Cranberry: one claim the trials carry, and the long tail they do not

Cranberry has one claim the evidence carries and a long tail it does not. Almost everything tested here was juice, capsules, powder or extract, so the fresh berry and the sweetened dried one have barely been studied at all. The strong result is urinary tract infection. Across 26 randomised trials with 6211 people, a Cochrane review found that cranberry products cut the risk of a culture-verified infection by 30 percent, with moderate certainty. Form is less settled. One 2021 meta-analysis of 23 trials found juice outperforming capsules by 35 percent, a comparison across trials rather than head-to-head, and the Cochrane review could not separate forms. The same 50-trial Cochrane review found little or no benefit, with low certainty, in three groups people most want it for: the elderly, pregnancy and people whose bladder does not empty properly. The EU register lists 16 health claims on cranberry and has authorised none of them, including the one about E. coli. The warfarin question is unresolved. Two weeks of cranberry raised the INR response to a single dose by 30 percent in 12 healthy men. Yet 30 patients on stable warfarin who drank a glass a day saw their drug levels unchanged and the INR move at one time point out of several. If you take warfarin, ask before you start, as the NIH centre advises.

The numbers, per 100 g

What your body absorbs

• In healthy women, 150 g of a puree of four berries in equal parts, cranberry one of them, eaten with white bread improved the glycaemic profile of the bread by 38 percent and lowered the insulin response. — healthy Finnish women, n=13 to 20 per study, three randomised crossover meal studies (n = 13 to 20 per meal study) Evidence B source
  Berry mixture (equal parts strawberries, bilberries, cranberries, blackcurrants) with white bread: glycaemic profile improved 38%, with rye bread 19%; postprandial insulin response significantly reduced

What it does to your health

• In 23 trials with 3979 people, cranberry products lowered UTI incidence by 30 percent, and in a subgroup comparison across trials rather than head-to-head, juice outperformed capsules or tablets by 35 percent. — susceptible populations: women with recurrent UTI, children, patients with indwelling catheters (n = 23 trials, 3979 participants) Evidence A source
  RR 0.70, 95% CI 0.59 to 0.83; women with recurrent UTI RR 0.68, children RR 0.55, catheter users RR 0.49; juice versus capsule or tablet RR 0.65, 95% CI 0.54 to 0.77
• Pooled across 17 randomised trials in people with cardiometabolic disease, blueberry or cranberry supplementation changed systolic pressure by 0.81 mmHg and diastolic by 0.15 mmHg, neither significant. — patients with cardiometabolic diseases in randomised trials of blueberry or cranberry intake or supplementation (n = 17 trials) Evidence A source
  SBP -0.81 mmHg, 95% CI -2.26 to 0.63, I2 0%; DBP -0.15 mmHg, 95% CI -1.36 to 1.05, I2 27%; neutral regardless of duration or age
• In 522 infected adults, juice standardised to 44 mg proanthocyanidins per 240 mL taken twice daily for 8 weeks cut the H. pylori infection rate by 20 percent, while encapsulated cranberry powder did nothing. — 522 H. pylori-positive adults in a region of high gastric cancer risk (n = 522) Evidence B source
  H. pylori-negative rate at week 8: placebo 7.35%, low-PAC 7.58%, medium-PAC 4.48%, high-PAC juice 20.00%; high-PAC juice twice daily decreased infection rate by 20% versus other dosages and placebo (P<0.05); powder capsules not effective
• Among 37,232 US adults followed 8 years, people who reported eating cranberries had a 31 percent lower all-cause mortality than non-consumers, HR 0.69. — US adults in NHANES 1999 to 2014, 24-hour recall, linked death certificates, 8 years of follow-up (n = 37,232) Evidence C source
  All-cause mortality HR 0.69, 95% CI 0.51 to 0.93 for cranberry consumers; cardiometabolic mortality HR 0.49, 95% CI 0.25 to 0.98; any berry HR 0.79

