Bananas: Nutrients, What Research Shows and Safety

Bananas are the fruit of tall tropical plants in the genus Musa (the common dessert banana is often listed as Musa x paradisiaca), in the banana family (Musaceae). The soft pulp inside the peel is what people eat. People often eat bananas for potassium, fiber and an easy snack. This page keeps the food apart from supplements and from hype, and says plainly what research does and does not show.

Read this first

• Allergy is possible, and bananas are linked to latex-fruit allergy. If someone has trouble breathing or swelling of the face or throat after eating, call 911. See food allergy basics and emergency signs.
• Bananas are a well-known source of potassium. People with advanced kidney disease, or who take medicines that raise potassium, may be told to limit them by their clinician. The kidney charity NKF lists half a banana among its higher-potassium choices for people with kidney disease. [2]
• Eating bananas has not been shown to prevent or treat a disease. The best-studied topics (potassium and blood pressure, green banana and diarrhoea in small children, unripe banana flour and blood sugar) each have limits, explained below.

What is in it (USDA values)

USDA FoodData Central lists "Bananas, raw" (SR Legacy). [1] The serving below is the USDA household portion "1 medium (7 to 7-7/8 inches long)", 118 g. Serving values are the USDA per-100 g numbers scaled to 118 g.

% Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage. [1]

Bananas are low in vitamin K and vitamin A, according to the USDA numbers. Unripe (green) bananas are studied for "resistant starch", a starch that is not fully digested in the small intestine. Our sources for resistant starch are a human review of unripe banana flour (small, short trials) [7] and a mouse study of green banana resistant starch (lab/animal only). [8] We did not find a source we could read that measured other plant compounds in bananas, so we do not list them.

What research says

Eaten as food vs taken as a supplement or extract. The potassium and normal nutrition information above applies to eating the fruit. The blood-sugar findings come from unripe banana flour, a processed powder, and the colitis finding comes from a purified starch fed to mice. None of these shows that a ripe banana does the same thing. We did not find a supplement trial that we could read, so we make no claim about banana capsules or extracts.

How much is a normal serving

USDA lists these household portions for raw bananas: one extra small (81 g), small (101 g), medium (118 g), large (136 g), 1 cup sliced (150 g) and 1 cup mashed (225 g). [1] This is information, not a prescription. We could not read the MyPlate fruit page in this round, so we do not state an official "cups of fruit per day" figure here. For potassium, the NHS states that adults aged 19 to 64 need 3,500 mg a day and that this can usually come from a normal diet. [4] MedlinePlus likewise says many people get the potassium they need from what they eat and drink. [3]

We did not find a source we could read that compares ripe, green, frozen, dried or banana-chip forms for health outcomes. Dried banana and chips are more concentrated in sugar and energy per gram than fresh fruit (this follows from water loss; we did not find a USDA figure for them in this round). See fresh, frozen and canned produce and fruit juice vs whole fruit.

Safety, allergy and medicines

• Allergy: Banana allergy is described in people in Thailand and Austria: the Thai adults mostly had whole-body reactions, while the Austrian adults more often had mouth symptoms only (oral allergy syndrome). The authors link reactions to a protein called thaumatin-like protein. [10] Researchers have also reported new possible banana allergens in a small group of allergic Thai adults. [12] For trouble breathing, widespread hives or swelling of the face or throat, call 911. [10]
• Latex-fruit syndrome: A 2024 review says 30 to 50% of people with natural rubber latex allergy also react to plant foods, particularly fresh fruits. [11] The abstract we read does not name bananas, so ask an allergist if you have a latex allergy and have reacted to fruit.
• Kidney disease and potassium: The National Kidney Foundation says people with high blood potassium may be told to limit higher-potassium foods, and lists half a banana among those foods; portion size matters, and a dietitian can help. [2] MedlinePlus says that with chronic kidney disease the kidneys may not remove extra potassium, so a special diet may be needed. [3]
• Medicines that raise potassium: MedlinePlus says some medicines can raise potassium. [3] A 2026 study of people taking renin-angiotensin-aldosterone system (RAAS) inhibitors (a class that includes ACE inhibitors and ARBs) found that adding another potassium-raising drug raised hyperkalaemia rates, with kidney disease and age 75 or older the strongest predictors. [14] We did not find a source we could read that tests bananas themselves with these medicines. Ask a pharmacist or doctor before changing potassium intake while on such medicines. See foods and medicine interactions.
• Too much potassium: The NHS says excess potassium can cause stomach pain, nausea and diarrhoea, and that older people, whose kidneys may clear potassium less well, should not take potassium supplements unless a doctor advises it. [4] This concerns supplements; we did not find a source describing harm from ordinary banana intake in people with healthy kidneys.
• Sugar and diabetes: USDA lists about 12 g of sugars per 100 g. [1] We did not find a source we could read on how banana ripeness affects blood sugar in people with diabetes. Proper evidence not found; a diabetes team can advise.
• Pregnancy and breastfeeding: Proper evidence not found in the sources we read. See foods in pregnancy: what official bodies advise.
• Babies and toddlers: Choking can happen with any firm food pieces; see foods for babies and toddlers.

Choosing, storing and food safety

• Pick fruit that is not bruised or damaged; cut away bruised areas and throw out fruit that looks rotten. [13]
• Rinse produce under running water, including items you peel, and do not use soap or produce wash. Washing reduces bacteria but does not remove all of them. [13]
• Refrigerate cut or peeled fruit, and keep fruit away from raw meat, poultry, seafood and their utensils. [13]

Related pages

• Food allergy basics and emergency signs
• Foods, kidney disease, potassium and oxalates
• Foods and medicine interactions
• Fruit juice vs whole fruit
• Fresh, frozen and canned produce
• Resistant starch foods