Bad news for gut health girlies who love juice cleanses: the two might not be so compatible. At least, that’s what a recent study in Nutrients says. Whether you’re drinking the beverage as a convenient way to consume more fruits and vegetables or restricting your diet to only juice for a few days in the name of digestive cleansing, it might not be as helpful as you’d hope.
After a three-day, juice-only diet, participants in the 2025 study saw strains of bacteria associated with inflammation, gut lining issues, and cognitive decline increase in both their oral and gut microbiomes. The research was done in just fourteen people, so experts (like the ones in this article) are hesitant to draw major conclusions, but there’s still plenty to learn from it—especially as it pertains to that $9 green juice order you were about to place.
Here are the main takeaways, according to experts.
Meet the experts: Roshini Rajapaksa, MD, is a gastroenterologist at NYU Langone and co-founder of YayDay. Chloe Tsang, DMD, is a dentist at Tend in New York City. Emily Van Eck, RD, is a dietitian and intuitive eating counselor at Emily Van Eck Nutrition.
Juice cleanses can increase “bad” bacteria in your oral and gut microbiomes.
Your gut microbiome is an ecosystem made up of all kinds of microorganisms including “good” bacteria that help with functions like digestion and immunity and “bad” ones that are associated with health problems like gastrointestinal issues and chronic illnesses. While researchers didn’t notice changes in the gut microbiome overall after a three-day juice-only diet, they found an increase of specific unhealthy bacteria linked to inflammation and cognitive decline, says Roshini Rajapaksa, MD, a gastroenterologist at NYU Langone.
“When you are juicing as opposed to having the whole fruits, you are eliminating most of the fiber,” says Dr. Rajapaksa. “And that is one of the really important nutrients that we get from fruits and vegetables that basically feeds and fosters the growth of a healthy microbiome.” Since you don’t have that reliable source of fiber, a juice cleanse could have slightly negative effects on oral and gut health in the short-term, per the study.
It’s a temporary effect (participants saw their microbiomes return to their baseline days after the cleanse), so if you did one juice cleanse months or years ago, your mouth and your gut shouldn’t still be feeling it. Still, researchers were able to observe changes to both the oral and gut microbiomes after three days, and some cleanses last anywhere from five to seven days, meaning that the changes could be bigger over longer time periods.
As for why it matters: having elevated levels of inflammation-causing bacteria long-term can cause health problems like heart disease, autoimmune conditions, and mood challenges, says Dr. Rajapaksa. “Our gut microbiome is linked to almost every health condition,” she says. Basically, it’s not something you’d want to neglect.
Don’t underestimate the oral microbiome either, says Chloe Tsang, DMD, a dentist at Tend. “The oral microbiome helps break down our food, and certain foods can lead to microbial imbalances in both the mouth and the gut,” she says. Sugary foods and beverages like juice can cause pathogens that lead to cavities, but they can also trigger systemic inflammation throughout the body or affect the gut’s microbiome, says Tsang. So, occasional juice consumption shouldn’t pose any significant risks, but exclusive cleanses, especially multiple over long periods of time, might not be the best approach for your health, she says.
Juice is not a replacement for whole fruits and vegetables.
A major reason why researchers think juice-only diets impact your microbiome is because they lack fiber. Fiber is one nutrient that we know for sure is beneficial for health, says Emily Van Eck, RD, a nutritionist in Austin, TX. Fiber is essential when it comes to gut health because it feeds the “good” bacteria in your mouth and gut, which ferments into short chain fatty acids that do things like lower cholesterol and improve mood, says Van Eck. (Yup, your gut health can even influence your mood.)
It’s not just fiber you’re missing out on. When you eat an apple, you’re getting a whole host of nutrients from the fruit including fiber, vitamin C, and potassium, and these extra nutrients also help with the digestion of another major molecule you’re getting from the fruit: sugar. Meanwhile when you’re drinking apple juice, a lot of those nutrients are stripped away, which could lead to blood sugar spikes and overall decreased nutritional benefits.
A 2018 study in Nutrients that compared the nutritional composition of an orange and orange juice measured 1.2 grams of fiber in the real-thing to .2 to .5 grams of fiber in juice. The juice also had lower levels of calcium, niacin, folate, and vitamins C, B6, A, and E, but higher levels of iron, magnesium, and potassium. So, while juice may be tasty, it’s not necessarily the health-drink it’s marketed as. This doesn’t mean you shouldn’t drink juice, but it does mean that it’s not going to give you the same benefits you’d get out of eating a whole fruit or vegetable. As Dr. Rajapaksa puts it: “Trying to get the shortcut to the fiber doesn’t work.”
Don’t skimp on fiber.
If this study tells you anything, let it be a reminder about how important fiber is, says Dr. Rajapaksa. Even after three days of a limited fiber supply with a juice-only diet, participants saw shifts in the bacteria in their oral and gut microbiomes, which shows just how much of an impact it makes. And, long-term, “having a shift to these unhealthy bacteria has been associated with so many diseases of the body,” she says.
The recommended fiber intake varies based on age and sex, but a general rule of thumb is 25 to 30 grams of fiber per day, says Dr. Rajapaksa. If you’re not hitting that already, you’re not alone. A whopping 90 percent of adult women aren’t meeting the recommended amount, according to the USDA’s 2020-2025 Dietary Guidelines for Americans. Though you can’t quite rely on juice to help you hit this goal, eating high fiber foods like berries, beans, and broccoli can get you there.
FWIW, you probably don’t need to “cleanse” anyway.
A cleanse sounds like a good idea, but according to experts, it’s not really going to give you the benefits you’re looking for. “Our bodies need protein, fat, carbohydrates, and fiber, and the idea that giving your body a rest from digesting all of those things is somehow beneficial to health is really not based in any science at all,” says Van Eck.
The best cleansers and detoxifiers are actually already within you. Your body uses your kidneys, color, and liver to “detox,” and you don’t need to do much to give those organs some love, says Dr. Rajapaksa. For your kidneys, it means staying hydrated, for your colon it means eating enough fiber, and for your liver, it means avoiding excessive alcohol or Tylenol.
It might feel good to go all-in on something like a cleanse, says Van Eck, but she suggests reflecting on what you’re hoping to get out of it and making a small, sustainable change instead. Maybe it is eating more fruits and vegetables to get that fiber in, or maybe it’s cooking more meals at home if you feel like you’re eating out a lot. But there’s not really a health reason to embark on a juice cleanse, Van Eck and Dr. Rajapaksa agree.
Olivia Luppino is an editorial assistant at Women’s Health. She spends most of her time interviewing expert sources about the latest fitness trends, nutrition tips, and practical advice for living a healthier life. Olivia previously wrote for New York Magazine’s The Cut, PS (formerly POPSUGAR), and Salon, where she also did on-camera interviews with celebrity guests. She’s currently training for her first half marathon, inspired by her many colleagues at WH who have run one.
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