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This fuzzy fruit smoothie is sure to get your system moving.

Reviewed by Dietitian Madeline Peck, RDN, CDN

Key Points

• Kiwis support regularity with their fiber, enzyme and micronutrient content.
• An after-dinner smoothie is an easy way to benefit from kiwi’s beneficial properties.
• Pairing kiwi with other digestion-supportive ingredients in a DIY smoothie is a great way to support regularity.

When feeling backed up at the end of the day, many people reach for prune juice, herbal teas or powdered fiber supplements. But one of the most effective ingredients for relieving constipation is sitting in the produce section, wrapped in a fuzzy brown skin. That ingredient is kiwi. And when blended into a smoothie, it becomes a refreshing, research-backed way to help support regular bowel movements. We spoke with registered dietitians to uncover why a kiwi smoothie is the best after-dinner drink for constipation, along with step-by-step instructions on how to make one.

It’s Filled with Fiber

One reason kiwi smoothies help ease constipation is their unique fiber profile. “Kiwifruit contains both soluble and insoluble fiber. Soluble fiber forms a viscous gel in the colon that helps to soften stools, and insoluble fiber adds bulk to the stool, making it easier to pass,” says Bianca Berton-Scarlet, B.Sc., M.Diet., RD.

The fiber in kiwis also has a high water-holding capacity. “This means that the fiber network in kiwifruit physically traps water molecules as it moves through the gut, adding more water to the stool, making it softer,” Berton-Scarlet explains. In fact, Lydia Carron, M.S., RDhighlights that the fiber in kiwis can hold more water than psyllium husk, a standard over-the-counter fiber supplement often recommended for constipation.

It Helps Keep Your Gut Moving

While fiber plays a big role in regularity, kiwi also contains a natural enzyme called actinidin that adds another layer of digestive support. Actinidin, Carron explains, is a protease, meaning it helps to break down protein more efficiently.

“Actinidin has been shown to help digest more difficult-to-digest proteins like beef and gluten, as well as accelerate the rate at which food leaves the stomach, facilitating easier digestion,” she explains. So, after dinner, or another larger meal, actinidin can stimulate gut motility, helping to move waste through your system faster. To get the most benefit, Carron notes that green kiwis contain more actinidin than the golden varieties.

It Helps Moisten Your Intestines

Sipping on a kiwi smoothie may also combat constipation through unique structures found in the fruit. “Kiwifruit contains calcium oxalate raphides, which are needle-shaped crystals embedded in the flesh of kiwifruit,” says Berton-Scarlet. She explains that these raphides help to stimulate mucus secretion in the gut, which acts as a natural lubricant helping the stool to pass through the bowel more easily. While this mechanism is still being studied, raphides, along with fiber and actinidin, work together to help soften stool and encourage bowel regularity.

It’s Low-FODMAP

If one’s constipation is accompanied by stomach discomfort, a kiwi smoothie may be an especially good choice. “Many people with constipation also have irritable bowel syndrome (IBS). High FODMAP (fermentable oligo-, di- and monosaccharides and polyols) foods can trigger bloating, gas and abdominal pain,” says Carron. Fortunately, kiwis are low-FODMAP fruits that can relieve constipation with less risk of triggering these gut side effects. Better yet, Carron shares that some studies show that eating kiwi has lower instances of unpleasant gastrointestinal side effects when compared to other constipation-relieving remedies like psyllium husk and prunes.

How to Make a Kiwi Smoothie for Constipation

Making a constipation-friendly kiwi smoothie after dinner doesn’t require a long list of ingredients. The trick is to let kiwi take center stage, while pairing it with ingredients that are gentle on the gut and support healthy digestion.

• Step One: Wash two ripe green kiwis, as this is the amount most commonly studied for constipation relief. Leave the skin on for the best results.
• Step Two: Choose a low-FODMAP liquid to blend them in. Carron recommends opting for water, almond milk or lactose-free milk.
• Step Three: Toss in some seeds. Both dietitians suggest adding either flaxseed or chia seeds for an additional soluble fiber boost.
• Step Four: Add gut-loving herbs or greens. Berton-Scarlet recommends using mint, as it contains menthol—a compound that helps relax smooth muscles in the gut, reduces cramping, alleviates stomach pain and settles nausea. Not a fan of mint? Carron suggests baby spinach as another low-FODMAP leafy green.
• Step Five (optional): Include ice or additional low-FODMAP frozen fruits. For added sweetness and flavor, Berton-Scarlet recommends adding in frozen pineapple or unripe banana. She shares that unripe banana contains resistant starch that acts as a prebiotic that supports  beneficial gut bacteria, while pineapple contains the enzyme bromelain, which can further support digestion.
• Step Six: Blend and enjoy!

While kiwi smoothies are generally well-tolerated, both dietitians share that those with a kiwi allergy or taking certain medications, such as blood thinners, should be cautious. “Kiwis are high in vitamin K, which is required for blood clotting. If someone is taking blood-thinning medications, like warfarin, they should know that significant increases in vitamin K intake can impact how well their medication works,” says Carron. Therefore, you should speak to a health care professional before adding kiwi smoothies to your nighttime routine.

Our Expert Take

Constipation doesn’t always resolve on its own. What you do after dinner can play a meaningful role in finding relief. One simple option is drinking a kiwi smoothie. Backed by a growing body of research, kiwis contain soluble and insoluble fiber, actinidin and raphides that have been shown to soften stool, encourage gut motility and help stool pass more easily. Not to mention, kiwi smoothies are low in FODMAPs and simple to make, requiring just a few gut-friendly ingredients. While no single food is a cure-all for constipation, including a kiwi smoothie in your nightly routine is a great way to support regularity throughout the week.