Edamame: When Green and Natural Doesn’t Equal Healthy| Updated: Dec 07, 2018
Even supermarkets and warehouses like Costco are cashing in on the edamame craze, with conventionally grown versions displayed en masse with the freezer foods next to innocuous and less enticing bags of broccoli, carrots, and peas.
Preparation of Edamame
Sourced from immature green soybeans, edamame pods are typically cut on the ends and then steamed, boiled or microwaved. If boiled, salt is usually added to the water. If steamed or microwaved, the salt is added after cooking with the soft green beans removed from the pods.
Edamame is usually served salted and cold as an appetizer in Japanese restaurants. Edamame is also found in modern cuisine from China, Korea and Hawaii, although the latter is largely due to Japanese influence rather than ancestral Polynesian traditions.
If frozen, fresh edamame is blanched first.
History of Edamame
It seems to make sense that edamame would be a traditional food since it is unprocessed and simple to prepare. Historical references appear to bear this out as the earliest documented reference for the word edamame occurred in 1275 AD when the Japanese monk Nichiren wrote a note thanking a parishioner for the gift of “edamame” he had left at the temple. However, it was not known if this edamame was for consumption or for simple crop rotation purposes.
Kaayla Daniel PhD, The Naughty Nutritionist writes in her article What’s Edamame? And Other Questions about Green Vegetable Soybeans that historian William Shurtleff of the Soyfoods Center in Lafayette, CA, knows of no early references to green vegetable soybeans in China. Further, she writes:
An herbal guide from 1406 (Ming Dynasty) indicates the whole pods of young soybeans could be eaten or ground for use with flour, but it recommended such uses only during times of famine. A Materia Medica from 1620 recommends edamame, but only for the medicinal purpose of killing “bad or evil chi.” By 1929, however, edamame was definitely on some menus. William Morse of the USDA reported on a field trip to China that “as early as May, small bundles of plants with full grown pods were seen on the market. At the present time the market is virtually flooded with bundles of plants with full grown pods, the seeds of which are also full grown. The pods are boiled in salt water and the beans eaten from the pods.”
Dr. Daniel also disputes the claims by industry that Asians have consumed soy for 5,000 or even 10,000 years. She says that digging into anthropology and history texts absolutely does not support this common claim that seems to have become regarded as fact in some health circles. “The oldest soyfoods, miso and tofu [bean curd] date back only about 2,500 years. Contrary to popular belief, soy was not eaten as a food 5,000 years ago, but it was highly regarded for its role in crop rotation.”
Green and Natural Doesn’t Always Equal Healthy
Looking a bit like a cross between cannellini beans and green peas, edamame seem like a dream come true for a parent seeking healthy snack alternatives. Children gobble them up by the handful due to their addictive sweetness, and adults who prefer salty snacks can chow down on the dry roasted versions available in large, economy sized bags.
While simple and quick to prepare and even easier to eat, edamame simply do not make the grade as a food that is healthy to eat on a regular basis.
One big reason why is because most edamame on the market in the United States is sourced from genetically modified soybeans. GMOs are not labeled in North America as of this writing and hence can stay under the radar of even alert shoppers. Most of the rest of the world requires labeling of GMOs, so edamame is not usually genetically modified in those locations because consumers simply won’t buy it if GMO is emblazoned on the label akin to a skull and crossbones.
Beware that most edamame served in Japanese restaurants and featured on salad bars in North America is also GMO! So enjoying that edamame appetizer that is served before your meal at the local sushi joint isn’t the healthy first course that most presume it to be.
GMO soy is not good for your health even when it it is green and unprocessed. Some of the most worrisome animal studies to date that should give any edamame lover pause include:
- A study of GMOs reported in the June 2013 issue of the peer-reviewed Journal of Organic Systems involved research conducted over 22.7 weeks using 168 newly weaned pigs in a commercial U.S. piggery. One group of 84 pigs ate a diet that incorporated genetically modified (GMO) soy and corn, and the other group of 84 pigs ate an equivalent non-GMO diet. The pigs that ate the genetically modified soy and corn had a higher rate of severe stomach inflammation – 32 percent of GMO-fed pigs compared to 12 percent of non-GMO-fed pigs. The inflammation was worse in GMO-fed males compared to non-GMO fed males by a factor of 4.0, and GMO-fed females compared to non-GMO-fed females by a factor of 2.2. (1)
- Scientists at the Russian Academy of Sciences reported between 2005 and 2006 that female rats fed GMO soy produced excessive numbers of severely stunted pups with more than half of the litter dying within three weeks, and the surviving pups completely sterile. (2)
- Russian research from 2010 found that hamsters fed GMO soy for two years (over three generations) developed sterility. In addition, the pups that did get born suffered from slow growth and a high mortality rate. Most disgustingly, the third generation of hamsters raised on GMO soy developed unnatural and profuse hair growth in their mouths (3).
Profuse hair growth in the mouth … from eating GMO soy for only 3 generations? Yes, this is what the Russian researchers were horrified to discover. No wonder Russia has imposed a ban on all GMOs essentially kicking Monsanto to the curb.
What About Organic Edamame?
Ok, so you know all about the dangers of GMO soy and edamame and have made every effort to source only organic. Isn’t this a better choice?
Yes, it is definitely better and avoids the potential for chronic health problems observed in animal studies involving GMO soy.
However, even organic edamame presents a health threat when it is consumed on a regular basis. This is due to the high amount of hormone disrupting phytoestrogens and anti-nutrients called protease inhibitors (primarily trypsin) in soy even when picked young and green for edamame.
