Because there is so much misinformation on the internet, I occasionally engage in Yahoo! answers. This one, by yours truly, was chosen as the best description of epigenetics. While I probably just did someone’s term paper for them, it may be useful to you as well, especially in keeping with my prior blogs on the topic.
The literal definition of the epigenetics is “around or on top of the genome”. It refers to the structural and functional complex of proteins and non-coding mRNA that activates and deactivates areas of the genome (DNA), suppressing or permitting transcription of specific genes. The science of epigenetics is the study of what results from that interaction – both heritable and mutable.
A simple analogy I use in lay public lectures is: your genome as the big library building, with all the books and blueprints you need for life and more – epigenetics is the books you check out and read.
The statement you refer to, concerning what your ancestors ate, means that while epigenetics is not really “genetic”, e.g. it is not the creation of new genes, or the changing of old ones. It is heritable and does carry on, from generation to generation, in the form of epigenetic markers, or more simply, “marks”. Your ancestors’ dietary habits determine a fair degree of the epigenetic marks they passed on to you. This means, you get patterns of histone proteins (and their activation and inactivation) from your parents and other ancestors that are less likely to change from generation to generation. It is a misconception, however, to think that they cannot change at all. As a matter of fact, they can be changed in weeks to months, in many cases. And from the moment you are born, you begin to forge your own epigenetic patterns. No one is 100% sure, if there are unchangeable epigenetic patterns that are inherited, but it is not likely, for most of what matters to us. Things like body composition, specifically obesity, muscularity, tendencies towards diabetes, heart disease, Alzheimer’s, etc are known to be changeable and not set in stone. The end result is, for most of what matters, you have at least 80% control, by lifestyle choices and environmental exposures, rather than being 100% limited by your genetics.
The processes that are involved in epigenetic expression and change are primarily the attachment of simple molecules like methyl groups, acetyl groups and a series of lesser known molecular changes, to the histone proteins that interpolate the DNA. Things like diet, exercise, sleep, meditation and much to the chagrin of traditional medical doctors, supplementation have major effects on epigenetic expression by providing these simple molecules, or effecting the enzymes involved in their placement. Said molecules, then attach to the protein structures that interpolate and give structure to the DNA (known as histones) and change the conformation of the histone-DNA complex, by folding or unfolding it, thus making it more or less likely that the genes, in this area, will be transcribed and the proteins products that result will be made and go out and “do what they do”, good or bad.
Some research examples are Milner, J.A. (2004) Molecular targets for bioactive food components. J. Nutrition 134, 2492S-2498S.
Egger, G Liang,G Epigenetics in Human disease and the prospects for epigenetic therapy. Nature 429,457-463.
Robertson ,K.D. Wolfe.A.P. (2000) DNA methylation in health and disease. Nat. Rev. Genetics. 1, 11-19
It is important to know that epigenetics, much like telomere science, is not new. It has been around for decades. It just so happens that now it’s hit the news media because there is enough intriguing info to catch the public eye. Stay tuned for more!