Beware of Beans

National Bean Day is January 6. Go ahead and celebrate – but do so carefully! Beans can be a problem if they are not prepared properly.

Do You Commonly Eat This Toxic Food?

Many people eat this toxic food on a daily basis and have no ill effects. Other people get severely sick with only half an ounce ingestion. The toxic food we discuss today? Beans.

Yes Beans Are Toxic

You may have heard that red kidney beans have a toxin in them, but they are not the only legume containing this toxin. All members of the bean family contain a number of different toxic compounds, all in varying amounts. Most problematic are lectins.



All legume bean seeds contain compounds commonly called lectins. Lectins are glycoproteins that are present in a wide variety of commonly eaten plant foods, not just beans. Some are not harmful, but the lectins found in undercooked and raw beans are toxic.

We recently posted a YouTube video on foraging Palo Verde beans. Some preparation tips are discussed in the video.

Palo verde flower buds do not have lectins in them and are safely made into capers – on this video.

A list of both articles and videos about foraging is provided on our “Forage” page

Plants are Just Protecting Their Babies

Seeds are a plants way of having babies. Parents want to protect their children, so from a plant’s point of view, this high concentration of lectins in seeds is just to protect their offspring. It works to keeps critters from eating the beans. As the seeds begin to grow, the levels of lectin drop, which is why we can eat raw bean sprouts.

Ever find a stash of palo verde beans in a packrat nest? Stored for several years, the lectin levels drop low enough that the rodents can eat them. Packrats are just packing their nests for that someday.


One Highly Toxic Lectin

The name of this lectin is phytohaemagglutinin (PHA) and it occurs naturally in all legumes. It comes in two forms and causes either white blood cells or red blood cells to clump together. The body can quickly recognize this danger in the digestive tract and does it’s very best to eliminate the danger from the body. Yes, your food has poisoned you! The reaction is termed “gastroenteritis,” a medical term that covers abdominal cramps, nausea, vomiting, and diarrhea. Unpleasant – yes. Deadly – yes, but generally only if there are other medical conditions.


The CDC estimates that up to 20 percent of annual food poisoning cases are attributed to consumption of under cooked beans. Furthermore, according to the CDC, an estimated 48 million Americans will become sick from a food borne illness this year. Of that number over a million will end up in the hospital and 3,000 will die.

Highest levels of phytohaemagglutinin (PHA) occur in broad beans, white kidney beans (cannellini), and red kidney beans. Black beans, soy beans, and edamame can also cause issues if not properly cooked.



Raw lima beans contain linamarin. When eaten, linamarin is converted into the toxic chemical hydrogen cyanide. Fortunately for lima bean-lovers, boiling lima beans for at least 10 minutes renders them safe. Lima beans sold in the U.S. are required to have relatively low cyanide levels.

Chickpeas and Green Beans

Inhibitor compounds found in chickpeas (garbanzo beans), green beans, soy beans, and edamame can cause potassium levels to increase in the blood. Most people will not have a problem – but heart patients and kidney patients need to be careful. Potassium helps manage blood pressure, but too much can be harmful for heart or kidneys. People who use beta-blockers should be careful about consuming these bean family members.


And It That Wasn’t Enough

All plant seeds contain phytic acid, or phytate.  It is an antioxidant found so you might think it is “good,” but….  Phylate is not toxic, but phytate blocks the absorption of iron, zinc, and calcium from the same meal. Over time this has been shown to increase the risk of mineral deficiencies in people who rely on legumes as a dietary staple.

Why Are We Telling You This?

You may have issues and not know it.  And consider this a PSA (Public Service Announcement) When someone tells you they can’t eat beans, or soy, or humus, or even alfalfa sprouts (yes, alfalfa is a legume) they are not making it up. Their body can not tolerate the bean toxins.

savor-southwest-souleScience Nerd Note

Break down the chemical name phytohaemagglutinin
phyto = plant
haema = hemaglobin in human blood,
glutinin = coagulation or clumping together


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