by Andy Gricevich, Newsletter Writer
Sometimes it seems like there’s a new dietary trend every time we sit down to a meal.
Have you noticed a profusion of diets focusing on the harmful effects of antinutrients? These compounds, naturally present in much of the food we eat, are being singled out as the root causes of many modern ailments. What are antinutrients, and why are they so dangerous, even in the healthiest of diets?
Unlike animals, which can hide, flee or attack when threatened, plants have had to develop subtler defenses against their natural predators. One such strategy involves the production of chemical compounds that can kill bacteria, fungi, and insects outright, and that will weaken and sicken larger animals over time. In general, they lock nutrients up into larger molecules that our digestive system can’t break down. That can starve us of essential minerals. Different antinutrients make this happen in different ways; the three most talked-about categories, each with its own potential for harm, are lectins, oxalates, and phytates.
As always, talk to your healthcare provider before making changes to your diet.
LECTINS
“Lectin-free” diets are all the rage these days, due in part to the popularity of Steven M. Gundry’s book The Plant Paradox. The term “lectins” covers a range of “sticky” proteins occurring in every living thing, many of them essential within their native organisms. The ones we’re told to watch out for are produced by plants, found especially in raw legumes (beans, lentils, soybeans, peanuts), whole grains, nuts and seeds, as well as the fruits we call vegetables (particularly tomatoes, cucumbers, peppers, and squash, where they’re concentrated most highly in the seeds and skin). We’ve all heard about the most famous lectin—gluten—but there are many more in some of what we often think of as the healthiest foods we can eat.
Lectins are very hard to digest. As they make their way through our digestive system, they stick to the walls of our small intestine and our gastrointestinal tract, where they’ll often hang around for a long time, binding with the phosphorus, calcium, iron, and zinc in our food and making it unavailable to our bodies. In addition, all lectins are “messengers” that tell other molecules how to behave—in this case, producing compounds that tell the tight inner lining of our gut wall to loosen up. This can lead to “leaky gut,” in which food materials and microbes that shouldn’t enter the bloodstream make it through, triggering an overaggressive immune system and leading to high long-term inflammation—a condition held responsible for a host of serious autoimmune disorders.
To make matters worse, lectins can also mimic the structure of other molecules. When they imitate our own gut tissue, our immune system, trying to eradicate the lectins, can lose the ability to distinguish between good and bad material, attacking the gut itself and damaging it further. Once lectins make it into the bloodstream and reach the brain, they can interfere with neural communications, leading to “brain fog.” That’s all in addition to the feelings of bloating and nausea that can accompany high lectin consumption.
On the other hand, plant lectins can also function as powerful antioxidants! They also slow digestion and absorption of carbohydrates, moderating spikes in blood sugar and evening out insulin production. Then there are the fiber and minerals in beans, or the valuable lycopene in tomatoes? Later, we’ll try to untie the knot of this paradoxical situation. For now, we’ll maintain suspense and look at our other main antinutrient categories.
OXALATES
Most plant foods contain some amount of oxalic acid, a compound also produced by our own bodies, which typically get rid of any excess in our urine. Plant-based oxalates bond easily with calcium, iron, and other minerals (as well as B vitamins), forming structures called oxalates. Oxalates can form larger crystals, and when they accumulate, they can become the basis for kidney stones. Additionally, recent research, based on extensive work on “oxalate poisoning” done in the latter half of the 19th century, has linked oxalate accumulation to fibromyalgia, lupus, glandular dysfunction, and some forms of autism. It appears that plant oxalates (oxalates in animal foods are no problem) worsen autoimmune conditions when they penetrate a damaged gut lining.
Here again, the list of foods with the highest oxalic acid concentration might seem shocking: spinach, beets and their greens, chard, sweet potatoes, almonds, and chocolate, among many others whose health benefits receive extensive praise. The oxalates in a raw spinach smoothie can actually make us unable to absorb the calcium so abundant in the greens! Does this mean we have to stop eating all these plants and get all our essential micronutrients from supplements? Again, we’ll try to clarify matters after visiting our third culprit.
PHYTATES
Phosphorus is an essential fuel for seeds when it comes time for them to sprout and begin growing a new plant. Nuts, beans, grains, and other seeds produce phytic acid (concentrated especially in their hulls), which holds onto phosphorus until it’s needed. Phytic acid, it turns out, is also excellent at holding onto calcium, magnesium, iron, copper, and zinc, among other nutrients, producing compounds known as phytates. Non-ruminant animals (like us) can experience harmful nutrient depletion when they eat a diet rich in these plant foods (ruminants have specialized digestive organs to break down phytates).
Conditions of poverty and certain dietary ideologies (like the Standard American Diet) typically feature a heavy dependence on grains and legumes. In such cultures, nutrient depletion can become a real problem (as it is in ours, with major shortages of magnesium in the diet). But aren’t beans supposed to be healthy? Should we switch to white flours (whether wheat-based or gluten-free), trading the benefits of whole grains for the reduction in phytic acid resulting from the milling process? What about the essential fatty acids found in nuts? If we dig a little deeper, we also find phytic acid credited for its antioxidant properties, destruction of tumors, and prevention of kidney stones. Are these superfoods, as we’ve been told, or supertoxins?
