Eating raw or undercooked beans can be dangerous. This is because beans contain natural toxins called lectins that can cause severe gastrointestinal issues if consumed before being properly prepared. Cooking beans at high enough temperatures breaks down lectins to safe levels. Eating just 4-5 uncooked beans could cause lectin poisoning. Symptoms include severe nausea, vomiting, diarrhea and abdominal pain. In rare cases, kidney failure has occurred. Fortunately lectin levels are reduced via proper soaking and thorough cooking of beans. Follow proper preparation guidelines and you can safely enjoy nutritious beans.
What are lectins?
Lectins are carbohydrate-binding proteins found in many plants, especially beans and grains. They serve as natural insecticides and protection for the plant. About 5-10% of the proteins in raw beans are lectins. The level of lectinic activity varies among different types beans. Raw kidney beans have the highest lectin content. Lentils, peas and peanuts have lower lectin levels. Lectins bind to cell membranes in the digestive tract. They damage the membranes which prevents proper absorption of nutrients. Lectins interfere with bacterial and viral activity as well as metabolism and growth.
Signs and symptoms
If you eat 4-5 raw kidney beans, symptoms generally occur within 3-4 hours. With red kidney beans, symptoms appear faster in 1-3 hours. Initial symptoms include:
Nausea and vomiting
One of the first signs is severe nausea followed by violent vomiting. The vomiting can persist for hours. This leads to dehydration and electrolyte imbalances.
Abdominal pain and cramping
As the beans travel through the digestive tract, intense abdominal cramping and pain develop. This mimics food poisoning. The painful cramps may come and go in waves. Bloating and gas also commonly occur.
Diarrhea
Profuse and watery diarrhea develops soon after ingesting raw beans. In some cases, the diarrhea contains blood and mucus. The frequency of bowel movements may be as often as every 30 minutes. The diarrhea can persist for 24 hours or longer.
What’s happening inside the body?
Inside the stomach and intestines, lectins bind to the lining of the digestive tract. This destroys the microscopic hair-like villi which are essential for absorbing nutrients. The lectins also disrupt the cells of the intestinal lining. This leads to damage along the gut wall, interfering with digestion and creating a “leaky gut.”
The cells of the stomach lining secrete more acid as well as histamine in response to the lectins. This leads to hyperacidity and inflammation. The intestinal walls become irritated and congested. The digestion process is severely impaired.
Soon the diarrhea results in dehydration and mineral losses, especially potassium. The situation worsens as pathogenic bacteria proliferate inside the damaged gut. Some lectins may enter the bloodstream where they can agglutinate red blood cells and disrupt oxygen delivery in the body.
Risk of kidney damage
In very severe cases, the toxins in raw beans can lead to kidney damage and failure. This is preceded by signs of impaired kidney function like darkened urine, swelling, and protein in the urine. The kidney damage may become apparent 1-3 days after ingesting the beans. Those already with compromised kidney function are especially susceptible.
Duration of symptoms
In mild cases with only a few raw beans eaten, symptoms may only last 8-12 hours before resolving. However, larger quantities can lead to 1-3 days of ongoing intestinal distress. Dehydration and mineral imbalances may linger even after the diarrhea ends. Damaged tissues take time to heal and regenerate. Those with prior bowel issues may experience symptoms for a week or longer.
Who is most at risk?
Young children
Children’s digestive systems are much more sensitive to toxins. Just 2-3 raw beans could trigger a reaction. Dehydration develops rapidly in kids.
Elderly
With age, digestive function declines. The lining of the GI tract thins and loses resiliency. Older adults have less acid secretion to destroy lectins. Dehydration also occurs faster.
Those with compromised digestion
People with conditions like IBS, IBD, leaky gut, SIBO or digestive enzyme deficiencies are unable to properly breakdown lectins. Those with prior bowel surgeries or resection are also at higher risk.
Individuals with kidney disorders
Those with existing kidney disease or susceptibility are in danger of kidney failure if they ingest raw bean lectins. The toxins can directly damage the kidney cells.
