There are few topics as emotionally driven as food choices. For most of us, our dietary choices are guided mostly by our taste preferences, familiarity (think comfort foods) and convenience. In fact, much of what passes as nutritional science in the popular media is incorrect or overstated. As a result there are often widely held misconceptions and untruths about what is a “healthy food.” A classic example is soy based food products. About 4 years ago, I wrote a column to debunk the popular (and inaccurate) belief that some of the hormone-like chemicals—called phytoestrogens—in these healthy beans could interfere with fertility. The latest research goes one step further suggesting that these foods actually boost the pregnancy rates in women undergoing advanced reproductive techniques (ART).
It’s been well established that adding soy based foods can lead to small changes in the hormone balance of people that eat them. But for too long, people that wanted to promote unhealthy dietary choices successfully created concerns among fertility patients. Then two clinical studies came along that demonstrated women taking soy supplements during either ovulation induction treatment or IVF cycles had higher pregnancy rates. The problem with these studies however was that the supplements that were used boosted the level of phytoestrogens to levels that are over 10 times higher than people eating a traditional Asian diet. New research has provided more practical insights into the health benefits achieved by simply switching to easily obtained soy based foods.
This latest study was very practical because they looked at the dietary choices in a group of 315 women that ultimately completed 520 ART cycles in 2013. Better still, they followed them prospectively to minimize the risk of obtaining biased results. They then looked at various results from their IVF cycles. They found that the eggs from women that were eating foods that contained soy had a higher fertilization rate. More specifically, they found that the clinical pregnancy rate was 11% and live birth rate was 13% when they compared women that were eating soy to age-matched women that were not. In fact, women that were consuming the most amount of soy had a nearly 80% higher chance of success. Bottom line was that soy containing foods seem to be very beneficial to women undergoing fertility treatment without making huge dietary changes.
An important step towards validating any finding is to then try to establish a theory of how the intervention may have resulted in the finding. The previous studies on soy supplements and IVF outcome suggested that the isoflavones—these are the estrogen-like chemicals in soybeans—resulted in a healthier uterine lining and thereby improved the ability of embryos to implant. They based this assumption on the fact that the ultrasound imaging of the lining appeared different. This recent study did not find any such changes. Instead, they hypothesized that the benefit are demonstrated by the fertilization rate of the eggs from the women eating soy vs. those that weren’t The fact that it was higher in the soy group suggests that eating soy may improve egg quality. Regardless of the mechanism, all of the research agrees that dietary soy is associated with higher pregnancy rate and greater chance at a live birth.
Maybe the most important aspect of clinical research is guiding and motivating patients on how and when to implement changes. Given the large number of products that now contain soy as well as the various “meat substitutes” (ie, veggie patties, soy milk, soy yogurt, soy butter) it makes sense to encourage women going through IVF to try to make some conscious changes to select these products or to eat soybeans. Another potential advantage of reducing meat, chicken and fish consumption is that plant based proteins contain far less of the unhealthy aspects of our modern diet like; hormone disrupting chemicals, pesticides and antibiotics. The end result is not only a higher chance of conceiving but also having a healthier pregnancy and giving your child the very best start possible.