An Introduction to Epigenetics
For centuries, both mainstream and alternative healthcare providers have asked, “Nature or nurture?” Which is the dominant factor in human development—is it biology or is it environment? Which has the greater impact, our genes or our experiences? Now, according to the Center on the Developing Child at Harvard University, “Nature vs. nurture is no longer a debate. It’s nearly always both! Epigenetics explains how early experiences can have lifelong impacts.”
What is epigenetics in simple terms?
You probably already know that your body is made up of billions of cells. Each cell has a specific purpose. The successful execution of cellular tasks is essential to physical, mental, and emotional wellness. To begin to understand epigenetics, first we have to take a trip back to high school and re-learn some of the details of cellular biology.
The instructions that your cells need to function properly is contained in a chemical known as deoxyribonucleic acid, or DNA. Human DNA is created of four types of bases—adenine, cytosine, guanine, and thymine. (You may remember their abbreviations, A, C, G, and T.) These four bases combine 20,000 different ways to create genes, strands of DNA that provide your cells with the specific instructions they seek. Usually these instructions involve the creation of a functional protein.
The flow of information from DNA to functional protein is referred to as the central dogma of genetics. It was first proposed to the scientific community by Francis Crick, one of the scientists who discovered DNA, more than 60 years ago. The central dogma of genetics says that the cells work by “reading” the DNA code.
In a healthy cell, the DNA communicates with another chemical called RNA, which then acts as a messenger. It carries these instructions to ribosomes, small components within the cell, and the ribosomes use the message to create the appropriate protein. For example, skin cells will take the DNA instructions and use them to create collagen, keeping skin supple and vital. This is gene expression.
Have you been wondering, “What is epigenetics?” We can define epigenetics as the influence of behavior and environment influence on the genes. Epigenetics turns the genes on or off, tells them to become expressive or dormant, and manages the flow of information throughout the cells and the body. Epigenetics does not alter your DNA; rather, it alters how your body reads the DNA sequence. The word epigenetics is also used to refer to the scientific study of these processes.
What causes epigenetics?
Epigenetics originates in nature, but is affected by external stimuli. Common epigenetic triggers include:
- Physical activity
- Tobacco use
- Environmental pollutants
- Alcohol consumption
- Sleep patterns
Childhood trauma is a common and long-lasting stress factor affecting epigenetics. For decades, experts have been looking at the correlation between these experiences, referred to as Adverse Childhood Experiences (ACEs), and adult health, including epigenetics. The CDC reports that “about 61% of adults surveyed across 25 states reported that they had experienced at least one type of ACE, and nearly 1 in 6 reported they had experienced four or more types of ACEs.” Life-long epigenetic issues can often be traced to ACEs such as:
- Physical, sexual, or verbal abuse
- Physical or emotional neglect
- A family member who is struggling with mental health issues or addiction, or one who is incarcerated
- Violence in the home
- Death of a parent
- Acrimonious divorce
What are examples of epigenetics?
DNA methylation is a common type of epigenetics. When a small collection of chemicals called a methyl group “caps” a gene, that gene is silenced and cannot send its instructions to the cell via RNA. It’s been switched off.
DNA assumes a double helix shape in the cell, wrapping around histones. When epigenetics lead to histone modification by adding or removing chemical groups, this modification alters how tightly the DNA is wrapped, which can turn a gene on or off and change its pattern of expression.
Epigenetics can cause the presence of non-coding RNA, which attaches to coding RNA and interferes with its ability to transmit protein-generating instructions. Essentially, it interferes with the messenger, affecting gene expression. Non-coding RNA is also believed to recruit destructive, histone-modifying proteins to its efforts.
How many generations does epigenetics last?
Epigenetic inheritance is at the forefront of current research. Scientists have observed epigenetic memories traveling through fourteen generations of C. elegans nematodes (roundworms). Of course, we have not been studying epigenetics long enough to have made a similar observation in people. The results of a recent human study, however, are startling.
During a 1944–45 World War II period known as the “Dutch Winter,” more than 20,000 Dutch people were killed when the Nazis blockaded Holland. Columbia University scientist Dr. L. H. Lumey and colleagues looked at a group of Dutch adults whose pregnant mothers had been exposed to starvation when the food supply was cut off. The scientists discovered that this “Dutch Winter cohort” was a few pounds heavier on average than their peers at adulthood. By middle age, they were more likely to be obese, diabetic, and schizophrenic than others. Longevity was affected. The data showed that, at every point after age 68, a member of the Dutch Winter cohort was more likely to have died than his or her peers. Dr. Lumey’s team published a study suggesting that epigenetics were to blame. They theorized that the starvation experienced by their mothers while they were pregnant created a methyl group that capped the PIM3 gene, which is involved in metabolism. Once turned off, the gene never turned back on. These epigenetic changes may be passed down to future generations.
How can epigenetics influence our health?
For years, the prevailing theory linking genes and cancer was that some forms of cancer were caused by genetic mutations. These days, another idea is taking hold. Dr. Jean-Pierre Issa of the MD Anderson Cancer Center says, “We now think that most cancers are a mixture of genetic and epigenetic changes. There is actually a lot more epigenetic change than genetic change in the majority of cancers.”
The good news is that many epigenetic modifications are partly or fully reversible.