Nutritionists have long known that ‘you are what you eat’ is not just an expression. Recent studies suggest that what you eat affects you and sometimes even your children and grandchildren.

This winter Nestlé convened esteemed experts in human and animal health to talk about the future of nutrition science. One theme to emerge was the epigenetic impact of diet and lifestyle on individual health. Epigenetics is the study of how different biological and environmental signals affect gene expression. Rather than change DNA itself, epigenetic signals can, for example, prompt changes in the number of methyl chemical groups attached to a gene, turning it on or off. A person’s diet is an important source of epigenetic signals, and scientists are now investigating how eating habits modify gene expression in adults and their offspring. Understanding that relationship could help researchers identify nutritional elements that might help prevent or treat diseases such as obesity, diabetes, coronary artery disease, cancer and Alzheimer’s.

At the Nestlé Research Center in Lausanne, Switzerland, more than 550 scientists, research assistants and technicians drive science and technology for all of Nestlé’s businesses worldwide. This includes exploring the relationship between diet and human health. Epigenetics is becoming progressively more important to this work, says Irma Silva-Zolezzi, the Maternal Nutrition Platform Leader at the Nestlé Research Center. “It’s critical to understand the role of nutrition in transgenerational health, particularly between mother and child,” she says. Epigenetics impacts cell differentiation and shapes how cells function in the long term, making it vital to understanding how nutrition during pregnancy may impact multiple generations.

Epidemiological studies show how certain exposures have shaped the health of specific populations over time, particularly between mother and child. One famous example is the Dutch Hunger Winter. In 1944, a famine struck the western Netherlands, forcing inhabitants—including pregnant mothers—to live on between 400 and 800 calories a day. When scientists later studied the babies conceived, carried, or delivered during this period, they found elevated rates of obesity, altered lipid profiles and cardiovascular disease in adulthood.

To better understand how epigenetics could guide the development of nutritional solutions for pregnant and lactating women, Nestlé established a partnership in 2011 with the EpiGen Global Research Consortium. The group comprises the University of Southampton, Singapore Institute for Clinical Sciences, National University of Singapore and Auckland UniServices Limited. The jointly-funded partnership focuses on how the diet and lifestyle of pregnant women, as well as other factors like early life microbiota, can influence their baby’s genes and development. In 2015, EpiGen and the Nestlé Research Center published a study in the journal mBio in which researchers found that the dynamics of infant gut microbiota can influence a subject’s body fat later in life.

Recently, EpiGen began an international clinical trial, NiPPeR, also known as the ‘Nutritional Intervention Preconception and During Pregnancy to Maintain Healthy Glucose Metabolism and Offspring Health’. The study is assessing whether a nutritional drink taken before conception and throughout pregnancy could help support healthy glucose metabolism in mothers. As Silva-Zolezzi explains, maternal blood glucose levels may already be high long before gestational diabetes is diagnosed at around 28 weeks of pregnancy. This could affect both mother and fetus, putting them at higher risk of metabolic conditions, such as type 2 diabetes, later in life. Adjusting nutrition early in pregnancy—or even before conceiving—could potentially help stop or slow down that process.

Nestlé and EpiGen are not the only groups investigating the epigenetic impact of diet. In a study conducted at the German Research Center for Environmental Health and published in Nature Genetics in 2016, genetically identical mice that consumed a high-fat diet were more likely to produce obese offspring with impaired glucose tolerance, an early sign of type 2 diabetes.

Nor are epigenetic impacts limited to obesity and diabetes. A 2014 study in Science conducted by the University of Cambridge revealed that undernourished pregnant mice bore offspring with glucose intolerance and pancreatic issues. Moshe Szyf, a geneticist at McGill University Medical School in Montreal, is investigating the epigenetic basis of multiple diseases, including depression and Alzheimer’s. He recently contributed to a paper in Biological Psychiatry in February 2017 on the connection between maternal infection in pregnant mice and the risk of neurodevelopmental disorders in their offspring.

Even so, Szyf says that drawing clear relationships between epigenetic signals and disease is difficult. “In animal studies we’ve seen that changes in diet may impact risk [for disease],” he says. “But it’s not yet clear in humans.”

One complication is the sheer complexity of the epigenome. Along with diet, exercise, environment, and mood may effect gene expression. In a 2014 study published in Epigenetics, scientists at the Karolinska Institute in Sweden asked 23 men and women to bicycle using only one leg for 45 minutes, four times a week over three months. In comparing muscle biopsies before and after the experiment, scientists found that, in the exercised muscle, new patterns had developed on genes associated with insulin response, inflammation and energy metabolism.

Even emotional traumas can be transmitted to subsequent generations through epigenetic inheritance. A 2016 study conducted by New York’s Mount Sinai hospital and published in Biological Psychiatry suggests that the genes of the children of Holocaust survivors showed evidence of an increased likelihood of stress disorders, for example.

“Nutrition, exercise and other environmental factors are just part of the puzzle that affects an individual’s risk to develop particular conditions or disease,” Silva-Zolezzi says. But the more we look, she says, “the more answers we’ll find, and the better we can work to improve health.”