Which beans are most dangerous?
| Bean Type | Lectin Content | Toxicity Level |
|---|---|---|
| Red kidney beans | Very high | Extremely toxic when raw |
| Broad beans | High | Highly toxic raw |
| Black beans | Moderately high | Moderately toxic raw |
| Pinto beans | Moderate | Moderately toxic raw |
| Navy beans | Moderate | Moderately toxic raw |
| Soybeans | Moderate | Moderately toxic raw |
| Kidney beans | Low | Mildly toxic raw |
| Lima beans | Low | Mildly toxic raw |
| Green beans | Very low | Minimally toxic raw |
| Peas | Very low | Minimally toxic raw |
| Lentils | Very low | Minimally toxic raw |
As shown, red and white kidney beans contain very high lectin levels and are extremely toxic when eaten raw. Broad beans, black beans and soybeans also have abundant lectins. Green beans and lentils have lower concentrations and therefore minimal toxicity in the raw state.
How many beans can cause a reaction?
As few as 4-5 raw kidney beans or 8-10 soybeans can trigger symptoms in sensitive individuals. Those with compromised digestion may react to even fewer beans. On average, consuming more than 15-20 raw beans poses a significant risk of lectin poisoning.
With lower toxicity varieties like lentils or green beans, a larger quantity would need to be eaten raw to potentially cause issues. However, it’s ideal to fully cook all beans and legumes rather than risk undercooking them.
Treatment
If you develop symptoms after ingesting raw beans, the main treatment involves supportive care while your body clears the lectins:
Hydration
Drinking oral rehydration fluids is key to replenish fluids and electrolytes lost through vomiting and diarrhea. Intravenous fluids may be given in severe dehydration.
Medications
Anti-nausea and anti-diarrheal medications provide symptom relief. Pain relievers ease abdominal cramps and discomfort.
Diet
Once tolerated, eat a bland, low fiber, BRAT diet – bananas, rice, applesauce and toast. Probiotics may help restore gut microflora after bacteria is lost.
Monitoring
Those severely ill may require hospitalization for close monitoring of hydration status, kidney function, electrolytes and weight.
Time
Within 12-48 hours after consuming the beans, symptoms typically start to resolve as the lectins pass through the digestive system. Complete recovery often takes 3-7 days in otherwise healthy individuals. Those with pre-existing conditions may require a longer recovery.
Can you die from eating raw beans?
Death from consuming a small amount of raw beans is extremely rare. Only a handful of deaths have ever been reported from lectin poisoning. These cases usually involved the elderly, children or those with compromised health that worsened the dehydration and kidney damage.
That said, professional medical care is recommended if severe, persistent vomiting, bloody diarrhea, confusion, significantly darkened urine or difficulty breathing occurs after eating raw beans.
Long-term consequences
In healthy people, the damaged intestinal lining repairs within several days after an acute episode of bean lectin poisoning. No long-lasting effects occur.
However, those with chronic kidney disease may suffer an irreversible decline in kidney function from the toxicity. Those with pre-existing bowel issues like IBS or leaky gut may experience a prolonged flare up of symptoms after the acute food poisoning resolves.
Prevention
Lectin toxicity can easily be prevented through proper preparation of beans:
Soaking
Before cooking, soak dry beans for 12-24 hours in water with a splash of lemon juice or vinegar added. The acidic soaking liquid helps deactivate lectins. Discard this soaking liquid before cooking.
Cooking
Beans, especially kidney beans, need thorough cooking at a sustained boiling temperature of at least 176°F-185°F to fully destroy lectins. Pressure cooking is an excellent method. Slow cookers may not reach adequate internal temperatures.
Canning
The high heat of pressure canning reduces lectin content in beans to low levels. If you grow your own beans, preserve them by pressure canning using tested recipes.
Sprouting
Sprouting beans like lentils before cooking helps reduce lectins. Cook sprouted beans thoroughly after sprouting.
Fermenting
Lacto-fermentation via sourdough or cultures helps degrade lectins while increasing digestibility of beans. Always fully cook fermented beans.
Following evidence-based preparation guidelines reduces lectins to safe levels in beans, allowing you to enjoy their tremendous nutritional benefits.
What to do if you accidentally eat raw beans
If uncooked beans were inadvertently consumed, take these steps:
– Drink large amounts of liquids like water, coconut water and herbal tea to stay hydrated
– Take activated charcoal capsules to help bind lectin toxins
– Monitor for signs of nausea, cramping or diarrhea
– Call your doctor if severe symptoms develop including bloody stools or vomiting despite hydration
– Avoid solid foods and eat a liquid diet like bone broth until symptoms resolve
– Consider taking digestive enzymes or probiotics to help repair damaged gut lining after the acute symptoms resolve
– In the future, inspect beans closely before consuming. Discard any that may be uncooked.
