Bananas are Hard to Digest: So Said Your Great Grandmother

Bananas are difficult to digest. This myth was being circulated in the early 1900s and probably earlier. The belief shows up in some health and nutrition books of the time. Was the myth inspired by the books? Or was this public belief repeated by the authors with no investigation?

It is a funny myth since bananas are such a highly recommended staple of nutrition, and are perhaps rated higher than any other fruit. No matter, this myth was already being busted by nutrition experts in the mid-1930s and on into the 40s, although I’m sure it took a while before it was completely stamped out. 1 2 Have you ever heard anyone say it?

You will often read or hear that unripe bananas are difficult to digest. Perhaps that is the origin of the myth and the ‘unripe’ part simply got discarded.

Well, we can figure it out if we look into banana history just a little bit. First, realize that the banana has always been the subject of rumors and even a little fear, since it was introduced into the Western market in the early 1900’s.

Have you heard the one about spiders (snakes too) hitchhiking around the globe in banana crates, hidden in the bunches? Unfortunate people buy the bananas, and when they get home and decide to peel and eat one of the bananas, they are bitten by a spider that happens to be the most poisonous in the world, and then their finger rots off, or other gruesome things happen.

Just an example. But the myth of the hard-to-digest banana can certainly be traced to the green banana. You see, there are many different varieties of bananas, and not all are suitable for eating raw.

Some of them are so starchy that they need to be cooked first, such as the familiar plantain. All these varieties are part of the genus Musa.

The bananas we consume raw are generally referred to as sweet bananas. Well, if you are someone wanting to export a sweet banana from South America in the early 1900s, and you wait until it is ripe, and thus sweet, by the time you get it to the U.S., or anywhere else, it will be rotten. As well, it is unwise to let cultivated bananas ripen on the plant, as I reveal in 6 Surprising Facts About Bananas.

But when it is rock-hard and green, you might realize, it can be picked but will still slowly ripen over weeks, or even months, while you’re shipping it. And for you, shipping means an actual ship, not a train ride or a truck haul.

To consumers of the time, however, this caused problems, adding to the natural distrust of a new food shipped from mysterious and dangerous foreign lands.

First of all, some of the consumers got the banana while it was still green. Second, some people didn’t think a fruit that had not ripened naturally but instead had ripened while sitting in crates on a ship, could be trusted. They weren’t really ripe.

Unripe bananas, or bananas that had been picked prematurely but had apparently ripened anyway were seen as the same thing. Hey, do you eat green unripe apples? No, they will give you a stomach ache. Everybody knows that. Well, don’t eat these unripe bananas either.

The starch in the green banana was explained, by experts of the time, to be much like the starch in a potato, which is certainly very difficult for us to digest, if uncooked. The heat of cooking modifies the starches and makes them easier to digest, much like the natural ripening process changes the starches to simpler sugars.

Bananas, and Possibly some Spiders and Snakes

Other Banana Myths

One health-related book written by, ahem, doctors, in 1895, entitled The Relation of Food to Health and Premature Death said that green bananas could bring on attacks of deadly cholera! They went on to claim that the fruits should not be eaten raw and should always be cooked until soft. Failing that, avoid them altogether.

Even later in 1935, a health book said that when a banana was harvested in the unripe state but subsequently appeared to be ripened, its “green starch” remained inedible. All this occurred before bananas were ripened by being artificially exposed to ethylene.

Recently, in 2007, the Chinese got into the banana-fearing spirit when it was rumored that bananas from the Chinese island of Hainan could spread the SARS virus! This was the same banana that was already accused of having a hand in cancer.

As I mentioned above, by the 1940s, the banana danger movement had died down and bananas were integrated into the food culture well enough for echoes to be ignored. But there were still jokes about it, and we know that jokes after the fact are often the manifestations of some lingering fear.

For instance, in the 1940s, there was one about two girls on a train who bought bananas for the first time. One girl peeled her banana and took a bite. Right after she bit into the banana, the train entered a dark tunnel.

“Have you started on your banana yet?” she asked the other girl. The other girl said, NO, she hadn’t yet. “Well, don’t…It makes you go blind.” 3

These rumors are nothing, however, compared to the Flesh-Eating Bananas from Costa Rica.

green bananas growing on plant — They Grow UP

Why Should Unripe Bananas be Hard to Digest?

So that describes the myths and other myths, and I think it is clear that it had to do with how bananas were shipped green, to be allowed to ripen while they sat.

But what of the hard-to-digest starch thing? Well, it is true. The starch in a green banana is, like the starch in an uncooked potato, a resistant starch.

Unripe bananas, in fact, are around 82% starch and only 7% sugar. Ripe bananas are about 26% starch and 63% sugar. And overripe bananas are 3% starch and 88% sugar.

Most people, once the banana is ripe, have no trouble with the starch that is left. If you tend to have a bit of GI trouble after eating bananas, you may be particularly sensitive to the small amount of resistance starch. An allergy is also possible, of course.

Banana Ripening and Cooking

Banana ripening is a kind of self-digestion, which is called autolysis. This involves hydrolysis of the starches, which results in the banana having more sugar content as it ages, and less starch. Digestion after consumption involves a similar process through the action of α-amylase and other enzymes.

Like potatoes and rice, the starches in bananas occur in very organized structures called grains. These are soluble in water and can resist the attack of digestive enzymes somewhat. Cooking disrupts the grains, which results in them being much more susceptible to digestion.

Interestingly, once the cooked bananas cool down, the starches go back, to some extent, to their original orderly arrangement, and again become more resistant to digestion. This is called the crystallization of starch. Reheating will return them to their disrupted and more digestible arrangement.

ripe bananas with spots — Contrary to popular belief, brown spots on bananas do not mean they are over-ripe.

The same kind of thing happens when bread goes stale. This happens because the starches in the bread have crystallized. Heating up the bread again will disrupt these crystallized starches and bring the bread back, somewhat, to its former desirable state. 4

Despite all this, the idea that unripe bananas cannot be digested is a stretch. They simply resist digestion, so that not all of the starch will be broken down by the digestive tracts innate action, but instead will stick around so that friendly gut bacteria will eventually break it down, through fermentation. We all know what that means!

You can eat a green banana and you may or may not get a stomach ache, depending on how sensitive you tend to be. Unless you are compromised in some way, you will certainly digest it eventually.

You can also eat a small amount of raw potato, and you’ll eventually digest that as well. But if you eat a large amount of either, then you can expect some problems. But who would do this?

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