© 2018 Steven Foster

A cranberry monograph for the home

Latin Name: Vaccinium macrocarpon, also known as Oxycoccus macrocarpos, Vaccinium oxycoccos

Common Names: cranberry, American cranberry, bearberry

This cranberry monograph provides basic information about cranberry—common names, usefulness and safety, and resources for more information.


Cranberry Basics

  • Cranberry is a native evergreen shrub that grows throughout North America.
  • Historically, cranberry fruits or leaves were used for bladder, stomach, and liver disorders, as well as diabetes, wounds, and other conditions.
  • Today, cranberry is used as a dietary supplement primarily for urinary tract infections (UTIs).
  • The berries are used in beverages and food. They are also made into dietary supplements in the form of extracts, powder, capsules, and tablets.

Cranberry in Health Research

  • There have been a lot of studies in people of cranberry for UTIs, but there’s very little high quality recent research on cranberry for other conditions.

Cranberry Research Summary

  • There’s mixed evidence that cranberry can help to prevent UTIs.
    • In a 2016 year-long study of 147 women living in nursing homes, taking two daily cranberry capsules decreased bacteria levels in their urine in the first 6 months of the study, but didn’t decrease their frequency of UTIs over the year of the study, compared to taking a placebo. The two capsules together contained as much proanthocyanidin, a compound that is believed to protect against bacteria, as 20 ounces of cranberry juice.
    • A 2012 research review of 13 clinical trials suggested that cranberry may help reduce the risk of UTIs in certain groups, including women with recurrent UTIs, children, and people who use cranberry-containing products more than twice daily.
    • A 2012 research review of 24 clinical trials concluded that cranberry juice and supplements don’t prevent UTIs but many of the studies were poor quality.
  • Cranberry hasn’t been shown to be effective as a treatment for an existing UTI.
  • NCCIH-supported research is looking at the possible effects of cranberry on cancer-related anemia and tumor cells.

Cranberry Safety

  • Drinking cranberry juice appears to be safe, although large amounts can cause stomach upset and may over time increase the risk of kidney stones.
  • Large doses of cranberry may alter levels of warfarin, an anticoagulant (blood-thinner).
  • People who think they have a UTI should see a health care provider for a diagnosis and treatment. Don’t use cranberry products in place of proven treatments for infections.

Cranberry References

PubMed Articles About Vaccinium macrocarpon

Source: National Center for Biotechnology Information (NCBI)[Internet]. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information; [1988] – [cited 2018 Apr 5]. Available from:

Search query:(Vaccinium macrocarpon AND diabetes AND (( Clinical Trial[ptyp] OR systematic[sb] ) AND Humans[Mesh]))

Delpino, FM., Figueiredo, LM., Gonçalves da Silva, T., Flores, TR., (2022) Effects of blueberry and cranberry on type 2 diabetes parameters in individuals with or without diabetes: A systematic review and meta-analysis of randomized clinical trials.

Blueberry and cranberry are rich in polyphenols that are associated with diabetes reduction. This study aimed: 1) to systematically review the literature on the effects of blueberry and cranberry consumption and type 2 diabetes parameters in individuals with or without type 2 diabetes and 2) to quantify these effects by carrying out a meta-analysis.

Zare Javid, A., Maghsoumi-Norouzabad, L., Ashrafzadeh, E., Yousefimanesh, HA., Zakerkish, M., Ahmadi Angali, K., Ravanbakhsh, M., Babaei, H., (2019) Impact of Cranberry Juice Enriched with Omega-3 Fatty Acids Adjunct with Nonsurgical Periodontal Treatment on Metabolic Control and Periodontal Status in Type 2 Patients with Diabetes with Periodontal Disease.

Cranberries, high in polyphenols, have been associated with a favorable glycemic response in patients with type 2 diabetes and also are beneficial for oral health. Because type 2 diabetes mellitus and periodontal disease have a physiological relationship, this study aimed to evaluate the hypothesis that cranberry juice enriched with omega-3 will improve glycemic and lipid profiles and periodontal status in patients with diabetes with periodontal disease.

Schell, J., Betts, NM., Foster, M., Scofield, RH., Basu, A., (2018) Cranberries improve postprandial glucose excursions in type 2 diabetes.

