How to Avoid Lectin Poisoning

How should we properly cook beans?

In the 1800s, a compound was discovered in castor beans, which we would come to know as the first of a class of lectin proteins, natural compounds found throughout the food supply, but concentrated in beans, whole grains, and certain fruits and vegetables. Every decade or two, a question is raised in both the popular literature and the medical literature as to whether dietary lectins are causing disease, which I discuss in my video How to Avoid Lectin Poisoning.

It’s easy to raise hysteria about lectins. After all, that first one found back in 1889 went by the name ricin, known to be a potent homicidal poison used by the Kremlin to assassinate anti-communist dissidents and by rogue chemistry teachers on TV. And, ricin is a lectin. Thankfully, however, many lectins are non-toxic, such as those found in tomatoes, lentils, and other common foods, and even the ones that are toxic—like those found in kidney beans—are utterly destroyed by proper cooking.

You can’t eat raw kidney beans anyway. If you do, you’ll be doubled over with nausea, vomiting, and diarrhea within hours, thanks to the lectins that would otherwise have been “destroyed by adequate cooking.” But how would you even eat raw kidney beans? The only way they’re sold uncooked is as dried beans, which are like little rocks. Well, in the first reported outbreak, “an impromptu supper” was made with a bag of beans dumped in a skillet and soaked in water overnight but never cooked. You can’t even just put dried beans in a slow cooker. Dried kidney beans have to be boiled. In fact, it has been “recommended that kidney beans should be soaked in water for at least 5 h[ours] followed by boiling in fresh water for at least 10 min[utes] before its consumption.” Ten minutes? Kidney beans wouldn’t be done after only ten minutes. Cooking presoaked beans for a couple of minutes can destroy the lectins, but it takes about an hour of boiling them before they’re edible, before you can flatten them easily with a fork. So, the lectins would be long gone before the beans are even palatable.

Without presoaking, it takes 45 minutes in a pressure cooker to get rid of all the lectins, but an hour to make kidney beans edible. So, basically, “[i]t appears that cooking beans to the point where they might be considered edible is more than sufficient to destroy virtually all of the…activity of lectins.” Even cooking them for 12 hours at 65 degrees Celsius, which is like the temperature of a cup of hot tea, won’t do it, though. But, you could tell they weren’t done, “being a firm rubbery texture,” though you can imagine someone might put those in a “raw” vegetable salad, which could make people sick. And, it has, with dozens of incidents reported over the years. They could have been easily prevented had the beans been soaked overnight, drained, and then boiled for at least ten minutes, or if canned beans had been eaten instead Canned beans are cooked beans; the canning process is a cooking process. “None of the confirmed incidents was due to canned beans.”

We’ve known since the early 1960s that conventional cooking methods can effectively destroy lectins in beans. Therefore, “it is possible to ignore any human nutrition-related problems that could be associated with lectins from properly processed legumes.” So, while you can show that feeding lectins to rats isn’t good for them or to cell tissues in a petri dish, in the articles that claim that dietary lectins may be “disease causing toxicants,” the only negative effect they can find in humans are those raw or undercooked kidney bean incidents. Do dietary lectins cause “diseases of affluence”? Researchers tested that hypothesis by performing a trial on 24 domestic pigs, and a paleo pig diet beat out “a cereal-based swine feed.” (Could they not find any people willing to eat paleo?)

In response to one such review of the evidence, based largely on laboratory rodents, one peer reviewer cautioned that we should not draw conclusions about the involvement of dietary lectins in the cause of diseases “without definite and positive proof.” That was written more than a quarter century ago, and no such clinical proof has yet to materialize. What we do have, however, is ever growing evidence that legumes—beans, split peas, chickpeas, and lentils—are good for us and are associated with a longer lifespan; significantly lower the risk of colorectal cancer, a leading cancer killer; and are considered part of a “natural, cost-effective, and free from side effects solution for the prevention and treatment of T2DM [type 2 diabetes].” Randomize people to eat five cups of lentils, chickpeas, split peas, and navy beans a week, and you see the same weight loss and metabolic benefits that you do with caloric restriction portion control. And, the whole lectins theory is based on lectin-containing foods being inflammatory. But, when researchers prescribed four servings a week of legumes, packed with lectins, they found a significant drop in C-reactive protein, which you can see at 5:10 in my video. They found a 40 percent drop in this leading indicator of systemic inflammation by eating more beans.

