In Chapter 4, Dr. Moalem introduces the idea that plants
develop defense mechanisms so they can survive and reproduce. Many of the most powerful defense
mechanisms present in plants exist at the chemical level. One example Dr. Moalem shared concerns
a group of plants including clover, sweet potato, and soy, which contains types
of chemicals, called phytoestrogens.
If too much phytoestrogen is ingested, it may “wreak havoc on [animals’]
reproductive capability” (pg 78).
In clover, if the plant has a bad year (due to environmental factors)
then it increases the production of formononetin–a type of phytoestrogen–in
turn, limiting the population of its predators for the next generation by
sterilizing the possible parents. (Big
idea #1) Furthermore, Dr. Maolem notes that soy is rich in a phytoestrogen called
genistein and indicates that there is growing concern of the long term effects
of soy in our diet (pg 79). Later
on in the chapter, Dr. Maolem states that Asian women are reported to
experience fewer problems with mid-life changes (menopause) due to the
phytoestrogen in soy (pg 92).
Questions: In
Asia, where soy is a major part of diet, is there any evidence of decreased
fertility in women? Also, as
humans ingest more soy, might there be increasing allergies or other adverse
reactions to soy to protect our ability to reproduce (one of evolution’s
driving factors)?
Rachel Chang (rchang4@students.d125.org)
From the research that I collected, I found very contradictory results; one article said that there is no evidence of decreased fertility in women (or men). Whereas another stated that new studies suggest that eating large amounts of soy’s estrogen-mimicking compounds might reduce fertility in women, trigger early puberty and disrupt development of fetuses and children. I also found that there is a major concern about eating GMO soy which contains higher than legally allowable levels of pesticide residue that remain on the crop, which we eventually ingest. The specific effects are currently unknown;however, it is known that it is unhealthy to ingest genetically modified food.
ReplyDeleteAn experiment was conducted on animals who were fed a high-soy diet. One study showed that genistein led to reduced fertility and abnormal embryo development in female mice. The highest doses of soy corresponded with the least amount of eggs that were successfully fertilized and increased cell death in developing embryos. In another study, female rats fed the highest doses of soy had an early puberty and irregular estrous cycles along with the production of smaller litters.
Although the long term effects have not been studied in depth, one study showed the results of being fed soy formula as a child.It found that women fed soy formula as infants had slightly longer periods and more menstrual cramping as compared to those who were not fed soy formula.
This relates to Big Idea 1: The process of evolution drives the diversity and unity of life. Evolution is effected by our ability to reproduce and if those who eat soy are inhibited by certain chemicals then they will be selected against compared to those who are not inhibited.
On the other hand I found many health benefits to having a soy diet. These benefits included Breast Cancer prevention, Cholesterol Reduction and Heart Disease Prevention among many others.
Studies have shown that Asian women who have consumed soy products since childhood or adolescence have significantly lower rates of breast cancer. This is primarily attributed to a group of chemical constituents in soybeans known as isoflavones. Isoflavones belong to a class of chemicals known as phytoestrogens and are structurally very similar to the estrogen in human bodies,but is much weaker. Therefore they bind with the estrogen receptor sites in breast tissue which prevents the stronger “endogenous” estrogen from binding. In summary, this prevents cancerous causing changes to occur in the tissue.
Although all of these results seem logical, not much research has been done on this topic so one can only draw conclusions from the given resources. Overall I believe that the key is moderation. Too much of anything in the end will most likely be bad for you
Journal Sources:
Soy and Women's Health - the Truth About Soy Benefits and Safety by Dr. Aviva
Scientific America - Could Eating Too Much Soy Be Bad for You? by Lindsey Konkel and Environmental Health News
(Dana Morgan, Dmorgan4@students.d125.org)