthma. Increased and prolonged exposure to adverse environmental factors increases the likelihood of epigenetic changes being irreversible.1
Epigenetic changes go beyond effecting the person being exposed to adverse environmental factors. Epigenetic changes can be hereditary. If a pregnant woman is exposed to certain environmental factors, the epigenetics of her child may be permanently altered, resulting in an increased risk of chronic disease.1,2 One of the most famous and well-studied examples of this is the Dutch Famine. In the later years of World War II, pregnant women who experienced famine gave birth to children with increased incidences of both heart disease and obesity due to the epigenetic changes which occurred while they were still in the womb.1
So why is epigenetics so important to minority communities? Epigenetics partially explain why minority populations are disproportionately affected by some chronic diseases. An example of this includes the effects antibiotics have on infants before they are even born. Antibiotics are the most common drugs prescribed to pregnant women. Scientists have found that when pregnant women take antibiotics they are more likely to have a child with low birth weight2. In turn, these children often under-go catch-up growth in early childhood, which often results in obesity2. Although this phenomena occurs across all races, it is much more common in black women.2
So what is going on to make this happen? The taking of antibiotics while pregnant creates a stressful environment for the fetus, so to ensure its survival epigenetic changes occur. Once the child is born and is no longer in a harsh environment they tend to become obese due to the fact that the epigenetic changes which occurred when they were still in the womb are still in effect.2 However, it is not just antibiotics that can cause these epigenetic changes. Many pharmaceutical drugs also cause epigenetic changes, increasing the risk of heart disease, cancer, neurological and cognitive disorders, obesity, diabetes, infertility, and sexual dysfunction3. Because of this it is very important to be careful what goes into your body.3
Stress is a major contributor of epigenetic changes. Unfortunately being black in America causes a lot of everyday stress. Although being of a lower socioeconomic class is correlated with higher stress and worse health outcomes, across all socioeconomic classes Black and Latino people were found to be more likely to have high levels of the stress hormone cortisol.4,5,6 Stress can cause a variety of epigenetic changes. Firstly, high stress levels during pregnancy can cause epigenetically induced asthma in infants.4 This is exacerbated by the mother also being obese while pregnant.4 High stress levels (marked by high cortisol levels) have also been shown to result in premature childbirth.6 This is thought to be a possible reason why black women have more premature births than white women.
The scary part about epigenetics is the fact that epigenetic changes can be inherited and can affect your children’s and even your grandchildren’s likelihood of having a disease. With epigenetics being a fairly new field, there is still a lot more research that needs to be done to see the role epigenetics plays in many chronic illnesses. Even though a lot of epigenetics cannot be changed, it is still important to educate ourselves on what may be responsible for our illnesses and to try to avoid the exposures that we can. Don’t take drugs (pharmaceutical or antibiotics) unless necessary, and adopt effective stress relieving behaviors. The more you know, the more likely you are to make better, healthier decisions.
2.AC Vidal et al. “Association between antibiotic exposure during pregnancy, birth weight and aberrant methylation at imprinted genes among offspring.” International Journal of Obesity 2013; 37,907-913.
3.AB Csoka & M Szyf. “Epigenetic side-effects of common pharmaceuticals: A potential new field in medicine and pharmacology.” Medical Hypotheses 2009; 73, 770-780.
4.RJ Wright et al. “Disrupted prenatal maternal cortisol, maternal obesity, and childhood wheeze.” American Journal of Respiratory and Critical Care Medicine 2013; 187(11), 1186-1193.
5.RJ Wright. “Epidemiology of stress and asthma: From constricting communities and fragile families to epigenetics.” Immunol Allergy Clin North Am. 2011; 31 (1), 19-39.
6.Janell Ross “Epigenetics: The Controversial Science Behind Racial and Ethnic Health Disparities.” The Atlantic March 20, 2014. http://www.theatlantic.com/politics/archive/2014/03/epigenetics-the-controversial-science-behind-racial-and-ethnic-health-disparities/430749/