The fully ripe banana produces a substance called TNF( Tumor Necrosis Factor) which has the ability to combat abnormal cells. As the banana ripens, it develops dark spots or patches on the skin. The more dark patches it has, the higher will be its’ immunity enhancement quality . Hence the Japanese love bananas for a good reason. According to a Japanese scientific research, banana contains TNF which has anti-cancer properties. This substance, according to their study, helps to increase the immune system capacity. The conclusion of the study was that eating those ripe bananas may just prevent certain lifestyle-related diseases and carcinogenesis.
The degree of anti-cancer effect corresponds to the degree of ripeness of the fruit, i.e. the riper the banana, the better the anti-cancer quality.
It is a fact that nutrient content of fruits change slightly as they ripen. As a banana ripens and turns yellow, its levels of antioxidants increases. In full ripe bananas with dark spots on skin, the starch content changes to simple sugars that are easier to digest.
It’s believed that bananas having reached the stage of multiple brown spots may have a considerable amount more of TNF-alpha — and be up to 8 times more effective than the green skin banana version or fresher bananas without the same dark patches or spots, i.e 8 times more effective in enhancing the property of white blood cells.
Tumor Necrosis Factor(TNF-α) is a cytokine, substances secreted by certain cells of the immune system that have an effect on other cells. This is indeed helpful in fighting abnormal turmor cells in body. Research done on ripening bananas has proved that the levels of TNF-α induction increased markedly with dark spots on skin before the entire banana peel turned brown. The research concluded that the activity of banana was comparable to that of Lentinan, a chemical immunostimulant that is intravenously administered as an anti-cancer agent. So, ripe banana can act as an anti-cancer agent by stimulating the production of white blood cells in the human cell line and preventing cell mutation.
Note: Once bananas ripen fully, store them in the refrigerator to minimize further vitamin loss. Fresh bananas with brown patches on the skin are ripe enough to eat immediately. Make sure to avoid over-ripe bananas whose skin has turned completely brown or split open.