This post was written by Amy Berger. Amy is working on her Masters Degree in Nutrition and holds a Bachelors in Creative Writing. She has put together an excellent primer on all things antinutrient. Enjoy!
Phytates, oxalates, and goitrogens, oh my! If you’re new to the world of antinutrients, these harmful substances can seem as scary as the lions, tigers, and bears Dorothy and the others thought they might come across on their way to see the Wizard of Oz. Maybe you know all about the properties of antinutrients, or maybe you’re scratching your head, bewildered, because you thought antinutrients only came in the form of delicious cookies and the nefarious but well-meaning girls who sell them. Either way, here’s a primer on just what the heck these things are, and some advice on how much you should—or shouldn’t—freak out about them.
What are antinutrients?
Let’s think about this logically. Animals have ways to make sure they don’t become some other animal’s dinner (including a human being’s). They can run away, or they can stay and fight with claws, horns, or teeth. If they win, great. If not, fire up the BBQ! Plants aren’t so lucky. Since they can’t defend themselves physically, they’ve evolved multiple insidious ways of warding off predators biochemically. Plants produce a variety of harmful substances collectively known as antinutrients. (Not harmful to the plants, but harmful to the poor saps who eat them.) They’re exactly what they sound like: they work against you absorbing nutrients from those foods.
One of these antinutrients you’re likely already familiar with: phytic acid. It’s found mostly in grains and legumes, so if you’re following a fairly strict paleo diet, it’s not much of an issue for you. Still, it’s worth knowing a little about, since it’s one more nail in the coffin of these problematic foods. (Not to mention, nuts contain a small amount, so if you’re eating copious amounts of nuts and nut flours it’s something you should be aware of.) Phytic acid binds to minerals and makes them unavailable to the body. Specifically, it binds to things like calcium, magnesium, zinc, and iron. There are ways to neutralize some of the phytic acid in foods, like soaking, sprouting, or fermenting (hence the “sprouted grain” breads or natural sourdoughs you see in artisan bakeries), but it should be no surprise that the vast majority of commercially available grains do not undergo this kind of meticulous preparation. In our grain-centric society, is it any wonder there’s rampant magnesium deficiency and osteoporosis?
But that’s not your problem. You’re off grains and legumes. Whew! In the clear, right? Wrong.
Unfortunately, many foods that are indisputably wonderful from a nutritional standpoint contain other antinutrients besides phytic acid. One class of these is goitrogens – yes, goitrogens, which means—you got it—they depress thyroid function. Goitrogens are found in some of the most benign foods you can imagine: broccoli, kale, Brussels sprouts, collard greens, cauliflower, and all types of cabbage, including Asian varieties like bok choy. (Anything in the Brassica category, for you plant geeks.) You can also find goitrogens in most legumes, especially soybeans (as if you needed another reason to steer clear). The good news is, goitrogens are mostly neutralized by cooking or fermenting. Kind of makes sense—have you ever tried to eat a raw Brussels sprout? Or collard greens? Have fun chewing; I’ll see you in about a week.
A third class of antinutrients is oxalates. Oxalates do pretty much the same thing as phytic acid—they bind to minerals, making it difficult for our bodies to get at them. Like goitrogens, oxalates are found in many foods you may have come to think of as paleo staples: spinach, chard, blueberries, and cocoa/chocolate, among others. (Okay, so maybe that last one’s not a staple, but admit it, it’s on your radar.) Oxalates are the reason rhubarb leaves are poisonous (the old wives’ tale is true!), and if you ever eat the green leafy tops from a bunch of beets, they’re loaded with ‘em, too. That’s the bad news. The good news is, cooking to the rescue again. Cooking reduces the mineral blocking effects of oxalates, which is good, because raw chard is as hard to chew as shoe leather, and tastes about as good.
There are other antinutrients, but you’re probably already sufficiently scared. So now that we know what these things do, the question is, how much worrying do they warrant? The answer is, not a whole lot. Yes, these substances can be problematic, but let’s not throw the baby out with the bathwater. Most of these foods—dark green leafy vegetables, berries, and nuts—are nutritional powerhouses and shouldn’t be avoided because of antinutrients that can be neutralized pretty easily anyway. It would be a shame to miss out on the good things because of overblown fear of antinutrients.
When you’re first starting out with a shift away from the grain-heavy, fat-phobic modern western diet, it can be a heck of a shock to your system. The psychological shift can be even more daunting than the physical one. All of a sudden, you’ve stopped eating the vast majority of foods that got you through the day. Once you’ve adapted, though, you’re feeling great, you’re looking better, and you’ve got a spring in your step. And then, WHAM. You find out that the new foods that sustain you are full of these antinutrients. Can’t eat spinach anymore. Can’t eat kale, and you won’t go near cabbage without a hazmat suit. And yet, you can’t live on air alone. What’s a person to do?