HOW TO KEEP EATING
There are other antinutrients we could touch on, including tannins, protease inhibitors, and glucosinolates—all found in some of the most nutrient-dense plant foods we typically consume. To stave off panic, though, let’s try to answer some fundamental questions. If you search for “antinutrients” online, you’re bound to find plenty of ideologically charged arguments for and against eating these foods (especially between Paleo devotees and vegans). Eventually, though, you can begin to find information that helps us understand why we seem to be so vulnerable now to the effects of antinutrients, how people have dealt with them in the past, and what we can do today.
We’ve been eating plant foods for a long, long time (though it’s significant that the foods highest in lectins have only been a major part of our diet since the relatively recent rise of agriculture). A healthy gut makes us much less vulnerable to the triggering of autoimmune conditions and other problems than one that’s already perforated and leaky. A healthy gut also means a healthy microbial population; our native bacteria have evolved to break down oxalates and phytates to a significant degree, and some of them can also handle lectins pretty well (for more on the microbiome, see my article in the December 2019 Reader issue). If we’re not frequently bombarding our systems with large doses of antinutrients, these microbes will multiply, increasing the resilience of our gut to their effects.
Unfortunately, most of us in the West probably have compromised guts, with microbial populations damaged by exposure to pesticides, herbicides, and other chemicals. Our microbes and our gut walls are further under attack by our standard dietary practices, with their heavy dependence on the grains and legumes highest in lectins and phytates, as well as an unprecedented lack of dietary variety. Pre-agricultural humans ate a much more varied diet, and both the food they ate and the ways they prepared it changed with the seasons. Even in the agricultural age, it’s only very recently that anyone could eat raw tomatoes with a salad in December.
Previously, we typically ate a diet rich in animal foods, with a significant plant component in which most species were only in prime condition for a short time; we’d then move on to something else. That meant we were only exposed to a given antinutrient in high concentrations for a short time, allowing us to benefit from its medicinal value before cleaning the rest of it from our bodies. The mineral-binding effects of antinutrients mostly don’t last very long; a high-oxalate breakfast won’t usually impede calcium absorption at dinner, and iron and zinc absorption has even been found to increase a week after a high-phytate meal. Many of our problems with antinutrients may be rooted in the loss of seasonality in our diet.
PREPARATIONS
Earlier humans didn’t just switch their diet up with the seasons. Like other animals, we learned how to reduce and compensate for antinutrients—but we have a wider range of tools available to do it. Cooking is the big one. After an early spring of eating raw greens, we learned to boil them briefly to reduce their oxalic acid content (we didn’t, of course, know oxalic acid by name, but we had plenty of time to observe its effects on our bodies, starting with the chalky feeling on our teeth after consuming greens). Oxalic acid isn’t water-soluble, but some of it precipitates into the cooking water, which can then be discarded. Later, we learned to soak beans and grains, ideally adding something alkaline (today, baking soda) before changing the water and boiling thoroughly. The result was improved digestibility, which—it turns out—is due to the deactivation of many of the lectins present in these foods (in the modern kitchen, a pressure cooker is by far the best cooking method for deactivating lectins). We’ve traditionally prepared peppers and tomatoes by removing skins and seeds, roasting and stewing, with similar effects on the biochemical level.
When the time comes to sprout (in the presence of warm water and, typically, slightly acidic soil), nuts and seeds produce phytase, a compound that shuts off the nutrient-binding capability of phytic acid, thereby releasing the phosphorus needed for growth. Humans learned to “trick” seeds into producing phytase by soaking them in water (often with a little added acid). This unlocks their valuable nutrients. In the case of grains, nuts, seeds, and legumes, sprouting further deactivates antinutrients.
Lacto-fermentation is by far the best method for mitigating, or entirely removing, the effects of many antinutrients. Making bread with a sourdough starter can result in a complete elimination of phytates. Fermenting soybeans in the form of tempeh or miso drastically reduces lectin content, and fermented vegetables feature much lower antinutrient contents than their raw forms. In contrast to the loss of some nutrients resulting from cooking, vegetable ferments are also still raw, with enhanced amounts of essential vitamins.
DO IT YOURSELF
Our modern food system has abandoned most of these traditional preparation techniques, but we can pick them back up pretty easily. It may take time, effort and skill to start a sourdough culture and bake our own bread, but it’s easy to soak beans and grains the night before we plan to cook them. It’s also not hard to learn what’s in season, and to change what we eat at different times of year in accordance with that knowledge. There’s abundant information out there as well about what to eat, or not eat, with certain foods, and much of it is pretty intuitive. Looking at traditional cuisines can tell us a lot here about food combinations.
For many people, home cooking feels like it takes too much time and planning. Even if we’re not preparing everything ourselves, we can maximize foods that promote gut health and avoid some commercially prepared foods that either skip essential preparation steps (like mass-produced bread products) or replace traditional staples with alternatives that turn out to be extremely high in antinutrients (examples include most gluten-free flours, as well as soy- or nut-based “dairy”).
All in all, the solutions depend on the state of your own health. How well do you digest grains and beans? Do you already have an autoimmune condition? What to eat, or not to eat—with exceptions—will depend on your own individual needs. Though there are universals here, everyone’s path to a nourished body will be a little different. They all, though, will return to some food traditions—chemical-free food, seasonality, and variety in both ingredients and preparations—that have made not only for healthy digestive and immune systems, but for cultures in which food is a foundational pleasure, rather than something we need to fear.