Apple and banana: potassium, fiber and a handful of small trials

The largest set of trials here is a treatment study in sick children, not advice for home care. A meta-analysis of 9 randomized trials in 3,996 children aged 8 to 34 months with acute or persistent diarrhea compared green banana foods with standard treatment and found faster recovery (HR 1.96, 95% CI 1.62 to 2.37), with seven of nine trials open-label. We hold no card on whether the banana was given alongside oral rehydration, so nothing here supports giving banana in place of rehydration or medical care to a child with diarrhea. The banana in those trials was green cooking banana, a different food from the ripe fruit in your bowl. The apple's best trial is smaller and about cholesterol. In 40 adults with mildly high cholesterol, mean age 51, two apples a day of one proanthocyanidin-rich variety, Renetta Canada, for 8 weeks left total cholesterol at 228 mg/dL (5.89 mmol/L) against 236 mg/dL (6.11 mmol/L) after a matched apple drink, with LDL at 3.72 against 3.86. On the basics the fruits split cleanly. Per 100 g, USDA samples put ripe banana at 326 mg of potassium against 98 to 116 mg in four apple varieties, with variety and ripeness moving both. We hold no card on banana potassium for people with kidney disease or on medicines that affect potassium. Fiber sits close, at 1.7 to 2.5 g in apples with skin and 1.7 g in banana. One absorption study below used dried apple peel powder, and its result belongs to that powder.

How much is actually in it

• USDA lab samples put a ripe banana at about 326 mg potassium per 3.5 oz (100 g), roughly three times the 98 to 116 mg measured in four apple varieties. — USDA FoodData Central Foundation Foods samples: Bananas, ripe and slightly ripe, raw (6 samples); Apples fuji, gala, honeycrisp, granny smith, with skin, raw (8 samples each) (n = 38 samples) Evidence E source
  Banana 326 mg/100 g (range 300-355); apples 98.04-115.9 mg/100 g (range 76.7-146)
• Per 100 g, apples with skin measured 1.7 to 2.5 g of fiber and ripe bananas 1.7 g, so the two are close and vary more within each fruit than between them. — USDA Foundation Foods samples: four apple varieties with skin (8 samples each); Bananas, ripe and slightly ripe, raw (10 samples) (n = 42 samples) Evidence E source
  Apples 1.721-2.514 g/100 g; banana 1.7 g/100 g (range 1.1-2.2)

What a real portion looks like

• In the USDA survey food table a medium raw apple weighs 7.1 oz (200 g) and one raw banana 126 g, so a piece of apple is about 60% heavier. — USDA FNDDS household measures, Apple, raw, code 63101000 and Banana, raw, code 63107010 Evidence E source
  Apple 165 g small, 200 g medium, 242 g large, 125 g per cup; banana 126 g each, 150 g per cup sliced, 225 g per cup mashed

What your body absorbs

• In a controlled crossover study in 8 men, a drink high in the banana enzyme polyphenol oxidase cut peak blood flavan-3-ol levels by 84% compared with capsules, while a low-enzyme drink did not. — healthy men (n = 8); follow-up study n = 11 with banana drink co-ingested without prior contact (n = 8) Evidence B source
  Cmax 96 +/- 47 vs 680 +/- 78 nmol/L, 84% lower
• In a randomized trial in 16 adults, quercetin from apple peel peaked at about 64 ng/mL in blood, about a quarter of the 273 ng/mL reached from onion. — healthy volunteers, eight females and eight males (n = 16) Evidence B source
  Cmax 63.8 +/- 22.4 ng/mL apple peel vs 273.2 +/- 93.7 ng/mL onion powder

What cooking and storage change

• By the USDA retention table, baked fresh non-citrus fruit such as apple or banana keeps 80% of its vitamin C, 60% of folate and 90% of potassium. — USDA Table of Nutrient Retention Factors Release 6, group Fruits and Fruit Juices, method code 151, table dated Sep-75 Evidence E source
  Vitamin C 80%, folate 60%, thiamin 80%, potassium 90%, iron and magnesium 100% retained