The purported “plant paradox” is that, on the one hand, whole healthy plant foods are the foundation of a good diet, yet, on the other hand, we supposedly need to avoid beans, whole grains, and certain fruits and vegetables because of the evil lectins. But, if you look at the actual science, all whole plant foods are associated with decreased mortality, meaning the more of them people ate, the longer people tended to live, and, this includes lectin-filled foods, such as whole grains and beans, as you can see at 5:36 in my video. So maybe there’s really no paradox after all.

Plant paradox? If you missed it, that was the subject of my video Dr. Gundry’s The Plant Paradox Is Wrong. And—spoiler alert!—there’s even evidence to suggest lectins may be good for you. See Are Lectins in Food Good or Bad for You? to learn more.


Speaking of paradoxes, you may be interested in The Hispanic Paradox: Why Do Latinos Live Longer?.

What about beans, beans, the musical fruit? See my blog post Beans and Gas: Clearing the Air.

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:

Combating Air Pollution Effects with Food

There is a food that offers the best of both worlds—significantly improving our ability to detox carcinogens like diesel fumes and decreasing inflammation in our airways—all while improving our respiratory defenses against infections.

Outdoor air pollution may be the ninth leading cause of death and disability in the world, responsible for millions of deaths from lung cancer, emphysema, heart disease, stroke, and respiratory infection. In the United States, living in a polluted city was associated with 16, 27, and 28 percent increases in total, cardiovascular, and lung cancer deaths, compared to living in a city with cleaner air. As well, living in a city with polluted air may lead to up to a 75 percent increase in the risk of a heart attack. “Additionally, the possibility of dying in a traffic jam is two and a half times greater in a polluted city.” No one wants to be living in a traffic jam, but it’s better than dying in one.

In addition to causing deaths, air pollution is also the cause of a number of health problems. It may not only exacerbate asthma but also increase the risk of developing asthma in the first place. These pollutants may trigger liver disease and even increase the risk of diabetes. Indeed, “even when atmospheric pollutants are within legally established limits, they can be harmful to health.” So, what can we do about it?

Paper after paper have described all the terrible things air pollution can do to us, but “most…failed to mention public policy. Therefore, while science is making great strides in demonstrating the harmful effects of atmospheric pollution on human health, public authorities are not using these data” to reduce emissions, as such measures might inconvenience the population “and, therefore, might not be politically acceptable.” We need better vehicle inspections, efficient public transport, bus lanes, bicycle lanes, and even urban tolls to help clean up the air, but, while we’re waiting for all of that, is there anything we can do to protect ourselves?

As I discuss in my video Best Food to Counter the Effects of Air Pollution, our body naturally has detoxifying enzymes, not only in our liver, but also lining our airways. Studies show that people born with less effective detox enzymes have an exaggerated allergic response to diesel exhaust, suggesting that these enzymes actively combat the inflammation caused by pollutants in the air. A significant part of the population has these substandard forms of the enzyme, but, either way, what can we do to boost the activity of whichever detoxification enzymes we do have?

One of my previous videos Prolonged Liver Function Enhancement from Broccoli investigated how broccoli can dramatically boost the activity of the detox enzymes in our liver, but what about our lungs? Researchers fed some smokers a large stalk of broccoli every day for ten days to see if it would affect the level of inflammation within their bodies. Why smokers? Smoking is so inflammatory that you can have elevated C-reactive protein (CRP) levels for up to 30 years after quitting, and that inflammation can start almost immediately after you start smoking, so it’s critical to never start in the first place. If you do, though, you can cut your level of that inflammation biomarker CRP nearly in half after just ten days eating a lot of broccoli. Broccoli appears to cut inflammation in nonsmokers as well, which may explain in part why eating more than two cups of broccoli, cabbage, cauliflower, kale, or other cruciferous veggies a day is associated with a 20 percent reduced risk of dying, compared to eating a third of a cup a day or less, as you can see at 3:41 in my video.