While eating edamame raw is the biggest no-no, cooking the pods doesn’t do enough to resolve these issues either. The phytoestrogens in edamame are basically untouched by cooking and the protease inhibitors are not reduced by very much. For decades, the USDA and other researchers put their efforts into finding safe and inexpensive ways to deactivate these protease inhibitors which wreak havoc with both digestion and the pancreas. Boiling, roasting and steaming can help, but don’t do enough. The only way that comes close is with traditional fermentation methods like those used to make miso, tempeh and natto.
Since edamame is only lightly cooked in most cases, you can count on most of the anti-nutrients remaining along with all of the hormone disrupting plant estrogens.
How Edamame Disrupts Digestion
With regard to the green bean’s effect on digestion, the protease inhibitors present in high amounts in edamame suppress some of the key enzymes that help digest protein.
Because these inhibitors block the protease enzyme needed to digest protein, the pancreas has to work overtime to produce more. If this happens only occasionally, the pancreas quickly recovers, no big deal. But if edamame is consumed frequently and in large amounts, there is no recovery period and this leads to an increase of both the number of pancreatic cells (hyperplasia) and the size of those cells (hypertrophy). Combine that with frequent drinking of soya milk or foods containing soy protein isolate, and you’ve really got problems!
Pancreatic hypertrophy and hyperplasia in humans results in the loss of the ability to secrete sufficient enzymes. Insufficient enzyme production by the pancreas means digestive distress for adults and growth problems for children.
Irvin Liener, PhD, professor emeritus at the University of Minnesota and the world’s leading expert on anti-nutrients and toxins in plant foods, has issued a warning to those who might be addicted to edamame, “Soybean trypsin inhibitors do in fact pose a potential risk to humans when soy protein is incorporated into the diet.”
How Edamame Disrupts Hormone Balance
Below are just a few of the many studies on how plant estrogens (also called isoflavones or phytoestrogens) in soy (edamame too) is can disrupt hormonal balance:
- Isoflavones (phytoestrogens) genistein and daidzein in soy appears to stimulate existing breast cancer growth indicating risk in consuming soy products if a woman has breast cancer. (Annals of Pharmacotherapy 2001 Sep;35(9):118-21).
- Direct evidence that isoflavones genistein and daidzein suppress the pituitary-thyroid axis in middle-aged rats fed 10 mg soy isoflavones per kilo after only 3 weeks as compared with rats eating regular rat chow (Experimental Biology and Medicine 2010 May;235(5):590-8).
- Don’t eat edamame or any other form of soy either when you are pregnant ladies! Scientific research has shown that the developing male fetus which is exposed to soy phytoestrogens may suffer from higher susceptibility to prostate cancer later in life (Prostate 1994;24(2):67-78).
- A study of 12 men aged 18 years and older experienced a 19% drop in serum testosterone in only 28 days when supplemented with 56 grams of soy protein over that same time period (Prev 2007;16:829—33).
Possibly the most worrisome research of all regarding soy consumption are the precancerous changes to breast tissue that can occur over time. If you want to know the truth about how an edamame habit can harm your breast health, Breast Cancer Boot Camp, coauthored with William B. Hobbins MD, Sellens provides striking, irrefutable visual evidence of adverse, precancerous effects on the breasts from estrogenic foods like edamame.
Your breasts don’t lie and these pictures of precancerous breasts from eating estrogenic foods will no doubt have you rethinking your edamame consumption in a hurry if the green bean is your go-to snack.
Sprouted Edamame is Worse
According to Kaayla Daniel PhD, world renowned soy expert who has appeared on the Dr. Oz Show among others and authored the must read The Whole Soy Story: The Dark Side of America’s Favorite Healthfood, sprouted edamame is worse than unsprouted.
She says, ” I would not recommend sprouting soybeans as it concentrates the toxins. Long-term fermentation neutralizes them, but short-term sprouting concentrates them.”
Love Edamame? Here’s What to Do!
If you love edamame and want to toss some in your salad, go ahead. A few here and there isn’t going to cause any problems for someone who is healthy unless there is a soy allergy present.
But … don’t go munching it like popcorn and developing a regular snackie habit eating a bowl or several handfuls at a time. Most especially, edamame is not a good snack to give to growing children (soy formula is a disaster too) or hormonal adolescents going through puberty. Even adults including menopausal women would be well advised to avoid eating it on a regular basis.
Make sure if you enjoy a handful of edamame from time to time that it is always cooked and labeled organic. This means skipping the edamame appetizer at restaurants in North America no matter how hungry you are (wait for the main course or order another appetizer!) because chances are very good it is GMO.
Remember: hairy mouths in hamsters within three generations of eating GMO soy and most edamame on the market in the United States is genetically modified. Spare your grandchildren people!
Sarah, The Healthy Home Economist
Sarah Pope has been a Health and Nutrition Educator since 2002. She serves on the Board of Directors for the Weston A. Price Foundation.
Sarah was awarded Activist of the Year at the International Wise Traditions Conference in 2010.
Sarah earned a Bachelor of Arts (summa cum laude, Phi Beta Kappa) in Economics from Furman University and a Master’s degree in Government (Financial Management) from the University of Pennsylvania.
Mother to three healthy children, blogger, and best-selling author, she writes about the practical application of Traditional Diet and evidence-based wellness within the modern household. Her work has been featured by USA Today, The New York Times, National Review, ABC, NBC, and many others.