Kidney Beans: Nutrition, Red Kidney Beans and Cooking Safety

Kidney beans are the large, kidney-shaped beans of the common bean plant, Phaseolus vulgaris, most familiar in chili, rice and beans, and bean salads. They come in dark red, light red and white varieties, and USDA data show a cup of cooked red kidney beans supplies plenty of fiber, plant protein, folate and iron for very little fat. There is one rule that sets them apart from most other beans: raw or undercooked kidney beans contain a natural toxin that the FDA links to sudden, severe vomiting, so dried beans must be soaked and boiled. Below are the USDA numbers, how canned and dried beans differ, what research says about beans and health, and how to cook them safely.

Peptide Labs does not sell kidney beans or bean products. This article is general nutrition information, not medical advice.

Kidney beans nutrition: USDA values

The table uses USDA FoodData Central (SR Legacy) entries for one cup of beans, with the percent Daily Value (%DV) based on FDA reference values. USDA keeps separate entries for several red varieties, and the numbers differ more than most people expect, especially for fiber and folate.

A cup of boiled red kidney beans (FDC 175194) also provides about 40 g of carbohydrate, 0.9 g of fat and well under 1 g of sugars, plus copper (48% DV), manganese (37%), thiamin (24%), phosphorus (20%), magnesium (19%), zinc (17%) and potassium (15%). Two things stand out in the data. First, the canned entries list far less folate than home-cooked beans, so the label is worth checking if folate matters to you (our methylfolate guide explains folate forms). Second, sodium is the big difference between canned and home-cooked: USDA lists 655 milligrams per cup for canned red kidney beans with their liquid and 421 milligrams for beans boiled with salt, compared with almost none for beans boiled without salt.

Red kidney beans vs other beans

“Red kidney beans” usually means dark or light red beans; USDA also lists California red and royal red varieties. White kidney beans, often sold as cannellini, are the same species with a pale seed coat. Nutritionally, kidney beans sit close to other common beans. Per cooked cup in USDA data, black beans have 227 calories, 15.0 g of fiber and 64% DV for folate; pinto beans 245 calories, 15.4 g of fiber and 74% DV for folate; navy beans 255 calories and 19.1 g of fiber. Kidney beans trail slightly on fiber in the red entry but lead on iron. See our black bean guide and chickpea guide for side-by-side numbers.

Like all plant foods, kidney beans supply nonheme iron, which the body absorbs less readily than the heme iron in meat. The NIH Office of Dietary Supplements notes that vitamin C eaten at the same meal enhances nonheme iron absorption, which is one reason beans pair well with tomatoes, peppers or salsa. Our foods high in iron list puts beans in context.

Are kidney beans healthy?

For most people, yes: properly cooked kidney beans are a nutrient-dense whole food. The Dietary Guidelines for Americans count beans, peas and lentils toward both the vegetable group and the protein foods group, which few foods manage. The research on beans is mostly about pulses as a group rather than kidney beans alone:

• Cholesterol: a 2014 meta-analysis in CMAJ pooled 26 randomized trials with 1,037 participants and found diets that emphasized pulses lowered LDL cholesterol by a small average amount compared with similar diets without them. It found no effect on apolipoprotein B or non-HDL cholesterol, and the authors called for longer, higher-quality trials.
• Fiber: most American adults eat less fiber than recommended, and beans are among the richest whole-food sources. Our high fiber foods list and fiber intake guide show where beans fit.
• Protein: about 15 g per cooked cup makes kidney beans a useful plant protein, though they are lower in the amino acid methionine than animal foods; mixing protein sources across the day covers this. See high protein foods.
• Eating patterns: beans are a staple of the Mediterranean diet, an eating pattern that has been widely studied.

None of this makes kidney beans a medicine, and the trials tested whole diets, not a single bean. If you have a condition that affects what you can eat, such as kidney disease with potassium or phosphorus limits, ask your clinician or a registered dietitian how beans fit.

Raw kidney beans: why undercooking matters

The FDA’s Bad Bug Book explains that phytohaemagglutinin, a natural lectin, is found in many species of beans and is in highest concentration in red kidney beans. Eating raw or undercooked kidney beans usually causes extreme nausea and vomiting within one to three hours, followed by diarrhea, and some people report abdominal pain. Recovery is usually fast, but some cases have needed hospital care. The FDA says the illness has most often followed raw, soaked beans eaten alone or in salads or casseroles, and several outbreaks were linked to slow cookers or casseroles that never got hot enough to destroy the toxin. White kidney beans contain less of it than red ones, about a third in the FDA’s figures, but still need the same care.

• Soak, drain, boil: the FDA’s consumer advice is to soak dried kidney beans, pour the soaking water away and boil the beans in fresh water. Follow the soaking and boiling times in the FDA guidance or on the package, and cook until the beans are completely soft.
• Slow cookers: the FDA says not to use slow cookers to cook kidney beans or dishes made with them, because low-temperature cooking may not destroy the toxin. Boil the beans first if a recipe finishes in a slow cooker.
• Soaking alone is not cooking: soaked but uncooked beans are a known cause of outbreaks, so never add them raw to salads.
• Canned beans: canned kidney beans are cooked during canning and can be eaten from the can or heated.

Our lectin guide explains why properly cooked beans are very different from raw ones. If you or someone you are with has sudden, severe vomiting or signs of dehydration after eating beans, get medical care.

Gas, sodium and other practical points

• Gas: gut bacteria ferment the resistant starches and oligosaccharides in beans, which can cause gas and bloating. Harvard’s Nutrition Source notes that soaking and cooking may help, and in feeding studies published in 2011 fewer than half of participants reported more gas in the first week of eating beans daily, with complaints tending to fade. See gas and bloating.
• Sodium: USDA’s low-sodium canned entry lists 300 milligrams per cup, and draining and rinsing regular canned beans lowers sodium by about a tenth in USDA data. Our low sodium foods guide explains label terms.
• Allergy: kidney beans are not one of the nine major food allergens US labels must declare, but any legume can cause a reaction. See an allergist for unclear symptoms.
• Supplements are different: extracts of white kidney beans are sold as “carb blocker” supplements. That is a separate product with its own evidence and cautions; our guide to the bean-extract supplement covers it. Eating cooked kidney beans is not the same thing.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Arrowroot: Powder, Nutrition and Arrowroot vs Cornstarch, Lectins: What They Are, Which Foods Have Them and What Cooking Does, Black Beans: USDA Nutrition per Cup, Protein, Fiber and Canned vs Dried.