By John McDougall
Plants have evolved to synthesize a variety of toxic substances to cope with their environment abundant with predators (insects, animals, etc.) and microbes (bacteria, viruses, fungi, parasites, etc.) and, thereby, fight an ongoing battle for survival. Lectins are a class of these natural disease-fighters consisting of proteins. Ubiquitously found in the plant kingdom these precisely synthesized proteins (lectins) combine with specific sugars (such as those on the surface red blood cells). (The word “lectin” is derived from Latin—”Legree,” which means to pick or select.)
The first such carbohydrate-binding proteins, lectins, were found in 1888 in the seeds of the castor bean. Lectins have gained the most attention since their discovery as a result of their ability to bind to and agglutinate (clump together) red blood cells, and have been used for blood typing (ABO classification and others); hence the lectins are also commonly called “hemagglutinins.”
Common dietary staples, such as cereal grains, legumes, and fruits have relatively high concentrations of a variety of different lectins. Although all foods contain some lectins, only about 30% of the foods we eat have potentially troublesome amounts. Legumes (including beans, soybeans and peanuts) and grains (wheat is commonly singled out) have the greatest content, followed by dairy, seafood, and plants in the nightshade family (such as potatoes).
The toxicity of lectins to people (and other animals) can vary greatly, ranging from merely anti-nutritional properties (such as producing excess bowel gas) to lethal effects. An important example of a highly toxic lectin is the phytohemagglutinin (PHA). It is found in the highest concentrations in uncooked red kidney beans and white kidney beans (also known as cannellini), and it is also found in lower quantities in green beans, broad beans (fava beans), and other common beans. Especially when consumed raw, all beans can uncomfortably affect the digestive tract, commonly with an over abundance of gas; however, vomiting, cramping, and diarrhea are experienced; fortunately, rarely requiring hospitalization.
A Little Truth Turns into Deadly Lies
The exaggeration of the frequency and severity of adverse reactions to lectins has caused these foods (grains, beans, and most other plant foods) to be deemed the major dietary issues underlying most chronic human illnesses. As expected, this has brought about the popularity of a variety of “low-lectin diet plans.” Translated into the foods on your plate, lowering lectins. according to these plans means, avoiding wheat, rice, corn, potatoes, all beans; and to instead to obtaining daily calories from the two major categories of food poisons: animals and vegetable oils. The ultimate outcome of asking people to seek health by “lectin-avoidance” soon means overweight and obesity; and not long afterwards, diabetes; heart attacks; arthritis; cancer of the breast, colon, and prostate; and much more pain and suffering.
Thus, this pathway of abstaining from lectin-containing foods (grains, beans, and potatoes) circuitously kills people, by recommending for them to instead eat the only remaining foods: animals and vegetable oils. The basic fallacy has so far resulted in at least two best-selling, “low-carb-leaning” diet books: Dr. Gundry’s Diet Evolution: Turn Off the Genes That Are Killing You—and Your Waistline—and Drop the Weight for Good, and Eat Right for Your Type: The Individualized Blood Type Diet Solution (based on how different ABO blood types react differently with the various specific protein lectins in commonly consumed foods).
This distracting nutritional nonsense also contributes to the real possibility of total species extinction for Planet Earth; Similar to how misinformation widely spread by two popular theories: 1) the gluten- and 2) GMO-containing-foods are our greatest threats to health. The “anti-lectin” diet joins the gluten– and the GMO– dogma to distract billions of people from recognizing the true sources of chronic epidemic human diseases and rapid destruction of Planet Earth: the livestock industries.
Lectins in Plants Are Very Healthful
While the various kinds of lectins cause different negative reactions (mostly minor in consequence), there are also health-promoting effects from these proteins that can decrease the incidence of epidemic deadly diseases. Live human population research and within the laboratory setting investigations demonstrate that lectins have protective effects against viruses and other microorganisms, and are potent modulators of immune responses, cell growth, and healing, and can cause cancer regression.
High Lectin-containing Starches Promote a Healthy Life
* A recent review (2012) of 45 prospective cohort studies and 21 randomized-controlled trials (RCT) compared people who rarely or never consume whole grains with those reporting an average consumption of three to five servings per day, and found by comprehensive meta-analysis that those consuming the grains had a 26% reduction in the risk of type-2 diabetes and a 21% reduction in the risk of heart disease (independent of known CVD risk factors). Furthermore, there is an inverse relationship between whole grain intake and weight gain. Examples of whole grains included whole wheat, dark bread, oats, brown rice, rye, barley, and bulgur.
* Whole Grains—Summary of American Society for Nutrition 2010 Satellite Symposium concluded, “There is consistent epidemiological evidence that whole grain foods substantially lower the risk of chronic diseases such as CHD, diabetes, and cancer, and also play a role in body weight management and digestive health.”
* The Journal of Cereal Science in 2014 reported their review on the health effects of dietary lectins: “… as consumed in cooked, baked, or extruded foods do not support negative health effects in humans. In contrast, consumption of WGA (wheat germ agglutinin) containing foods, such as cereals and whole-grain products, has been shown to be associated with significantly reduced risks of type 2 diabetes, cardiovascular disease, some types of cancer, as well as a more favorable long-term weight management… Despite numerous speculative assumptions that wheat germ lectins cause intestinal damage and disease, there is at present neither evidence that this is the case nor reason to recommend the healthy population to abstain from whole-grain food products.”
The same review concluded, “Hitherto, the consumption of most whole-grain foods prepared for human consumption (cooked, baked, extruded) has been associated with numerous health benefits. It is therefore recognized and advised to consume breakfast cereals and a variety of whole-grain foods. Although this advice is contradicted by some health professionals based on their lectin contents, it can be concluded from the current available scientific evidence that there are no data to generalize this negative opinion to consumption of whole grain products.”
* Lectins have also drawn a lot of attention because of their possible anti-tumor activities. The anti-tumor activities of different plant lectins has been shown for several cancer cell cultures, such as, human hepatocarcinoma cells, human bladder cancer cells, human melanoma cells, and rat pancreatic cells. It has also been suggested that some lectins induce apoptosis (death) and/or autophagy (eating and destroying) of cancer cells.
* Based on the existing evidence, there are four consensus authoritative statements from national organizations, namely the U.S. FDA, the U.K. Joint Health Claims Initiative, and the Sweden and Danish Dietary Recommendations that link consumption of whole grains with improved heart health. For example, U.K. products composed of whole grains can claim, “People with a healthy heart tend to eat more whole grain foods as part of a healthy lifestyle.” In Sweden, products with at least 50% whole grains can state, “A healthy lifestyle and a balanced diet rich in whole-grain products reduce the risk of heart disease.”
Note: Lectins are not gluten proteins and should not be confused with them. Gluten intolerance is uncommon (fewer than one in a hundred people) but very important for those who have celiac disease.
Lectins Are Health-promoting, Not Health-harming
The healthfulness of plants, especially grains and beans, must be considered when planning a starch-based diet. But at the same time, the risk of adverse side effects, even as common as little as extra bowel gas (flatus), must be minimized for enhancing the popularity and consumption of these important food groups. Research shows that by cooking (at temperatures above 176 F or 80 C), soaking (for 12 hours in water), sprouting, and/or fermenting foods that are high in lectins can easily reduce their lectin content to negligible amounts. My August 2002 McDougall Newsletter will teach you plenty about taming bad cramps and reducing socially unpopular gas.