Irritable Bowel Syndrome and Digestive Health Support Forum banner
1 - 1 of 1 Posts

744 Posts
The Surprising, All-Natural Anti-Nutrients and Toxins in Plant Foods

Mother Nature puts anti-nutritional factors and toxins in grains, nuts, seeds and beans for a variety of reasons. Phytates, for example, block seeds from sprouting prematurely. Protease inhibitors, saponins, lectins and phytoestrogens harm insects, animals and other predators that would otherwise eat too many of them. If evolutionary theories are correct, wounded plants produce extra inhibitors and other anti-nutrients to save the plant species.

The idea is to cause predators-including plant-eating humans-to experience slowed growth and diminished reproductive ability.


Protease inhibitors inhibit some of the key enzymes that help us digest protein. The best known of these protease enzymes is trypsin. Most of the USDA studies performed over the years have looked at trypsin inhibitors in soybeans, but these anti-nutrients are also found in other beans, grains, nuts, seeds, vegetables of the nightshade family (potatoes, tomatoes and eggplant) and various fruits and vegetables.

Traditionally, few of these foods caused health problems because they were rarely eaten every day and because cooking deactivates most of the protease inhibitors. But given the growing tendency to fill up on plant foods, and the fashionability of al dente cooking and "live food" (raw) vegan diets, more and more people are eating foods with their protease inhibitor content intact. Proponents of plant-based diets generally believe their diets provide plenty of protein, but this premise fails to take into account the fact that protein swallowed is not the same as protein digested when protease inhibitors are in the picture. Without high-quality, usable protein, growth, repair, immunity, hormone formation and all metabolic processes will suffer.

The protease inhibitors in soybeans are not only more numerous than those found in other beans and foods, but more resistant to neutralization by cooking and processing. Only the old-fashioned fermentation techniques used to make miso, tempeh and natto come close to deactivating all of them. With all other cooking processes, some trypsin inhibitors remain. The levels of active protease inhibitors remaining in modern soy products vary widely from batch to batch, and investigators have found startlingly high levels in some soy formulas and soy protein concentrates.

Given the fact that heat deactivates the protease inhibitors in soy, and enough heat could dispatch all of them, the obvious solution would seem to be to cook the soybeans to death. Unfortunately, extra heating damages the structure of the essential amino acids methionine and lysine and in extreme cases damages the total protein so much that it is hard to digest, assimilate and utilize by the body. When modern food manufacturers use alkaline solutions to speed things up, the essential amino acid lysine can be turned into the toxic lysinoalanine. Even if food manufacturers made it a priority to cook soybeans just right, some protease inhibitors would be undercooked and others overcooked. Despite scores of USDA studies, no practical method of solving this problem has ever been devised. To this day, the only way to solve the protease inhibitor problem is old-fashioned fermentation.

Many people dismiss the protease inhibitor conundrum, saying that a few of them here and there don't pose a problem. That is undoubtedly true for people eating a richly varied omnivorous diet. But for soy formula-fed infants, vegetarians and others who eat soy every day, the numbers add up. Even the small quantities used as extenders in meat products, canned tuna, bakery goods and other ordinary supermarket and health food store products and fast foods can adversely affect people whose digestive capacities are already compromised by low hydrochloric acid levels, pancreatic insufficiency, bowel diseases, gluten intolerance and other health challenges.

Worse, the average American may be eating soy protein along with soy or corn oils, a deadly combination that has led to pancreatic cell proliferation and cancer in laboratory rats. Both these oils have been shown to initiate or fuel cancers, and because of a synergistic effect, the danger appears to be greatest when the combined intake is high. Soy protein, soy oil and corn oil are all familiar ingredients in processed supermarket foods as well as vegetarian "health foods."

The organ in greatest danger is the pancreas. When protease inhibitors keep the pancreas from producing enough trypsin and proteases, the body compensates by increasing the number of pancreatic cells (hyperplasia) and their size (hypertrophy). If this happens here and there, the pancreas rises to the challenge and then recovers. However, when the pancreas is stressed day after day, pancreatitis and even cancer become distinct possibilities. In the 1970s and 1980s, researchers studying protease-inhibitor damage to the pancreas noted that pancreatic cancer had moved up to fifth place as a cause of cancer death among humans, and wondered whether there might be a soybean-protease inhibitors connection. Recently pancreatic cancer moved up to fourth place as a cause of cancer deaths in men and women in the United States.


