Raw foods get a lot of hype for their nutritional power, and it's deserved in many cases. While a 100 percent raw diet's health value is questionable, cooking or overcooking does destroy some of the vitamin content in certain foods [source: Furhman].
For a person eating the standard American diet heavy on meat, dairy, and overcooked vegetables, adding more raw fruits and veggies will certainly do more good than harm. But don't raid the farm just yet – some foods should never be eaten raw.
Many of the compounds that make plants on this list too toxic to eat raw are part of their defense mechanisms. Toxins like deadly ricin in castor beans or hydrogen cyanide in almonds are designed to deter pests. To plants just trying to survive, we come across as much of a pest as slugs or aphids do.
Some of the foods that you should never eat raw are on this list because they're poisonous without cooking. Not all of the toxic foods here will kill the average healthy adult. Some will just give you a wretched belly ache or other mild to moderate symptoms. And one of these foods isn't unsafe, but it needs to be treated to keep it from tasting terrible. Read on, and while you're at it, go ahead and put that water on to boil.
Raw beans contain proteins called lectins that break down with cooking. Not all lectins are toxic; some are even beneficial. The lectin in kidney beans, though – called phytohemagglutinin – is harmful at high doses [source: Andrews]. There are other beans that contain phytohemagglutinin, but red kidney beans contain them in the highest concentration by far [source: Medic8]. When it comes to this toxin, it's all about dosage.
Just a handful of raw kidney beans is enough to cause gastrointestinal problems like nausea and vomiting. The more you eat, the more intense your symptoms will be. Some folks have even been hospitalized with red kidney bean poisoning. [source: Medic8]
You don't have to give up your red beans and rice just yet. To destroy the lectins in kidney beans, you just need to soak, drain, and then cook them on the stovetop. Stovetop cooking reaches higher temperatures than a slow cooker, and kidney beans really do need to be boiled to be completely safe. To prepare dry kidney beans safely, soak for at least five hours, drain and rinse, then boil for at least 30 minutes on the stove [source: FDA].
Do you remember the Whole Foods almond recall in late 2014? The recalled almonds were different from the ones we normally eat. The almonds we usually see in stores are known as sweet almonds, but their close cousin – the bitter almond – contains dangerous levels of hydrogen cyanide. Bitter almonds aren't very common in the U.S., but in Europe many chefs love them [source: Karp].
Children who ingest just a few raw bitter almonds are at risk of death. Adults can eat far more and survive, though you would experience some symptoms that might make you wish you hadn't. Hydrogen cyanide poisoning includes symptoms from dizziness and headache to vomiting and convulsions, depending on how much you've eaten [source: Food Safety News].
As with all of the foods on this list, proper cooking is the key to making bitter almonds safe to ingest. Blanching or roasting destroys the hydrogen cyanide in bitter almonds, but there doesn't seem to be any solid research on what temperatures you need to reach or for how long [source: PICSE]. If you're planning to cook with bitter almonds, your best bet is to follow a tried-and-true recipe.
Have you ever wondered why raw foodies don't eat potatoes? It's not because of an aversion to carbs; it's for safety reasons. Raw potatoes are potentially toxic because of a compound called solanine [source: MedlinePlus].
Not every potato contains enough solanine to kill you, but the risk is high enough that it's not really worth taking. In general, green potatoes – even ones just a little green near the skin – or ones that are starting to sprout eyes have a higher solanine content. Symptoms of potato poisoning include stomach pain, headache, and paralysis. Potatoes with a very high concentration of solanine will have some green discoloration when you cut into them, and you shouldn't eat a green potato, even cooked. [source: MedlinePlus]
Even if the raw potato you're eating doesn't have a lot of solanine, you're still better off cooking it. Uncooked potato is rich with resistant starch. While some resistant starch can be good for your gut, the amount in raw potato is enough to give most people unpleasant side effects like severe gas and bloating [source: Blonz].
Cooking potatoes properly isn't hard. Roast, mash, boil or even grill them, and you won't have to worry about any of these things.
People eat both the leaves and roots of the taro plant, but you shouldn't eat either one raw.
Think of taro root as the potato's healthier cousin. It has more fiber than a potato and is a good source of potassium, vitamin C, calcium, vitamin E, B vitamins, and trace minerals [source: Erman]. Taro gets some solid superfood cred, but make sure to fully cook this starchy root vegetable before eating.