What it does to your health

• In a randomized crossover trial in 40 adults with mildly high cholesterol, two apples a day for 8 weeks lowered total cholesterol to 228 vs 236 mg/dL (5.89 vs 6.11 mmol/L) on a matched apple drink. — healthy mildly hypercholesterolemic volunteers (23 women, 17 men), mean age 51, 8 weeks per arm (n = 40) Evidence B source
  Total cholesterol 228 vs 236 mg/dL (5.89 vs 6.11 mmol/L); LDL 144 vs 149 mg/dL (3.72 vs 3.86 mmol/L); triglycerides 104 vs 115 mg/dL (1.17 vs 1.30 mmol/L)
• Observational data from 341,519 Europeans link a high combined intake of apple or pear, banana, mushrooms and onion or garlic with a lower Crohn's disease risk (aHR 0.58, CI crossing 1). — EPIC cohort, median follow-up 13.4 years (n = 341519) Evidence C source
  Fourth vs first quartile aHR 0.58 (95% CI 0.33-1.02), P trend 0.03

Safety, limits and interactions

• In a randomized trial of birch-pollen apple allergy, 17 of 27 people eating slowly increasing amounts of apple for 8 months could tolerate a whole apple, vs none of 13 controls. — 40 patients with birch pollen rhinoconjunctivitis and oral allergy syndrome to apple (n = 40) Evidence B source
  17/27 vs 0/13 tolerated a whole apple, P = 0.0001; tolerance transient after stopping
• NIH ODS states that in people who cannot excrete potassium normally, because of chronic kidney disease or drugs such as ACE inhibitors or potassium-sparing diuretics, even dietary potassium intakes below the Adequate Intake can cause hyperkalemia. This includes potassium from apples and bananas. — people with chronic kidney disease or taking ACE inhibitors or potassium-sparing diuretics Evidence E source
  Hyperkalemia possible even below the Adequate Intake, no threshold given

What people believe that the data does not support

• The EU did not authorize a claim that bananas are a major dietary source of antioxidants that protect cells from oxidative damage. — EU nutrition and health claims register Evidence E source
  Status Non-authorized
• The EU did not authorize a claim that apple juice helps maintain a healthy cardiovascular system. — EU nutrition and health claims register Evidence E source
  Status Non-authorized

Who this works differently for

• In a randomized crossover trial in 14 trained cyclists, bananas fueled a 75-km time trial as well as a 6% carbohydrate drink (2.41 vs 2.36 h). — trained cyclists, 0.2 g/kg carbohydrate every 15 min (n = 14) Evidence B source
  Performance 2.41 +/- 0.22 vs 2.36 +/- 0.19 h, P = 0.258
• A meta-analysis of 9 randomized trials in 3996 young children found green banana foods nearly doubled the rate of diarrhea resolution (HR 1.96). — children aged 8 to 34 months with acute or persistent diarrhea (n = 3996) Evidence A source
  HR 1.96 (95% CI 1.62-2.37)

What is still unknown

• USDA samples put vitamin C in ripe bananas at about 12 mg per 3.5 oz (100 g), falling to about 10 mg when overripe. Raw apples have no comparable sampled value in this dataset. — USDA Foundation Foods: Bananas, ripe and slightly ripe, raw (12 samples); Bananas, overripe, raw (6 samples) (n = 18 samples) Evidence E source
  Ripe 12.3 mg/100 g (range 9.2-15.1); overripe 9.7 mg/100 g (range 8.3-12.0)
• A 2026 systematic review of 38 human studies on apples found possible short-term benefits for blood sugar and blood vessels but called the evidence insufficient for firm conclusions. — 38 human intervention studies (13 postprandial, 22 medium or long term, 3 both) (n = 38 studies) Evidence C source
  Direction only; no pooled estimate