Phytates found in beans, grains and other seeds are anti-nutrients that block proper absorption of iron, zinc, calcium and other minerals. They are a leading cause of poor growth, anemia, immune system incompetence and other health woes in Third World countries where plant-based diets are the norm, and are increasingly a problem in First World countries where plant-based and vegan diets are widely considered chic and healthy.

In the plant kingdom, phytates serve two primary functions: they prevent premature germination and they store the phosphorous that plants need to grow. Phytates are valuable to humans because they allow us to store seeds safely over the winter, but a potential problem when we want to eat those seeds, grains and beans. The way phytates deactivate the life force is by binding tightly with minerals. In order for seeds to leave their dormant phase and begin to sprout and grow, they are planted in warm, moist, slightly acidic soil each spring. To eat grains, nuts, beans and other seeds, we are wise to do much the same by preparing them in a warm, moist and slightly acidic medium.

Advocates for plant-based diets often point out the high mineral content of their foods, but rarely take into account how phytate content might affect their assimilation of these minerals. Zinc is particularly affected. A component of more than three hundred enzymes, zinc affects every function in the body. Growth, immunity, wound healing, mental health, intelligence, digestion, blood sugar regulation , thyroid function, weight, sex hormones and skin are all adversely affected by zinc deficiency.

Iron loss through phytate blockage can lead to "iron-poor blood" and iron deficiency anemia, resulting in fatigue, lethargy, weakened immunity and learning disabilities. Iron deficiencies also affect the thyroid gland by reducing the output of thyroid hormone, which in turn leads to lower body temperature, lethargy and weight gain.

Calcium absorption, also adversely affected by phytates, is worsened when these foods are processed using alkaline chemicals. Claims that plant-based diets contain plenty of the calcium we need for bone building and other functions are seriously undercut when one considers the phytate content and modern processing methods. In products naturally low in calcium such as soy milk, manufacturers like to boast about added calcium while remaining mum about phytates. Finally, phytate-induced mineral deficiencies facilitate displacement of needed minerals by toxic metals, for examples, iron by lead and zinc by cadmium.

So what about the phosphorous that is essential for growth and bones? There's plenty of it in beans, grains and other seeds, but 50 to 75 percent of it's tied up in the phytates and not readily bioavailable.


Lectins are proteins with a "sweet tooth." Mother Nature created them to help bacteria fix atmospheric nitrogen into the roots of plants. That helps plants grow, and when the plants die makes them useful as fertilizers. Soybeans, for example, are high in lectins and have traditionally served as "green manure."

Found most heavily in beans, grains and other foods, lectins "bite" into carbohydrates, particularly sugars, and can cause "leaky gut," immune system reactions and blood clotting. Because they agglutinate blood-glue it up- lectins are also known as hemagglutins, hemagglutinins and phytohemagglutins.

Lectins really shouldn't be a problem in human nutrition. The enzymes present in fermented foods can take care of most lectins. So can heat processing and cooking. But those lectins that do not succumb are unlikely to be perturbed by normal digestive processes.

Unlike ordinary food proteins, lectins are not easily broken down by enzymes in the gut. At least 60 percent remain biologically active and immunologically intact, a combination that can represent a time bomb in the digestive tract. Lectins bind to the villi and crypt cells of the small intestine, where they can contribute to cell death, shortened villi, a diminished capacity for digestion and absorption, cell proliferation in the crypt cells, interference with hormone and growth factor signaling and unfavorable population shifts among the microbial flora.

Lectin damage is not confined to the gut. As the body attempts to maintain the integrity of the small intestinal lining at all costs, proteins that would ordinarily be used for normal growth and repair elsewhere may be appropriated instead for emergency repairs in the intestinal tract. Furthermore, lectins consumed with the diet may travel through the damaged "leaky gut" into general circulation, provoking allergic reactions and immune system disruption. Research to date suggests that lectins of both plant and microbial origin provoke allergic reactions in the gut, usually of the delayed hypersensitivity type IgG.

Lectins can also affect the gut by causing shifts in the gut flora, including overgrowth by E. coli, streptoccocus and lactobacillus bacteria. Although most of the studies were done with a toxic lectin from kidney beans known as PHA, other lectins act similarly, though less strongly.

Lectins gain strength in the company of other anti-nutrients such as protease inhibitors and saponins. Researchers at USDA and elsewhere who've tested lectins have found that the damage tends to be mild. Tested together, the damage is not simply additive but synergistic.

