Monday, September 02, 2019

What will we do without the humble banana?

I found out a couple of interesting factoids about the humble banana recently, one good, one distinctly not.
Firstly, those brown spots that appear on ripe bananas are not actually a bad thing. There is no doubt that bananas are healthy fruits: they are high in energy, vitamins and minerals; they act as antacids, relieving heartburn and acid reflux; they are high in fibre, to prevent constipation; they increase potassium and reduce sodium, which helps reduce high blood pressure; they can help line the stomach, preventing corrosive acids and stomach ulcers; they are high in iron, boosting hemoglobin and red blood cell production; they contain tryptophan, which can help fight depression; they are rich in vitamin B, which can help relax the nervous system and improve mood.
But hey, what about those brown spots? Well, apparently riper bananas contain more Tumour Necrosis Factor (TNF), which can help block the growth of tumour cells, and promotes communication between the immune system and body cells. These cancer-fighting properties are supported by the fruit's high level of antioxidants, which boosts the immune system and blood cell count.
So, the more brown spots, the better bananas work in the fight against cancer? Well, yes and no: TNF is acually a double-edged sword, acting to induce cancer cell death, but also potentially stimulating the growth of cancer cells. As usual, nothing is simple in the field of health and medicine. And whether you can deal with the taste of an "overripe" banana is another matter entirely.
The bad news about bananas came as quite a surprise to me: bananas as we know them are dying out. For decades the dominant breed of bananas commercially was the Gros Michel, but in the 1950s it was all but wiped out by a fungus known as Panama Diseas or banana wilt (technically the Tropical Race1 strain of a fungus called fusarium oxysporum cubense, or TR1). Banana growers then turned to the Cavendish banana, which was found to be immune to Panama Disease. Nowadays, almost al the world's commercially-traded bananas, including all Chiquita and Dole bananas, are the Cavendish breed, clones of a breed of banana first cultivated on Chatsworth Estate in England back in the 1830s (just a few miles from where I was brought up, as it happens).
In the meantime, though, the Panama Disease fungus was morphing and adapting, and a new virulent strain (TR4) is capable of infectng the previously immune Cavendish banana (as well as most other local breeds throughout the world). Now, almost all bananas worldwide are at risk, not necessarily in the next few years, but eventually. Containment of the fungus is all but impossible at this point, so the search is on for a breed of banana (or possibly a genetically modified version) that is resistant to Panama Disease.
The banana is essential to the economies of many countries, particularly in South and Central America, and an important part of the diet of many poorer countries. Worldwide it is the fourth most important crop, after wheat, rice and corn. Let's hope we can save it.

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