Are Bean Seeds Edible?


Bean seeds come in a wide range of colors and sizes. Photo:

Question: I was a bit slow harvesting my green and yellow beans this summer and many dried out and went to seed. I’ll use some as seeds for next year’s crop, but since I have a lot of them, I wondered if the seeds were edible.


Answer: Yes, the dry seeds of the common bean (Phaseolus vulgaris) are edible. In fact, they have been used for thousands of years for soups, chilies, stews, etc. Boston baked beans, a classic dish I’m sure you’ve eaten many times, are, in fact, made from dry beans.

Dry beans need to be soaked and boiled before being eaten. Photo:

That said, it’s important to prepare dry beans properly, including soaking them in water for at least 5 hours (discard the water used to soak them) before boiling them for at least 15–20 minutes (the US FDA recommends 30 minutes).

This is because the dry seeds of all types of common bean contain phytohemagglutinin (PHA), a toxin that is destroyed by prolonged cooking. It’s not all that rare that people end up in the hospital after consuming soaked beans that they thought were cooked. Interestingly, rats seem to know dry beans are poisonous, as they will raid stores of cereals and other crops, but never touch dry beans.

The level of phytohemagglutinin varies considerably from one type of bean to another and it is generally quite low in beans harvested from green and yellow beans, but very high in kidney beans, both red and white. Even so, proper soaking and cooking are recommended for all beans, regardless of the color of the seed.

10 Strange Facts About Vegetables




“Eat your vegetables”, my mother used to say, “they’re good for you!” But I’d feed them to the dog if I got a chance.

She was right, of course, that vegetables are good for us. They’re richer in vitamins and minerals than just about anything else we can eat. But there are also a lot of fascinating facts about them that most people don’t know. Here are a few:

1. Tearless Onions

20170323A.jpgWhat gives onions their pungency and irritates our eyes to the point they tear up is the presence of various volatile sulfur compounds in their cells. Cut into an onion and the air is instantly full of tiny irritating particles. They evolved in onions as protection, to discourage animals from munching on them. However, in the rare occurrence of sulfur-free growing conditions, onions completely lose their pungency… even “onion breath” becomes a thing of the past. Even so-called “sweet onions”, genetically less pungent than most of their kin, have to be grown in soil that is poor in sulfur in order to have the mild taste we expect. Certain soils in the US West and South and in the heart of Europe, for example, are poor in sulfur… and that’s where sweet onions are grown. Try growing a sweet onion in normal garden soil, rich in sulfur, and it will leave  you crying.

2. Baby Carrots Aren’t Babies

20170323b.jpgThe so-called baby-cut carrots aren’t miniature carrots, they’re full-sized carrots trimmed down to size by industrial machines.

This technique was first used to convert substandard carrots, with blemishes or marks, ones that had no market value, into saleable items. Now, though, there is an entire industry based on producing the pre-peeled, ready-to-eat babies. Surprisingly little goes to waste: shavings account for only 0,84% of the production, largely because special carrot cultivars and tight spacing during sowing lead to long, narrow carrots easily cut into 3 to 4 pieces. Shavings are either used for animal feed or in the food processing industry (think “carrot cake”).

Of course, there are also true baby carrots: naturally miniature strains that you can grow… but you rarely find those in supermarkets!

3. Tomatoes are Legally Vegetables

20179323C.jpgBotanically speaking, tomatoes are  fruits. In fact, they are technically berries, since they are a simple fleshy fruit with many seeds and no stone (stone fruits are called drupes). However, in the United States, they are legally vegetables. Following a controversy about the tomato’s status, the U.S. Supreme Court officially decided that the tomato is a vegetable. That was way back in 1893 and the decision still holds today.

4. Eat Those Peels!

20170323D. ALice Wiegand, WCjpg.jpg

Photo: Alice Wiegand, Wikimedia Commons

Peeling your vegetables before you eat them is a nutritional faux pas. In most vegetables, such as carrots, potatoes, and cucumbers, a good percentage of the nutrition is actually stored in the skin or just below the skin. That means when you peel them, you’re actually removing many of the nutrients they contain. Vegetable skins also contain a lot of fiber and fibers too are good for you.