Safety, limits and interactions

• In 10 randomised trials with 2166 participants, gastrointestinal side effects were about as common on cranberry products as on placebo, RR 1.33 with a confidence interval touching 1. — participants of 10 placebo-controlled or no-treatment-controlled trials reporting side effects (n = 10 trials, 2166 participants) Evidence A source
  RR 1.33, 95% CI 1.00 to 1.77, I2 0%, moderate certainty
• Two weeks of cranberry raised the INR response to a single 25 mg dose of warfarin by 30 percent in 12 healthy men, without changing warfarin blood levels. — 12 healthy male volunteers of known CYP2C9 and VKORC1 genotype (n = 12) Evidence B source
  Area under the INR-time curve increased by 30 percent with cranberry pretreatment; S- and R-warfarin pharmacokinetics and protein binding unchanged; garlic had no effect
• The NIH centre for complementary health describes the warfarin interaction evidence as conflicting and tells people on warfarin to ask a clinician before using cranberry. — — Evidence E source
  No effect size; a position statement on a page last updated November 2024
• One litre of cranberry juice a day for 7 days raised urinary calcium from 154 to 177 mg and oxalate from 26.4 to 29.2 mg per day, pushing calcium oxalate saturation up 18 percent in 24 adults. — 12 normal subjects and 12 calcium oxalate stone formers on a controlled metabolic diet (n = 24) Evidence B source
  Urinary calcium +23 mg/day (p=0.0008), oxalate +2.8 mg/day (p=0.04), calcium oxalate saturation +18%; urinary pH fell 5.97 to 5.67; urinary uric acid fell 544 to 442 mg/day
• A 240 mL glass of cranberry juice taken with 200 mg cyclosporine left the drug's exposure within 5 percent of water in 12 healthy volunteers, unlike pomelo juice which raised it 19 percent. — 12 healthy male volunteers, fasting (n = 12) Evidence B source
  Cyclosporine AUCt ratio with cranberry juice 95.0% (95% CI 90.3 to 100.1), AUCinf 93.4%, Cmax 95.2%; pomelo juice AUCt 119.4% (113.4 to 125.8)
• A systematic review of 166 food-drug studies across 32 beta-lactam antibiotics found no significant interaction between cranberry juice and the two antibiotics tested with it, amoxicillin and cefaclor. — pharmacokinetic studies of beta-lactam antibiotics with food, beverages, antacids or mineral supplements (n = 166 studies, 32 beta-lactams; beverage data for 11 antibiotics) Evidence A source
  No significant interaction with cranberry juice for amoxicillin and cefaclor; by contrast milk cut absorption by more than 40 percent for cefalexin, cefradine, penicillin G and penicillin V

What people believe that the data does not support

• The EU register lists 16 health claims on cranberry and none of them is authorised, including the one about blocking E. coli attachment in the urinary tract. — — Evidence E source
  The wording Cranberry helps to inhibit the attachment of certain E-coli bacteria to the urinary tract is Non-authorised; the register snapshot of 2026-09-21 holds 16 cranberry entries, 0 authorised and 16 non-authorised, while the US 21 CFR 101 has no cranberry entry at all

Who this works differently for

• Across 26 randomised trials with 6211 participants, cranberry products cut the risk of culture-verified urinary tract infection by 30 percent, with moderate certainty. — people in six susceptibility groups, 50 randomised or quasi-randomised trials, 8857 participants; 26 trials meta-analysed for symptomatic culture-verified UTI (n = 26 trials, 6211 participants) Evidence A source
  RR 0.70, 95% CI 0.58 to 0.84, I2 69%; women with recurrent UTI RR 0.74, children RR 0.46, people susceptible after an intervention RR 0.47
• The same 50-trial Cochrane review found little or no benefit from cranberry, with low certainty, in three groups: the elderly, people with bladder emptying problems and pregnant women. — elderly institutionalised men and women (3 studies, 1489 participants), pregnant women (3 studies, 765), adults with neuromuscular bladder dysfunction (3 studies, 464) (n = 9 trials, 2718 participants across the three groups) Evidence A source
  Little or no benefit, low certainty: elderly RR 0.93 (0.67 to 1.30), pregnant RR 1.06 (0.75 to 1.50), neuromuscular bladder RR 0.97 (0.78 to 1.19)
• In children with a normal urinary tract, cranberry halved UTI recurrence against placebo, RR 0.48, and did not differ significantly from low-dose antibiotic prophylaxis, RR 0.92, in a comparison too small to show equivalence, 95% CI 0.56 to 1.50. — children in 16 randomised trials of non-antibiotic prophylaxis, 1426 participants (n = 16 trials, 1426 children) Evidence A source
  Cranberry versus placebo or no therapy RR 0.48, 95% CI 0.28 to 0.80; cranberry versus antibiotic prophylaxis RR 0.92, 95% CI 0.56 to 1.50

