by Within the last century, researchers’ understanding of genetics has undergone a profound transformation.
Genes, regions of DNA that are primarily responsible for our physical characteristics, were considered to be unchanged under the original genetic model established by biologist Gregor Mendel in 1865. That is, a person’s environment was considered to have little influence on genes.
The emergence of the field of epigenetics in 1942 undermined this concept.
Epigenetics refers to changes in gene expression that occur without changes in the DNA sequence. Some epigenetic changes, such as those associated with aging, are a feature of cell function.
However, environmental factors also affect the functions of genes, which means that people’s behaviors are influenced by their genetics. For example, identical twins develop from a single fertilized egg, and as a result, share the same genetic makeup. However, as the twins age, their appearance may differ due to specific environmental exposures. One twin may eat a balanced healthy diet, but the other may eat an unhealthy diet, causing differences in the expression of their genes that play a role in obesity, helping the former twin to have a lower body fat percentage .
Some of these factors, such as air quality, are beyond people’s control. However, other factors are more within a person’s control: physical activity, smoking, stress, drug use and exposure to pollution, such as that from plastics, pesticides and burning fossil fuels, including car exhaust.
Nutrition is another factor, giving rise to the subfield of nutritional epigenetics. This discipline is about the notions “you are what you eat” – and “you are what your grandmother ate.” In short, nutritional epigenetics is the study of how your diet, and the diet of your parents and grandparents, affects your genes. Because the dietary choices a person makes today affect the genetics of their children in the future, epigenetics may provide motivation to make better dietary choices.
There are two of us working in the field of epigenetics. The other studies look at how diet and lifestyle choices can help keep people healthy. Our research team is made up of fathers, so our work in this area only adds to our already intimate knowledge of the transformative power of parenthood.
A story of famine
The roots of dietary epigenetics research can be traced back to a fruitful chapter in history – the Dutch Hunger Winter in the closing stages of World War II.
During the Nazi occupation of the Netherlands, the population had to live on rations of 400 to 800 kilograms per day, a far cry from the usual 2,000-kilocalorie diet used as a standard by the Food and Drug Administration. As a result, around 20,000 people died and 4.5 million were malnourished.
Studies have found that the famine caused epigenetic changes in a gene called IGF2 which is involved in growth and development. These changes inhibited muscle growth in the children and grandchildren of the pregnant women who suffered the famine. For subsequent generations, that suppression increased the risk of obesity, heart disease, diabetes and low birth weight.
These results were a pivotal moment in epigenetics research – and they clearly showed that environmental factors, such as famine, can lead to epigenetic changes in offspring, which can have serious implications for their health.
The role of the mother’s diet
Until this pioneering work, most researchers believed that epigenetic changes could not be passed from generation to generation. Rather, the researchers thought that epigenetic changes could occur with early life exposure, such as during gestation – a very vulnerable period of development. Early nutritional epigenetic research therefore focused on dietary intake during pregnancy.
The results of the Dutch Hunger Winter were later supported by animal studies, which allow researchers to control how animals are bred, which can help control for background variables. Another advantage for researchers is that the rats and sheep used in these studies reproduce faster than humans, allowing for faster results. In addition, researchers can completely control the diets of animals throughout their entire lifespan, allowing specific aspects of the diet to be manipulated and examined. Together, these factors allow researchers to better investigate epigenetic changes in animals than in humans.
In one study, researchers exposed pregnant female rats to a commonly used fungicide called vinclozolin. In response to this exposure, the first generation born showed a reduced ability to produce sperm, leading to an increase in male infertility. Crucially, these effects, like those of the famine, were passed on to subsequent generations.
As significant as these works are for shaping nutritional epigenetics, they neglected other periods of development and completely ignored the role of fathers in the epigenetic inheritance of their offspring. However, a later study in sheep showed that a paternal diet supplemented with the amino acid methionine given from birth to weaning affected the growth and reproductive characteristics of the next three generations. Methionine is an essential amino acid involved in DNA methylation, an example of epigenetic modification.
Healthy choices for future generations
These studies highlight the lasting impact that parents’ diets have on their children and grandchildren. They also serve as a powerful motivator for parents-to-be and current parents to make healthier dietary choices, as the nutritional choices parents make influence their children’s diets.
Meeting with a nutrition professional, such as a registered dietitian, can provide evidence-based recommendations for making practical dietary changes for individuals and families.
There are still many unknowns about how diet affects and affects our genes. The research showing nutritional epigenetics is a powerful and compelling reason to make lifestyle changes.
Researchers already know a lot about the Western diet, which is what many Americans eat. The Western diet is high in saturated fat, sodium and added sugar, but low in fibre; not surprisingly, Western diets are associated with negative health outcomes, such as obesity, type 2 diabetes, cardiovascular disease and some cancers.
A good place to start is to eat more unprocessed whole foods, especially fruit, vegetables and whole grains, and less processed or convenience foods – including fast food, chips, cookies and candy, ready meals, frozen pizza , canned soups and sweetened beverages.
These dietary changes are well known for their health benefits and are described in the 2020-2025 Dietary Guidelines for Americans and by the American Heart Association.
Many people find it difficult to accept a change in their lifestyle, especially when it involves food. Motivation is a key factor in making these changes. Fortunately, this is where family and friends can help – they play a big role in lifestyle decisions.
However, at a wider societal level, food security – meaning people’s ability to access and afford healthy food – should be a critical priority for governments, food producers and distributors, and non-profit groups . Food insecurity is associated with epigenetic changes that are linked to negative health outcomes such as diabetes, obesity and depression.
Through relatively simple lifestyle modifications, people can have a significant and measurable impact on the genes of their children and grandchildren. So when you reach for a bag of chips – and opt for a fruit or veggie instead – remember: It’s not just for you, it’s for generations to come.
This article is republished from The Conversation, a non-profit, independent news organization that brings you facts and analysis to help you make sense of our complex world.
It was written by Nathaniel Johnson University of North Dakota; Hasan Khatib, University of Wisconsin-Madisonand Thomas D. Crenshaw, University of Wisconsin-Madison.
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Nathaniel Johnson receives funding from the United States Department of Agriculture and the National Institutes of Health. He has previously received funding through the National Science Foundation, the National Cattle Beef Association, and the North Dakota Beef Check.
Hasan Khatib receives funding no. 2023-67015-39527 from the USDA National Institute of Food and Agriculture
Thomas D Crenshaw receives funding from the Hatch Multistate Research Formula Funds; USDA/Natl. the Institute of Food and Agriculture; DHHS, PHS, National Institutes of Health.
