Gina Gasparotto ’22 and Zander Maitland ’22


There is a constant barrage of information about cancer-causing chemicals, damaging pollution, and other toxins making us sick. With headlines like “11 potentially cancer-causing things you might use every day” and news stories about “Environmental pollution killing more people than war”, it’s understandable that the public has become hyper-aware of the health consequences of chemicals and pollution. So, the prospect of protecting yourself and your loved ones with a simple diet change is intriguing. 

The so-called “Epigenetics Diet” claims to provide a protective barrier against the harmful effects of environmental pollution and cancer. Hundreds of studies have found that different forms of this diet have protected against diseases like Alzheimer’s, cancer, and COVID-19. Scientists have mostly shown this using experiments on human tissue cultures and in animal models, as well as using blinded trials in humans, which is the gold standard of clinical research. The elements of this diet include chemicals like resveratrol, genistein, and other minerals, and you can find them in common foods like dark leafy greens, soybeans, and grapes1. Scientists believe these chemicals can suppress tumors and reduce the effects of environmental pollution by changing the epigenome1

The term “epigenetics” refers to the epigenome, which sits on top of your DNA. Your DNA is a blueprint with instructions for how to make everything in your body that contains genes, which are specific instructions for everything from your eye color to how many times a cell should divide. Altering the epigenome that sits above your DNA can change what genes are expressed, which go on to make the proteins that build everything in your body. Think of this like a field growing crops with clouds overhead. When the clouds cover a patch of soil so sunlight can’t reach it, plants won’t grow there. But, a few feet over, where there isn’t any cloud cover and sunlight can reach the soil, the crops can grow. In this analogy, we can think of the cloud cover above the field as the epigenome, the soil below as the DNA, and the plants as genes being turned into proteins. If parts of the DNA (i.e. the soil below) are “covered” by the clouds above (i.e. the epigenome), then those genes won’t be expressed. If parts of the DNA aren’t covered by the epigenome, then they’ll have sunlight to grow and the genes will be expressed. In reality, this covering by the clouds is accomplished by adding bulky “tags” that prevent DNA from being read properly and expressing certain genes. These differences in how genes are expressed can affect what proteins are made and change how organisms develop, survive, and reproduce.

Image source: BioMed Central

Proponents of the epigenetic diet like Dr. Tolefsbol specifically argues that eating more of these compounds that affect your epigenome can 1) prevent cancer by inhibiting tumor growth, and 2) counteract the harmful changes to gene expression caused by environmental toxins like air pollution and heavy metals like mercury1

Addressing the Cancer Claim

First, Dr. Tollefsbol and his colleagues claim that adding specific foods to your diet can prevent cancer by returning abnormal gene changes back to normal. We know this from a study in mice which showed that subtracting certain foods could lead to cancer. So why did this happen? 

Normally, cells go through a number of stages to make sure they’re dividing correctly and that they are healthy. At each stage, certain genes can be switched on or off. Think of these stages as a “red light” at an intersection that can prevent an unhealthy cell from dividing too much, spreading in the body, and becoming cancerous. One mechanism for how these genes can be turned on and off is by tiny chemical groups called methyl “tags” added by a process called DNA methylation. When more methyl “tags” are added, there are more red lights, so the gene switches off. By changing your diet with foods that do or don’t have methyl, you can add or subtract “red lights” which can lead to cancer or prevent it. The study showed that by giving the mice food without methyl that normally creates “red lights,” their bodies couldn’t turn off genes like the HRAS oncogene, which helps make a protein that’s important for cells to divide properly.  Not adding the “red lights” meant that the expression of this gene wasn’t stopped when it was supposed to, which led to cells dividing too much, which promoted liver cancer. However, when the mice had their diets corrected to include methyl-containing compounds, like dark leafy greens, they stopped developing liver cancer. The scientists, therefore, found that altering diet may help with the prevention or treatment of cancers2. However, it’s important to note there are many cancers with diverse causes. Although there are many common cancers with established epigenetic origins like cancers in the cervix, liver, and colon3, it’s not yet clear if some of these changes can be modified by diet, but cancer treatments are certainly possible. 

Addressing the Environmental Pollution Claim

Next, the effects of environmental pollution on the epigenome. The epigenome in humans is vulnerable to many different environmental toxins like air pollution and heavy metals, which can negatively affect the body by adding “red light” tags to decrease the expression of genes that help your body’s immune response against diseases.

Image source: Conserve Energy Future

Air pollution is a major public health concern worldwide, leading to diseases like lung cancer and chronic obstructive pulmonary disease (COPD)5. Researchers have found that particulate matter, one of the most common air pollutants, can interfere with the normal methylation patterns of certain genes (meaning the adding of “red lights”), which is important for inflammation and oxidative stress responses6. The oxidative stress response balances the levels of reactive and dangerous oxygen molecules, which your cells need to produce energy, but can also damage your DNA. The inflammatory response causes swelling to defend the body against things like bacteria, trauma, or heat7. Specifically, particulate matter causes an increase in methylation at the oxidative stress and inflammatory genes, which acts as a “red light” signal for the molecules that make proteins from these genes. This leads to an overall decrease in proteins important to these responses, which makes it harder for your body to fight environmental damage and disease. 