What is still unknown

• In 30 patients on stable warfarin, 240 mL of cranberry juice daily for 2 weeks left warfarin blood levels unchanged and moved the INR at only one of the measured time points. — 30 patients on stable warfarin anticoagulation, INR 1.7 to 3.3; 14 on cranberry juice, 16 on placebo (n = 30) Evidence B source
  No difference in plasma R- and S-warfarin; mean INR differed only on treatment day 12 (P<.02); 4 patients in each arm had minimally elevated INR 3.38 to 4.52
• In 20 young men drinking 500 mL of cranberry juice diluted to 2 litres for 2 weeks, urinary oxalate and phosphate fell and citrate rose, the opposite of the 1-litre result. — 20 South African male students with no history of kidney stones (n = 20) Evidence B source
  Oxalate and phosphate excretion decreased, citrate excretion increased, relative supersaturation of calcium oxalate decreased versus water alone; effect sizes not given in the abstract
• In a meta-analysis of 45 fruit trials lasting at least a week, cranberry juice lowered systolic pressure by 1.52 mmHg and diastolic by 1.78 mmHg, a borderline and small effect. — adults in 45 chronic randomised trials of berries, citrus and cherries on cardiovascular risk factors (n = 45 trials) Evidence A source
  Cranberry juice subgroup: SBP -1.52 mmHg, 95% CI -2.97 to -0.07, P=0.05; DBP -1.78 mmHg, 95% CI -3.43 to -0.12, P=0.04
• Across 4 randomised trials with 1935 people, adding cranberry raised the odds of Helicobacter pylori eradication 1.27 times, and the interval 0.63 to 2.58 includes no effect. — H. pylori positive adults in randomised trials, 4 RCTs, 5 effect sizes (n = 4 trials, 1935 participants) Evidence A source
  OR 1.27, 95% CI 0.63 to 2.58, not significant; I2 63.4%
• Cereal bars fortified with 0.5 or 1 percent cranberry extract produced no change in glucose, insulin or appetite hormones over 3 hours in 20 young adults. — 20 young adults, 18 men and 2 women, mean age 24, BMI 27 (n = 20) Evidence B source
  No treatment effect of either cranberry bar on glucose or glucoregulatory hormones, oxidative stress, appetite hormones or appetite; black raspberry at 20% lowered peak insulin 17%

The bottom line

If you get urinary tract infections that keep coming back, and you are not pregnant, not elderly and your bladder empties normally, a daily cranberry product is a reasonable thing to try, and juice has the better record. For children with a normal urinary tract it halved recurrence against placebo. Whether it can stand in for an antibiotic is a decision to make with the paediatrician, because the trials cannot answer it. Cranberry did not differ significantly from low-dose antibiotic prophylaxis, RR 0.92, but the interval 0.56 to 1.50 is too wide to show equivalence. Stomach upset was about as common on cranberry as on placebo across 10 trials, though the interval just touched the line, so a small excess is possible. Two other drugs showed no interaction, on thin evidence. A single glass of juice with one dose left cyclosporine exposure within 5 percent of water in 12 healthy men, which says nothing about daily juice on long-term treatment, and a review of 166 studies found no interaction with amoxicillin or cefaclor, the only two antibiotics ever tested with cranberry, on evidence the authors rate as low quality. Kidney stones are the place to be careful. A litre of juice a day for a week raised urinary calcium from 154 to 177 mg and oxalate from 26.4 to 29.2 mg in 24 adults, half of them stone formers, and pushed calcium oxalate saturation up 18 percent. A different trial, 500 mL diluted to 2 litres in 20 young men, found the opposite. Dose and dilution seem to decide the answer, and nobody has settled it. Blood pressure is a similar story. Seventeen trials in people with cardiometabolic disease found no significant change, and a wider 45-trial analysis found a drop of 1.52 over 1.78 mmHg for cranberry juice, borderline and small. The Helicobacter pylori result rests on one trial of 522 adults where juice standardised to 44 mg proanthocyanidins per glass, twice a day for 8 weeks, cut infection by 20 percent, and capsules of the powder did nothing. Pooled across 4 trials the eradication odds were 1.27 with an interval that includes no effect, so treat it as a lead rather than a treatment. People who reported eating cranberries in a US survey had 31 percent lower mortality over 8 years. That is a diet record and a death certificate, and it cannot tell you the berries did it. The one glucose result, a 38 percent better glycaemic profile from white bread, came from a puree of four berries in equal parts, cranberry one of them, in 13 to 20 women, and cereal bars with cranberry extract changed nothing. What this page cannot tell you is anything about the berry as food. Our cards hold nothing on how the sweetened dried kind compares with fresh, on what cooking into a sauce does, or on what a serving looks like in a real meal. Those searches came back empty, and that is a gap rather than an all-clear.