Step 1: Relax. Remember, most of these bad boys are taken care of by cooking or fermentation. (In the case of cabbage, it’s a great reason to make some homemade sauerkraut or kimchi!)
Step 2: Relax more. In terms of worry-inducing issues, there are much bigger fish to fry. A couple of spinach salads and a little dark chocolate aren’t going to cause mineral deficiencies in a matter of days. Our bodies are surprisingly robust. We have multiple feedback loops and checks and balances to make sure nothing gets too far out of whack. These foods are only troublesome when eaten in excess. What is excess? It’s partly in the eye of the beholder, and partly in the homemade cole slaw you love and have been eating six cups of every day for eight months. Even eating antinutrient-rich foods for several days in a row won’t do much harm. It’s when these foods are eaten in large quantities over long periods of time, in the absence of other foods, that they can turn on you.
Step 3: Eat a varied diet. Eating a wide variety of plant and animal foods is practically a guarantee that you won’t overdose on any particular antinutrient. It’s also a good way to make sure you get the full complement of vitamins, minerals, and phytonutrients you’d miss out on by limiting yourself to a handful of beloved foods. How do you eat a varied diet? One simple way is to take a look at the colors in your shopping cart or farmer’s market bags. Is green all you see? How about tossing in some red peppers, carrots, or blueberries? The more “colors” you eat, the more phytonutrients you’ll get—most of which scientists are only scratching the surface of in terms of health benefits. Another way is to buy what’s on sale. If zucchini’s on sale this week, chances are, something else will be marked down next week. Eggplant, maybe, or asparagus. What a good way to try something outside your culinary norm. (And if it sucks, well, okay, dump it and go back to the zucchini!)
But the best way to make sure you’re eating a good variety of plant foods is to stick with the seasons. It is only thanks to the wacky hijinks of our modern global food economy that you can go to a supermarket in Michigan in January and buy a papaya. Certain foods are symbolic of certain times of year: asparagus in spring, peaches and tomatoes in summer, butternut squash in fall. Even when you can get them at other times, they just don’t taste as good. Eating what’s in season makes it difficult to eat the same limited foods all year long. Granted, this isn’t always possible. Not everyone lives in places with year-round growing seasons or farmer’s markets, and maybe in the middle of December, you’re jonesing for some blueberries with your coconut milk. Not a big deal. Canned tomatoes and frozen berries can be lifesavers some days!
Remember, these are general guidelines. Eating the same things a couple days in a row won’t kill you. The overall picture, over time, should include a wide variety of animal and plant foods. The poison is in the dose. Most good things can enter not-good territory in massive quantities: exercise, fish oil, and yes, raw cauliflower. But don’t stress out. The cortisol from overwhelming anxiety in the produce aisle will do you more damage than anything from the broccoli boogeyman.
Chris D says
From an evolutionary point if view, anti nutrients are a rather ineffective weapon. As opposed to straight up toxins, which may kill or incapacitate an animal fairly quickly, anti nutrients don’t stop the plant getting eaten and their effects can take a rather long time to present. Also, an animal is unlikely to associate the consumption of the plant with whatever negative digestive effects it has and keep eating it (see: humans.) Is it the case that animals have co- evolved with plants to develop digestive aids that neutralize these anti nutrients? If yes, why not humans? Is it possible these anti-nutrients came about strictly in response to reduce human consumption? Food for thought (no pun intended.)
Matt Lentzner says
I suspect that plants are much more worried about attacks from insects than megafauna like people. These natural pesticides have unpredictable effects on people.
Nicotene is a great example. Very potent insecticide (Black Flag was simply a nicotene spray when it was first developed). The fact that people can get a serious buzz off it is just an accident.
Amy B. says
Food for thought, indeed. I don’t know the answers to your questions, but it’s possible that at least some animals do possess the ability to digest these foods without problems. This isn’t an antinutrient example, but think of how ruminant animals digest cellulose, and human’s don’t. That’s why they can, for lack of a better explanation, turn grass into protein, but for humans, beyond extracting some vitamins and minerals out of them, leafy greens are mostly just “roughage.” The rumens also contain some different species of bacteria from the human intestines and that might also help them digest things we can’t. (Either the animals themselves or their gut bacteria produce cellulase, the enzyme humans lack to break down grass.)
You’re right about the negative effects sometimes taking a while to develop. From an evolutionary standpoint, all nature wants us to do is live long enough to reproduce. After that, if we’re magnesium or iron deficient, the universe at large doesn’t really care. Our genetic material has already been passed on. (And the universe might not care, but we humans sure do, especially when we can’t get out of bed, are depressed, can’t make it around the block, etc.)
