In her new book, YOU ARE WHAT YOUR GRANDPARENTS ATE: What You Need to Know about Nutrition, Experience, Epigenetics & the Origins of Chronic Disease, Judith Finlayson takes us on a journey from Oregon to Helsinki and from Southampton to Amsterdam, where much of the original research into the developmental origins of chronic disease is focused. She brings us to the cutting edge of science, showing how the study of epigenetics has heightened our understanding of the mechanisms underlying diseases such as obesity, diabetes, hypertension and heart disease.
“Broadly speaking, epigenetics is the connection between our genes and the environment,” Finlayson writes. “In simple terms, a wide variety of experiences have an impact on what is known as gene expression. Over the past few decades, scientists have learned more and more about how our genes react to external stimuli, such as the nutrition our bodies received when we were no more than an embryo in our mother’s womb. While our DNA doesn’t change, stresses, including poor nutrition, can spark reactions that change how our genes express themselves, increasing the risk for a wide variety of chronic diseases, from heart disease and diabetes to some types of cancer. These changes, some of which take place in utero, have the potential to be passed on to future generations.”
In this excerpt, Finlayson focuses on Nutritional Epigenetics:
Nutritional Epigenetics: An Emerging Science
Do you need a cup of coffee to get your day off to the right start? Or does a jolt of caffeine keep you awake all night? You may not realize it, but your response to your morning joe depends on your genome. People break down coffee at very different rates, and there is more than disrupted sleep at stake. Numerous genes participate in how your body metabolizes coffee, which helps explain why studies on the possible benefits of drinking coffee produce conflicting results. It’s not a one-size-fits-all solution because too many genetic variables are involved.
Interestingly, at least one of the genes involved in metabolizing coffee also metabolizes numerous medications. Genetic differences help to explain why many people have negative reactions to prescribed drugs. Pharmacogenomic tests are becoming common, likely because adverse drug reactions are one of the major causes of accidental death in Western societies. Gene testing can help predict whether a medication is likely to be effective or potentially dangerous.
The same holds true for other ingestibles. Salt and alcohol consumption have very different effects on people, as does green tea. One study showed that women whose genotype produced high activity of the angiotensin-converting enzyme (ACE) had a lower risk of breast cancer if they drank green tea regularly. In contrast, drinking green tea did not reduce breast cancer risk in women with low ACE activity. In other words, the beverage’s capacity to protect against cancer benefits only women with a specific genotype. Knowledge like this allows us to target nutritional recommendations to the people they are most likely to benefit. Your genetic variations can also determine your nutrient requirements, which clarifies why distinct dietary approaches don’t work for everyone.
Genes Influencing Nutrients
Have you ever wondered why some people consume calories without gaining an ounce, while others seem to expand just by looking at a french fry? Although the connection between a person’s genetic makeup and their susceptibility to gaining excess weight is complex, the differences may reflect their genes, which determine their response to various nutrients and/or foods. Scientists have found, for instance, that variations in the APOA2 gene influence whether you gain weight or experience an increase in your BMI after consuming saturated fats.
Today an entirely new field of science is emerging. Nutrigenomics (often called nutrigenetics) is based on the notion that genetic variants can explain why individuals experience different outcomes in response to specific nutrients. The study of gene–nutrient interaction examines how your unique genetic variations, or single-nucleotide polymorphisms (SNPs), affect how your body absorbs, stores and uses nutrients.
Nutrients Influencing Genes
Nutri-epigenomics is the study of how nutrients and food affect gene expression. It is still a murky area in terms of research, in part because we don’t yet know how maternal nutrients cross over the placenta in pregnancy. However, many researchers are working to identify the various pathways.
To understand nutrient–gene interaction, it is important to know that the basic business of your body is conducted by proteins. Proteins transport oxygen through your blood and help to transform foods into the nutrients that keep you functioning. Proteins are created by processes regulated by your genes. These processes can be altered by environmental impacts, thus changing your gene expression.
Transcription is the first step of gene expression. Some nutrients, such as vitamin A, vitamin D and zinc, directly influence this stage of protein production. The timing of exposure to certain foods and nutrients (or the lack of nutrients) at critical points in development can profoundly affect the function of organ systems. One well-known example is the link between inadequate folate intake in pregnancy and neural tube defects in offspring.
Metabolic processes, including methylation, histone modification and RNA expression, can strongly influence the degree to which a gene is turned on or off, and these processes can be affected by nutrients. As principal author Kent Thornburg wrote in a 2010 paper, “It is becoming clear that many dietary compounds and regiments acting as methyl donors or as inhibitors of enzymatic activity can be used to regulate epigenetic modifications.” We know, for instance, that in humans sulforaphane, a sulfur-rich compound found in cruciferous vegetables such as broccoli and Brussels sprouts, influences histone acetylation in colon cancer cells by enhancing genes that inhibit tumor growth. It’s common knowledge that eating an abundance of cruciferous vegetables may help to reduce your risk of cancer, but now epigenetics helps to explain why.
Although we can see associations, for the most part there is no direct connection between cause and effect. We do know, however, that providing nutrients to cells impacts how genes are expressed.
Can Diet Change Your DNA?
Accepting that our metabolism is in constant communication with the outside world, often via the food we eat, the question is, are you really what you eat? Can diet change your DNA? In simple terms, the answer appears to be no. However, we have known for some time that gene expression influences metabolism.
Cells process nutrients for two basic reasons: to generate the energy that keeps you going and to support their ongoing processes related to growing, dividing and maintenance. Having an abundant supply of nutrients helps to sustain these chemical reactions. A study published in Nature Microbiology in 2016 indicates that nutrition may also play an important role in how some DNA sequences are expressed. The study showed that how genes behave is strongly influenced by the food we consume. Even so, we are still a long way away from the kind of personalized medicine that will furnish definitive nutritional therapies to treat a wide spectrum of conditions.
Courtesy of YOU ARE WHAT YOUR GRANDPARENTS ATE by Judith Finlayson © 2019 www.robertrose.ca Reprinted with permission. Available where books are sold.