The biggest problem with lectins comes when people eat an insufficiently varied diet. In one study, rats put on rotation diets showed significantly less damage from lectins than rats fed soy proteins continuously. Because the rats did nearly as well with the rotation diet as they did on a steady diet of high quality, low-lectin feed, the take away message is for us to eat a richly varied diet and to reduce repeated exposure to all lectin-rich legumes, especially soybeans and kidney beans.

Infants fed soy formula and vegans who eat a lot of soy-based meat and dairy replacements do not experience sufficient variety in their diets and are especially vulnerable. In the average adult with "leaky gut" and other GI tract problems, lectin-rich foods are likely to be one factor among many, with cumulative damage coming from food allergies and intolerances, antibiotics, aspirin, ibuprofen and other NSAID drugs, heavy metal contamination, alcoholism and other factors.

Lectins are three to four times more likely to move into the bloodstream through the "leaky gut" than other food proteins, a fact that shows why maintaining the integrity of the gut lining is crucial to keeping undigested and partially digested food proteins, lectins and environmental toxins out of the bloodstream.


In soybeans, a toxic protein called "soyatoxin" causes clotting, just like lectins do. In mice, large doses have proved lethal, having caused breathing difficulties, convulsions and partial paralysis prior to death.


Saponins are bitter, biologically active components that foam up like soap suds in water. They are named after the soapwort plant (Saponaria), the root of which was used traditionally as a soap. Foods containing saponins include soybeans, chick peas and other beans, forage crops such as alfalfa, as well as other plants. Saponins contribute largely to the foam that rises to the top of the pot when you cook beans; this foam, which can taste quite bitter, should be carefully skimmed off.

Ingestion of saponins has been linked to poor growth and bloating in foraging animals, although it takes massive doses to create such problems.

The greater risk in humans would be to the mucosa of the intestines. This occurs because saponins bind with cholesterol, causing injuries that result in "leaky gut." This effect is probably weak, but allergens, lectins, gluten gliadin and other components wreak similar havoc, suggesting a cumulative risk. Not surprisingly, the cholesterol-binding effect may lead to the eventual marketing of saponins as all-natural cholesterol lowerers.

Saponins may also soon be promoted as "bile binders" for cancer prevention and reversal. The idea is that saponins bind with bile, and that bile acids poison the cells and so promote tumors. Reducing the absorption of bile through the cell membrane could make precancerous epithelial cell proliferation in the colon less likely.

The theory is that cancer cell membranes contain more cholesterol than normal cell membranes and saponins could bind more easily to them, thus triggering their destruction.The problem is destruction occurs in normal cells as well, albeit at lower levels. If that sounds like a reasonable trade off, consider the fact that "leaky gut" with its attendant malabsorption, dysbiosis and other problems increases cancer risk.

Saponins also break down red blood cells in a process known as hemolysis. This action is also weak, but the human body's ability to resist this type of damage decreases with age along with an age-related decline in the quality of red cell membranes. Another potential problem is the fact that saponins inhibit important enzymes such as succinate dehydrogenase, a key player in the citric acid cycle of the body, which must function properly if we are to properly absorb nutrients, heal and grow.

Digestive enzymes disturbed by saponins include trypsin and chymotrypsin, which are also adversely affected by protease inhibitors. Finally, saponins may be goitrogenic and spur enlargement of the thyroid. Saponins shouldn't take all the rap for thyroid disease, but given the fact that they tend to be found in plant foods that also contain isoflavones, coumestans, lignans, gossypol glycosides and other known goitrogens, we can't rule them out as a contributor to thyroid disease.

On a more positive note, saponins in spinach and oats may increase and accelerate the body's ability to absorb calcium and silicon. Boiling, steaming, sautéing and otherwise cooking foods won't have much effect on saponins, as it takes alcohol extraction to remove them. When the soybean is separated into oil and protein, the saponins stick with the protein, making them an unavoidable component in every soy product except soy oil and lecithin. Soy protein isolates contain the highest levels of saponins of any soy product.

The good news is old-fashioned fermented soy products have a much reduced saponin content as well as lower levels of protease inhibitors, phytates and other anti-nutrients. Aspergillus oryzae used in the fermentation of miso and soy sauce produces an enzyme known as soybean saponin hydrolase, which is capable of hydrolyzing soybean saponins. While it is true that saponins are metabolized by bacterial enzymes, this does not occur in the human body until they have scrubbed their way around the many twisting loops of the small intestine to arrive in the large intestine.


