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Monday, June 4, 2012


Vegans and Vegetarians get asked all. the. time. where they get protein. I would venture to guess it is the most common query as to their diet. Some would surprise the unknowing person by telling them how much protein some vegetables actually have. Others would cite the complete proteins in some "superfoods" like hemp, quinoa and chia. Those not strictly vegan might mention eggs and certain dairy products. Many would respond with the usual: beans, nuts, and legumes. And of course, there is the ubiquitous soy.
Many people have fallen prey to the notion that soy is the best place to obtain protein if you don't eat meat or animal products, or if you eat very little of them. But the truth is, there are plenty of protein sources that also provide other nutrients, WITHOUT the risks soy carries. Let's explore those risks. 

Phytic Acid
Soybeans and soy products contain high levels of phytic acid, which is called phytate in its salt form. Phytate inhibits assimilation of calcium, magnesium, copper, iron, and zinc partly because it is indigestible by humans and partly because it chelates. And, methods used by humans to prepare/cook soy do not neutralize phytic acid. Diets high in phytic acid have been shown to cause growth problems in children. (I would think this is because so many crucial nutrients are not being made available to the child.) Phytate is not just of concern to human health- since so many livestock animals are fed soybeans (which would not be a part of their natural diet...) and so many of those animals cannot digest the phytate, it passes through unabsorbed and raises levels of phosphorus in the manure. (source and source) This can lead to eutrophication, which is an environment's response to the addition of artficial or natural substances to an aquatic system. (example: blooms of algae or phytoplankton which can lead to water oxygen depletion, which then leads to fish kills.) (source)
A lot of women going through menopause or who are pre-menopausal ingest soy (in various forms- soy milk, tofu, etc) specifically for the phytoestrogens. They have been told by the medical profession that it will balance their hormones, relieve hot flashes, and night sweats. But the truth is that they disrupt endocrine function. Endocrine function is the proper functioning of the glands that produce hormones! These estrogens also have the potential to cause infertility as well as to promote breast cancer in adult women. Haven't women been told soy will help prevent breast cancer??? At the very least there seems to be conflicting evidence. Avoiding soy and getting protein from other sources would seem to me to be the safest route. (source and source)
The thyroid and Soy
Soy contains Goitrogens, which are substances that block the synthesis of thyroid hormones and interfere with iodine metabolism, thereby interfering with your thyroid function. A diet low in iodine and high in soy will block the T4-T3 hormone conversion. Intefering with the thyroid like this may be the cause of hyperthyroidism and thyroid cancer, as well as autoimmune thyroid disease (infant soy formula may be linked to this.) (source and source)
The "Soy is Consumed in Asian Cultures" argument
Many would argue that Asian cultures have always consumed soy and have been among the healthiest people in the world. There are several things wrong with this argument. 
1. The soy they historically consumed was fermented and used as a condiment, not the basis of a meal (So, that would include miso, nama shoyu, tamari, tempeh, NOT tofu or soy milk.) 
2. The soy they consumed was not genetically modified. (This is historically speaking- GMO soy is quite pervasive throughout the world now.) 91% of US soy is GMO- it has been made to be resistant to Roundup, the herbicide, so it can be grown quickly, pest-free, and cheaply, but then it contains high levels of the herbicide.
3. Asian cultures often consume large amounts of sea vegetables and fish. Sea vegetables (seaweed) and certain fish have naturally high levels of iodine, and iodine is very important for thyroid function. (source and source
Soy in Children
There is mounting concern over the amount of soy infants consume in ratio to their body size. There is almost no phytoestrogen in cow's milk (or cow's milk baby formula.) There is almost none in human breastmilk, even if the mother eats soy herself. And yet, babies fed soy formula have 13,000-22,000 times the estrogen of babies fed cow's milk formula or breastmilk. This may be causing delays in maturation (including sexual maturation) of boys, while it may be partially to blame for girls showing signs of puberty earlier and earlier. (To be fair, babies are being exposed to environmental elements that act like estrogens in the body as well. These would include BPA, PCBs, and DDE.) Also, the soy in infant formula (as well as most processed foods containing soy) is soy protein isolate. Because of how it is processed the isolate inhibits the body's absorption of many nutrients- even more so than with less processed soy, noted above. Aluminum is also leached during processing, and can affect the nervous system, kidneys and brain. (source and source)
There are many concerns when it comes to soy, not all covered here (it would take a whole book to cover them all.) While some concerns are well established, others are preliminary. However, there is enough evidence to be sure that soy consumption should be avoided, or at least kept to a minimum. 

Do you eat soy? In what forms? Do you read labels of packaged foods in hopes of avoiding it? (We have eaten it in the past, and we used to use soymilk, but we have slowly switched to whole food sources of it- like edamame. I occasionally also use fermented soy like miso, tamari, and nama shoyu. We never really liked tofu to begin with.)


  1. Early in my childhood, there was a soybean field beyond the fence of my backyard. I used to go out and pick little pods that were left behind after they'd been harvested. I would collect SO MANY pods and just rip the beans right out and eat them raw. I ate too many one day and had a stomach ache. I'm unsure whether or not they were GMO but it was the early 90's.
    I'm skeptical of the people who say they avoid soy partially because of the reasons above or simply because it's an ingredient commonly found in highly processed foods.

    I do like tofu and soymilk (though I stopped drinking it because of the damn additives!) but it's not a regular occurrence in my diet (anymore).

    I'm confused about tempeh though. I thought it was almost exactly like tofu except with a meatier texture.

    1. In my opinion, it is still ok to eat it in whole form, like edamame the way you did as a kid, but not everyday and not as the mainstay of meals. But I did a search for soy on twitter and found COUNTLESS tweets about meals people were having, mostly centered on tofu. I am sure not all that tofu is organic, which means it is most likely GMO. I think you might be right about tempeh- I think it more closely resembles meat. Thanks for commenting :)

  2. Does the phytate issue mean it could lead to a person being sluggish, sleepy, brittle, and more susceptible to getting sick? All the minerals inhibited wouldn't seem to leave you performing well.

    It would be interesting to see how a person feels after a week of a high soy diet and then a week of no soy. Also, how long might it take to purge the soy?

  3. Good point- hadn't thought about that. All the nutrients noted contribute to mood and immune system. (Some of them contribute to much more, too.)

    Funny enough, can't find anything on how long soy takes to leave the body. Since it is a plant based food, I would think less than 12 hours, but that is only based on what I have read about other foods...(raw fruit/vegetable matter taking under an hour in most cases; beans, legumes (unprocessed) taking 3-4 hours; meat/dairy taking 1-3 days.) Soy products other than the bean form are processed, so I would think that slows digestion down. And thanks for reading/commenting honey haha :)