What about air pollution? We know that the cruciferous compound “is the most potent known inducer” of our detox enzymes, so most of the research has been on its ability to fight cancer. But, for the first time, researchers tried to see if it could combat the pro-inflammatory impact of pollutants, such as diesel exhaust. They put some human lung lining cells in a petri dish, and, as you can see at 4:11 in my video, the number of detox enzymes produced after dripping on some broccoli goodness skyrocketed. Yes, but we don’t inhale broccoli or snort it. We eat it. Can it still get into our lungs and help? Yes. After two days of broccoli sprout consumption, researchers took some cells out of the subjects’ noses and found up to 100 times more detox enzyme expression compared to eating a non-cruciferous vegetable, alfalfa sprouts. If only we could squirt some diesel exhaust up people’s noses. That’s just what some UCLA researchers did, at an amount equal to daily rush hour exposure on a Los Angeles freeway. Within six hours, the number of inflammatory cells in their nose shot up and continued to rise. But, in the group who had been getting a broccoli sprout extract, the inflammation went down and stayed down, as you can see at 4:58 in my video

Since the dose in those studies is equivalent to the consumption of one or two cups of broccoli, their study “demonstrates the potential preventive and therapeutic potential of broccoli or broccoli sprouts,” but if broccoli is so powerful at suppressing this inflammatory immune response, might it interfere with normal immune function? After all, the battle with viruses like influenza can happen in the nose. So what happens when some flu viruses are dripped into the nostrils of broccoli-sprout eaters compared with people consuming non-cruciferous alfalfa sprouts? After eating broccoli sprouts, we get the best of both worlds—less inflammation and an improved immune response. As you can see at 5:55 in my video, after eating alfalfa sprouts, there is a viral spike in their nose. After eating a package of broccoli sprouts every day, however, our body is able to keep the virus in check, potentially offering “a safe, low-cost strategy for reducing influenza risk among smokers and other at risk populations.”

So, better immune function, yet less inflammation, potentially reducing the impact of pollution on allergic disease and asthma, at least for an “enthusiastic broccoli consumer.” But what about cancer and detoxifying air pollutants throughout the rest of our body? We didn’t know, until now. Off to China, where “levels of outdoor air pollution…are among the highest in the world.” By day one, those getting broccoli sprouts were able to get rid of 60 percent more benzene from their bodies. “The key finding…was the observed rapid and highly durable elevation of the detoxification of… a known human carcinogen.” Now, this was using broccoli sprouts, which are highly concentrated, equivalent to about five cups of broccoli a day, so we don’t know how well more modest doses would work. But if they do, eating broccoli could “provide a frugal means to attenuate…the long-term health risks” of air pollution. More on air pollution here.

I’ve been reading about the terrible effects of air pollution for a long time and I am thrilled there’s something we can do other than uprooting our families and moving out to the countryside.


For more on cruciferocity, see my videos Lung Cancer Metastases and Broccoli and Breast Cancer Survival Vegetable.

There’s a secret to maximizing broccoli’s benefits. See Flashback Friday:Second Strategy to Cooking Broccoli.

For more on Cooking Greens: How to Cook Greens and Best Way to Cook Vegetables.

What about broccoli sprout pills? See Broccoli: Sprouts vs. Supplements.

Speaking of respiratory inflammation, what about dietary approaches to asthma? Learn more:

There are sources of indoor pollution, too. See Throw Household Products Off the Scent.

There is one way what we eat can directly impact air pollution, beyond just personal protection. Check out Flashback Friday: Diet and Climate Change: Cooking Up a Storm.

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: