Are Lectins in Food Good or Bad for You?

Might lectins help explain why those who eat more beans and whole grains have less cancer?

Lectins are to blame for the great “white kidney bean incident” of 2006 in Japan. One Saturday evening, a TV program introduced a new method to lose weight. The method was simple: toast some dry, raw, white kidney beans in a frying pan for three minutes, grind the beans into a powder, and then dust it onto rice. Within days, a thousand people fell ill, some with such severe diarrhea and vomiting they ended up in the hospital. Why? Lectin poisoning. Three minutes of dry heat is not enough to destroy the toxic lectins in kidney beans. If you don’t presoak them, you need to boil large kidney beans for a full hour to completely destroy all the lectins, though if you first soak them overnight 98 percent of the lectins are gone after boiling for just 15 minutes and all are gone by half an hour, as you can see at 0:44 in my video Are Lectins in Food Good or Bad for You?. And, indeed, when researchers tested the white beans, they found that toasting them for three minutes didn’t do a thing. It’s no wonder people got sick. But, 95 percent of the lectins were inactivated after boiling them for three minutes and completely inactivated after ten minutes of boiling. Evidently, “‘Do not eat raw beans’ is a traditional admonition in Japan to prevent intestinal problems”—and now we know why.

While canning may completely eliminate lectins from most canned beans, some residual lectin activity may remain in canned kidney beans, though apparently not enough to result in toxicity. And, ironically, “How doses of lectins may be beneficial by stimulating gut function, limiting tumor growth, and ameliorating obesity.” What? I thought lectins were toxic.

For as long as people have speculated dietary lectins are harmful, others have conjectured that they may be protective. “If this theory is correct, appropriate lectins by mouth should be of use in the prophylaxis [prevention] (and possibly treatment) of colon cancer.” Or, of course, we could just eat our beans.

Interest in the purported antitumor effect of plant lectins started with the discovery in 1963 that lectins could distinguish between cancer cells and normal cells. Researchers at Massachusetts General Hospital found a substance in wheat germ—the lectin in whole wheat—that appeared to be “tumor cell specific,” clumping together the tumor cells, while the normal cells were left almost completely alone. In fact, it is so specific that you can take a stool sample from someone and, based on lectin binding to the colon lining cells that get sloughed off into the feces, effectively predict the presence of polyps and cancers.

Subsequently, it was discovered that lectins couldn’t only distinguish between the two types of cells, but also extinguish the cancer cells, while largely leaving the normal cells alone. For example, that same white kidney bean lectin, as you can see at 2:53 in my video, was found to almost completely suppress the growth of human head and neck cancer cells, liver cancer cells, breast cancer cells, and cervical cancer cells (at least most of the way), within about three days—but that was in a petri dish. Those petri dish studies are largely the basis of the evidence for the antitumor activity of plant lectins. How do we even know dietary lectins are absorbed into our body?

Colorectal cancer is one thing. The fact that lectins can kill off colon cancer cells in a petri dish may be applicable, since lectins we eat may come in direct contact with cancerous or precancerous cells in our colon, “providing a mechanism” by which bean consumption may help in “the prevention and treatment of colorectal cancer.” Even more exciting is the potential for effectively rehabilitating cancer cells. The “loss of differentiation and invasion are the histological hallmarks of malignant cells,” meaning that when a normal cell transforms into a cancer cell, it tends to lose its specialized function. Breast cancer cells become less breast-like, and colon cancer cells become less colon-like. What these researchers showed—for the first time—is that the lectin in fava beans could take colon cancer cells and turn them back into looking more like normal cells. As you can see at 4:13 in my video, before exposure to the fava bean lectins, the cancer cells were growing in amorphous clumps. But, after exposure to the fava bean lectins for two weeks, those same cancer cells started to go back to growing glandular structures like normal colon issue. Therefore, dietary lectins or putting them in a pill “may slow the progression of colon cancer,” potentially helping to explain why dietary consumption of beans, split peas, chickpeas, and lentils appears to reduce the risk of colorectal cancer based on 14 studies involving nearly two million participants. Okay, but what about cancers outside of the digestive tract?

“Although lectin containing foods,” like beans and whole grains, “are frequently consumed cooked or otherwise processed, these treatments may not always inactivate the lectins…For example, lectins have been detected in roasted peanuts….” Peanuts are legumes, and we don’t tend to eat them boiled but just roasted or even raw. Are we able to absorb the lectins into our system? Yes. As you can see at 5:12 in my video, within an hour of consumption of raw or roasted peanuts, you can detect the peanut lectin in the bloodstream of most people. Same with tomatoes. Some of the non-toxic lectin in tomatoes also makes it down into our gut and into our blood. Wheat germ agglutinin, the wheat lectin known as WGA, doesn’t seem to make it into our bloodstream, though, even after apparently eating the equivalent amount of wheat germ in more than 80 slices of bread. And, if you ate something like pasta, the boiling in the cooking process might wipe out the lectin in the first place anyway.

In terms of phytochemicals in the fight against cancer, lectins are able to “resist digestion resulting in high bioavailability,” potentially allowing “the cellular mechanisms of the host to utilize the full potential of the…dramatic anti-cancer benefits” lectins have to offer. But, these dramatic benefits have yet to be demonstrated in people. We do know, however, that population studies show “that the consumption of a plant-based diet is strongly associated with a reduced risk of developing certain types of cancer.” People eating a plant-based diet could just be eating fewer carcinogens, but plants do have all those active components that do seem to protect against the “initiation, promotion, or progression” of cancer. So, maybe lectins are one of those protective compounds. We know people who eat more beans and whole grains tend to get less cancer overall, but we’re just not sure exactly why. Now, you could say, “Who cares why?” Well, Big Pharma cares. You can’t make as much money on healthy foods as you can on “lectin based drugs.”

Interested in learning more about lectins? Check out my videos Dr. Gundry’s The Plant Paradox Is Wrong and How to Avoid Lectin Poisoning.


Lectins remind me of the story about phytates. Other components of beans and whole grains, phytates were thought at first to be harmful, but, more recently, evidence is coming to light that suggests the opposite may be true. Check out Phytates for Rehabilitating Cancer Cells and Phytates for the Prevention of Osteoporosis.

What else may explain the protective effect of beans? See, for example, Gut Dysbiosis: Starving Our Microbial Self. Soybeans may be particularly protective against certain cancers, as you can see in BRCA Breast Cancer Genes and Soy.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Do the Pros of Brown Rice Outweigh the Cons of Arsenic?

Are there unique benefits to brown rice that would justify keeping it in our diet despite the arsenic content?

For years, warnings had been given about the arsenic levels in U.S. rice potentially increasing cancer risk, but it had never been put to the test until a study out of Harvard. The finding? “Long-term consumption of total rice, white rice or brown rice[,] was not associated with risk of developing cancer in US men and women.” This was heralded as good news. Indeed, no increased cancer risk found even among those eating five or more servings of rice per week. But, wait a second: Brown rice is a whole grain, a whole plant food. Shouldn’t brown rice be protective and not just neutral? I discuss this in my video Do the Pros of Brown Rice Outweigh the Cons of Arsenic?.

If you look at whole grains in general, there is “a significant inverse”—or protective—“association between total whole-grain intake and risk of mortality from total cancers,” that is, dying from cancer. My Daily Dozen recommendation of at least three servings of whole grains a day was associated with a 10 percent lower risk of dying from cancer, a 25 percent lower risk of dying from heart attacks or strokes, and a 17 percent lower risk of dying prematurely across the board, whereas rice consumption in general was not associated with mortality and was not found to be protective against heart disease or stroke. So, maybe this lack of protection means that the arsenic in rice is increasing disease risk, so much so that it’s cancelling out some of the benefits of whole-grain brown rice.