Oxalates are indigestible compounds in foods that prevent the proper absorption of calcium. Contrary to popular belief, oxalates are not significantly neutralized by cooking. The foods highest in oxalates are soy protein, spinach and rhubarb. Years ago, these rarely posed a problem because soy protein isolate had yet to be invented, and few people other than Popeye ate much spinach. Fewer still ever ate rhubarb. Many health conscious people now eat a gigantic spinach salad every day, thinking it's the ticket to good health. Instead, it can be a ticket to kidney stones, vulvodynia and other oxalate-related health problems.

Other oxalate-containing foods likely to be eaten to excess are peanuts and chocolate. Given that these popular and addictive foods can represent whole food groups to vegans, caution is warranted. Although studies on rice, wheat, rye and soy indicate that phytates cause more calcium binding than oxalates, such foods are high in both anti-nutrients. Increased calcium excretion and increased oxalic acid excretion ride tandem and have been linked to osteoporosis.


"When in doubt, eat fruits and veggies." Might seem like good advice except for the fact that fruits and vegetables are not only high in carbs but also contain all-natural phytochemicals known as salicylates. As with other plant foods that bite back, salicylates evolved to fight predators. And organic fruits and vegetables seem to have more of them.

These are not-too-distant chemical cousins of the salicylates found in hundreds of over-the-counter (OTC) medications and prescription drugs used to relieve minor aches and pains, reduce fever and inflammation, thin the blood, dry up diarrhea and treat skin conditions such as acne, warts and psoriasis. The most famous OTC members of the salicylate family are aspirin (acetylsalicylic acid), Ben Gay (methyl salicylate), Pepto Bismol (bismuth subsalicylate) and Doan's (magnesium salicylate). Salicylates are also increasingly found in alternative medicines and Chinese herbs, particularly topical oils.

Many people today are so salicylate intolerant that they experience adverse reactions not only to drugs but also to salicylate-rich foods like fruits and vegetables. Reactions are caused when arachidonic acid is tripped into the inflammatory chemicals called leukotrienes, causing dilated blood vessels, constricted bronchial passages and mucus production.84 In addition to experiencing allergy-like symptoms, people sensitive to salicylates may suffer from asthma, hives, nasal polyps, chronic swelling and a wide variety of gastrointestinal symptoms, including irritable bowel.

Although individuals prone to inflammatory responses are typically advised to cut out meat and other foods rich in arachidonic acid, the surprising culprit for some health conscious individuals might be fruits and vegetables. Researchers in Scotland who tested vegetarians versus non-vegetarians found much higher levels of salicylates in the vegetarians' urine, though considerably less than subjects taking aspirin.

Most people can handle average amounts of salicylate in food, products and medications without adverse health effects. People with salicylate intolerance, however, are unable to handle more than a certain amount of salicylates at a time. The amount varies from person to person. Salicylates also have a cumulative effect in the body and build up over time. Thus some people may feel great when they first start a raw vegan diet with lots of juicing, only to later develop salicylate intolerance.

The levels of salicylates found in food can vary greatly, with raw foods and dried foods containing higher levels than the same cooked foods. But cooked foods concentrate salicylates in products such as sauces, purées and syrups. People who are salicylate sensitive may find it helpful to peel fruits thickly (so as to cut off areas just under the skin) and to throw away the outer leaves of vegetables. It is also crucial to eat only fruits and vegetables that have been allowed to ripen.

Fruits high in salicylates include all dried fruits and most berries, including the blueberries we're all told to eat because they are a "superfood." Cherries, oranges, pineapples, plums, grapes, peaches, nectarines, watermelon, cantaloupe, grapefruit and most varieties of apples pose problems for salicylate sufferers. Indeed the only fruits low in salicylates are banana, lime, pear, golden delicious apples and papayas.

Vegetables high in salicylates include cooked tomatoes, chili peppers, water chestnut, alfalfa sprouts, broccoli, cucumber, eggplant, spinach, sweet potato and zucchini. Moderate levels are found in asparagus, beets, carrots, potatoes and mushrooms. Sadly very high levels of salicylates are found in coconut oil, a fact that might explain why some people seem to be allergic to this otherwise healthy oil. Olive, sesame and walnut oils are also high in salicylates. The good news is that there are negligible amounts in butter. For an extensive Food Guide, visit

An elimination diet accompanied by a food diary is the best way to determine whether salicylates are causing any health problems. To do this, avoid any medications containing salicylates and limit the diet to foods that either do not contain salicylate or are very low in salicylates for a month to six weeks. Once the body has cleared any stored salicylate, symptoms will abate if, in fact, you are salicylate intolerant. Although strict avoidance is generally recommended, researchers have shown that fish oil can reduce salicylate sensitivity;90 cod liver oil with its needed vitamins A and D should work even better.