5. If You Hate the Taste of Brussels Sprouts, It May Be In Your Genes

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Photo: Rainer Zens, Wikimedia Commons

Studies all over the world suggest that Brussel sprouts are world’s most hated vegetable. American President George H.W. Bush famously hated Brussel sprouts so much he banned them from the White House. Recent studies have shown that your like or dislike of Brussel sprouts (and other cabbages) is encoded in your DNA. There is actually a gene shared by about half the world’s population that allows them t0 enjoy the taste of Brussel sprouts, as they are genetically incapable of tasting highly bitter compounds called glucosinolates found in all cabbages, but more abundantly in Brussels sprouts. To glucosinolate tasters, that is, the other half of the population, Brussels sprouts are incredibly bitter. The researchers doing the DNA study found that for these people, Brussels sprouts taste about as appealing as (and I am quoting) “eating a rubber shoe.”

6. Carrots Are Not Really Good for Night Vision


Part of a WWII poster encouraging people to eat carrots for improved night vision.

Unless your diet is seriously lacking in Vitamin A, carrots don’t help you see better at night. The belief that eating them does improve night vision actually stems from a WWII propaganda campaign. At the time, Great Britain was developing new radar technologies to help their aircraft better find their targets in the dark, but didn’t want the Nazis to know. So they started running stories in British newspapers claiming Royal Air Force pilots were being fed carrots to improve their night vision, thus creating a plausible explanation for their improved nocturnal aerial success. This propaganda piece was so successful that the information spread around the world and even to this day, many people still believe that eating carrots helps you see better at night.

7. The Downside of Beans

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Photo: cookbookman17, Flickr

“Beans, beans, they’re good for the heart…” So goes the first part of a popular child’s rhyme. As to being good for the heart… well, they’re as good for the heart as just about any vegetable, but what is far truer is that they assuredly do contribute to flatulence. That’s because our stomach and small intestines lack the enzymes necessary to completely break down two sugars found in beans, raffinose and stachyose. Instead, bacteria found in our large intestines tackle the job and break them down into hydrogen, nitrogen, carbon dioxide… but especially the malodorous gas methane, with often explosive results. Yes, you can take an enzyme called alpha-galactosidase (sold as Beano) before eating beans and it will break the sugars down without any unfortunate consequences. Soaking beans for several hours before cooking will also help, as this allows yeasts to start digesting the sugars.

8. Popeye Was Wrong About Spinach

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Image: jean pierre Gallot, Flickr

When I was a kid, the popular Popeye comics and cartoons showed Popeye ingesting a can of spinach and suddenly becoming incredibly strong. This wasn’t enough to encourage me to eat any more spinach than I was forced to, but it did lead to spinach gaining massively in popularity. Unfortunately, the entire idea that spinach made you stronger was based on a simple notational mistake. In 1870, German chemist Erich von Wolf reported that a 100 g serving of spinach contained 35 mg of iron, far more than any other vegetable. And iron is associated with strength, as it helps carry oxygen to your muscles. The problem is that von Wolf had mistakenly misplaced a decimal point. 100 g of spinach contained the more modest and normal quantity of 3,5 mg of iron, not 35 mg. Spinach is good for you, but not as good as many people today still believe.

9. Many Vegetables Contain Toxins

20170223I.pngThis is not something we like to think about, but many if not most vegetables (kale, carrots, Swiss chard, tomatoes, etc.) contain products (alkaloids, goitrogens, oxalic acid and others) that are toxic to humans. Fortunately, they are present in such small quantities they cause no harm. The poison, goes the saying, is in the dose and that is very true. Still, people subject to kidney stones or gout should avoid eating too much spinach  or asparagus (they contain fairly important quantities of oxalic acid, a toxin that can exacerbate both conditions) and any green parts should be removed from potatoes, as they contain solanine and other toxic alkaloids. Eating green potatoes could theoretically kill you! Also never eat the foliage or stems of any Solanaceae (tomato, potato, pepper, eggplant, etc.) as they really do contain enough solanine to make you seriously ill.

