How far back does "health" go?
When does health begin? And how far back do you have to go to be truly healthy? That's the gist of an article I just read in the Nov. 8 issue of Newsweek, entitled "Sins of the Grandfathers," by Sharon Begley.
The article focuses on the work of Michael Skinner, a molecular biologist at Washington State University, who recently published a paper "confirming epigenetic changes in sperm which are carried forward transgenerationally" and can become "permanently programmed."
In laymen's terms, as Begley masterfully explains, this means that whatever your grandparents did - or, as evidenced by Skinner's research, up to four generations back, so your great-great-great grandfather or mother - could have caused changes in their DNA, which were then passed down to you.
Skinner's research focuses on genetic "on-off switches" or clusters called methyl groups, which can switch on or silence genes, for example, turning off insulin in the brain but making it active in the cells of the pancreas. As Begley explains, researchers believed that these "on-off" switches were reset with every generation, so that a father's exposure to a toxic chemical or to a high-fat diet would be "reset" when his DNA was passed along to his son.
Skinner's research apparently shows otherwise. In a research summary on his website, he explains that "(i)f gestating mothers are exposed to endocrine disruptors at the time of fetal gonadal sex determination, a sub-fertility phenotype is observed in the adult male. Interestingly this phenotype is transgenerational, such that what your pregnant great grandmother was exposed to may cause disease in you with no subsequent exposure (italics mine). This has been termed epigenetic transgenerational inheritance."
If that's the case, then what Skinner is finding means that your health begins way before the womb - even, incredibly, the one that produced you. His research would support, for example, the "slavery" theory of diabetes, which holds that African Americans are at higher risk today of diabetes due to the metabolic changes that arose as a result of the "feast or famine" diet they endured more than 200 years ago. It also has profound implications for public health initiatives, which tend to deal with the here and now (lower smoking rates, increase teen exercise rates). In a way, I think, it even supports the idea of healthy communities as a public health goal - meaning a transgenerational, longtitudinal and sustainable change in a community, in which the target is not a particular disease or illness but the overall quality of life and health measures for a group of people. Begley's article and Skinner's research make a strong case for looking at a person's health as a sum of his/her genetic and environmental experiences.