The scientists behind the epigenetic diet claim that the loss of DNA methylation caused by air pollution can be countered by B vitamins, which can be found in foods like salmon, legumes, and eggs. By adding more B-vitamins (like folic acid, vitamin B6, and vitamin B12) to human diets, you can avert negative effects on the epigenome caused by exposure to air pollution8. B vitamins prevent the attachment of these “red light” signals by interfering with proteins that connect methyl groups to DNA in response to air pollution8. This allows for the normal production of important proteins from these oxidative stress and inflammatory genes that regulate normal and healthy responses to disease and environmental toxins. 

The epigenetic diet also touts the positive effects of supplementing diets with folic acid, found in foods like beans, peanuts, and spinach9. These are effective at preventing the damaging effects of heavy metals, like heart problems and gastrointestinal issues. Scientists have actually found that higher levels of folates can prevent harmful increases in DNA methylation caused by arsenic exposure10. Arsenic is a heavy metal that adds more of these “red light” signals to the genes that make white blood cells, which are important to the immune system response10. Higher dietary levels of folates interfere with the addition of these “red light” signals. This allows for the normal production of white blood cells that can help the body fight infections and cancers.

Looking at all these results together, they show that altering diet can change how the epigenome functions. Eating foods with more folates and B vitamins may protect against some of the damage caused by environmental pollution. However, these studies only investigate air pollution and arsenic exposure, so further studies should examine the effects of this diet on other environmental toxins, like those found in plastics11

Conclusion

It’s important to remember that there isn’t enough evidence to suggest that the epigenetic diet is an adequate treatment plan for any of the diseases mentioned. If you have any of these diseases, it’s best to talk to your doctor about whether supplementing your diet with these foods is recommended and to use established treatments. The mechanisms of the epigenetic diet are complicated, which might cause unintended side effects and possibly interfere with “stop sign” signals attached to genes that are supposed to be turned off. Further studies should investigate the systemic effects of putting these bioactive chemicals into your diet and how they interact with medications and existing therapies for cancers, for example. Scientists should also investigate how to tailor treatments and diet recommendations to specific cancers or diseases caused by environmental pollutants based on their distinct epigenetic profiles. Currently, some research is being done to determine the distinct locations on DNA where methylation “red light” signals are being added or subtracted in cases of cancer and environmental toxicity. Scientists are attempting to map exactly where this methylation is occurring in the most prevalent cancers, like kidney and breast cancers12, and in common environmental toxins like BPA and formaldehyde11 to better treat patients. However, more studies should be done to capture the toxins and cancers that have been left out thus far. Overall, studies do support the claims that these changes in diet can limit cancer through epigenetic mechanisms, and counteract the harmful effects of environmental toxins.

References

  1. Li, S., Li, R., & Tollefsbol, T. (2019, May 20). The epigenetics diet: A barrier against environmental pollution [web log]. Retrieved from https://blogs.biomedcentral.com/on-biology/2019/05/20/the-epigenetics-diet-a-barrier-against-environmental-pollution/.
  2. Poirier L. A. (1994). Methyl group deficiency in hepatocarcinogenesis. Drug metabolism reviews, 26(1-2), 185–199. https://doi.org/10.3109/03602539409029790
  3. Blair, L. P., & Yan, Q. (2012). Epigenetic mechanisms in commonly occurring cancers. DNA and cell biology, 31 Suppl 1(Suppl 1), S49–S61. https://doi.org/10.1089/dna.2012.1654
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  6. Janssen, B., Godderis, L., Pieters, N., Poels, K., Kicinski, M., Cuypers, A., Fierens, F., Penders, J., Vangronsveld, J., Gyselaers, W., & Nawrot, T. S. (2013). Placental DNA hypomethylation in association with Particulate Air Pollution in early life. ISEE Conference Abstracts, 2013(1), 4728. https://doi.org/10.1289/isee.2013.o-4-20-05
  7. Huber-Lang, M., Lambris, J. D., & Ward, P. A. (2018). Innate immune responses to trauma. Nature immunology, 19(4), 327–341. https://doi.org/10.1038/s41590-018-0064-8
  8. Zhong, J., Karlsson, O., Wu, T., & Baccarelli, A. A. (2017). B vitamins attenuate the epigenetic effects of ambient fine particles in a pilot human intervention trial. Proceedings of the National Academy of Sciences, 114(13), 3503–3508. https://doi.org/10.1073/pnas.1618545114
  9. Bobroff, L. B. (2018). Facts About Folate: FCS8632/FY186, rev 2/2018. EDIS, 2018(1).
  10. Pilsner, J. R., Liu, X., Ahsan, H., Ilievski, V., Slavkovich, V., Levy, D., Factor-Litvak, P., Graziano, J. H., & Gamble, M. V. (2007). Genomic methylation of peripheral blood leukocyte DNA: Influences of arsenic and folate in Bangladeshi adults. The American Journal of Clinical Nutrition, 86(4), 1179–1186. https://doi.org/10.1093/ajcn/86.4.1179
  11. Marczylo, E. L., Jacobs, M. N., & Gant, T. W. (2016). Environmentally induced epigenetic toxicity: potential public health concerns. Critical reviews in toxicology, 46(8), 676–700. https://doi.org/10.1080/10408444.2016.1175417
  12. Baylin, S. B., & Jones, P. A. (2016). Epigenetic Determinants of Cancer. Cold Spring Harbor perspectives in biology, 8(9), a019505. https://doi.org/10.1101/cshperspect.a019505