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Social media posts shared thousands of times claim that eating overripe bananas can prevent cancer because they contain “a type of substance that boosts the immune system.” The articles appear to cite a study conducted by Japanese researchers, but the claim is misleading: the article does not say that the fruit contains the immune-boosting protein, nor does it encourage the consumption of overripe bananas. Experts told AFP that the substance is only found in mammals and not in plants.
The misleading claim was shared on Facebook Publish dated April 12, 2022.
The message in Thai translates to English as: “Japanese researchers have said that ripe bananas contain TNF (tumor necrosis factor) which fights irregular cells such as cancer cells. These cells will strengthen your immune system.”
“Please be advised of eat about one to two bananas a day to prevent any illness, including fever and flu. Ripe bananas will boost your immune system more than eight times as green ones.”
TNF is a substance made by the white blood cells of a mammal; it causes inflammation when the body’s immune system is triggered by an infection, according to the American society National Cancer Institute.
The Thai language claim has been circulating since at least 2014 and most recently in 2021 and 2022.
It was also shared in English here in 2019, garnering over 6,500 shares.
But the claim is misleading.
japanese study
A keyword search found this study published in the Food science and technology research journal on February 4, 2009, suggesting that bananas have the potential to “prevent lifestyle-related diseases and carcinogenesis”.
In the peer-reviewed study, Japanese researchers tested the effects of banana juice injected into mice on their ability to mount an immune response, including the production of TNF. They found that a banana strain induced a higher response as it matured.
But the study did not suggest that humans should increase their consumption of overripe bananas, or that the fruit could prevent illnesses such as the flu or cancer.
And he didn’t say that bananas contain TNF.
A biology professor at Chulalongkorn University in Thailand told AFP that TNF is not found in plants.
“TNF is a substance that is part of the mammalian immune system. It does not exist in bananas and other plants,” said Dr Jessada Denduangboripant.
“It’s an old hoax that isn’t true,” he told AFP on May 11.
High sugar content
Health experts have warned that a diet containing lots of overripe bananas may not be healthy.
“Overripe bananas contain starch and high sugar content, which can lead to obesity,” Bang-earn Thongmon, a nutritionist at the Ministry of Health’s Thai Nutrition Bureau, told AFP. , May 10.
Bang-earn said there is no evidence that eating bananas can prevent disease.
But she encouraged eating “no more than two bananas one day” — ideally when the skin of the fruit has turned yellow but still has a hint of green.
Jessada also stated that “although bananas are nutritious fruits, those that are overripe have a very high sugar content”.
AFP has debunked other misinformation about the health benefits of bananas here and here.
