Black Beans: Nutrients, What Research Shows and Safety

Black beans are the seeds of the common bean plant, Phaseolus vulgaris (pea family), picked for their glossy black seed coat. They are a staple in Latin American cooking and are sold dried or canned. People eat them for fiber, plant protein and folate. This page looks at the whole bean as food and keeps it apart from lab studies of pigment extracts and from supplements.

Read this first

• Evidence in one line: pooled trials of beans and other pulses (not black beans alone) show a small drop in LDL cholesterol, and observational studies link legumes with better heart health. [1] [2] We found no black-bean-only trial in the sources we read.
• Cook dried beans fully. The FDA says raw or undercooked beans contain the lectin PHA and advises soaking for at least 5 hours and boiling for at least 30 minutes. [3] Health Canada names red kidney beans as the main concern, and does not name black beans. [4] We did not read a bean-specific boil time for black beans. Canned beans are already cooked. [3]
• Gas is common but often smaller than feared. Beans contain fibers that gut bacteria ferment. [2] In feeding studies of pinto beans, baked beans and black-eyed peas (black beans were not tested), fewer than half of people noticed more gas in the first week. [5]
• Allergy: we did not read a source on black bean allergy. For trouble breathing or swelling of the face or throat after any food, call 911 (or your local emergency number). [6]
• Plant pigments: the dark seed coat holds anthocyanins. The evidence for health effects comes from cell experiments, not people. [7]

What is in it (USDA values)

The main columns are for black beans, mature seeds, boiled without salt (USDA FoodData Central item 173735, SR Legacy) [8]. The serving is the USDA household portion of 1 cup cooked (172 g). The last column is the same bean dry and uncooked (item 173734) [9]; do not compare it with the cooked columns, because cooking adds water. Canned black beans usually contain salt and are a different product, so their numbers differ from the USDA boiled item.

% Daily Value uses the FDA 2016 Daily Values; the cup column is the 100 g value multiplied by 1.72. USDA lists no Daily Value for energy or sugars. Values vary with variety, growing place and cooking time. A dash means USDA has no value.

Plant compounds: the black seed coat (hull) contains anthocyanins, mainly delphinidin-3-O-glucoside, with smaller amounts of petunidin-3-O-glucoside and malvidin-3-O-glucoside, in a 2026 analysis of Mexican black bean hulls. In cultured mouse immune cells, extracts of those hulls reduced reactive oxygen species made after a chemical stress. The authors said studies in living animals or people are needed before any health use. [7] This is laboratory evidence on hull extracts, not on a serving of cooked beans. Beans also contain resistant starch and fermentable sugars [2] and phytic acid, which can reduce mineral absorption; soaking, germination and fermentation lower it. [10]

What research says

Eaten as food vs taken as an extract. The trials above used cooked or processed pulses as food, mostly mixed kinds. Pigment extracts from the hull were only tested in cells. Observational findings show an association, not proof. The abstracts we read did not state who funded the work.

How much is a normal serving

The USDA household portion is 1 cup of cooked black beans (172 g), with about 227 kcal, 15.2 g of protein and 15 g of fiber (see the table). [8] The NHS counts 80 g of beans and pulses as one portion and says they count only once a day toward 5 A DAY. [16] Trials in the cholesterol analysis used a median of about 130 g of pulses a day. [1] This is information, not a prescription.

Safety, allergy and medicines

• Raw or undercooked beans: the FDA lists PHA as a lectin in raw or undercooked beans that can cause nausea, severe vomiting and diarrhea at high levels. [3] Health Canada says the main concern is red kidney beans, with symptoms 1 to 3 hours after eating. [4] See lectins in beans.
• Gas, bloating, cramping: resistant starch and oligosaccharides ferment in the colon. [2] People with a sensitive gut may differ; see beans, gas, FODMAP and digestion.
• Mineral absorption: legumes contain phytic acid, tannins and lectins that can reduce mineral absorption; soaking, germination and fermentation lower them. [10] We did not find a measure of the effect in a mixed diet.
• Allergy: food allergy symptoms usually begin within minutes to 2 hours and range from hives to anaphylaxis; call 911 for anaphylaxis. [6] We read no source on black bean allergy. See food allergy basics.
• Kidney disease, medicines, pregnancy, children: USDA lists 611 mg of potassium (13% of the Daily Value) and 241 mg of phosphorus per cup cooked. [8] We did not read a source on beans and kidney disease limits, medicines, or pregnancy. See foods, kidney disease, potassium and oxalates, food and medicine interactions and foods in pregnancy.

Choosing, storing and food safety

• Dried beans: the FDA says to soak at least 5 hours and boil in fresh water for at least 30 minutes for beans with PHA. [3] Black beans were not named in the sources we read, so check the guidance on lectins in beans.
• Canned beans: canned and properly cooked beans carry PHA at levels that are not a concern. [3] We did not read a source on sodium in canned black beans; see dried vs canned beans, soaking and sodium.
• Processed bean products: Harvard advises checking labels for added sodium in processed legume products. [2]

Related pages

• Lectins in beans: cooking dried beans safely
• Dried vs canned beans, soaking and sodium
• Beans, gas, FODMAP and digestion
• Kidney beans
• Pinto beans
• Legumes as food: what trials found
• Foods for cholesterol and heart health