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Cranberries

The Color of Health in One Super Food

Packed with antioxidant and antibacterial properties as well as phytochemicals, cranberries offer one of the best nutrient combinations found in any food. Even studies examining cranberry juices with high-fructose corn syrup have documented beneficial effects in diabetes patients.

What's the Reality?

Among commonly available fresh fruits, cranberries contain the highest amount of antioxidants.1 A 2008 study examining antioxidant contents of cranberries and pure cranberry products such as frozen cranberries, 100% juice, and dried cranberries found that each of these contains a high amount of antioxidants. Next in antioxidant content are cranberry juice cocktail and other cranberry products.2 Dried cranberries provide more antioxidants than other commonly consumed dried fruits, such as apricots and dried plums, on a fresh weight basis.3

Cranberries also contain phenols, which are phytochemicals that have cardioprotective properties. Plant sterols and stanols, flavonoids and sulfur compounds also have cardiovascular protective mechanisms and contain phytochemicals.4 Quercetin, which is prevalent in flavonoids, accounts for 75% of the total flavonoids in cranberry juice.5 Compounds such as quercetin inhibit macrophage-mediated low-density lipoprotein (LDL) oxidation and potentially block the cytogenic effects of oxidized LDL.5 The heart-healthy effects of red wine, such as increased high-density lipoprotein (HDL), are equivalent to that provided by cranberry juice, thus making cranberry juice a powerful nonalcoholic alternative.2

Studies show that the addition of high-fructose corn syrup to cranberry juice may not alter the positive effects of cranberries in the juice. Ingredients in cranberry juice may block and even overcome the oxidative stress of high-fructose corn syrup.2 This is likely an indirect effect of decreasing postprandial glucose and triglycerides, which are responsible for inducing oxidative stress, as well as a direct in vivo antioxidant mechanism.2

Research shows that specific phytochemicals in cranberries, known as proanthocyanidins (PACs), prohibit bacterial adhesion and proliferation that can cause urinary tract infections (UTIs).6,7 Cranberries and the fructose they contain can prevent pathogenic P-fimbriated Escherichia coli from adhering to uroepithelial cells, thereby reducing their ability to proliferate the urinary tract.5,8

Marketing claims that cranberries can help prevent urinary tract infections as opposed to treating UTIs have scientific basis.8 This is an exception in patients with neurogenic bladder or with spinal cord injuries, in which the evidence for preventive use of cranberries is not significant.8

PACs in cranberries are structurally unlike those in other plant foods. This distinctive structure clarifies why, despite methodical testing, polyphenol-loaded apple and grape juices, green tea, raisins and chocolate do not produce the same antiadhesion activity as cranberries.9,10

One study of patients with type 2 diabetes found that ingestion of unsweetened low-calorie cranberry juice produced lower peaks of blood glucose 30 minutes after ingestion than sweetened cranberry juice.11 This particular study also cast doubt on the use of high-fructose corn syrup to make a difference in blood sugar levels among patients with diabetes.11

Participants in this study were diabetes patients with an average age of 65.3, an average BMI of 34.7, and an HgbA1c of 6.7. The findings suggest that diabetes patients often have reduced intakes of fruits and vegetables possibly due to a paradoxical perception of fruit sugars having adverse effects on glycemic control.11 This lowered fruit intake may contribute to higher risk for cardiovascular disease (CVD) and its complications in people with diabetes, since fruits and vegetables (plant products) protect and enhance heart health.12

Encouraging patients with diabetes to ingest cranberry products can aid in protecting against CVD and UTIs. People with diabetes are at high risk for UTIs due to the periods of glyosuria that may accompany periods of poor glycemic control.11

In addition to preventing UTIs and improving blood sugar and heart health, cranberry PACs also may inhibit dental caries and cancer.13-16 Cranberry components promote oral health as they inhibit acid production, attachment and biofilm formulation by Streptococcus mutans, while successfully blocking the binding of bacteria to sites in saliva and glucans.13,14 Lab results indicative of anti-cancer behavior demonstrate that polyphenolic extracts from cranberries inhibit the growth and proliferation of breast, colon, esophageal, lung and prostate tumor cells.15-16 By reducing their ability to invade surrounding tissue and inducing cell death, cranberry compounds may inhibit cancer cell growth. One study found that cranberries have the highest phenol content among 20 fruits.17

How Much Should Patients Consume?

It's clear that cranberry juices, frozen cranberries and dried cranberries are all beneficial food and drink options, but how much should patients ingest? This depends on the patient and the goals of your plan of care.

