In the first part of our special series on how nutrition affects genetics and the genome, we take a look at the rapidly emerging area of epigenetics.
Defined as the study of changes in gene activity that doesn’t involve a change to DNA, epigenetics is getting a lot of attention from some very influential sources. Indeed, the 7th annual Nestlé International Nutrition Symposium , which ran from October 27-29, 2010 in Lausanne, Switzerland, was all about epigenetics.
And Nestlé provides two out of three authors of a paper in Nutrition Reviews which asks the question, where are we with genetic and epigenetic markers for disposition and susceptibility?
Increasingly, biologists are finding that non-genetic variation acquired during the life of an organism can sometimes be passed on to offspring—a phenomenon known as epigenetic inheritance. An article July 2009 issue of The Quarterly Review of Biology lists over 100 well-documented cases of epigenetic inheritance between generations of organisms, and suggests that non-DNA inheritance happens much more often than scientists previously thought.
Biologists have suspected for years that some kind of epigenetic inheritance occurs at the cellular level. The different kinds of cells in our bodies provide an example. Skin cells and brain cells have different forms and functions, despite having exactly the same DNA. There must be mechanisms—other than DNA—that make sure skin cells stay skin cells when they divide.
Led by Dr Martin Kussman, head of proteomics and metabonomics core at the Nestlé Institute of Health Science, the review states that “modern nutrition focuses on disease prevention and health maintenance, and epigenetics may provide the means to understand and achieve these goals.
“Ultimately, comprehensive knowledge of the human epigenome is required, because the epigenome is not only tissue and stage-of-life dependent, it also varies markedly between individuals and species.”
The majority of epigenetic changes occur at specific times in an individual’s life, explain the authors, from their time in the womb, to the development as newborns, then in puberty, and again in old age.
Epigenetics does not result in changes to the DNA sequence, but it does encompass molecular modification to DNA like DNA methylation, explained Dr Kussman and his co-authors, Lutz Krause from the Functional Genomics Group at the Nestlé Research Center (Lausanne) and Winfried Siffert from the Institute of Pharmacogenetics at University Hospital Essen.
As such nutrition has epigenetic implications regarding cancer risk.
According to Cornelia Ulrich from the German Cancer Research Center and National Center for Tumor Diseases and William Grady from the University of Washington in Seattle (Cancer Prev. Res. 2010, Vol. 3, pp. 1505-8): “Modifying the epigenome to prevent cancer is particularly intriguing because epigenetic alterations are potentially reversible, unlike gene mutations, and because certain dietary factors, such as the B-vitamin folate, may affect genes' DNA methylation status.”
At the other end of the age-scale, studies are ongoing to analyse the role of epigenetics in newborns. For example, the Newborn Epigenetics STudy (NEST) , a prospective study of women and their children is investigating how differences in the global epigenetic profile are related to a range of factors, including maternal diet and use of vitamin and mineral supplements. Data from this study have recently been published in BMC Public Health (2011, 11:46).
One piece of the jigsaw
Despite the potential of epigenetics, Kussman, Krause and Siffert see it as part of a bigger genomic picture, which should include genetics (our ‘blueprint’), transcriptomics (what actually happens), proteomics (making it happen), and metabolomics (what did happen).
All of these things are “required to understand human variability and to develop biomarkers for response and efficacy, individual disposition, and programming of an organism, respectively”, they wrote.
“This concept applies, in our view, to nutrition just as much as it does to pharmaceutical research.”
“One of the reasons the understanding of environmental modeling of a genome is only beginning may be that the aforementioned integration of genomics (expression), genetics (predisposition), and epigenetics (programming or imprinting) is just emerging and that the tools for genome-wide analyses are still maturing.
“In the fields of infant nutrition, diabetes, obesity, and the metabolic syndrome, the term “metabolic programming” has been coined to give a name to the observation that environmental experiences early in life may be “genomically” remembered and give rise to health outcomes manifesting later in life. Epigenetics emerges as an important mechanism underlying this phenomenon,” concluded Kussman, Krause and Siffert.
Source: Nutrition Reviews