10. There is No Such Thing as a Negative-Calorie Vegetable

20170323J.JPGThose of us who need to lose a bit of weight (or a lot of it) may have been encouraged by claims that some vegetables (celery, kale and lettuce are often cited) are negative-calorie foods, that digesting them requires more energy than the energy they release when we digest them. That means you’d lose weight just by eating them. But unfortunately, that isn’t true. Even celery, usually touted as the best negative-calorie vegetable, and which is indeed mostly composed of water and fiber, still contains about 6 to 10 calories per stalk, yet digesting it requires only about ½ calorie. Still, if you stuffed yourself with celery, you wouldn’t have much room for calorie-rich foods and you’d certainly lose weight.

Vegetables: we eat them on a daily basis, yet we know so little about them.20170323K

Edible Plants With Poisonous Habits


20160829MIt may seem strange to think that a plant can be both edible and toxic and yet that is in fact a common situation.

For example, many plants produce edible fruit to attract the birds and mammals that will help distribute the seeds found inside, yet don’t want those same animals to consume their leaves and stems, so have evolved ways of infusing their other parts with deterrents, including toxic elements. Also, often the flesh of the fruit will be edible, but the seed or nut toxic, thus ensuring that the “carrier” doesn’t eat it.

And other “edible” plants can only be consumed if they are properly prepared.

In fact, many of the most popular edible plants can also be toxic under certain circumstances.

Edible But Toxic

Here are a few common “edible but toxic plants”.

Note that, unless otherwise specified, the toxicity of the plants mentioned here is relatively weak. Eating the wrong part or eating it without proper preparation will probably simply cause intestinal discomfort or maybe nausea, but will rarely require medical treatment.

And yes, in case you wondered, all the plants described here are also toxic to pets.

Almond (Prunus dulcis)


Almonds in their shell.

Almond trees are poisonous from top to bottom. Even the shell surrounding the edible kernel is poisonous!

The almond commonly found on the market in North America and most parts of Europe is the sweet almond, so called because the poisonous properties have been bred out of it, and it can be eaten without concern. However, wild almond trees produce a kernel that is called “bitter almond” because of its bitter taste. Bitter almonds contain amygdalin, a product that converts to cyanide inside the body and even a few raw kernels can kill a child. They have to be cooked before they can be used safely.

In spite of their bitterness, bitter almonds are considered much more flavorful than sweet almonds and are favored by many chefs. They are popular and widely available in the Middle East and in North Africa. The sale of bitter almonds is prohibited in North America… but that doesn’t prevent certain merchants (and chefs!) from sneaking them across international borders.

Apple (Malus domestica)


Apples are delicious, but watch out for the seeds!

Apple seeds contain cyanide, or rather amygdalin, which the body converts into cyanide. Accidentally swallowing a few apple seeds is not a problem: they’ll pass through your digestive system intact. However if you munch the seeds before swallowing them, which will release the amygdalin, that can send you to the hospital, especially if you make a habit of it. The leaves and stems of apple trees are poisonous too.

Crabapples, by the way, have the same poisonous properties as full-size apples.

Don’t let dogs or cats eat apples, because sometimes they crush the seeds as they eat.

Asparagus (Asparagus officinalis)


Asparagus berries.

You can munch away on the spring shoots without concern, but the red berries produced by female plants are slightly toxic.

Cashew (Anacardium occidentale)


The cashew apple (fruit) is edible, but the nut, which grows exposed, is toxic until properly prepared.

No, Northern gardeners will not find cashew trees in their garden: it is a strictly tropical tree. However, you might well see them when you travel, so be aware that the nut (which, curiously, grows outside fruit) is highly poisonous unless properly treated. It must be extracted from its shell and roasted to destroy the toxins. Curiously, the fruit itself, the “cashew apple”, is edible and can be consumed without cooking. It is commonly eaten in many tropical countries.

