Sunday, 20 July 2014

Ripe or Not? IBS, Bananas and FODMAPs.

Anyone else confused about whether bananas should be ripe or unripe (or maybe inbetween) on a low-FODMAP diet? I must admit this has been fascinating me as I remember reading some years ago that bananas benefit some people with IBS while being problematic for others. Could this be why? But then when I started reading up on it I found the info out there was more than a little bit confusing! Well, I've done a bit of digging and I think I've got it. So here goes.

It seems to me (if I've understood it correctly) that the issue with bananas is not just limited to the fructose/glucose content but also to something called 'resistant starch'. As you may already know, the fructose/glucose content of a banana varies according to how ripe or unripe it is.

'At harvest, when bananas are green and unripe, the fruits are 20 percent starch and 1 percent sugar. As the bananas ripen over 21 to 28 days, the starch turns into several types of sugars. Sucrose forms first but remains at a constant amount as fructose and glucose content increases. A fully ripe banana, which is yellow with some brown spots, is 14 percent fructose, 20 percent glucose and 66 percent sucrose, note researchers from a study published in "Food Chemistry" in May 2005.' (1) So as the glucose content is higher than fructose a ripe banana is fine. As for the sucrose, Monash University explains 'Sucrose is a disaccharide (2 sugar units) made up of equal parts of glucose and fructose. Sucrose is broken down and absorbed efficiently in the small intestine.' (2) So Sucrose isn't an issue.

But as for the starch content ...

Unripe bananas are difficult to digest as they contain something called resistant starch. 'In many ways, resistant starch is similar to and behaves like fermentable fiber in the digestive tract.' (3) And as we know 'Fermentable' is not good. Resistant starches are categorised according to four groups. Unripe bananas are classified RS2 (resistant starch type 2). 'RS2 – Is intrinsically resistant to digestion before cooking. RS2 includes unripe bananas, uncooked potatoes, along with many other foods.' (ibid).

So there you have it - two reasons to opt for ripe bananas. Hope that clears things up a bit.


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