Advising diabetes patients to consume about 3 cups per day of unsweetened cranberry juice would save about to 300 kcals per day total over consuming regular cranberry juice. This also meets three of the five recommended servings of fruit a day for a person with diabetes, who may be concerned that consuming fruits will increase their blood sugar. As described above, unsweetened cranberry juice can provide the nutrients diabetes patients may be missing by avoiding fruits in their diet - without increasing blood glucose.12

For patients in general, the heart-healthy effects of cranberry juice can be obtained by drinking 1 cup plus 375 mL (about 12 ounces) per day.2 This amount provides plasma antioxidant capacity and increases HDL levels. Cranberry juice can be an alternative to alcoholic beverages that also contain phytochemicals.

For prevention of UTIs, the ingestion of about 10 ounces per day is recommended.4 Thus, an overall recommendation would be to drink 1 to 2 cups per day of unsweetened cranberry juice. Diabetes patients looking to replace fruit intake can consume slightly more per day without the negative effects of worsened daily glucose levels or infringing on HgbA1c with close monitoring.

The use of frozen cranberries and dried cranberries in salads or trail mix is a simple way to add cranberries to the diet. In fact, using any type of cranberry product - a true super food - will be beneficial for your patient's health.

Robyn Kievit is a family nurse practitioner who is a registered dietitian and a certified specialist in sports dietetics. She operates a private nutrition practice in Boston. E-mail your nutrition and weight loss questions to robyn@robynkievit.com or visit her website at www.robynkievit.com. On Facebook and Twitter, search for nutritionmentor.

References

1. Vinson JA, et al. Phenol antioxidant quantity and quality in foods: fruits. J Agric Food Chem. 2001;49(11):5315-5321.

2. Vinson JA, et al. Cranberries and cranberry products: powerful in vitro, ex vivo, and in vivo sources of antioxidants. J Agric Food Chem. 2008;56(14):5884-5891.

3. Vinson JA, et al. Dried fruits: excellent in vitro and in vivo antioxidants. J Am Coll Nutr. 2005;24(1):44-50.

4. Dunford M. Sports Nutrition: A Practice Manual for Professionals. 4th ed. Diana Faulhaber; American Dietetic Association; Chicago, Ill.; 2006.

5. Chen H, et al. Separation and determination of flavonoids and other phenolic compounds in cranberry juice by high-performance liquid chromatography. J Chromatogr A. 2001;913(1-2):387-395.

6. Howell AB. Cranberry proanthocyanidins and the maintenance of urinary tract health. Crit Rev Food Sci Nutr. 2002;42(3 Suppl): 273-278.

7. Gupta K, et al. Cranberry products inhibit adherence of p-fimbriated Escherichia coli to primary cultured bladder and vaginal epithelial cells. J Urol. 2007;177(6): 2357-2360.

8. Fragakis, A, Thomson C. Popular Dietary Supplements. 3rd ed. Diana Faulhaber; American Dietetic Association; Chicago, Ill.; 2007.

9. Greenberg JA, et al. Consumption of sweetened dried cranberries versus unsweetened raisins for inhibition of uropathogenic Escherichia coli adhesion in human urine: a pilot study. J Alt Compl Med. 2005;1(5):875-878.

10. Howell AB, et al. Bacterial anti-adhesion activity of cranberry vs. other foods. Fed Am Soc Exp Biol. 2005;66(18):2281-2291.

11. Wilson T, et al. Favorable glycemic response of type 2 diabetics to low-calorie cranberry juice. J Food Sci. 2008;73(9):H241-H245.

12. Ford ES, MokDad AH. Fruit and vegetable consumption and diabetes mellitus incidence among U.S. adults. Prev Med. 2001;32(1):33-39.

13. Yamanaka-Okada A, et al. Inhibitory effect of cranberry polyphenol on cariogenic bacteria. Bull Tokyo Dent Coll. 2008;49(3):107-112.

14. Koo H, et al. Influence of cranberry juice on glucan-mediated processes involved in Streptococcus mutans biofilm development. Caries Res. 2006;40(1):20-27.

15. Neto CC. Cranberry and its phytochemicals: a review of in vitro anticancer studies. J Nutr. 2007;137(1 Suppl):186S-193S.

16. Kresty L, et al. Cranberry proanthocynaidins induce apoptosis and inhibit acid-induced proliferation of human esophageal adenocarcinoma cells. J Agric Food Chem. 2008;56(3):676-680.

17. Porter M, et al. Cranberry proantocyanidins associate with low-density lipoprotein and inhibit in vitro Cu2+ -induced oxidation. J Sci Food Agric. 2001;81:1306-1313.


Nutrition Now Archives
 

Still under investigation. I'd suggest the real product for not vs pills or supplements.

Robyn Kievit,  NP, RD, CSSDDecember 02, 2010
Boston, MA



Just a question....are cranberry tabs as effective as juice, etc...?

Catherine ,  NPNovember 19, 2010




     

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