Cassava (Manihot esculenta)


Cassava tubers.

Very popular in tropical countries around the world, cassava tubers (also called manioc) are a staple food that is consumed in much the same way as potatoes. In the North, the best known form of cassava is tapioca, typically used in making pudding. It is prepared from cassava flour. And you can find imported cassava tubers in many northern fruit markets as well.

However, the cassava tuber is actually highly toxic if not properly prepared, and can even be fatal, as it contains a whole host of toxins, notably various chemicals that are transformed into cyanide by the human body.

Imported cassava tubers are “sweet”: the poisonous properties found in wild tubers (linamarin and other products) have been largely bred out of them. Still, they do remain poisonous until they are properly prepared, which can be done by peeling them (the poisons are concentrated in the outer skin) then boiling, baking or fermenting the tuber or pounding it into flour.

Bitter cassava, closer to the wild form, is nevertheless still consumed in many countries, often as a starvation food. It needs to be boiled repeatedly to remove its toxic properties.

Variegated tapioca (Manihot esculenta ‘Variegata’) is sometimes cultivated as an ornamental plant in northern regions. If so, be aware that it is toxic in all its parts.

Elderberry or Black Elder (Sambucus nigra)


Mature elderberries.

Maybe your grandma used to make delicious elderberry wine, but she did so from cooked berries. All parts of the elderberry plant except the flowers and the ripe berries are poisonous. In fact, although the ripe berries can be eaten, ideally you should do so without swallowing the seeds, which will release some toxic elements if broken open. That’s why, in general, it’s best to cook the berries before use, because that will destroy the toxins in the seeds.

By the way, other species of elderberry, notably the red elderberry (Sambucus racemosa) are even more toxic than black elder (S. nigra) and most authorities consider them poisonous period. In truth, though, the berries can theoretically be eaten if they are cooked.

Kidney Bean (Phaseolus vulgaris)


Kidney beans.

The mature seeds of most beans are somewhat toxic if eaten raw, but kidney beans contain far more phytohemagglutinin, the toxic element, than other types of beans. They must be soaked for several hours, usually overnight, in order to soften them, then boiled for a minimum of 10 minutes so the toxin drops to an acceptable and safe level. Sometimes accidents occur, though, when someone eats beans that were soaked but not yet cooked. As little as five raw beans can send an adult to the hospital.

Plum, cherry, peach (Prunus spp.)



The flesh of various Prunus species (plums, cherries, peaches, etc.) is edible, but the leaves, stems and pits are toxic, containing a precursor of cyanide.

Potato (Solanum tuberosum)


Green parts of potato tubers are poisonous and should be cut off.

Only the tuber is edible: the roots, leaves, stems, flowers and especially berries are toxic. Occasionally people are poisoned by mistaking potato berries for green tomatoes. Even green parts of the tuber (and a tuber exposed to the sun will turn green) are toxic. You can however eat a tuber that is partly green if you cut away the green section.

Rhubarb (Rheum spp.)


Rhubarb petioles are the only edible part.

Only the leaf petiole is edible. The leaf blade is too rich in oxalic acid, toxic to humans if consumed in large quantities.

Tomato (Solanum lycopericum)


Ripe tomato fruits are edible, their leaves not so much.

Although it’s often claimed that all parts of the tomato plant are poisonous except the ripe fruit, in fact, tomato plants are only slightly toxic. Yes, the green parts contain toxic elements like tomatine, solanine and other alkaloids, but not in quantities important enough to make you sick under normal circumstances. So, while you could say that green tomatoes, for example, are slightly toxic, you’d have to eat over a pound (500 g) of them before you felt ill, so it’s perfectly safe to use them in relishes, chutneys and fried green tomatoes … as long as you don’t pig out!

And Many More

There are many other examples of plants, not to mention mushrooms, with both toxic parts and edible parts. The important thing is to not presume that if one part of a plant is edible, the rest must be too, or that a plant usually served cooked is also edible raw. Or that a plant found in a vegetable garden is necessarily edible! Getting that wrong could send you to the hospital!20160829M