We often hear that fresh, natural foods are healthier when eaten as close to their original form as possible.

But that isn’t always true.

Some foods that are perfectly healthy and nutritious after proper preparation can become dangerous when eaten raw or undercooked. In some cases, the problem is bacteria. In others, the food naturally contains toxins that cooking or processing helps remove or deactivate.

That means washing a food isn’t always enough.

Some hazards are already part of the food itself, so no amount of rinsing can make certain raw foods safe.

The surprising part is that these foods aren’t necessarily “bad” foods. Most are nutritious and perfectly safe when prepared correctly. The danger comes from eating them raw, improperly cooked, or insufficiently processed.

Here are nine foods that deserve extra caution.

1. Raw Red Kidney Beans

Red kidney beans are a common ingredient in chili, soups, salads, and grain bowls. They’re also packed with nutrients when properly cooked.

But eating them raw is a completely different story.

Raw and undercooked kidney beans contain high levels of a lectin called phytohaemagglutinin (PHA). Consuming enough of this compound can cause acute food poisoning, with symptoms often appearing within a few hours.

In fact, eating just four or five raw or improperly cooked kidney beans can cause severe symptoms in some people.

Why Cooking Matters

Proper cooking dramatically reduces the amount of PHA in kidney beans.

Simply warming the beans isn’t necessarily enough. The source material notes that heating them to around 80°C (175°F) can actually increase the toxicity, which is one reason improperly used slow cookers can be a problem.

The safer approach is straightforward:

• Soak dried kidney beans before cooking.
• Discard the soaking water.
• Bring the beans to a proper boil for at least 10 minutes.
• Continue cooking until they are completely tender.

Canned kidney beans are generally already cooked through commercial processing and can be eaten directly from the can.

The important lesson: Don’t treat dried kidney beans like a food you can simply soak and eat. They need proper cooking.

2. Raw Chicken

Raw chicken may look harmless, especially when it is fresh and doesn’t have an unusual smell.

Unfortunately, you cannot reliably judge chicken’s safety by its appearance or smell.

Raw chicken can carry harmful bacteria including Campylobacter, Salmonella, and Clostridium perfringens.

Eating undercooked chicken can lead to stomach cramps, nausea, vomiting, diarrhea, and fever. Serious complications can occur in some cases.

One particularly important point is that contamination isn’t always obvious.

A package of chicken can look completely normal and still contain harmful bacteria.

The Safest Way to Cook Chicken

The USDA recommends cooking chicken to an internal temperature of 165°F (74°C).

Use a food thermometer and check the thickest part of the meat.

Don’t rely only on the color of the chicken or whether its juices appear clear.

And remember that food safety doesn’t end when the chicken goes into the oven.

Raw chicken can contaminate cutting boards, countertops, knives, plates, and other foods. Cross-contamination can spread bacteria even if the chicken itself is eventually cooked properly.

Keep raw chicken separate from ready-to-eat foods and clean surfaces carefully after handling it.

3. Raw Milk

Raw milk is milk that hasn’t been pasteurized.

Some people choose raw milk because they believe it is more natural or may have health benefits. But skipping pasteurization also removes an important safety step.

Raw milk can contain harmful germs such as:

• Campylobacter
• Cryptosporidium
• E. coli
• Listeria
• Salmonella

Pasteurization works by briefly heating milk to kill dangerous pathogens.

In other words, the heating process isn’t simply changing the milk. It’s an important food-safety barrier.

Raw Milk Can Carry Serious Risks

The FDA recorded 202 outbreaks linked to raw milk between 1998 and 2018, involving thousands of illnesses and hundreds of hospitalizations.

The risk can be particularly concerning for:

• Young children
• Pregnant women
• Older adults
• People with weakened immune systems

Although raw milk advocates sometimes claim that pasteurization reduces its nutritional value or destroys beneficial properties, the source material notes that the scientific consensus does not support a health benefit from choosing raw milk that outweighs its documented pathogen risk.

4. Raw Eggs

Raw eggs are often used in homemade recipes, including some desserts, sauces, dressings, and cookie dough.

The problem is Salmonella.

One reason raw eggs can be tricky is that contamination may occur inside the egg itself. An egg can look perfectly clean and normal while still carrying bacteria.

According to the source material, approximately 1 in 20,000 eggs in the U.S. is internally contaminated with Salmonella Enteritidis.

The risk from one egg may be relatively small, but repeated exposure can add up over time.

The risk can also become more relevant when recipes use several raw eggs at once.

Examples include:

• Homemade Caesar dressing
• Certain mousse recipes
• Raw cookie dough
• Some homemade sauces and desserts

A Safer Alternative

Cooking eggs until both the white and yolk are firm eliminates Salmonella.

If you need eggs for a recipe that requires them to remain raw or lightly cooked, pasteurized eggs are another option.

Pasteurized eggs undergo controlled heating designed to kill harmful bacteria without fully cooking the egg.

5. Raw Oysters and Shellfish

Raw oysters may be considered a delicacy, but they can carry a serious bacterial risk.

The CDC says most people who develop a Vibrio infection get it from eating raw or undercooked shellfish, particularly oysters.

One especially dangerous species is Vibrio vulnificus.

According to the source material, approximately 1 in 5 people infected with Vibrio vulnificus die, sometimes within a very short period after becoming seriously ill.

Why Oysters Can Be Risky

Oysters are filter feeders.

They can concentrate bacteria that naturally exist in coastal waters.

Vibrio bacteria also thrive in warmer water, which means the risk can increase during warmer months. Refrigeration doesn’t necessarily eliminate the bacteria.

