UPDATED: June 17, 2025
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Complementing my article praising oranges, this Post about bananas includes currently available health and nutrition information backed up by reputable scientific research. If you’re a banana eater, as I am and so many of us are, you’ll want to optimize their benefits while minimizing potential harms.
Credible Information
Credible nutrition information can be difficult for consumers to identify. Accurate information about the relationship between diet and health can be found in replicated, high-quality scientific studies published in leading peer-reviewed journals. People making claims about foods and dietary supplements need to back them up by citing reputable sources. It is then incumbent upon readers to check those sources and determine if they are reputable.
In contrast, there is a lot of misinformation being pushed by social media influencers. Some are offering personal opinions. Others have a hidden agenda. A Washington Post investigation found that the food industry and their trade groups pay diet influencers who have large social media followings to promote products and messages that go against the scientific evidence. Be especially wary of anyone online who conceals their identity.
Why Pick on Bananas?
Bananas are the most popular fruit in the world and are heavily promoted by those who profit from their consumption. Americans eat an average of 10 pounds of bananas per year. Consequently, this article is likely to offend both banana fans and those dietitians who mistakenly believe this ubiquitous comestible is a healthy snack and the perfect fruit for breakfast.
Although there are more than a thousand varieties, the one most frequently produced for export is the Cavendish. Typically grown as a monoculture, the Cavendish banana is highly susceptible to eradication by diseases and insects. The lack of genetic diversity makes them an easy target for plant pathogens. Originally developed through selective breeding as a disease-resistant replacement for the now extinct Gros Michel variety, the Cavendish banana has dominated the world's market for the past 40 years. It is now facing the same fate due to a fungal pathogen called Fusarium.
Pesticide Dangers
There is a deadly side to banana cultivation. Banana cultivation is chemical-intensive, and commercial growers need to use a variety of products to maximize productivity. Banana plantations have long had a devastating impact on the environment, as well as on the health of agricultural workers.
Prostate cancer rates are among the world’s highest on the islands of Guadeloupe and Martinique in the French Caribbean. The prime suspect is the exposure of agricultural workers to chlordecone, a highly toxic pesticide, that was used on plantations to combat the banana weevil for two decades. The persistent chemical has contaminated the islands' soil and groundwater, impacting almost the entire population.
Contrary to what many people think, pesticides aren't confined to the peels. They are absorbed throughout the entire fruit. From the moment that new banana buds appear, they are covered in an insecticide-soaked bag that remains in place until the bunch is picked. Chemicals intended to kill nematodes are pumped into the soils in which bananas are grown. The plants are also treated with a variety of fungicides.
Bananas are picked long before they are ripe, then treated with gaseous “ripening” chemicals so they won’t be too green when they arrive at their destination. Whatever nutritional value they might have had if picked when ripe is lost when they have to be transported halfway around the world.
A review of pesticide residues in the flesh of non-organic bananas concluded that the established maximum concentrations do not assure consumer safety. According to an EU analysis, pesticide residues were found in about two-thirds of banana samples. A new study found that pesticide use increased cancer risk as much as smoking. This makes a persuasive argument for a banana boycott, or buying organic bananas if you're going to eat them at all. To learn more about the dirty side of the banana business and its geopolitical repercussions, take a look at The Fish That Ate the Whale.
Genetically Modified Bananas
Bananas have been genetically modified to enrich their provitamin A content in order to address widespread childhood deficiencies in parts of Africa. World wide, it is estimated that as many as 700,000 children a year die from vitamin A deficiency, with hundreds of thousands more suffering from blindness as a result of an inadequate diet. The $10 million dollar project is seen as a significant humanitarian effort.
Another recent innovation is a CRISPR-edited banana that was developed to delay browning after being peeled, potentially reducing waste. Bananas are highly perishable, and by some estimates half of the bananas grown are never eaten. Extending their shelf life through genetic engineering could produce the “super banana” of the future.
Bananas and Nutrition
I love bananas as much as the next person, and perhaps even more. I grew several varieties when I lived in Hawaii, and enjoyed their abundance all year long. I also became adept at making banana bread, so as not to waste any that were too ripe. It wasn't until I looked at their nutritional profile that I realized how my unlimited supply of bananas had contributed to my weight gain, despite my very active lifestyle.
According to the USDA’s nutrition website, a 100 gram (3.5 oz) serving, about half of a large Cavendish banana, provides 89 Calories, but who eats only half a banana, especially when there’s a whole bunch getting too ripe at the same time? The same unrealistic serving size contains 23 grams of carbohydrates, 12 grams of total sugars (providing more than 6 grams of both fructose and glucose), and only 2.6 grams of dietary fiber.
From a biochemical perspective, bananas are not nutrient-dense, and there is no way they could be considered a superfood. A half-banana has 358 mg of potassium, which is a lot but not as much as zucchini, which is also healthier in a number of ways. Zucchini is also a fruit, one that’s low in calories, fat, and simple sugars, while being high in fiber and rich in micronutrients such as vitamin C, potassium, manganese, folate, and vitamin B6.
One of my pet peeves has to do with dietitians giving people specific food advice that’s biased in favor of their own preferences and prejudices. I’ve previously taken issue with vegan dietitians, and those who become social media influencers and conceal their financial ties to certain industries and trade organizations. Know that if you’re getting nutritional advice online it may be coming from someone who is disreputable. If they are trying to sell products, that’s a clue to their hidden agenda.