Consumer Reports suggested moderating one’s intake of even brown rice, but, given the arsenic problem, is there any reason we should go out of our way to retain any rice in our diet at all? With all of the other whole grain options out there, should we just skip the rice completely? Or, are there some unique benefits we can get from rice that would justify continuing to eat it, even though it has ten times more arsenic than other grains?

One study showed that “a brown rice based vegan diet” beat out the conventional Diabetes Association diet, even after adjusting for the extra belly fat lost by the subjects on the vegan diet, but that may have been due to the plant-based nature of their diet rather than just how brown rice-based it was.

Another study found a profound improvement in insulin levels after just five days eating brown rice compared to white rice, but was that just because the white rice made people worse? No, the brown rice improved things on its own, but the study was done with a South Indian population eating a lot of white rice to begin with, so this may have indeed been at least in part a substitution effect. And yet another study showed that instructing people to eat about a cup of brown rice a day “could significantly reduce weight, waist and hip circumference, BMI, Diastole blood pressure,” and inflammation—and not just because it was compared to white. However, a larger, longer study failed to see much more than a blood pressure benefit, which was almost as impressive in the white-rice group, so, overall, not too much to write home about.

Then, another study rolled around—probably the single most important study on the pro-rice sideshowing a significant improvement in artery function after eight weeks of eating about a daily cup of brown rice, but not white, as you can see at 3:18 in my video, and sometimes even acutely. If you give someone a meal with saturated fat and white rice, you can get a drop in artery function within an hour of consumption if you have some obesity-related metabolic derangements. But, if you give brown rice instead of white, artery function appears protected against the adverse effects of the meal. Okay, so brown rice does show benefits in interventional studies, but the question is whether it shows unique benefits. Instead, what about oatmeal or whole wheat?

Well, first, researchers needed to design an artery-crippling meal, high in saturated fat. They went with a Haagen Daaz, coconut cream, and egg milkshake given with a bowl of oatmeal or “a comparable bowl of whole rolled wheat.” What do you think happened? Do you think these whole grains blocked the artery-damaging effects like the brown rice did? The whole oats worked, but the whole wheat did not. So, one could argue that brown rice may have an edge over whole wheat. Do oats also have that beneficial long-term effect that brown rice did? The benefit was of a similar magnitude but did not reach statistical significance.

So, what’s the bottom line? Until we know more, my current thinking on the matter is that if you really like rice, you can moderate your risk by cutting down, choosing lower arsenic varieties, and cooking it in a way to lower exposure even further. But, if you like other whole grains just as much and don’t really care if you have rice versus quinoa or another grain, I’d choose the lower arsenic option.

Tada! Done with arsenic in the food supply—for now. Should the situation change, I’ll produce another video on the latest news. Make sure you’re subscribed so you don’t miss any updates.


Here are all 13 videos in the series, in case you missed any or want to go back and review:

And you may be interested in Benefits of Turmeric for Arsenic Exposure.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

What White Blood Cell Count Should We Shoot for?

At the start of my video What Does a Low White Blood Cell Count Mean?, you can see what it looks like when you take a drop of blood, smear it between two pieces of glass, and view at it under a microscope: a whole bunch of little, round, red blood cells and a few big, white blood cells. Red blood cells carry oxygen, while white blood cells are our immune system’s foot soldiers. We may churn out 50 billion new white blood cells a day. In response to inflammation or infection, that number can shoot up to a 100 billion or more. In fact, pus is largely composed of: millions and millions of white blood cells.

Testing to find out how many white blood cells we have at any given time is one of the most common laboratory tests doctors order. It’s ordered it hundreds of millions of times a year. If, for example, you end up in the emergency room with abdominal pain, having a white blood cell count above about 10 billion per quart of blood may be a sign you have appendicitis. Most Americans fall between 4.5 and 10, but most Americans are unhealthy. Just because 4.5 to 10 is typical doesn’t mean it’s ideal. It’s like having a “normal” cholesterol level in a society where it’s normal to die of heart disease, our number-one killer. The average American is overweight, so if your weight is “normal,” that’s actually a bad thing.

