What are the disadvantages of banana shakes?

December 5, 2025 •

4 min read

According to a study published in Food & Function, adding a banana to a berry smoothie can reduce the absorption of heart-healthy flavanols by as much as 84%. This enzyme, polyphenol oxidase (PPO), is just one of several factors contributing to the disadvantages of banana shakes, which may surprise many people who consider them a health drink.

Quick Summary

This article explores the potential health drawbacks of consuming banana shakes, focusing on factors like high sugar content, weight gain implications, digestive discomfort, and reduced nutrient absorption from other ingredients. We discuss how preparation methods influence these risks and provide alternatives for healthier blends.

Key Points

High Sugar Content: A banana shake can lead to rapid blood sugar spikes, especially concerning for diabetics, as blending accelerates sugar absorption.
Potential for Weight Gain: Due to high calorie density from bananas and added ingredients, regular consumption can contribute to weight gain if not balanced with overall diet.
Digestive Discomfort: The combination of bananas and milk can be heavy on the stomach, and ripe bananas can sometimes cause bloating or gas in sensitive individuals.
Reduced Nutrient Absorption: The PPO enzyme in bananas can significantly inhibit the absorption of beneficial flavanols from other ingredients, like berries.
Risk of Allergic Reactions: As with any food, there is a risk of allergic reactions, not only to the banana itself but to other added ingredients like dairy or nuts.
Nutrient Imbalance: Relying too heavily on bananas can result in a diet that lacks the diverse vitamins and minerals found in a wider variety of fruits and vegetables.

High Sugar and Calorie Content

Many people view banana shakes as a healthy, quick meal or snack, but their sugar and calorie content can be surprisingly high, especially when made with commercial sweeteners or high-fat dairy products. A single medium-sized banana contains around 14 grams of sugar and 105 calories, and when combined with milk and other additions like honey, yogurt, or ice cream, the total can escalate quickly.

Impact on Blood Sugar Levels

For individuals with diabetes, prediabetes, or insulin sensitivity, the high sugar content in banana shakes can cause a rapid spike in blood sugar levels. When bananas are blended, the natural fibers are broken down, allowing the fruit's sugar (fructose) to be absorbed more quickly into the bloodstream. This can lead to a quick energy boost followed by a crash, making it unsuitable for those aiming for stable blood sugar.

Contribution to Weight Gain

If your goal is weight management, frequent consumption of calorie-dense banana shakes can contribute to weight gain. The calories from bananas combined with milk can add up, particularly if you don't adjust your overall diet. While this is beneficial for individuals looking to gain weight, it's a significant drawback for others.

Digestive and Ayurvedic Concerns

Combining milk and bananas, a common practice in many shakes, is a subject of debate. According to Ayurvedic food principles, this combination is considered incompatible and can disrupt the digestive process.

The Ayurvedic Perspective

Ayurveda, the traditional Indian system of medicine, suggests that mixing fruits with dairy can diminish 'agni' or digestive fire, leading to the buildup of toxins and causing discomfort. It is anecdotally claimed that this can result in sinus congestion, bloating, and other digestive issues, though scientific evidence is limited. To mitigate this, some recommend consuming them separately or with added spices like cardamom to aid digestion.

Potential for Constipation or Bloating

While bananas are known for their fiber, unripened bananas or excessive consumption in shakes can sometimes cause digestive distress. This is especially true for individuals with irritable bowel syndrome (IBS) or sensitive stomachs. For some, the combination of sugars and dairy can lead to bloating, gas, or other stomach discomfort.

Reduced Nutrient Absorption

One of the most surprising disadvantages of adding bananas to smoothies, particularly those with antioxidant-rich berries, is the reduction in nutrient absorption.

The PPO Enzyme

Bananas contain a naturally occurring enzyme called polyphenol oxidase (PPO). This enzyme reacts with beneficial compounds called flavanols, which are found in berries, apples, and cocoa, and are known for supporting heart and brain health. A study found that adding a banana to a berry smoothie can significantly inhibit the absorption of these flavanols.

To Maximize Flavanol Absorption:

Use low-PPO fruits like oranges, pineapples, or mangoes instead of bananas in your berry smoothies.
Consider eating your banana separately from your flavanol-rich drink.
Reduce the time the banana is blended with other ingredients to minimize the enzyme's effect.

Comparison: Banana Shake vs. Whole Banana


Feature	Banana Shake	Whole Banana
Fiber Content	Blending breaks down fiber, leading to faster sugar absorption.	Higher intact fiber content slows sugar absorption, promoting satiety.
Satiety	Less filling due to liquid form, potentially leading to overconsumption.	More satiating, as chewing signals fullness to the brain.
Nutrient Absorption	Enzyme (PPO) can reduce flavanol absorption from other ingredients.	Nutrients are absorbed without interference from other blended ingredients.
Blood Sugar Impact	Higher glycemic index and potential for rapid blood sugar spikes.	Lower glycemic index, resulting in a more gradual rise in blood sugar.
Calorie Control	Can be difficult to track and control total calorie intake, especially with added ingredients.	Easier to control portions and calorie intake.

Potential Allergic Reactions

For some individuals, banana shakes can trigger allergic reactions. While a banana allergy is the most obvious cause, other components like dairy, nuts, or seeds added to the shake can also be allergens. Symptoms can range from mild itching and hives to more severe reactions.

Conclusion

While banana shakes can offer a quick and convenient way to consume nutrients, they are not without their downsides. The potential for high sugar and calorie content, negative digestive effects, and reduced nutrient absorption from other ingredients warrants consideration. For most people, consuming a whole banana and enjoying other fruits and milk separately or in moderation is a more balanced approach. For those with specific dietary goals, such as weight management or controlling blood sugar, paying close attention to ingredients and portion sizes is crucial. By understanding the disadvantages of banana shakes, you can make more informed choices to better support your health.

How to make a healthier banana smoothie:

Use half a banana instead of a whole one to reduce sugar and calories.
Opt for unsweetened dairy alternatives like almond or oat milk.
Avoid adding extra sweeteners like honey or sugar.
Add protein powder, chia seeds, or flax seeds to boost protein and fiber.
Include leafy greens like spinach or kale for added nutrients without affecting flavanol absorption significantly.

Frequently Asked Questions

Yes, a banana shake can be bad for weight loss if not prepared mindfully. Because it can be high in calories and sugar, it may lead to weight gain if consumed frequently without proper portion control and without adjusting your overall calorie intake.

Blending a banana does not destroy all its nutrients, but it can break down dietary fiber, leading to faster sugar absorption. Furthermore, the PPO enzyme can reduce the bioavailability of flavanols from other ingredients blended with it, like berries.

Yes, for some people, banana shakes can cause stomach problems like bloating, gas, or general digestive discomfort. This is often attributed to the combination of fruit and dairy, which Ayurveda suggests can be difficult to digest.

Diabetics should be cautious with banana shakes due to their high sugar and carbohydrate content, which can cause rapid spikes in blood sugar levels. Portion control and ingredient choices, such as using half a banana and unsweetened milk, are crucial.

Bananas have a very strong, distinct flavor that can overpower the more subtle flavors of other ingredients, like spinach or delicate berries. To experience the full flavor profile of other fruits, you might consider omitting the banana.

For most people, eating a whole banana is better. A whole banana retains its full fiber content, which slows sugar absorption and promotes a greater feeling of fullness compared to a blended shake.

Yes, you can minimize the effect of the PPO enzyme by pairing flavanol-rich fruits like berries with low-PPO fruits such as oranges or mangoes, or by consuming the banana separately.