The banana is a powerhouse — a terrific source of fibre, carbohydrates, potassium, vitamin B6, vitamin C and magnesium.
But should you eat them green or wait until they’re browning? Partly it’s a matter of taste, though bananas have different benefits depending on where they are in their life cycle. This is a guide.
Underripe
Good for gut health
Underripe bananas “contain resistant starches, which act like a prebiotic by feeding beneficial gut bacteria”, says Rob Hobson, author of Unprocess Your Life. “They’re also lower in sugar than ripe bananas and may have a slightly lower glycaemic index, which could help some people manage blood sugar better, although individual responses vary.” But avoid if you have a sensitive stomach, as “resistant starch can be harder to digest and may cause bloating or gas in some people”.
Potential cancer-fighting properties
In 2022 a 20-year study co-led by Newcastle and Leeds Universities concluded that resistant starches, such as those found in underripe bananas, could reduce upper gastrointestinal cancers — including oesophageal, gastric, biliary tract, pancreatic and duodenal — by more than half. “The dose used in the trial is equivalent to eating a daily banana. Before bananas become too ripe and soft, the starch resists breakdown and reaches the bowel, where it can change the type of bacteria that live there,” says Professor John Mathers, professor of human nutrition at Newcastle University.
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Perfectly ripe
Peak benefits
The micronutrients found in bananas are at their most potent when they’ve got that perfect yellow hue. “Bananas are praised for their potassium but they’re an even better source of vitamin B6,” Hobson says. “A medium banana provides about 12 per cent of your recommended daily intake of potassium, but nearly 30 per cent of your daily vitamin B6 needs. B6 is key for converting food into energy and maintaining a healthy nervous system.” There are also small amounts of vitamin C.
The ideal snack
The average 120g banana has about 100 calories, making it a calorie-efficient and filling snack. “When bananas are perfectly ripe, they strike a balance between starch and sugar,” Hobson says. “They provide quick energy and are easier to digest than greener ones.”
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Overripe
Highest in sugar, best for sport
Bananas that are a little past their prime, characterised by brown spots, have the highest sugar content. “These are great if you’re pre-workout or mid-run,” Hobson says. “They are also much gentler on a sensitive stomach, which is good if you are doing a bit of exercise.” The only downside is that “they have a little less fibre because a lot of that resistant starch is converted into sugar”, Hobson adds. The high sugar level may also make them a poor choice for diabetics.