In fact, having excess fat itself causes inflammation within the body, so it’s no surprise that those who are obese walk around with two billion more white cells per quart of blood. Given that, perhaps obese individuals should have their own “normal” values. As you can see at 2:06 in my video, if someone with a 47-inch waist walks into the ER with a white blood cell count of 12, 13, or even 14, they may not have appendicitis or an infection. That may just be their normal baseline level, given all the inflammation they have in their body from the excess fat. So, normal levels are not necessarily healthy levels.

It’s like smoking. As you can see at 2:31 in my video, if you test identical twins and one smokes but the other doesn’t, the smoker is going to end up with a significantly higher white cell count. In Japan, for example, as smoking rates have steadily dropped, so has the normal white count range. In fact, it’s dropped such that about 8 percent of men who have never smoked would now be flagged as having abnormally low white counts if you used a cut-off of 4. But, when that cut-off of 4 was set, most people were smoking. So, maybe 3 would be a better lower limit. The inflammation caused by smoking may actually be one of the reasons cigarettes increase the risk of heart attacks, strokes, and other inflammatory diseases. So, do people who have lower white counts have less heart disease, cancer, and overall mortality? Yes, yes, and yes. People with lower white blood cell counts live longer. Even within the normal range, every one point drop may be associated with a 20 percent drop in the risk of premature death.

As you can see at 3:39 in my video, there is an exponential increase in risk in men as white count goes up, even within the so-called normal range, and the same is found for women. The white blood cell count is a “stable, well-standardized, widely available and inexpensive measure of systemic inflammation.” In one study, half of the women around 85 years of age who had started out with white counts under 5.6 were still alive, whereas 80 percent of those who started out over 7 were dead, as you can see at 4:05 in my video—and white blood cell counts of 7, 8, 9, or even 10 would be considered normal. Being at the high end of the normal range may place one at three times the risk of dying from heart disease compared to being at the lower end.

The same link has been found for African-American men and women, found for those in middle age, found at age 75, found at age 85, and found even in our 20s and 30s: a 17 percent increase in coronary artery disease incidence for each single point higher.

As you can see at 5:00 in my video, the higher your white count, the worse your arterial function may be and the stiffer your arteries may be, so it’s no wonder white blood cell count is a useful predictor of high blood pressure and artery disease in your heart, brain, legs, and neck. Even diabetes? Yes, even diabetes, based on a compilation of 20 different studies. In fact, it may be associated with everything from fatty liver disease to having an enlarged prostate. And, having a higher white blood cell count is also associated with an increased risk of dying from cancer. So, what would the ideal range be? I cover that in my video What Is the Ideal White Blood Cell Count?.

A higher white blood cell count may be an important predictor for cardiovascular disease incidence and mortality, decline in lung function, cancer mortality, all-cause mortality, heart attacks, strokes, and premature death in general. This is no surprise, as the number of white blood cells we have circulating in our bloodstreams are a marker of systemic inflammation. Our bodies produce more white blood cells day to day in response to inflammatory insults.

We’ve known about this link between higher white counts and heart attacks since the 1970s, when we found that higher heart attack risk was associated with higher white blood cell counts, higher cholesterol levels, and higher blood pressures, as you can see at 0:53 in my video What Is the Ideal White Blood Cell Count?. This has been found in nearly every study done since then. There are decades of studies involving hundreds of thousands of patients showing dramatically higher mortality rates in those with higher white counts. But why? Why does white blood cell count predict mortality? It may be because it’s a marker of inflammation and oxidation in the body. In fact, it may even be a biomarker for how fast we are aging. It may be more than just an indicator of inflammation—it may also be an active player, contributing directly to disease via a variety of mechanisms, including the actual obstruction of blood flow.