Sources

1. crnb-r1-19 · randomised crossover meal trial
   In study 3, WB or RB was served with a mixture of berries consisting of equal amounts of strawberries, bilberries, cranberries, and blackcurrants...Only strawberries (36%) and the berry mixture (with WB, 38%; with RB, 19%) significantly improved the glycemic profile of the breads.
   J Nutr, 2013 · checked 2026-09-23
2. crnb-r1-04 · meta-analysis of RCTs
   This meta-analysis included 23 trials with 3979 participants. We found that cranberry-based products intake can significantly reduce the incidence of UTIs in susceptible populations (risk ratio (RR) = 0.70; 95% confidence interval(CI): 0.59 ~ 0.83; P<0.01)...a relative risk reduction of 35% in people who use cranberry juice compared with those who use cranberry capsule or tablet was observed in the subgroup analysis (RR = 0.65; 95% CI: 0.54 ~ 0.77).
   PLoS One, 2021 · checked 2026-09-23
3. crnb-r1-11 · meta-analysis of RCTs
   Pooled results revealed statistically non-significant reductions of -0.81 mm Hg for SBP (95% confidence interval [CI]: -2.26, 0.63; I2 = 0%) and -0.15 mm Hg for DBP (95% CI: -1.36, 1.05; I2 = 27%).
   Phytother Res, 2024 · checked 2026-09-23
4. crnb-r1-14 · randomised double-blind trial
   Consumption of high-proanthocyanidin juice twice daily (44 mg proanthocyanidin/240-mL serving) for 8 weeks resulted in decreased H. pylori infection rate by 20% as compared with other dosages and placebo (P < 0.05)...Encapsulated cranberry powder doses were not significantly effective at either time point.
   J Gastroenterol Hepatol, 2021 · checked 2026-09-23
5. crnb-r1-17 · prospective cohort analysis of a national survey
   Compared with nonconsumers, the multivariable-adjusted hazard ratio for all-cause mortality was 0.79 [95% confidence intervals (CI): 0.7, 0.89] for any berry consumption, 0.86 (0.75, 0.99) for strawberry consumption 0.79 (0.66, 0.95) for blueberries, and 0.69 (0.51, 0.93) for cranberries.
   J Nutr, 2024 · checked 2026-09-23
6. crnb-r1-03 · Cochrane meta-analysis of RCTs
   The number of participants with gastrointestinal side effects probably does not differ between those taking cranberry products and those receiving placebo or no specific treatment (10 studies, 2166 participants: RR 1.33, 95% CI 1.00 to 1.77; I² = 0%; moderate certainty evidence).
   Cochrane Database of Systematic Reviews, 2023 · checked 2026-09-23
7. crnb-r1-06 · randomised crossover trial
   Cranberry significantly increased the area under the INR-time curve by 30% when administered with warfarin compared with treatment with warfarin alone. Cranberry did not alter S- or R-warfarin pharmacokinetics or plasma protein binding.
   Br J Pharmacol, 2008 · checked 2026-09-23
8. crnb-r1-08 · agency fact sheet
   There is conflicting evidence about whether cranberry interacts with the anticoagulant (blood thinner) warfarin.
   NCCIH (NIH), Cranberry: Usefulness and Safety, updated November 2024 · checked 2026-09-23
9. crnb-r1-09 · randomised crossover trial
   CBJ significantly increased urinary calcium (from 154 to 177 mg per day, p =0.0008) and urinary oxalate (from 26.4 to 29.2 mg per day, p =0.04), thereby increasing urinary saturation of calcium oxalate by 18%.
   J Urol, 2005 · checked 2026-09-23
10. crnb-r1-15 · randomised crossover trial