Certain people face a much higher risk of severe illness, especially those with:

• Liver disease
• Diabetes
• Weakened immune systems

For these individuals, avoiding raw shellfish is particularly important.

Cooking oysters to an internal temperature of 145°F can eliminate the pathogen.

6. Raw Potatoes

This one may surprise you.

Potatoes aren’t generally thought of as dangerous foods, but raw potatoes can contain naturally occurring compounds called glycoalkaloids.

Two of the most important are solanine and chaconine.

These compounds are especially concentrated in potatoes that are:

• Green
• Sprouted
• Damaged
• Exposed to light

Glycoalkaloids are natural plant compounds that help protect the plant from insects and other threats.

Why Green Potatoes Deserve Attention

A normal potato contains relatively low levels of these compounds.

But green potatoes can contain dramatically higher concentrations, and the skin of a green potato may contain particularly high levels.

High levels can cause gastrointestinal problems and neurological symptoms.

And here’s an important point:

A severely green or sprouted potato should be discarded rather than simply peeled and cooked.

Cooking doesn’t necessarily make a potato with very high glycoalkaloid levels safe.

Raw potato flesh is also difficult for the body to digest and doesn’t offer a meaningful nutritional advantage over properly cooked potatoes.

So if your potato is green, heavily sprouted, or badly damaged, don’t take the risk.

7. Raw Sprouts

Sprouts often appear on lists of healthy foods.

They’re commonly added to salads, sandwiches, wraps, and other meals.

But their growing environment creates a unique food-safety problem.

Sprouts need warm and humid conditions to grow.

Unfortunately, those are also excellent conditions for bacteria such as Salmonella and E. coli to multiply.

If a seed carries even a small amount of bacterial contamination, the bacteria can multiply as the sprout grows.

And simply rinsing the finished sprouts may not remove bacteria that have become established within the sprout itself.

Who Should Be Especially Careful?

The FDA advises the following groups to avoid raw sprouts:

• Children
• Older adults
• Pregnant women
• People with weakened immune systems

For everyone else, thoroughly cooking sprouts can greatly reduce the risk.

Stir-frying or steaming them until they are visibly cooked is a safer option.

8. Raw Cassava

Cassava is a staple food in many parts of the world.

But eating improperly processed cassava can be dangerous.

Cassava contains compounds called cyanogenic glycosides, including linamarin.

When cassava is cut, crushed, grated, or chewed, these compounds can release hydrogen cyanide.

That is what makes improperly processed cassava potentially toxic.

Not All Cassava Has the Same Risk

The amount of cyanide-producing compounds varies considerably between varieties.

Some types of cassava contain relatively low levels, while bitter varieties can contain much higher amounts.

That’s why proper preparation is so important.

Traditional processing methods can include:

• Peeling
• Soaking
• Boiling
• Fermenting
• Drying

Using several processing methods helps reduce the cyanide risk.

Commercially processed cassava products, such as tapioca and properly processed cassava flour, have already undergone safety processing.

The key takeaway: Never assume that raw cassava is safe simply because it looks like an ordinary root vegetable.

9. Raw Cashews

Cashews may be one of the biggest surprises on this list.

When you buy cashews at a grocery store, they are generally safe because commercially processed cashews have already been treated.

But genuinely raw, unprocessed cashews are a different matter.

Cashews and their shells can contain urushiol, the same irritating compound associated with poison ivy.

Commercial producers steam or otherwise process cashews to remove this hazard before they reach consumers.

Exposure to urushiol can cause serious skin irritation and allergic reactions.

If the compound is swallowed, it can affect the mouth, throat, and digestive system.

People who are especially sensitive to poison ivy may experience particularly severe reactions.

What About Store-Bought Cashews?

The cashews sold in ordinary grocery stores have already undergone processing designed to make them safe.

The real concern is unprocessed cashews, especially those still in their outer shells or from an uncertain source.

If you encounter cashews that haven’t been properly processed, don’t eat them.

What to Do With This Information

The good news is that you don’t have to eliminate these foods from your diet.

In most cases, the problem isn’t the food itself—it’s the way the food is prepared.

Kidney beans need proper boiling.

Chicken needs to reach a safe internal temperature.

Eggs can be cooked thoroughly or replaced with pasteurized eggs in recipes that call for raw eggs.

Cassava needs appropriate processing and cooking.

And commercially processed cashews have already had their dangerous outer compounds removed.

The most important lesson is that some foods can look, smell, and taste completely normal while still presenting a health risk.

Salmonella-contaminated chicken doesn’t necessarily smell different from uncontaminated chicken.

A potato can look normal except for a green or sprouted area.

And some foods, such as kidney beans and cassava, can contain naturally occurring toxins that can’t simply be washed away.

A Few Simple Food-Safety Habits

You don’t need to become afraid of these foods.

Instead, make proper preparation part of your routine.

Use a food thermometer when cooking meat and poultry.

Don’t skip the boiling step when preparing dried kidney beans.

Keep raw chicken away from ready-to-eat foods and clean surfaces after handling it.

Choose pasteurized eggs for recipes that require raw or lightly cooked eggs.

Avoid raw shellfish if you’re in a high-risk group.

Throw away heavily green or sprouted potatoes rather than trying to rescue them.

Cook sprouts thoroughly, especially when serving vulnerable family members.

And make sure cassava has been properly processed before eating it.

The biggest takeaway is simple:

Raw doesn’t always mean healthier or safer.

Many foods on this list are nutritious and completely safe when prepared correctly. The danger comes from eating them raw, undercooked, or improperly processed.

Knowing the difference can help you enjoy these foods without taking unnecessary risks.

Note: All images used in this article are AI-generated and intended for illustrative purposes only.