The bottom line

A medium apple weighs 7.1 oz (200 g) in the USDA survey table and one banana 126 g, so the per 3.5 oz (100 g) figures need scaling before you compare one piece with another. USDA samples put vitamin C in ripe banana at 12.3 mg per 3.5 oz (100 g), falling to 9.7 mg when overripe, and the same dataset has no sampled vitamin C value for raw apple. Baking fresh non-citrus fruit keeps 80 percent of vitamin C, 60 percent of folate and 90 percent of potassium by the USDA retention table, a factor for the whole food group that was never measured on apples or bananas themselves. In 16 adults, quercetin from dried apple peel powder peaked at 63.8 ng/mL in blood against 273.2 ng/mL from onion powder, a result for a powder and not for a fresh apple. In 14 trained cyclists, bananas eaten during a 75 km time trial gave a finishing time of 2.41 hours against 2.36 on a 6 percent carbohydrate drink, a difference that did not reach significance (P = 0.258) in a single ride. Observational data from 341,519 Europeans followed for a median 13.4 years link the highest combined intake of apple or pear, banana, mushrooms and onion or garlic with a lower risk of Crohn's disease (aHR 0.58, 95% CI 0.33 to 1.02). That rests on 149 cases, and the interval crosses 1. A 2026 systematic review of 38 human studies on apples saw possible short-term effects on blood sugar and blood vessels and judged the evidence insufficient for firm conclusions. The EU did not authorize a claim that bananas are a major dietary source of antioxidants. It also refused a claim that apple juice helps keep the cardiovascular system healthy, a claim about juice. Under safety, the one finding is about apple allergy. In a randomized open-label trial in 40 people with birch pollen hay fever and oral allergy to apple, 17 of 27 who ate slowly increasing amounts of apple could then tolerate a whole apple, against none of 13 controls. That was a study protocol in patients with a diagnosed apple allergy, and no card here tests it outside a trial. The tolerance faded once they stopped. We have no card on medicines, kidney disease or pregnancy for either fruit.