The leaves of the taro plant are no nutritional slumps, either. They taste sort of like spinach but have a hardier texture. They're also good sources of fiber, vitamins A and C, and protein [source: Specialty Produce].
Raw taro contains calcium oxalate, and you do not want any part of this compound. Think of it as tiny knives that cover the leaves and root of the taro plant. When you eat uncooked taro, the calcium oxalate makes your mouth feel numb. Eat too much, and you'll feel like you're choking [source: Croll]. This toxin also contributes to kidney stones [source: Big Oven].
Thoroughly cooking taro leaves and roots destroys enough of the calcium oxalate to make them edible. Because this compound can also irritate your skin, you should wear gloves when you're handling the raw plant.
Cassava goes by many names: arrowroot, manioc, tapioca, kassave, mandioca and yuca, but it's different from yucca, an inedible, ornamental plant [sources: USDA, Durand]. Whatever you call it, you should only eat it cooked, and only eat the root if it was peeled before cooking [source: China Daily].
As with taro, you can eat both the roots and leaves of the cassava plant. This native South American plant is easy to grow in humid climates, and the root is a good source of nutrients, which is why it's now cultivated across South America and parts of Africa. Cassava leaves are also edible when cooked. [source: O'Hair]
The toxic culprit in uncooked cassava is a group of compounds that turn into hydrogen cyanide in your body. Hydrogen cyanide interferes with your body's use of oxygen, basically causing you to drown without the trouble of being submerged [source: CDC].
To cook cassava roots properly, you should always peel them first and discard the peel. Then, you can fry them like you would potato chips or french fries. You can also boil the roots just like potatoes, but make sure that they're completely cooked through. If the cassava that you have seems bitter, you can grate and soak the roots before cooking. [source: O'Hair]
Cassava leaves don't require quite as much care, but you still need to cook them. Boiled thoroughly, they're safe to eat and taste similar to collards or other hardy dark, leafy greens [source: Kwok].
Chaya – a native Mexican shrub – is also called the spinach tree because its cooked leaves taste similar to spinach. Cooked chaya actually beats spinach when it comes to nutrient content. It's a better source of protein, calcium, and iron, for example [source: Weil].
It's actually pretty rare to run across chaya at all in most parts of the world. There are people growing it in Florida, Texas, and parts of Mexico, but cooking with it has become uncommon [source: Weil]. That doesn't mean you can't safely cook chaya!
Like with cassava and bitter almonds, hydrogen cyanide is the danger when eating raw chaya. And like these other foods, sufficient cooking renders the leaves safe to eat. You can season it just as you would any leafy green vegetable. To cook chaya, just boil the leaves for 20 minutes on the stove, and make sure that you don't inhale the cooking fumes or steam, and that the pan you're using isn't aluminum; chaya plus aluminum equals explosive diarrhea [source: Deane].
Castor bean plants are beautiful. They have vibrant, red leaves and they produce red and yellow flowers. They're also extremely toxic to both people and animals. Like red kidney beans, castor beans contain high concentrations of a particularly harmful lectin. The lectin in castor beans is called ricin.
Yep, the ricin in castor beans is the same poison that Jesse helped Walter White cook up in "Breaking Bad." It's actually very easy to distill ricin from castor beans, and a terrorist tried to poison President Obama and U.S. Senator Roger Wicker with envelopes of the stuff in 2013 [source: Nosowitz].
Even cooking castor beans isn't enough to destroy ricin. In fact, you make the poison using the mash leftover from processing castor beans for their oil [source: CDC]. Castor oil is the only castor bean product that's safe to eat; since ricin is water soluble, it doesn't end up in processed castor oil, as long as the processing was done properly [source: Cornell].
Unprocessed olives won't make you sick or kill you, but chances are you won't want to eat one. Olives right off of the tree contain a high concentration of a compound called oleuropein, which gives them a bitter taste. Brining olives breaks down the oleuropein, yielding the delicious olives that we all know and love [source: Cook's Info].
What's interesting about raw olives is that while they don't taste good, there's some evidence that oleuropein has potential health benefits, and olives are the only known food-based source of the compound [source: Phenol-Explorer]. You can actually buy oleuropein supplements, and some research suggests that it's an antioxidant and anti-inflammatory compound that could protect heart and brain health [source: Omar].