So, when grains and legumes are cooked, does that not destroy as many of the anti-nutrients as when veggies are cooked?
Robb Wolf says
Different animals! Or plants I guess. Whole classes of chemicals. And there are folks who do not do well with even cooked veggies.
ChrisD, in the wild, a lot of those seeds can pass undigested through an animal’s intestinal tract, assuming they aren’t all chewed, and after excretion can grow. For the animals there’s not much of an evolutionary deterrent, but for the seeds it’s a great adaptation. Naturally, the ramification for us humans, who tend to eat seeds (in grain form) by the ton, and who aren’t adapted to do so the way, say, rodents or seed-eating birds are, is that the cumulative effect of the anti-nutrients is a lot more harmful.
So still an evolutionary component, just more for the seeds than the animals who consume them. 🙂
David Pryor says
In your artice, you stated the anti-nutrients are “Not harmful to the plants, but harmful to the poor saps who eat them.” Isn’t it more likely these chemicals were an adaptation to prevent the seeds from sprouting prematurely or to protect against micro-organisms, and not necessarily to prevent against large herbivores or omnivores from chowing down? I think either Robb or Mark Sisson actually described this in more detail in their book(s). Thanks.
Robb Wolf says
Dual actions actually. Stabilize seed, and anti-nutrient.
Amy B. says
Of course, David. You’re right about the main reason the antinutrients are there — they keep the minerals bound up until it’s time for the seed/legume to sprout and grow. My purpose in writing this article was to ease some of the anxiety surrounding antinutrients. Some folks get (in my opinion) disproportionately worried about things like oxalates in spinach when there are much more important pieces to the paleo puzzle. I’m not saying we shouldn’t care *at all* about these issues, but we need keep things in perspective, too. You’re spot on about the fact that the antinutrients are there mostly to keep the seeds from sprouting too soon.
Phil Bear says
Catching Fire: How Cooking Made us Human is an awesome book that goes into detail about how we became the apex predator, and continue to be so (for now).
They have it at my local library! Just put it on hold for myself until I can swing by and pick it up. Thanks for the rec.
I often see positive references on paleo sites to “homemade” sauerkraut. Is that just because it’s a regular rockstar party/raucous good time to make it at home, or is there something preferable about it if it is homemade? Assuming the ingredients are otherwise clean/organic/etc (e.g., the organic stuff in the jar in my fridge has only four ingredients, all clean), I assume the to-be-avoided anti-nutrients are also not a problem in commercial sauerkraut? Or is that wrong?
Anxiously awaiting your answer because I have just about been bathing in stuff recently….
Robb Wolf says
Store bought is typically pasteurized and therefore has no live culture.
Whole Foods sells unpasteurized sauerkraut. It’s kept in a refrigerated display.
You can sometimes get unpasteurized sauerkraut at a farmers’ market too.
Amy B. says
Storebought is also sometimes made with vinegar and is actually more “pickled” than fermented. It’s the fermentation that gets rid of the antinutrients. If it’s shelf-stable, it’s DEAD — no live enzymes or good bacteria. (If you find it in the refrigerated section, it’s probably still live, but check the ingredients label. You don’t want to see vinegar.)
debbyK Fitness says
So, how often would it be OK to have a veggie shake using raw kale, bok choy, spinach and cabbage in it? I was doing this for a while almost everyday. But tt also had tomatoes, all colorful peppers, lettuces and other veggies in it too.
But I also made cooked all of these in curry, then pureed them, and it made a much tastier soup, with some meat in it!!
The idea that plants would develop antinutrients as a defense against being eaten seems to come up often. I wonder, however, whether being eaten is necessarily such a bad thing for a plant from a reproductive standpoint relative to its species. For example, being appetizing to humans has resulted in plant species such as corn and wheat to become propagated to insane proportions. It could just as easily be argued that being eaten by animals (at least by those animals capable of domesticating said plant) is a highly effective evolutionary strategy for a plant.
I think it might not be such a great idea to tell people not to worry about these anti-nutrients. When I began the paleo diet almost two years ago, I was in excellent health and in great shape (had been gluten free for over a year at that point). Two months into paleo, I developed burning mouth syndrome. From there things just went downhill with excruciatingly painful menstrual cycles, adrenal fatigue, brain fog, depression, and acne. After trying everything from suppements to bio identical hormone replacement to acupuncture and anything else my functional doc could think of, I stumbled upon the trying low oxalates group on yahoo. It appears as though oxalates can wreak havoc on people who have a leaky gut. They don’t get properly excreted, but instead find their way into various tissues throughout the body and cause major disfunctions. It’s not just spinach and chocolate that are high. Most nuts (including nut butters and flours), sweet potatoes, carrots, celery, and MANY other paleo staples are extremely high in oxalates. I really suggest more study into this. I was very confused about why my health was declining so horribly when all of the research that I had done suggested that I was doing all the right things. And I’m not the only one, my friend (and a few of my doc’s other patients) also had health declines after going paleo with heart palpitations, adrenal fatigue, and carpal tunnel type symptoms. I feel that I am on the right track now eating paleo and low oxalate, but I wish there had been more information about this stuff on Robb’s site. I think it could have saved a lot of pain and anguish.
