Have you ever longed for that one perfect food that would cure everything? I have, even though I know it's not rational, and I don't seem to be alone, particularly when I see graphics like this:
1) Anti-diarrheal (green banana). One small study done in Bangladesh indicated that rice and cooked green banana seemed to reducethe amount of diarrhea and need for oral and intravenous rehydration fluids. (Link). Would this work in adults as well? And does it work for people with chronic diarrhea from conditions Irritable Bowel Syndrome (IBS) as well as diarrhea from a virus and/or bacteria? Doesn't seem to be any evidence against trying this as long as the green banana is cooked and mashed, you are still watching out for signs of dehydration in the child or yourself, and you are actively working on eliminating the cause of the diarrhea.
2) Provide energy. This is one of those vague statements used by makers of infographics that doesn't seem to mean anything. Do they mean provides glucose which many people (except for those on ketogenic diets) use for fuel? Well, yes, bananas provide that, as do any other fruits or grains, so there is nothing special there. Do they mean provide a special burst of energy? Well, yes, many people will eat carbohydrates (or overeat on carbohydrates) to provide a "burst" of energy, but see above on other fruits. So, nothing to see hear people, let's move on.
3) Help circulation. I have a feeling what they are getting at here is that people with poor circulation do want to make sure that they are getting enough B-vitamins in their diet. Once again, bananas do have b-vitamins, but they don't own the rights to it. Here is a chart that gives a brief overview of food sources for vitamins/minerals including the "B" ones.
4) Fight infections. This seems to be another intentionally vague phrases that makers of infographics love to use. As I said in this post, "I think in this context, the definition they are trying to employ is "The invasion of the body of a human or an animal by a pathogen such as a bacterium, fungus, or virus. " and " Infections can either be localized, as in the case of sinusitis, or they can be a nasty systemic infection (often called "blood poisoning)." So what kind of infections are they suppossed to fight? Possibly they were thinking of a substance that is derived from bananas that is looking promising in the treatment of HIV, but that is a pretty big leap to say bananas fight infections. I have seen anecdotal stories of people using banana peels to treat wounds, but considering that bananas can carry bacteria like pseudomonas and most of my patients with wounds are immune compromised I would not recommend this. I did find a small study that showed good results using banana leaves--but after the preparation was made the banana leaves were put through an autoclave to kill bacteria.
5) Protect skin from damage from U-V light. This one seems to be patently false. There was a small study done using strawberry extract on skin cell cultures in Spain (Link), but no bananas seemed to be harmed in that study. There was speculation that the anthocyanins in the berries might be what protected the cells, but bananas do not contain the same abundance of these. And remember, we are dealing with 1) an extract as oppossed to the whole fruit, 2) it was applied topically as oppossed to consuming/taking internally, 3) it was a strawberry, not a banana, 4) bananas do not have as high an anthocyanin content, 5) the study was done on cell cultures, not actual humans.
6) Anti-ulcer. If someone has peptic ulcer diseaes (PUD) or gastro-esophageal reflux disease (GERD), foods with greater acidity often cause more pain when eaten, so a lower acid banana would be much better tolerated than an orange. Unfortunately, there are no good studies to indicate that bananas actually help knock out the bacteria (H. pylori) that cause ulcers. I did see one claim that bananas contained anti-viral agents, which means they wouldn't work on bacteria. The other claim I saw was that bananas contain serotonin to help regulate gastric acid production; yes, you do actually have sertonin in your GI tract cells, but there is no serotonin in food. Your body MAKES serotonin when you eat carbohydrates and also from tryptophan when enough carb isn't present.
7) Suppress prostate gland enlargement. Maybe, except according to this small study you have to 1) take a banana peel extract, 2) be a castrated mouse taking large doses of testosterone. Might want to study that one a little bit more.
8) Suppress oxalate kidney stone formation (banana extract). At least this time they pointed out that there was an extract used (every time I see that, I wonder how many bananas you would have to eat to get the same properties, and it's probably an unrealistic amount). Once again, this might work if you are a rat, but we don't know what this will do for humans. (Link)
Will cover the other points over the next couple days. So far, however, the anti-diarrheal properties of cooked green banana are all that's holding up.