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Epigenetics — An Emerging Field in Fertility Nutrition
a blog by Beth Heller, MS, Pulling Down the Moon, December 24, 2010
It’s impossible to ignore the growing body of research suggests that a variety of chemicals in our environment are associated with infertility and miscarriage. A short list of the main offenders include PAHs found in cigarette smoke and exhaust fumes, BPA and pthalates found in plastics, and other endocrine-mimicing chemicals present in fertilizers and industrial solvents. Yet, at the recent American Society for Reproductive Medicine conference in Denver, the message from the experts studying the impact of environmental toxins on fertility was one of hope — a focus on the emerging field of epigenetics and a solution that may prove as simple as green leafy vegetables.
What Is Epigenetics?
In simple terms, epigenetics is the study of how lifestyle factors like stress and diet can impact the way our inherited genetic make-up (our DNA) plays out without altering the genetic material itself.
By now we are all fairly familiar with the term genome, which refers to the DNA strands that hold the blueprint for life. DNA is made up of sequences of nucleic acids (genes) that contain the “recipe” for all components and processes of cells. For a long time scientists believed our DNA was the key determinant of our physical characteristics, including our risk for disease.
But now the plot has thickened. Scientists have recently identified a new layer in the world of genetics: the epigenome. To imagine what the epigenome is, think about an assortment of seeds that are dormant in a patch of earth, each with the potential to grow. Some of the seeds are beautiful wildflowers, others are weeds. The combination of sun, nutrients, temperature and soil quality all determine whether the seeds grow or remain latent.
The epigenome is analogous to a set of conditions, like sunshine, adequate water or frost, that either activate or deactivate DNA “seeds,” or genes. Key players in the epigenome include proteins called histones, around which the strand of our DNA are wrapped, and special chemical groups, methyl groups, that act like “switches” that turn genes off and on. Changes to the shape of the histones or modifications to these chemical switches modify which genes are active and which remain dormant — all without any change to our inherited DNA code.
How Does This Relate to Fertility?
So what does any of this have to do with fertility? One chemical in particular is receiving a great deal of press for its association with infertility and negative birth outcomes. This chemical, Bisphenol-A (commonly called BPA) is ubiquitous in our environment in plastic bottles, baby toys, food containers, medical equipment and dental sealants.
Recently a team of researchers from Duke University identified the exact mechanism by which BPA affects female fertility. It turns out that a specific gene (HOXA10) that is responsible for normal uterine development in mice and humans was chemically modifed in the female offspring of pregnant mice treated with BPA. In particular, these offspring were found to have missing methyl groups in the HOXA10 gene. As a result, females born to mice exposed to BPA had uterine tissue that was hypersensitive to estrogen and likely to be out-of-sync with the needs developing embryos. As a result of this modification, the researchers said, these mice would ovulate/conceive normally but would be predisposed to difficulty in staying pregnant.
The next step in this exploration is fascinating and has far-reaching implications for the potential treatment and prevention of infertility due to environmental exposure. After noting that BPA seemed to affect HOXA10 methylation of the female mice pups in utero, the researchers turned to nutrition for a potential solution. Familiar dietary compounds including folic acid, B vitamins and s-Adenosyl methionine are known to be key components in our body’s methyl-making pathways, so what if increasing amounts of methyl-donating nutrients in the diet could mitigate the impact of BPA?
In a follow-up study, the Duke team did just that. The findings were exciting. Supplementing the diets of BPA-treated mice with the methyl-donor folate or a phytoestrogen found in soy erased the effects of BPA in their female offspring.
Dietary Intervention to Provide a More Fertile Environment
While these findings may seem to be more relevant to pregnant women who may be concerned about passing BPA-related problems on to their daughters, there is also grounds for believing that dietary intervention might provide protection against the negative impact of BPA in women who are currently trying to conceive. In fact, other areas of study where epigenetics are in play, like colorectal cancer and mental illness, are looking at dietary modification and folate supplementation as a novel for treatment and/or prevention of these diseases in adults.
This research is a welcome glimmer of hope for many women who are trying to conceive. News that the environment is impairing our fertility is very discouraging. Taking steps to avoid toxic exposure is great, but many of the offending chemicals are found almost everywhere. Making sure that we are eating ample amounts of nutrients that support DNA methylation is an extra step we can take to empower ourselves and potentially deter negative effects from the environment.
In our book, Fully Fertile: A Holistic 12-Week Plan for Optimal Fertility, we discuss the importance of eating ample fruits and vegetables as part of a fertility-friendly diet. Any woman who is trying to conceive should also be taking a prenatal vitamin that provides ample folate. But folate from prenatals is not enough. Studies show that folate from food sources provides greater benefits than that from supplementation.
In addition to good dietary intake, women should be aware of certain factors can impair folate levels, including alcohol intake, smoking, conditions that challenge the intestinal mucosa (such as celiac disease) and congenital deficiencies in the enzymes necessary for folate metabolism.
Key nutrients that support the body’s methylation processes and the foods in which they are found are:
- Folic Acid: Green leafy vegetables (romaine lettuce, spinach, endive, kale), sunflower seeds and liver
- Vitamin B12: Meat, liver, shellfish and milk
- Vitamin B6: Whole grains, vegetables, nuts, meat
- Choline: Egg yolks, soy products, cooked meats
- Methionine: Sesame seeds, cottage cheese, Brazil nuts, fish, peppers and spinach