What are the Potential Health Benefits of Cranberries?

Cranberries are famous for their potent bitter taste, powders and extracts of cranberry are used in supplements and health supporting formulas. The plant compounds in cranberry are famously used for urinary tract infections.

Nutrients in cranberries

Cranberries contain mainly carbohydrate and fibre. The fibre is mainly comprised of insoluble fibre types such as pectin and cellulose, which pass through the digestive system intact. This action helps to bulk the stools and thus helps to in the body’s detoxification processes by removing toxins and unwanted substances through the bowel.

Vitamin C, which may also be named ascorbic acid, is one of the main antioxidants in cranberries. It is needed for the maintenance of healthy connective tissue such as skin, bones and joints. Other vitamins in cranberry include vitamin E, which is also needed for antioxidant effects in the body and vitamin K1 required for blood clotting function to facilitate healing of wounds [I].

Phytochemicals in cranberries

The plant chemicals, known as phytochemicals are said to be synonymous with their health benefits through particular molecular mechanisms involved in the body. The health benefits of flavonoids, in particular abundant flavonoids and pigments such as anthocyanidins and proanthocyanidins have directed recent scientific research into cranberries. There is compelling evidence for protection from bacterial pathogens, cardiovascular disease and chronic inflammation. Other upcoming areas of research include the neuro-protective benefits (against neurodegenerative diseases such as Alzheimer’s) and the antiviral activity from cranberry constituents. Cranberries are said to be well absorbed by the body with regards to the bioavailability of the active compounds [ii].

Many of these plant compounds are concentrated in the skin of the fruit and therefore may be reduced; as seen in a comparative study which found the whole fruit contained more active plant compounds [iii]. Quercetin and ursolic acid is found in cranberry, along with myricetin. All these compounds are found to have anti-inflammatory and antioxidant benefits [iv] [v].

Consuming cranberry regularly can increase the amount of salicylic acid in the body. Salicylic acid is an important part of aspirin, which contributes to the action in reducing swelling, pain and inflammation [vi].

Common therapeutic uses of cranberries

Urinary tract infections

Urinary tract infections (UTI’s) are common, especially among women [vii]. These infections are most commonly caused by E. Coli bacterium originating from the large intestine. This bacteria can attach to the mucosal lining surface of the bladder and urethra, causing infection.

Cranberries are said to be especially high in Type A proanthocyanidins [viii]. The Type A subtype of proanthocyanidins can prevent adherence of E. Coli bacterium to the mucus linings, it is therefore a preventative approach against UTI’s [ix] [x]. Urinary tract infections which affect the kidneys can be very dangerous and require medical attention, please speak with a healthcare professional if this type of infection is suspected.

Cranberry supplements can contain concentrated amounts of Type A proanthocyanidins [xi], as certain types of food processing may cause them to be lost in other cranberry products [xii].

A pilot study was performed to examine the ability of a concentrated cranberry preparation to prevent UTIs in women with a history of recurrent infections. The women took one capsule twice daily for 12 weeks containing 200 mg of a concentrated cranberry extract standardised to 30% polyphenol content. All 12 subjects whom participated in the 12-week study were available for follow up 2 years later. During the study none of the women had a UTI, and no adverse events were reported. Two years later, eight of the women who continue to take cranberry, continue to be free from UTIs [xiii].

Another study found cranberry juice prevented the recurrence of UTI in females over 50, with a 24-week intake of a cranberry beverage, as compared to placebo. These subjects drank 1 bottle (125 mL) of cranberry juice once daily, for 24 weeks [xiv].

Maintenance of prostate health

A study found daily consumption of a powdered cranberry fruit lowered serum PSA (prostate specific antigen) in patients with prostate disease. The trial was randomised, with a group provided cranberry fruit powder versus a placebo group. It was concluded that the cranberry fruit contains constituents that may regulate the expression of androgen-responsive genes. Androgens are sex hormones and can be involved in the development and progression of prostate-associated issues [xv].

Another study also found that cranberry supplementation could be an effective and safe approach, for the prevention of recurrent UTIs in elderly men suffering from benign prostatic hyperplasia (BPH), avoiding some antibiotic treatments. 43 men aged over 65 years, were enrolled in the study, they received standard treatment only, or oral supplementation of cranberry extract once daily, for 60 consecutive days. In the supplemented group, the mean number of UTI episodes reported during the experiment significantly decreased [xvi].

Cardiovascular disease and chronic disease

Cranberry is suggested as a preventative measure for common diseases many of which are often chronic such as atherosclerosis and hypertension. The development and progression of such diseases are associated directly with oxidative stress. The cranberry fruit is characterised by the high antioxidant capacity of the compounds contained within it, such as naturally occurring phenolic compounds. As such, the natural antioxidant defines system of the body can be supported to prevent damage to tissues caused by oxidative stress [xvii].

It was found cranberry constituents can counteract oxidative stress, have the ability to decrease inflammation and modulate expression of genes associated with chronic disease processes. The evidence suggests a potential role for dietary cranberry in vascular diseases affecting blood circulation [xviii].

Precautions

Allergy

Cranberries contain high amounts of salicylic acid. Salicylic acid is similar to aspirin. Avoid drinking large quantities of cranberry juice if you are allergic to aspirin, or have a known allergy to salicylates.

Kidney stones

Cranberry juice and cranberry extracts may contain a large amount of oxalate. There is some evidence that some cranberry extract tablets can boost the level of oxalate in the urine [xix]. For this reason, they are considered a risk factor for kidney stones when consumed in high amounts It is advisable to avoid excessive use in kidney stones [xx] [xxi](19).

Potential interactions

Warfarin: Warfarin is a medication used to slow blood clotting. Cranberry can interact with how the body process the drug, meaning the drug stays active in the body for longer, this may increase risk of bruising and bleeding at higher intakes. Please see your doctor to ascertain if the prescription needs to be adjusted accordingly.

Certain medications involving the CYP2C9 pathway

Medications which are changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates) can interact with cranberry. Drug metabolism related to how some medications are changed and broken down by the liver. Cranberry may slow drug metabolism in some cases and this can mean the drug stays in its active state in the body for longer, which can increase the effects of the medications. Please discuss with your prescribing doctor prior to supplementing cranberry.

image credit Rasa Kasparaviciene