Reputable dietitians should have in-depth biochemical knowledge and be able to fully understand their client’s medical issues, metabolic state, and unique requirements. When it comes to claiming specific health benefits (or harms) based on observational studies, with the data derived from diet questionnaires, such claims are utterly worthless, as Dr. Katz explains:
Notice that I’m not claiming health benefits from eating zucchini. In fact, to avoid pesticide residues, it might be better to purchase the organic version, or grow your own. Because this article is about bananas, I’m simply pointing out that zucchini has a healthier nutritional profile. So, if you’ve been stuck in the mind-set that only bananas go with cereal or yogurt, think again. Try a breakfast experiment with some cooked zucchini. You might be pleasantly surprised.
Banana GI and GL
Of the starches found in bananas, much of them are resistant starches that release less glucose into the bloodstream. That’s the good news. Green bananas contain more resistant starch than ripe ones. Plantain cooking bananas are even starchier. I’ve microwaved green bananas in their peels, after poking a lot of holes with a fork so they don’t explode.
Refrigerate your bananas when they are mostly yellow and just starting to show some brown spots. Although their peels will darken, the flesh will remain perfectly edible. If the bananas become too ripe, peel and freeze them in an airtight container. Martha Stewart has some more tips about the culinary aspects of bananas.
The bad news is that due to their high sugar content, ripe bananas have a glycemic index (GI) of 51- 63 (depending upon the study). In comparison, sugar-sweetened soft drinks have an average GI of 64. The riper a banana is, the higher its GI, with over-ripe bananas having a GI as high as 69.
The GI represents the relative rise in a person's blood glucose level two hours after consuming a particular food, in comparison to pure glucose. Generally speaking, blood sugar spikes are unhealthy, and a lower GI is therefore better for reducing the risk of insulin resistance, obesity, and type 2 diabetes. What also needs to be considered in addition to the GI is a food's glycemic load (GL), both of which can be found at this website.
The GL is calculated by multiplying the weight of available carbohydrates in the food by the food's glycemic index, and then dividing by 100. Bananas are about 23 percent carbohydrate by weight, and have a moderate GL of 12.4. That makes bananas healthier than white bread and white rice, but it still doesn't make them a health food.
For people with diabetes or pre-diabetes, it would be advisable to limit banana consumption if they produce blood glucose spikes. One's blood glucose response can be determined by a continuous glucose monitor (CGM). Eating a banana along with both protein and fat, such as found in whole-milk, plain Greek yogurt, will potentially slow down the rate at which blood glucose rises and prevent spikes.
Polyphenols
While primarily plant-based diets are considered to be the healthiest, some fruits and vegetables don’t get along well with others, and bananas appear to be one of those. That's because bananas contain an enzyme (a protein-based catalyst) known as polyphenol oxidase (PPO), which helps to protect plants from parasites. PPO breaks down important phytonutrients known as polyphenols.
Polyphenol oxidase can reduce the bioavailability of flavonoid polyphenols. A well-controlled crossover study found that the combination of bananas and berries in a smoothie resulted in an 84 percent reduction in the amount of available flavonoids, compared to smoothies containing only berries. It didn’t matter whether the bananas were mixed into a smoothie, or were eaten separately from berries but in the same meal.
Dietary Flavonoids
There are more than 8,000 different types of polyphenols, and they are the most abundant natural antioxidants found in the human diet. Some of them such as flavonoids also have potent anti-inflammatory properties. Dietary flavonoids are associated with a lower risk of all-cause mortality and major chronic diseases, according to a 2025 British study.
The main source of dietary flavonoids was black and green teas, providing about 157 mg a day. That was followed by apples, red wine, grapes, berries, dark chocolate, and oranges. Other key contributors of flavonoids in the typical British diet included grapefruit, sweet peppers, and onions. Be aware that overheating tea and overcooking foods can destroy their polyphenols.
A study of cardio-metabolic health focused on a particular class of flavonoids called flavanols, also known as catechins or flavan-3-ols, high concentrations of which are found in green and black tea, cocoa, and berries, especially blackberries. The study noted that beneficial effects were observed across a range of disease biomarkers and clinical outcomes. The Academy of Nutrition and Dietetics recommends 400–600 mg of flavanols daily from food-based sources, rather than supplements.
Dietary flavonoids have been associated with a number of health benefits. People in the study who consumed the greatest quantity and widest diversity of flavonoids had as much as a 20 percent lower risk of cardiovascular disease (heart disease and stroke), type 2 diabetes, cancer, respiratory disease, and neurodegenerative disease.
Flavonoids have also been associated with improved cognitive function and protection against age-related cognitive decline; reduced cell damage caused by free radicals; decreased skin damage caused by UV radiation; improved gut health by promoting the growth of beneficial bacteria and suppressing the growth of harmful bacteria; facilitating weight loss through improved metabolism. For more about flavonoids and health, see:
Milligrams of flavonoids per 100 grams:
Parsley, dried (13,530), then oregano, thyme, dill
Cocoa powder, unsweetened (3,600-5,000)
Green tea leaves, dried (2,000-4,000)
Dark chocolate with more than 70% cacao (500-1,200)
Elderberries (700-1,000)
Black currants (400-700)
Blueberries (200-400)
Blackberries (150-250)
Cranberries (150-300)
Red cabbage (150-200)
Onions, especially red (100-200)
Apples, with skin (50-100)
Broccoli (50-80)
Citrus fruits (50-80)
The Verdict
When it comes to convenience, taste, and nutritional value, bananas are superior to ultra-processed snack foods. If you don’t grow your own, it is better to buy organic bananas.
Remember that bananas don’t get along well with foods that contain health-promoting flavonoids, and will decrease their flavonoid content. They are also high in calories, so don't “go bananas” and binge on them!
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