The average diameter of a white blood cell is about seven and a half micrometers, whereas our tiniest vessels are only about five micrometers wide, so the white blood cell has to squish down into a sausage shape in order to squeeze through. When there’s inflammation present, these cells can get sticky. As you can see at 2:20 in my video, a white blood cell may plug up a vessel as it exits a small artery and tries to squeeze into a capillary, slowing down or even momentarily stopping blood flow. And, if it gets stuck there, it can end up releasing all of its internal weaponry, which is normally reserved for microbial invaders, and damage our blood vessels. This may be why in the days leading up to a stroke or heart attack, you may find a spike in the white cell count.

Whether white count is just a marker of inflammation or an active participant, it’s better to be on the low side. How can we reduce the level of inflammation in our body? Staying away from even second-hand smoke can help drop your white count about half of a point. Those who exercise also appear to have an advantage, but you don’t know if it’s cause and effect unless you put it to the test. In one study, two months of Zumba classes—just one or two hours a week—led to about a point and a half drop in white count. In fact, that may be one of the reasons exercise is so protective. But is that just because they lost weight?

Fitness and fatness both appear to play a role. More than half of obese persons with low fitness—51.5 percent—have white counts above 6.6, but those who are more fit or who have less fat are less likely to have counts that high, as you can see at 3:47 in my video. Of course, that could just be because exercisers and leaner individuals are eating healthier, less inflammatory diets. How do we know excess body fat itself increases inflammation, increases the white count? You’d have to find some way to get people to lose weight without changing their diet or exercise habit. How’s that possible? Liposuction. If you suck about a quart of fat out of people, you can significantly drop their white count by about a point. Perhaps this should get us to rethink the so-called normal reference range for white blood cell counts. Indeed, maybe we should revise it downward, like we’ve done for cholesterol and triglycerides.

Until now, we’ve based normal values on people who might be harboring significant background inflammatory disease. But, if we restrict it to those with normal C-reactive protein, another indicator of inflammation, then instead of “normal” being 4.5 to 10, perhaps we should revise it closer to 3 to 9.

Where do the healthiest populations fall, those not suffering from the ravages of chronic inflammatory diseases, like heart disease and common cancers? Populations eating diets centered around whole plant foods average about 5, whereas it was closer to 7 or 8 in the United States at the time. How do we know it isn’t just genetic? As you can see at 5:38 in my video, if you take those living on traditional rural African diets, who have white blood cell counts down around 4 or 5, and move them to Britain, they end up closer to 6, 7, or even 8. Ironically, the researchers thought this was a good thing, referring to the lower white counts on the “uncivilized” diet as neutropenic, meaning having too few white blood cells. They noted that during an infection or pregnancy, when more white cells are needed, the white count came right up to wherever was necessary. So, the bone marrow of those eating traditional plant-based diets had the capacity to create as many white cells as needed but “suffers from understimulation.”

As you can see at 6:26 in my video, similar findings were reported in Western plant eaters, with an apparent stepwise drop in white count as diets got more and more plant based, but could there be non-dietary factors, such as lower smoking rates, in those eating more healthfully? What we need is an interventional trial to put it to the test, and we got one: Just 21 days of removing meat, eggs, dairy, alcohol, and junk affected a significant drop in white count, even in people who started out down at 5.7.

What about patients with rheumatoid arthritis who started out even higher, up around 7? As you can see at 7:03 in my video, there was no change in the control group who didn’t change their diet, but there was a 1.5 point drop within one month on whole food plant-based nutrition. That’s a 20 percent drop. That’s more than the drop-in inflammation one might get quitting a 28-year pack-a-day smoking habit. The most extraordinary drop I’ve seen was in a study of 35 asthmatics. After four months of a whole food plant-based diet, their average white count dropped nearly 60 percent, from around 12 down to 5, though there was no control group nor enough patients to achieve statistical significance.

If white blood cell count is such a clear predictor of mortality and is so inexpensive, reliable, and available, why isn’t it used more often for diagnosis and prognosis? Maybe it’s a little too inexpensive. The industry seems more interested in fancy new risk factors it can bill for.

I touch on the health of the rural Africans I discussed in How Not to Die from Heart Disease.


For more on fighting inflammation, see:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: