Ren Ecosystem. I’m a gastroenterologist. Here’s why I tell my patients to eat this one fruit.

(Photo: Washington Post illustration; iStock)

Is there something I can eat to help with constipation? A lot of high-fiber foods and supplements make me bloated, but I don’t want to take a laxative.

I get this question often in my gastroenterology clinic. Gut symptoms like bloating and constipation are incredibly common, affecting up to a third of the population. Many people don’t want to take medication if there are more natural ways to help. But I also know that simply recommending people increase their fiber intake is vague and not always useful.

That’s whyI’ve been “prescribing” a dose of two kiwis a day to my patients for years now.

A small but mighty green or gold fruit, kiwis are bursting with nutrients: A single kiwi contains 80 percent or more of an adult’s daily vitamin C requirement and packs two to four grams of fiber. In addition to vitamins E and K and other beneficial antioxidants and phytochemicals, one of the kiwi’s most important properties is an enzyme called actinidin. Actinidin is present in only a few dietary sources besides kiwis (including mango and pineapple), and it can help break down proteins, aiding in our digestion. Actinidin is so powerful that it’s used commercially as a meat tenderizer.

So how does this help your gut? Let me fill you in on the findings of a randomized controlled trial that electrified gastroenterologists everywhere. The study was funded by a kiwifruit marketer, but its methods were rigorous and showed clear measurable outcomes.

In the 2022 study, scientists from three countries — New Zealand, Italy and Japan — found that eating two green kiwis per day for four weeks helped people have more complete bowel movements. On average, people pooped between one and two more times each week.

For people with constipation at baseline, kiwis improved symptoms such as abdominal pain, indigestion and straining during bowel movements — often even more so than psyllium, a type of fiber sold in powders and capsules over-the-counter. These people also reported an improvement in overall quality of life.

Consuming a diversity of plants is always the overarching goal for a healthy microbiome, and I tell patients that kiwis can be a great addition to that approach. I’ve seen the benefits firsthand in my patients and even my own family.

The power of fruits and vegetables

Besides fiber, the benefits of eating a diet rich in vegetables and fruits like kiwis are commonly attributed to their antioxidants. These compounds are known to protect against cancer, cardiovascular diseases and diabetes. But — and this is a big one — it’s an effect that mainly appears to occur through a healthy diet — and not through antioxidant supplementation.

As is often the case with other supplements, when you try to distill the compound of interest into a capsule or pill, that beneficial health effect of antioxidants vanishes — and may even be potentially harmful.

So why does this happen?

Scientists suspect that the kiwi’s antioxidants, like vitamin C, synergize with its other naturally occurring phytochemicals to boost its protective power — something we lose when we distill these nutrients into a commercialized supplement.

Kiwi’s benefits may go beyond the gut

In 2011, Norwegian researchers randomized healthy volunteers to a month of eating either one or two gold kiwis daily. When the scientists analyzed DNA samples, they found fewer DNA strand breaks — a sign of improved fortitude that can theoretically reduce opportunities for cancerous growth. And indeed, after one month, the volunteers’ DNA had become about 30 percent more resistant to a kind of injury called oxidative damage that can lead to dangerous mutations.

Besides studying DNA, researchers also looked at plasma triglycerides, a kind of fat circulating in the bloodstream that increases heart attack risk. At the end of the month, triglycerides had decreased by about 13 percent.

Though not a perfect study design, a 2023 meta-analysis of retrospective studies of kiwi and other fruit consumption found that people who ate more kiwis had a 13 percent decreased risk of colorectal cancer.

More research needs to be done to fully understand kiwi consumption and cancer risk — but the scientific groundwork has been laid.

What are other natural ways to help with constipation?

Supplementing with psyllium husk fiber has long reigned as queen in the gastroenterology world: Psyllium is specific, easy to take and does wonders for the body.

Prunes have been hailed for their laxative properties, but, if I’m being honest, have you ever tried to tell a college student with constipation to go buy some prunes? Trust me, it won’t happen. And for many people, prunes can actually make bloating worse due to high levels of sorbitol, a naturally occurring sugar that gets fermented by your colon’s microbiome. That’s why I tend to recommend kiwis instead.

What I want my patients to know

No, you don’t have to eat the kiwi’s peel. Plenty of studies have found notable health benefits sans peel. But if you feel so inclined, go on, have a little nibble on the skin. It’s totally edible and packed with fiber. Just be sure to keep your doctor in the loop about your gut issues. For lots of people, the underlying condition causing their symptoms is past the point of a simpler dietary intervention. It’s why it’s important to find a doctor you trust who can consider multiple angles in approaching your health concerns.

This article appeared in The Washington Post (https://www.washingtonpost.com/wellness/2025/07/07/kiwi-help-ibs-constipation/).