Recent research supports a favorable role of cranberries on cardiometabolic health. Postprandial metabolism, especially hyperglycemia, has been shown to be an independent cardiovascular risk and few clinical studies have reported the role of berries in improving postprandial dysmetabolism. We investigated the postprandial effects of dried cranberries following a high-fat breakfast challenge in obese participants with type 2 diabetes (T2DM), in a randomized crossover trial. Blood draw and vascular measurements were conducted at fasting, 1, 2 and 4 hours (h), following the consumption of a fast-food style high-fat breakfast (70 g fat, 974 kcal) with or without cranberries (40 g). Analyses of our data (n = 25; BMI (kg m) (mean ± s.d.) = 39.5 ± 6.5; age (years) = 56 ± 6) revealed that postprandial increases in glucose were significantly lower in the cranberry vs. control at 2 & 4 h (p < 0.05). No significant differences were noted in insulin, insulin resistance evaluated by homeostasis model assessment, lipid profiles and blood pressure between the cranberry and control groups. Among the biomarkers of inflammation and oxidation, postprandial serum interleukin-18 and malondialdehyde were significantly lower at 4 h, and serum total nitrite was higher at 2 h in the cranberry vs. control group (all p < 0.05). No effects were noted on C-reactive protein or interlukin-6. Overall, dietary cranberries had notable effects in improving high-fat breakfast induced postprandial glucose and selected biomarkers of inflammation and oxidation in participants with T2DM. These findings provide evidence that adding whole cranberries to a high-fat meal may improve postprandial blood glucose management and warrant further investigation.

Rocha, DMUP., Caldas, APS., da Silva, BP., Hermsdorff, HHM., Alfenas, RCG., (2022) Effects of blueberry and cranberry consumption on type 2 diabetes glycemic control: A systematic review.

The metabolic effects of cranberry and blueberry consumption on glycemic control have been evaluated and in animal models as well as in human studies, although findings have not been systematically reviewed yet. Therefore, a systematic review was carried out of relevant randomized clinical trials (RCTs) in order to assess the effect of berries (blueberry and cranberry) consumption on type 2 diabetes (T2DM) glycemic control. Some evidences were also discussed on the anti-diabetic mechanisms exerted by berries polyphenols. Studies were identified by searching electronic databases: LILACS, PubMed/MEDLINE, Scopus, The Cochrane Library and Web of Science. Three authors independently searched and extracted RCTs in which the effect of berries (cranberry or blueberry) consumption on T2DM glycemic control was assessed. A total of 7 RCTs, involving 270 adults with type 2 diabetes were included. Despite the heterogeneity of the administration forms (, dried, extract, preparations - juice), dosage, duration of the intervention and type of population of the studies involving these two berries some studies highlight the potential benefit of berries, especially of blueberry, on glucose metabolism in T2DM subjects. Daily cranberry juice (240 mL) consumption for 12 weeks and blueberry extract or powder supplementation (9.1 to 9.8 mg of anthocyanins, respectively) for 8 to 12 weeks showed a beneficial effect on glucose control in T2DM subjects. Those results indicate a promising use of these berries in T2DM management; although more studies are required to better understand the mechanisms involved.

Hsia, DS., Zhang, DJ., Beyl, RS., Greenway, FL., Khoo, C., (2022) Effect of daily consumption of cranberry beverage on insulin sensitivity and modification of cardiovascular risk factors in adults with obesity: a pilot, randomised, placebo-controlled study.

Cranberries are high in polyphenols, and epidemiological studies have shown that a high-polyphenol diet may reduce risk factors for diabetes and CVD. The present study aimed to determine if short-term cranberry beverage consumption would improve insulin sensitivity and other cardiovascular risk factors. Thirty-five individuals with obesity and with elevated fasting glucose or impaired glucose tolerance participated in a randomised, double-blind, placebo-controlled, parallel-designed pilot trial. Participants consumed 450 ml of low-energy cranberry beverage or placebo daily for 8 weeks. Changes in insulin sensitivity and cardiovascular risk factors including vascular reactivity, blood pressure, RMR, glucose tolerance, lipid profiles and oxidative stress biomarkers were evaluated. Change in insulin sensitivity via hyperinsulinaemic-euglycaemic clamp was not different between the two groups. Levels of 8-isoprostane (biomarker of lipid peroxidation) decreased in the cranberry group but increased in the placebo group (-2·18 v. +20·81 pg/ml; P = 0·02). When stratified by baseline C-reactive protein (CRP) levels, participants with high CRP levels (>4 mg/l) benefited more from cranberry consumption. In this group, significant differences in the mean change from baseline between the cranberry (n 10) and the placebo groups (n 7) in levels of TAG (-13·75 v. +10·32 %; P = 0·04), nitrate (+3·26 v. -6·28 µmol/l; P = 0·02) and 8-isoprostane (+0·32 v. +30·8 pg/ml; P = 0·05) were observed. These findings indicate that 8 weeks of daily cranberry beverage consumption may not impact insulin sensitivity but may be helpful in lowering TAG and changing certain oxidative stress biomarkers in individuals with obesity and a proinflammatory state.