There are a few different ways to prepare olives so that they're palatable. Soaking in fresh water will remove some of the bitterness, but brining them for a few weeks or even a few months in salty water or packing them in salt are preferred [source: Bradley]. Different olives require different brining times, so this is sort of a "taste it and see" process. Prepared olives still contain some oleuropein, but not enough to taste off-putting [source: Phenol-Explorer].
There are two main reasons to cook wild mushrooms rather than serving them up raw. Raw wild mushrooms can be tough to digest, so cooking helps you avoid gastrointestinal distress, but also many are actually toxic and potentially deadly when raw. Cooking breaks down the harmful compounds, leaving you with a bowlful of mushroomy goodness [source: Michigan Mushroom Hunters Club].
While many raw foods can be hard to digest, wild mushrooms are especially difficult. Mushrooms' cell walls are different from the cell walls of fruits and veggies, and cooking breaks those down, so our bodies can handle processing the tough fungal cells. Breaking down those cell walls with cooking also helps you get more of their nutritional value [source: Campbell].
One caveat: There are a very few wild mushrooms that you can eat raw, but you'd better be an expert in identifying them. Mycologist David Campbell says that you can eat witch's butters and toothed jellies raw. He also describes eating a raw wild mushroom called the coccoli, which he marinates in lemon juice to make a mushroom ceviche [source: Campbell].
Different wild mushrooms need to be cooked differently. Some toxins break down when you expose them to heat. Others need to be boiled away [source: Campbell]. Campbell's lemon marinade is actually a sort of "chemical cooking" that works on certain mushrooms, but not others. Your best bet with wild mushrooms is to do your research to make sure that you cook them safely, and only buy wild mushrooms from trusted, reliable purveyors. It's literally a life-and-death issue.
While the danger associated with eating uncooked or undercooked pork has decreased since the '70s and '80s, you still shouldn't eat your pork raw or rare. Pigs are raised a lot differently than they used to be, but there's still a risk that you'll contract one of two nasty parasites from eating pork: trichinosis or pork tapeworm [source: The Daily Meal].
You've probably heard of trichinosis before. It's a parasite that takes up residence in your small intestine after you eat infected meat, and pigs aren't the only animals that can harbor it. Raw bear, cougar, wolf, fox and walrus are also potential carriers [source: CDC]. So next time you prepare a walrus steak, cook it to well done.
The first signs of trichinosis are stomach issues like nausea and vomiting. In the week after infection, the parasites reproduce, and their babies enter your bloodstream. When this happens, you can show symptoms from muscle pain to pink eye. Very severe cases can lead to death, though it's rare [source: Mayo Clinic]. Trichinosis cases have gone down drastically as the pork industry has made systemic safety changes and awareness of proper cooking has increased; the CDC now only receives about 20 reports of trichinosis per year [source: CDC].
Pork tapeworm is actually worse than trichinosis. An infected person can range from having no symptoms at all to having seizures. In fact, pork tapeworm is one of the top causes of seizures worldwide [source: Doerr].
The good news is that it's not hard to cook pork safely. All you need are patience and a meat thermometer. Cook ground pork until there is no pink flesh inside at all and the meat reaches an inner temperature of 160 F (71 C), though large cuts of pork may still be slightly pink and cooked to just 145 F (63 C) [source: FoodSafety.gov].
There is one place where people eat raw pork semi-regularly and manage to live, though. In parts of Germany there's a minced raw pork dish called mett that's a cultural staple. Germany did report 52 cases of trichinosis in the 1999 due to people eating raw pork, though, so take that into consideration when you see mett on the menu [source: Lawley]. Traditionally, chefs form the raw, ground pork into the shape of a hedgehog, using raw onion slices for the "spines" [source: Melican].
This list might make you feel like you're taking your life into your hands every time you pick up your fork, but with proper cooking, even these foods are safe to eat. Bon appetit!
Do you need soap to get your dishes clean? HowStuffWorks bursts that bubble.
Author's Note: 10 Foods You Should Never Eat Raw
I'm a longtime vegan who definitely enjoys a raw meal here and there, so this topic was particularly interesting to research. Most of the foods on this list were not new to me, but I was surprised to learn that you need to cook wild mushrooms before eating. Fancy, exotic mushrooms are one of the things I like to splurge on at the farmers market, so now I know to be more careful about how I prepare them. And I've got to try that mushroom ceviche!
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