Every day in our kitchens, a familiar fruit steadily darkening on the counter may hold more than just sweet flavour—it could hint at a remarkable scientific discovery. New research suggests that as bananas ripen, they may produce compounds that exert powerful anti-cancer effects. While the findings are early and caution is warranted, the possibility that something as accessible as a ripe banana might support cancer prevention is both exciting and hopeful.
What the studies show
Several laboratory and animal studies have explored the anti-cancer potential of bananas. For example, a review of scientific findings outlines how extracts from the fruit (including ripe bananas) demonstrated antioxidant and antiproliferative (i.e., anti-cell-growth) effects in experimental settings.
In one large human trial, the focus was not specifically ripe bananas, but a key component: resistant starch, a type of dietary fibre found in slightly green bananas (and other foods). The trial, known as the CAPP2 Trial, involved people with a genetic predisposition to cancer (Lynch syndrome). Researchers found that taking 30 g/day of resistant starch (equivalent to the starch content of about one banana a day) for two years was associated with roughly a 50% reduced risk of non-colorectal cancers (like those in the upper gastrointestinal tract) compared with placebo.
However — a word of caution: the trial did not find a significant effect of resistant starch on colorectal (bowel) cancer in the same group.
Another review highlights that banana fruit extracts (including ripe ones) showed anti-cancer potential in cells and animal models, though these findings are pre-clinical.
What this doesn’t mean
Despite the attractive headlines, it’s essential to temper optimism with realism. The claim that “overripe bananas produce a powerful natural compound capable of targeting and destroying malignant cancer cells” goes beyond what the evidence currently supports. Some media and social-media posts have inaccurately claimed that fully brown-spotted bananas produce tumour-necrosis factor or directly cure cancer — but fact-checkers warn that such claims are misleading or unproven.
In short: while bananas (and their components) may contribute to cancer-prevention pathways, they are not a standalone cure — nor is the evidence strong enough yet to prescribe them as a therapeutic intervention.
Why the science makes sense
There are several plausible mechanisms by which bananas (especially components like resistant starch and bioactive compounds) might influence cancer risk:
Resistant starch reaches the large intestine largely undigested, where it is fermented by gut bacteria. This fermentation may produce beneficial changes in bile-acid metabolism and reduce DNA-damaging secondary bile acids — a pathway proposed for reduced upper GI cancer risk.
Banana extracts have shown antioxidant activity — meaning they may help neutralise free radicals and reduce oxidative stress, which can damage cells and lead to cancer development.
Some banana-derived compounds in lab tests have displayed antiproliferative effects (slowing the growth of tumour cells) in vitro (cell culture) or in animal models.
What this means for you
Given the current state of evidence, here are balanced take-aways:
Including bananas — whether ripe or slightly green — as part of a varied, plant-rich diet can contribute to overall health. Bananas bring fibre, potassium, vitamins, and other beneficial nutrients.
If you are looking to maximise potential gut-health and cancer-prevention benefits, slightly green bananas (with higher resistant starch) may be of interest — but note that they may taste firmer and less sweet.
Don’t rely on bananas alone for cancer prevention or treatment. They should complement, not replace, well-established healthy habits (like avoiding tobacco, limiting alcohol, maintaining healthy weight, staying active, and following medical-screening guidelines).
If you or a family member have a high genetic risk of cancer (for example, Lynch syndrome), speak to a healthcare professional about what preventive strategies apply to your case — diet is one piece of the puzzle but not the only one.
Be cautious of online claims that bananas are a “miracle cure” for cancer. Always check the source of the research, whether human trials exist, and what the independent review says.
The future of the research
Scientists are keen to dig deeper. Questions for future studies include: Which banana varieties or ripeness stages yield the most beneficial compounds? What doses apply? Can these compounds be isolated, refined and used as part of therapy (in combination with conventional cancer treatments)? And how do the effects observed in high-risk groups translate to the general population?
Final Word
Bananas remain a humble, affordable, and nutritious fruit — and emerging research hints at interesting cancer-prevention potential when they’re part of a healthy lifestyle. While they are not magic bullets, choosing bananas — whether ripe or gently green — alongside other plant-based foods is a smart, accessible strategy for overall wellbeing. As the science progresses, they may well play a supporting role in future nutrition-based approaches to health and disease prevention.
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Source References:
Mondal A, et al. “Cancer Preventive and Therapeutic Potential of Banana and its Bioactive Constituents.” PMC, 2021.
“Resistant starch equivalent to eating a daily banana cuts hereditary cancer risk.” Cancer World, August 2022.
“A banana a day could keep cancer at bay.” University of Leeds, July 2022.
Kim DK, et al. “Antioxidant activity of banana flesh and antiproliferative effect.” PMC, 2022.
Ha T. “Cancer and ripe bananas: How bogus claims can harm your health.” ABC News, September 2018.