What is the best condition for eating your banana?

Some people prefer their yellow bananas with a tint of green, while others prefer the sweet sweetness of a banana that has brown spots on the skin.

But it’s not just the flavor that’s different, as there are distinctive effects on your body and health that depend on maturity…


Unripe green bananas have been shown to contain 20 times more resistant starch than ripe bananas.

This is a form of starch that the body has trouble breaking down (it “resists” the digestion process), so it passes directly into the intestine.

This slows down the rate at which the carbohydrates in the fruit are converted into glucose and absorbed into the blood.

During ripening, the starch in a banana is converted into sugar - from 3.2g/100g in an unripe banana to 12g/100g in a ripe banana

During ripening, the starch in a banana is converted into sugar – from 3.2g/100g in an unripe banana to 12g/100g in a ripe banana

A green banana generally has a glycemic index (GI) of 30, compared to 58 for a ripe banana.

Not only is resistant starch good for stabilizing your blood sugar levels, but the “good” bacteria in the colon also feed on it.

In turn, they stimulate digestive enzymes that help us digest carbohydrates and absorb vitamins from food, as well as protect us against unwanted microorganisms.

Professor Gordon Carlson, consultant gastric surgeon at Salford Royal NHS Foundation Trust, told Good Health that he eats a relatively unripe banana every day to improve his gut health. The benefits of green bananas were confirmed in a major review of 18 studies on their nutrition, published in the journal Nutrients in 2019.

This revealed that green bananas can help relieve gastrointestinal symptoms (such as diarrhea and constipation) and illnesses (such as intestinal cancers).

A green banana generally has a glycemic index (GI) of 30, compared to 58 for a ripe banana.

A green banana generally has a glycemic index (GI) of 30, compared to 58 for a ripe banana.

They may also help prevent or treat type 2 diabetes.

Unlike other foods, bananas contain a form of resistant starch that is increased, rather than broken down, by heating.

In fact, a study published in the Malaysian Journal of Nutrition in 2018 found that boiling green bananas increased their resistant starch content.

Other research has shown that cooling cooked green bananas in the refrigerator increases resistant starch by an additional 50%.

The cooling process causes the starches to form a new structure that is even more resistant to digestion (called “starch retrogradation”).


During ripening, the starch in a banana is converted into sugar – from 3.2g/100g in an unripe banana to 12g/100g in a ripe banana.

“That’s what makes it a good source of quick-release energy for athletes,” says dietitian Dr. Sarah Schenker.

The low amounts of resistant starch also mean that yellow bananas are easier to digest. If you have digestive issues, green bananas may make you feel gassy or bloated.

Dr. Schenker suggests that the health benefits of yellow bananas outweigh those of green ones.

“Bananas contain several compounds, such as carotenoids, which are linked to eye health and cancer prevention, and which become more ‘bioavailable’ [available to the body] when the banana ripens,” she says.

“With less starch to break down, your digestive system will absorb nutrients faster.”

Bananas contain B vitamins as well as the antioxidant vitamins A and C, as well as the minerals iron, magnesium, manganese and potassium.

Some of these micronutrients are lost as the banana ages, but levels of antioxidants, which help support the immune system, peak.

Studies, including one published in 2014 in the International Food Research Journal, showed that vitamin C levels increase with the ripening process, but decrease as the banana becomes overripe.

“These antioxidants exist to prevent the fruit from being eaten and tend to increase as the fruit ripens,” says Dr Sangeetha Thondre, senior lecturer in nutrition at the Oxford Brookes Center for Nutrition and Health.

Yellow with brown spots

Brown spots on a very ripe banana indicate that even more starch has been converted into sugar.

Scientists have discovered that a ripe banana produces a substance called tumor necrosis factor (TNF) which has the ability to fight off abnormal cells and boost our immunity against cancer.

In a 2009 study published in the journal Food Science and Technology Research, scientists from Teikyo University in Japan found that bananas with brown spots were eight times more effective at improving the power of white blood cells (which fight infections) than green-skinned bananas. .

They reported that the degree of anti-cancer effect of the fruit corresponds to the degree of ripeness – the more plaques a banana has, the greater its immunity-boosting power.


Bananas produce ethylene gas, a natural compound that regulates the ripening process, causing them to turn brown.

This changes their texture and flavor as well as their nutritional value. When a banana becomes overripe, much of the starch is converted into sugars, making it an excellent natural source of sweetness.

Dr. Schenker recommends using brown bananas in baking and freezing them to blend in a blender to make sugar-free ice cream.

“Using overripe bananas instead of sugar is a healthier way to sweeten foods because bananas provide several essential nutrients: potassium, vitamin B6, folate, and some vitamin C,” she says.

Eventually, overripe bananas can begin to ferment, losing many of their nutritional benefits. They may start to smell more of alcohol than sugar and may contain up to 0.5g of alcohol per banana.

Laboratory studies have shown that you can extract ethanol (alcohol) from extremely ripe bananas, but only after adding yeast and sugar.

Hot cross buns test

Here, Sophie Medlin, of City Dietitians in London, reviews various ‘healthier’ hot rolls – and we rated them next.

Tesco Free from

4 rolls of 70g, £2.20, tesco.com

Claim: “Free of gluten, wheat and milk.

Per bun: 161 calories; saturated fat 0.2 g; sugar 12.2 g; fiber 6.3g; 2.8g protein.

Verdict: A blend of gluten-free grains, fibrous psyllium husk, and bamboo fiber, provides 21% of your daily fiber. Butter and milk have been replaced with rapeseed oil and dried egg white.

Health rating: 8/10

Palate: Nice, sticky fruit and cinnamon, but very dry. 4/10

Very low carb

4 rolls of 55g, £3.99, seriouslowcarb.com

Claim: “A fraction of the carbohydrates in a regular hot bun. Rich in protein and fibre.’

Per burn: Calories, 113; saturated fat 1.2g; sugar 4.2 g; fiber 4.6g; 10.7g protein

Verdict: Using low-carb, high-protein wheat flour, these rolls have 80% fewer carbs than regular rolls. The low calorie sweetener erythritol can cause bloating.

Health rating: 6/10

Taste: too spicy; minimal fruit. 2/10

Very low carb

Very low carb

Be good to yourself

6 x 70g buns, £1.10 saintsburys.co.uk

Claim: “Less than 3% fat”.

Per bun: 186 calories; saturated fat 0.7g; sugar 11.6 g; fiber 1.9g; 5g protein

Verdict: These contain slightly more calories and fat than some rolls, and there are several ultra-processed ingredients.

Health rating: 2/10

Taste: Juicy but heavy and a bit dry. 3/10

Complete Waitrose

4 buns, £1.65 waitrose.com

Claim: “Made with wholemeal flour. »

Per bun: 187 calories; saturated fat 1.5 g; sugar 12.4 g; 4g fiber; protein 6.7g

Verdict: Not as much extra fiber as you might expect, just 13% of your daily requirement – ​​and three teaspoons of sugar, most of it naturally from the fruit, but also some dextrose.

Health rating: 6/10

Taste: Premium quality fruit. 7/10

Mandy Francois

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