Health benefits of properly prepared beans
When soaked, sprouted and thoroughly cooked, beans offer tremendous nutritional and health benefits:
Protein
Beans provide abundant high-quality plant-based protein needed for energy, muscle maintenance and growth. The protein is substantial with approximately 15g protein per cooked cup of beans.
Fiber
The indigestible carbohydrates in bean fiber promote digestive regularity and feed beneficial gut bacteria. Beans contain a blend of both soluble and insoluble fiber.
Iron
Beans supply a highly bioavailable form of iron needed for healthy blood and preventing anemia. The iron in beans is more readily absorbed compared to grains.
Folate
A cup of cooked beans can provide up to 90% of the RDA for folate, a B-vitamin essential for cell growth and preventing birth defects.
Magnesium
An often lacking mineral, magnesium is abundantly supplied by beans. Magnesium relaxes muscles, aids nerve transmission and maintains bone density.
Antioxidants
Beans contain a spectrum of phytonutrient antioxidants including flavonoids like quercetin that reduce inflammation and oxidative stress.
Heart health
Clinical studies show regular bean consumption lowers LDL cholesterol, blood pressure and CRP levels while beneficially modulating blood sugar.
Cancer prevention
The pattern of antioxidants, fiber and phytosterols in beans offer protection against colon, breast and prostate cancers.
Blood sugar control
Despite their carbohydrate content, beans have a low glycemic index that prevents unhealthy spikes in blood glucose.
When properly prepared to destroy lectins yet retain nutrients, beans are one of the healthiest foods to include in your diet. In fact, eating beans 4+ times per week confers significant health advantages.
Types of beans and their benefits
While all beans offer similar benefits, different varieties have unique advantages:
Black beans
High in anthocyanin antioxidants, calcium, folate, magnesium, phosphorus, protein. Benefits heart health.
Garbanzo beans (chickpeas)
Excellent source of fiber, folate, iron, magnesium, manganese, phosphorus and zinc. Helps lower cholesterol.
Kidney beans
Rich in molybdenum, folate, fiber, magnesium, copper. Helps detoxification processes in the body.
Pinto beans
Abundant protein, fiber, folate, magnesium, phosphorus, iron, copper, manganese. May improve blood sugar control.
Navy beans
High in soluble fiber, folate, magnesium, potassium, iron and phosphorus. Helps regulate blood pressure.
Lima beans
Excellent source of fiber, iron, copper, manganese, phosphorus, riboflavin. Useful for muscle building.
Cannellini beans
Loaded with thiamin, folate, iron, magnesium, phosphorus, potassium and zinc. Helps boost energy.
Cranberry beans
Rich in protein, fiber, calcium, iron, magnesium, phosphorus, potassium. Contains disease-fighting anthocyanins.
Anasazi beans
Abundant protein, calcium, iron, magnesium, potassium. High antioxidant levels benefit cellular health.
Explore different bean varieties to take advantage of their unique nutritional attributes.
Tasty ways to use beans
Once properly prepared, beans are endlessly versatile in meals and snacks:
– Chili – Kidney, pinto and black beans star in hearty classic chili.
– Tacos – Mash black or pinto beans with taco seasoning and fill corn tortillas for a protein-rich taco.
– Burgers – Make bean burgers with black beans, chickpeas or cannellini beans as the base.
– Soup – Purée white beans into creamy soups. Add beans to minestrone or lentil soup.
– Salad – Chickpeas and kidney beans add protein, fiber and nutrients to leafy green salads.
– Dip – Blend edamame or cannellini beans into creamy, protein-packed dips and spreads.
– Bake – Mix black beans, white beans or lentils into breads, bars and muffins for added nutrition.
– Rice bowls – Top cauliflower rice with sautéed beans like pinto beans seasoned with spices.
– Breakfast – Heat pinto beans with eggs for a hearty breakfast burrito filling.
With minimal prep time, beans can be incorporated into many quick meals and snacks throughout the day. Creatively use them to boost nutrition in your diet.
Takeaway
Raw beans contain natural toxins called lectins that can cause severe food poisoning. However, properly soaking and then thoroughly cooking beans destroys lectins to safe levels while preserving essential nutrients. Consuming beans regularly is linked to multiple health benefits, so long as evidence-based preparation methods are followed to remove lectins yet retain nutrition. Just 4-5 improperly prepared beans could make you sick, but properly prepared beans are a disease-fighting superfood.