    Cranberry juice had no clinically significant effect on the overall disposition of cyclosporine. After administration of cyclosporine with cranberry juice, the ratios of least squares means for AUCt, AUCinf, and Cmax for cyclosporine were 95.0% (95% CI, 90.3%-100.1%), 93.4% (95% CI, 89.2%-97.8%), and 95.2% (95% CI, 86.9%-104.2%), respectively.
    Clin Pharmacol Ther, 2006 · checked 2026-09-23
11. crnb-r1-16 · systematic review with meta-analyses of pharmacokinetic studies
    No significant interaction occurred with cranberry juice for two tested drugs (amoxicillin and cefaclor).
    J Antimicrob Chemother, 2024 · checked 2026-09-23
12. crnb-r1-18 · regulatory register entry
    POL-HC-7798 Proanthocyanidins in cranberry juice Cranberry helps to inhibit the attachment of certain E-coli bacteria to the urinary tract Non-authorised
    EU Register on nutrition and health claims, snapshot 2026-09-21 · checked 2026-09-23
13. crnb-r1-01 · Cochrane meta-analysis of RCTs
    In moderate certainty evidence, cranberry products reduced the risk of UTIs (6211 participants: RR 0.70, 95% CI 0.58 to 0.84; I² = 69%).
    Cochrane Database of Systematic Reviews, 2023 · checked 2026-09-23
14. crnb-r1-02 · Cochrane meta-analysis of RCTs
    The evidence currently available does not support its use in the elderly, patients with bladder emptying problems, or pregnant women.
    Cochrane Database of Systematic Reviews, 2023 · checked 2026-09-23
15. crnb-r1-05 · meta-analysis of RCTs
    Cranberry was as effective as antibiotic prophylaxis (RR: 0.92; 95% CI: 0.56-1.50) but better than placebo/no therapy (RR: 0.48; 95% CI: 0.28-0.80) in reducing UTI recurrence.
    Eur J Pediatr, 2021 · checked 2026-09-23
16. crnb-r1-07 · randomised double-blind trial
    Cranberry juice has no effect on plasma S- or R-warfarin plasma levels, excluding a pharmacokinetic interaction. A small though statistically significant pharmacodynamic enhancement of INR by CJ at a single time point is unlikely to be clinically important and may be a random change.
    J Clin Pharmacol, 2009 · checked 2026-09-23
17. crnb-r1-10 · randomised crossover trial
    The ingestion of cranberry juice significantly and uniquely altered three key urinary risk factors. Oxalate and phosphate excretion decreased while citrate excretion increased.
    BJU Int, 2003 · checked 2026-09-23
18. crnb-r1-12 · meta-analysis of RCTs
    In subgroup analysis, these associations were limited to cranberry juice (SBP by 1.52 mmHg [95% CI - 2.97 to - 0.07; P = 0.05], DBP by 1.78 mmHg [95% CI - 3.43 to - 0.12, P = 0.04] and cherry juice (SBP by 3.11 mmHg [95% CI - 4.06 to - 2.15; P = 0.02]).
    Eur J Nutr, 2021 · checked 2026-09-23
19. crnb-r1-13 · meta-analysis of RCTs
    Based on five effect sizes with a total sample size of 1935 individuals, we found that according to the OR, there was a positive effect of cranberry supplementation on H. pylori eradication, increasing the chance of H. pylori eradication by 1·27 times, but this relationship was not statistically significant (overall OR: 1·27; 95 % CI 0·63, 2·58).
    Br J Nutr, 2022 · checked 2026-09-23
20. crnb-r1-20 · randomised crossover trial
    No treatment effects were observed for the cranberry bars regarding glucose and glucoregulatory hormones, nor were there any treatment effects for either berry type regarding ex vivo oxidation, appetite-mediating hormones or appetite.
    Br J Nutr, 2019 · checked 2026-09-23