In conclusion, the plant world has marshaled a formidable army of anti-nutrients and toxins, programmed to kill predators-including human plant eaters-through phytochemical warfare. These can contribute to malnutrition, digestive distress, thyroid disorders, immune system breakdown, infertility, autism, ADD, ADHD, allergies and even heart disease and cancer.

Proponents of plant-based diets claim that the evidence against protease inhibitors, phytates, saponins and other plant toxins is exaggerated, inconclusive and irrelevant to humans because so much of it has been done in animals. While the evidence against any single anti-nutrient might not be conclusive, it is important to remember that anti-nutrients and toxins rarely appear singly but in combination. Foods that contain protease inhibitors, for example, tend to contain lectins and saponins. Foods rich in salicylates might also be nightshades. Sorry to say, but phytochemical damage is not just additive but synergistic. And the evidence is substantial and relevant to all mammals, including the human mammal.

Adding to the potential damage, five additional categories of antinutrients and non-nutrients pose risks. Gluten has wreaked so much havoc on guts and brains that "gluten free" is a buzz word in the health world and a booming new industry. Goitrogens block the synthesis and utilization of thyroid hormones, leading to an epidemic of thyroid dysfunction. Oligosaccharides are the pesky gas-producing sugars that give beans their reputation as "musical fruits." Fiber, an indigestible and non-nutritive element, which although "everyone knows" is somehow good for us, can wreak havoc on digestive capability, gut health, immunity and brain function. Phytoestrogens (plant estrogens) include isoflavones, coumestans and lignans; they are found in quantity in such popular "health foods" as soybeans, alfalfa and clover sprouts, and flaxseeds. Although not the same as true mammalian hormones, they are close enough to fool the body and cause significant endocrine disruption.



Interestingly enough, phytates do have benefits. Many alternative MDs and other health care practitioners recommend them for detoxification because of their ability to bind not only with needed minerals such as zinc and calcium, but also unwanted toxic metals such as cadmium and lead. To date, most of the research has centered on phytates as a chelators of excess iron. Unusable iron causes oxidizing, a form of "rusting" in the body.

When phytates grab this iron and usher it out of the body, they serve as "antioxidants" against cancer, heart disease, diabetes and neurogenerative diseases such as Alzheimer's, ALS and Parkinson's. Keep in mind that toxic iron loads do not come from eating meat, which is rich in the absorbable, useful form known as heme iron, but from the non-heme iron in "enriched" flour, cereals, fortified soy foods, and most vitamin and mineral supplements. Synthetic, inorganic non-heme iron is poorly utilized and accumulates in the body, contributing to numerous diseases. Men begin accumulating non-heme forms of iron shortly after puberty. Women rarely start accumulating it until they stop menstruating.

The best attitude to take regarding phytates is to recognize both their dangers and benefits.


As incompatible lectins cause the immune system to react and overreact, the stage is set for autoimmune diseases. "Leaky gut" correlates with numerous disorders, including food and environmental allergies; bowel problems such as IBS, Crohn's disease and celiac disease; inflammatory joint diseases such as rheumatoid arthritis; dermatological disease such as psoriasis, and many forms of cancer.

A healthy body with full digestive and assimilative capabilities is capable of handling a variety of food lectins provided the gut is healthy. Sadly, regular assaults by large servings of lectin-rich soybeans, kidney beans, wheat or other foods will breach the integrity of the intestinal lining, allowing lectins and incompletely digested food proteins and other toxins to move into the blood stream. These people often do better when they eat according to their type, although a better method might be to dump plant-based diets rich in lectins and other gut harming anti-nutrients and take steps to heal the gut.

Just going off wheat has tremendous benefit for most Americans. In addition to the wheat germ lectin, wheat contains gluten, which can bite into the human intestinal mucous lining much like lectins. Indeed, ever increasing amounts of wheat and gluten in the modern diet have been associated with rising rates of a gut disorder known as celiac disease.

Whether it's high levels of lectins found "on occasion" or low levels found in foods eaten in large quantities on a regular basis, lectins hold the potential to cause health problems.

That said, those who eat rich and varied omnivorous diets will probably not have problems from lectins, provided they go easy on the soybeans, kidney beans and other legumes, avoid wheat and heal the gut with broth, cultured foods and other foods recommended on a nourishing traditional diet.
1 - 1 of 1 Posts