Cranberries have long been touted for their potential health benefits, including their supposed ability to ‘clean’ the stomach. But is there any truth to this claim? Let’s take a closer look at the evidence.
What are cranberries?
Cranberries are small, tart red berries that grow on low, creeping shrubs. They are native to North America and commercially grown in US states like Massachusetts, New Jersey, Oregon, Washington, and Wisconsin.
Cranberries are harvested in the fall. To harvest them, the beds where cranberries grow are flooded with water. The cranberries float to the surface, making them easier to gather. Most cranberries are processed into products like juice, sauce, and sweetened dried cranberries.
Nutrients and compounds in cranberries
Fresh cranberries are a good source of the following nutrients:
- Vitamin C: Provides antioxidant protection and supports immune health.
- Vitamin E: A fat-soluble antioxidant that helps protect cells from damage.
- Vitamin K1: Important for blood clotting and bone health.
- Manganese: A mineral that helps metabolize nutrients and regulates blood sugar.
- Copper: Needed for iron absorption and nerve transmission.
- Magnesium: Supports muscle, nerve, and heart health.
- Polyphenols: Plant compounds that act as antioxidants.
Cranberries also contain a diverse mixture of polyphenols, including flavonols, proanthocyanidins, anthocyanins, benzoic acid, and ursolic acid. These compounds are thought to be responsible for many of cranberries’ purported health benefits.
Do cranberries have antioxidant effects?
Many of the polyphenols in cranberries act as antioxidants. This means they help neutralize harmful free radicals and reduce oxidative damage to cells.
In laboratory studies, cranberry juice and extract have been shown to have antioxidant capacities equivalent to those of vegetable and fruit juices like tomato, spinach, and orange juice.
Here is an overview of the antioxidant capacity of some common fruit and vegetable juices:
|Juice||ORAC value (μmol TE/mL)|
ORAC stands for Oxygen Radical Absorbance Capacity. It’s a measure of antioxidant strength. As seen above, cranberry juice has a very high ORAC value, demonstrating potent antioxidant effects.
Do cranberries prevent urinary tract infections?
One of the most well-known benefits of cranberries is preventing urinary tract infections (UTIs). Studies show cranberries can reduce adhesion of E. coli bacteria to urinary tract walls, potentially stopping infection.
In a 2011 review of 13 clinical trials, daily intake of cranberry products significantly reduced the occurrence of UTIs compared to placebo, juice, or no treatment:
|Group||UTI risk reduction|
|Placebo||No significant reduction|
|No treatment||No significant reduction|
The European Food Safety Authority (EFSA) also concluded that cranberry products can help reduce the risk of UTIs. However, cranberry juice alone may not contain enough of the active compounds.
Do cranberries improve heart health?
Emerging research suggests cranberries may support heart health in a few ways:
- Lowering LDL (bad) cholesterol: A review of clinical trials found daily cranberry juice consumption significantly reduced LDL cholesterol levels compared to placebo.
- Reducing blood pressure: One study found drinking low-calorie cranberry juice daily lowered blood pressure in people with hypertension.
- Increasing HDL (good) cholesterol: Some evidence indicates cranberry juice can raise levels of HDL cholesterol.
- Preventing oxidation of LDL cholesterol: Oxidized LDL is more likely to form plaque in arteries. Cranberries’ antioxidants may help prevent this process.
Overall, cranberries’ effects on heart health are promising but need more robust clinical studies.
Do cranberries have anticancer effects?
Test tube studies show promise for cranberries’ anticancer abilities. Cranberries are rich in polyphenols that may slow cancer cell growth and spread. Possible anticancer mechanisms include:
- Inducing cancer cell death (apoptosis)
- Reducing inflammation linked to cancer
- Blocking tumor formation and proliferation of cancer cells
- Decreasing expression of genes involved in cancer growth
However, human studies are needed to confirm if cranberries can prevent or treat cancer.
Do cranberries promote digestive health?
Cranberries are often marketed as improving digestive health and ‘cleansing’ the body. But is there any truth to these claims?
Here’s what the research says about cranberries and digestion:
- Prebiotic effects: Cranberries contain indigestible fibers that provide food for healthy gut bacteria. They may act as prebiotics.
- Probiotic effects: Compounds in cranberries can inhibit growth of harmful bacteria like H. pylori, implicated in ulcers and gut inflammation.
- Improved regularity: Like other high fiber foods, cranberries add bulk to stool and may relieve constipation.
- Reduced stomach inflammation: Cranberries contain salicylic acid, related to aspirin, that may soothe stomach inflammation.
So while cranberries aren’t a miracle ‘cleanser,’ they do appear to support overall digestive health.
Are there any risks or side effects?
For most people, moderate amounts of cranberries are safe. Potential side effects may include:
- Upset stomach or diarrhea
- Kidney stones in those predisposed
- Drug interactions like warfarin (blood thinner)
- Allergic reactions (rare)
Unsweetened varieties are best for health to avoid added sugar. Cranberry supplements should be avoided by pregnant women as safety is unknown.
Research suggests cranberries provide antioxidant, antimicrobial, and prebiotic benefits. They show particular promise for boosting urinary tract health. Early studies indicate they may also benefit heart health and have anticancer abilities.
Cranberries’ effects on digestion are mixed. They appear to support gut bacteria and reduce stomach inflammation. However, claims they ‘cleanse’ the body are exaggerated.
At moderate amounts, cranberries are safe for most people. But pregnant women should avoid cranberry supplements due to insufficient safety data. Overall, incorporating fresh or low-sugar cranberry products into a balanced diet can provide valuable health benefits.