Stacy Lundblad says
Laurie, how is your mouth now? Curious did you also have issues of fizzures on the tongue, numbness in your liips and awful flora in your mouth that was not the proper saliva like normal and tight roof of mouth? I have been having this for over 2.5 years and just discovered low oxalates which is helpimg me greatly. Now the tongue is only like sand paper and grainy …is that oxalates> I had my organic acids test done and my oxalates were 164 HIGH.
thanks for your reply.
My mom has had burning mouth syndrome for over 10 years along with an autoimmune disease. Have you found any other ways to releve burning mouth.
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fay lee says
im a bit surprised by the fact you are taking nutrition because what you are saying goes against what every single academic book i have read on nutrition says…
1- cooking does not get rid of oxalates
2- sprouting does not get rid of phytates
could you elaborate on that please?
I was about to contribute to this discussion with a very similar remark. Recently I considered that perhaps these “anti-nutrients” are given a bad rap. Yes they limit bioavailability of certain micronutrients, but it is not as though copious amounts of these vitamins/minerals are necessary. We shouldnt absorb 100% of what we consume. The daily values can be met whether you eat paleo or not. What I am saying is, without phytate or oxalate we may be at risk to receive toxic amounts of the aforementioned nutrients.
The paleo diet has many things going for it, though I am reluctant to promote it as the diet people EVOLVED to eat. Everyone would benefit from from taking some of the Paleo theory into crafting their own diet, think eating a paleo meal or two per week. But I regard labeling something as an anti-nutrient is a sexy and misleading way to lure unsuspecting followers into an unnecessarily restricted lifestyle.
I am new to the paleo diet. I am somewhat confused because I have read that the paleo diet can cause Hemochromatosis because is the lack of phylic acid in the diet? And can cause appendicitis as well. How can I avoid these diseases on the paleo diet?
Hemochromatosis is a genetic condition, not something that eating a paleo diet would cause. I don’t see any reason why a paleo diet would cause appendicitis.
Brenda Debenham says
I have a hypothroid condition so I am pleased to see information regarding the goitrogens. I wonder if people who embark on large quantities of these plants can develop a temporary depressed thyroid and all the (depressing) symptoms. I look at Laurie’s post and wonder was she tested for this?
In my youth I ate the Mediterranean diet with gusto and developed a painful shoulder. after a year of allopathic guessing I went to a naturopath. It was suggested I give up the foods (temporarily – 3 weeks) that are in the deadly nightshade family and voila after 2 weeks the pain went away. I gently reintroduced these foods in my diet and my body no longer treats them as toxic. Variety is key to a balanced eating plan
Joseph Arvizzigno says
Just finished a lovely Raw Kale Salad with Red Onion &Orange Segments EVOO. Tasty Little bugger that is bullet proof when it comes to dressing.
According to “Paleoista” Nel Stephanson she mentioned you can couteract Goitergens with Kelp granules, and the Vit C in the Orange helps with Iron Absorbtion. Olive Oil helps gather fat soluble nutrients.
So technically there are work arounds yes??
Seems that Lectins are the ones everyone fears most which is why legumes and wheat are off the table.
China, the home of grain eating, (Rice) average life expectancy 75.2 years, Japan 83.10, USA 78.7, go figure. All your money all your science, all your don’t eat this and that, just beggars belief. USA would be better off eating grains, fruit and veg, and some meat and fat, ditch the franken foods added sugar, added seed oils, and denatured grains tax them to the limit, and use that tax to subsidise real food, instead of talking shit about who has the healthiest diet. Dunb arses.
Lectins are also an anti-nutrient. They are indigestible and can wreck havoc on our gastrointestinal system. Beans, legumes and whole grains are high in lectins and those who go on a lectin-free diet avoid them. Or some just soak them overnight and cook them thoroughly to get rid of them. I’ve read that here: https://gundrymd.com/what-are-lectins/ and if you want to know more about lectins and why we should avoid them too, I suggest you check it out.
Kim C. says
Please someone corroborate, but I believe I read that the antinutrients in these foods also protect the plants from other life forms, such as molds and fungi. It’s not just about not getting eaten by humans.
Robb Wolf says
Yes, that’s correct.