Sources

1. apbn-r6-01 · food composition dataset
   Bananas, ripe and slightly ripe, raw: Potassium, K 326.0 MG range 300.0-355.0 median 326.0 n=6 · Apples, fuji, with skin, raw: Potassium, K 103.8 MG range 79.3-119.0 n=8 · Apples, gala, with skin, raw: 105.9 MG range 85.2-126.0 n=8 · Apples, honeycrisp, with skin, raw: 98.04 MG range 76.7-126.0 n=8 · Apples, granny smith, with skin, raw: 115.9 MG range 85.4-146.0 n=8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
2. apbn-r6-02 · food composition dataset
   Apples, fuji, with skin, raw: Fiber, total dietary 2.075 G range 1.89-2.32 n=8 · Apples, gala, with skin, raw: 2.109 G range 1.79-2.73 n=8 · Apples, honeycrisp, with skin, raw: 1.721 G range 1.49-1.95 n=8 · Apples, granny smith, with skin, raw: 2.514 G range 2.15-3.07 n=8 · Bananas, ripe and slightly ripe, raw: Fiber, total dietary 1.7 G range 1.1-2.2 median 1.7 n=10
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
3. apbn-r6-04 · food survey portion dataset
   FNDDS 63101000 Apple, raw: 1 small 165 g · 1 medium 200 g · 1 large 242 g · 1 extra large 295 g · 1 cup 125 g; FNDDS 63107010 Banana, raw: 1 banana 126 g · 1 slice 6 g · 1 cup 150 g · 1 cup, mashed 225 g
   USDA FNDDS 2021-2023, codes 63101000 and 63107010 · checked 2026-10-02
4. apbn-r6-06 · randomized crossover trial
   The peak plasma concentration (Cmax) of flavan-3-ol metabolites after capsule intake was 680 ± 78 nmol L-1, which was similar to the levels detected after the intake of the low PPO drink. In contrast, the intake of the high PPO drink resulted in a Cmax of 96 ± 47 nmol L-1, 84% lower than that obtained after capsule intake.
   Food Funct, 2023 · checked 2026-10-02
5. apbn-r6-07 · randomized crossover trial
   Consumption of the OP resulted in C(max) = 273.2 ± 93.7 ng/mL, t(max) = 2.0 ± 1.7 h, and t(1/2) = 14.8 ± 4.8 h, whereas the AP resulted in C(max) = 63.8 ± 22.4 ng/mL, t(max) = 2.9 ± 2.0 h, and t(1/2) = 65.4 ± 80.0 h.
   J Agric Food Chem, 2012 · checked 2026-10-02
6. apbn-r6-05 · retention factor dataset
   USDA-RETN-R6:151 FRUITS,FRESH(NOT CITRUS),BAKED, group Fruits and Fruit Juices: folate_total_ug 60% retained, vitamin_c_mg 80%, thiamin_mg 80%, potassium_mg 90%, iron_mg 100%, magnesium_mg 100%
   USDA Table of Nutrient Retention Factors, Release 6, 2007, Retn_Code 151 · checked 2026-10-02
7. apbn-r6-08 · randomized crossover trial
   Whole apple (WA) consumption decreased serum total (WA: 5.89 mmol/L; CB: 6.11 mmol/L; P = 0.006) and LDL cholesterol (WA: 3.72 mmol/L; CB: 3.86 mmol/L; P = 0.031), triacylglycerol (WA: 1.17 mmol/L; CB: 1.30 mmol/L; P = 0.021)
   Am J Clin Nutr, 2020 · checked 2026-10-02
8. apbn-r6-12 · prospective cohort
   Pooled consumption of apple/pear, banana, mushrooms, and onion/garlic was associated with a lower risk of CD (fourth vs first quartile aHR 0.58; 95% CI: 0.33-1.02, P trend 0.03).
   Am J Gastroenterol, 2026 · checked 2026-10-02
9. apbn-r6-11 · randomized controlled trial
   Seventeen of 27 patients in active group and none of 13 patients in control group (P = 0.0001) could tolerate a whole apple after the intervention.
   Allergy, 2012 · checked 2026-10-02
10. sf-khyp-r1-applebanana-1 · agency advice
    However, in people with impaired urinary potassium excretion due to chronic kidney disease or the use of certain medications, such as angiotensin converting enzyme (ACE) inhibitors or potassium-sparing diuretics, even dietary potassium intakes below the AI can cause hyperkalemia.
    NIH Office of Dietary Supplements, Potassium Fact Sheet for Health Professionals · checked 2026-10-08
11. apbn-r6-14 · regulatory register
    POL-HC-6676 Banana Banana is a major dietary source of antioxidants Antioxidants from dietary sources contribute to the protection against free radicals which cause cell damage Contributes to the protection of cells and tissues from oxidative damage Help strengthen our body's natural defences against oxidative stress Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6676, snapshot 2026-09-21 · checked 2026-10-02
12. apbn-r6-15 · regulatory register
    POL-HC-6628 Apple juice Apple juice helps to maintain a healthy cardiovascular system Clarification provided Apple juice : - helps to maintain a healthy cardiovascular system - plays an important antioxidative function on cardiovascular system Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6628, snapshot 2026-09-21 · checked 2026-10-02
13. apbn-r6-09 · randomized crossover trial
    Blood glucose levels and performance did not differ between BAN and CHO (2.41±0.22, 2.36±0.19 h, P = 0.258).
    PLoS One, 2012 · checked 2026-10-02
14. apbn-r6-10 · meta-analysis of RCTs
    GB-based food consumption significantly increased the hazard of resolution of diarrhea compared to standard treatment (HR 1.96, 95% CI [1.62; 2.37], p < 0.01; I2 = 52%).
    Eur J Pediatr, 2024 · checked 2026-10-02
15. apbn-r6-03 · food composition dataset
    Bananas, ripe and slightly ripe, raw: Vitamin C, total ascorbic acid 12.3 MG range 9.2-15.1 median 12.6 n=12 · Bananas, overripe, raw: 9.7 MG range 8.3-12.0 median 9.4 n=6
    USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
16. apbn-r6-13 · systematic review
    However, the current evidence remains insufficient to draw definitive conclusions. Additionally, substantial heterogeneity in study design, populations, and products tested limits the ability to generalize results.
    Food Funct, 2026 · checked 2026-10-02