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Comment by rendaw | Hacker News Reader

Bananas have a pH of around 4.5 for unripe bananas to 6 for ripe bananas, so are acidic.

Huh. I am admittedly neither a doctor nor chemist, but I was told this by a doctor, and anecdotally bananas seem to help me with reflux. Looking on the web, there does seem to be conflicting advice.

They are high in fibre and can thicken the fluid in the stomach. Maybe that's how they help.

I'd heard claims like that before and I was curious so I googled a bit more.

It sounds like there's this thing "PRAL" or "potential renal acid load" https://en.wikipedia.org/wiki/Potential_renal_acid_load where the affect on stomach acid can be different from a food's pH. But again, the wikipedia article links to some random people's blogs and a single research article from 2019. I'm not sure if this is well supported by research.

Exactly- this is based on how it alters urine pH, and there is a whole alternative medicine thing around assuming this is extremely important- but the entire idea seems unconvincing to me. Both stomach and blood pH are carefully regulated by feedback control and don’t themselves change much based on foods.

It is extreemly important because it is easy to measure and varies wildly based on concious decisions: things that make it easier to sell the snake oil. Blood pressure is another. Many a "tonic" of flavored alcohol seemingly cured symptoms of high blood pressure... long enough to make the sale.

I can see why the directly observable effect could help here, but what are these “alkaline diet” people selling exactly? I’ve mostly seen it just from individuals giving me unsolicited health advice. Also are these people really measuring the pH of their urine?

It depends. There are varieties of bananas & plantains that are high in latex, and can cause reflux and allergies for some people.

I assume 99% of the bananas consumed in the US are Cavendish.

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