The Article

Epigenetics: How to Turn off Bad Genes and Stay Healthy


Your genes are not your destiny.

My patients say, “Hey, doc, my husband and I both have diabetes. Will our child have diabetes?”

My answer: “Not necessarily. Let’s not let that happen.”

Some traits, such as those for eye color, are entirely determined by the genes inherited from your parents. However, the expression of most genes, such as those associated with chronic diseases, including diabetes and cancer, is much more complicated.

You can be born with certain genes that are linked to chronic disease, but other factors—nutrition and exercise foremost—affect whether or not you get that disease. You are born with your gene sequence. That doesn’t change. But the expression of your genes changes based on lifestyle. Various factors up- and down-regulate genes—turn them on and off. These external factors are controllable: Epigenetics is the study of how biological mechanisms switch genes on and off.

In the last 50 years, rates of diseases such as diabetes have increased at a pace that cannot be matched by changes in genetic sequencing. We were not born with these diseases any more than our ancestors were.

Lifestyle factors—starting with nutrition—are responsible for elevated rates of disease.

The Basic Science

Epigenetic mechanisms allow us to respond to our environment through changes in gene expression.

Multiple scientific pathways for epigenetic change have been identified, including DNA methylation and histone modification.

DNA methylation is the addition or removal of a methyl group (one carbon and three hydrogen atoms—CH3) to or from the gene base. Chemical reactions can add or subtract a methyl group to or from the gene, turning the gene on or off.

Histone modification is another common way of changing gene expression. Histones are basic proteins that spool around DNA; their modification can affect the way the DNA wraps around them and thereby influence which genes are expressed.

Epigenetics is a young science. The human genome was first mapped in 2003, and studies are just beginning. So far, research has analyzed environmental factors, the exact chemical changes that occur to regulate genes, and specific diseases affected by gene regulation. Environmental factors include toxins, nutrition, sleep and exercise. Specific diseases include cancer, diabetes, autoimmune disorders and neuro-psychiatric disorders including Alzheimer’s.

Cancer was studied first and most extensively. Researchers have looked at the genes that are affected and how environmental factors interact with genes for many different cancers, including lung, colorectal, brain and blood cancer. Studies have supported that low-sugar diets can suppress breast-cancer cells via epigenetic mechanisms (teleromerase mRNA mechanism), and others have looked at nuts, berries, turmeric, soybeans, and broccoli and epigenetic changes related to cancer. Research has also linked selenium (chicken, game meat and beef) and folate (green vegetables) to specific epigenetic changes.

More epigenetic research is now being conducted on diabetes, and we know DNA methylation and histone modification can play a role in the development of the disease. Studies have shown that elevation of blood glucose can cause long-term epigenetic changes (gene p65) that promote diabetes.

Studies have also shown that hyperglycemia induces modifications of genes involved in the complications of diabetes, such as vascular inflammation. Many studies show that sugar causes inflammation. These epigenetic studies link what we know clinically and biochemically to the genes. It’s not the genes that cause the diabetes but the environmental factors that turn on and off certain genes linked to diabetes.

ALT TEXTStudies on twins reveal that identical genes express themselves differently when influenced by diet and exercise. (

Identical-twin studies have been done with both humans and mice. These studies are easy to understand: Identical twins start with exactly the same genes, so differences in their health can only be explained by factors other than gene sequence. Identical-twin studies have shown that younger twins and those with similar lifestyles have similar methylation patterns, while older twins and those with different lifestyles have dramatically different patterns.

Epigenetic studies have been done with agouti mice, in which genetically identical twin mice look different based on up- or down-regulation of their genes. Their genes are identical, but their expression is different. For example, one twin mouse can be small and brown while the other twin is obese, yellow and more likely to suffer from diabetes and cancer. Diet has been shown to affect the methylation of these agouti mice.

Preliminary data suggests reversibility of gene regulation is also possible: So positive lifestyle changes made today can counter effects of previous decisions.

Your Power

Epigenetic research confirms that what you do matters. Your health is not predetermined. You are not a passenger on a ride. Your decisions shape how your genes express themselves.

You cannot say, “I have diabetes because my parents do.”

We doctors cannot accept that diabetes is a genetic condition. It is a lifestyle affliction, and we all know it.

The same goes for many other chronic conditions.

So turn off the bad genes. How? You’ve heard it before from CrossFit Inc. Founder Greg Glassman: “Get off the carbs, get off the couch.” We need to limit the sugar we eat—no sugar is best—because we know sugar is a toxin that creates genetic changes that switch on diabetes and cancer genes.

Exercise studies have previously demonstrated beneficial clinical and cellular responses. Now studies have linked exercise to direct epigenetic changes. This science provides more explanation of what we already know: Exercise will keep you healthy.

While lifestyle epigenetics might be a next-level scientific discipline, the lifestyle solution is not rocket science.

Additional Reading

  1. What is epigenetics? Available here.
  2. Kirkpatrick B. The epigenetics lurking in your Halloween candy. Oct. 29, 2014. Available here.
  3. Landecker H. Food as exposure: Nutritional epigenetics and the new metabolism. Biosocieties 6(2): 167-194, June 2011. Available here.
  4. Weinhold B. Epigenetics: The science of change. Environmental Health Perspectives 114(3): A160-A167, March 2006. Available here.
  5. Adams JU. Obesity, epigenetics and gene regulation. Nature Education 1(1): 128, 2008. Available here.
  6. Hardy TM and Tellefsbol TO. Epigenetic diet: Impact on epigenome and cancer. Epigenomics 3(4): 503-518, August 2011. Available here.
  7. Cloud J. Why your DNA isn’t your destiny. Jan. 6, 2010. Available here.

All links accessed Nov. 28, 2017.

About the Author: Founder of Coast Pediatrics Del Mar and Coast Pediatrics Carmel Valley, Shakha Gillin, MD, FAAP, has been a pediatrician since 2001. She attended the University of California-San Diego for her undergraduate education and for medical school. She did her residency at the University of California-Irvine and was the chief resident at Miller Children’s Hospital in Long Beach. She has worked in private practice in Southern California and at the Rady Children’s Hospital Emergency Department. Dr. Gillin has a special interest in preventative care and creating healthy, active lifestyles for children in particular. She is a contributing author for the AAP. San Diego Magazine recognized her as a “top doctor” from 2006 to 2017. Follow her on Instagram: @drshakha.

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