The Juicy Truth About Juice Cleanses
I periodically have clients who ask (or have done) a “juice cleanse” as a fresh start to their wellness journey. Most have seen health claims of weight loss or improved gut health on TikTok or Instagram. While some boast that they feel better since it helps their bowels move, few have seen any long-lasting effects. In reality, this trend could be harmful.
American Gastroenterological Association Spokesperson Fazia Mir, MD, clinical assistant professor at the University of New Mexico and a gastroenterologist with Presbyterian Healthcare Services, both in Albuquerque, New Mexico, notes, “The majority of juice cleanses impact gut health negatively. They can cause irregular bowel habits and even precipitate inflammatory bowel disease, as the gut microbiota is disrupted due to the lack of fiber in these cleanses. And we see patients all the time whose irritable bowel syndrome worsens after they’ve embarked on a juice cleanse.”
Is there evidence of benefits?
According to the US National Center for Complementary and Integrative Health, little evidence supports using juice cleanses to detoxify the body. Cleanses may include fasting, eating only certain foods, or consuming only liquids. They advise that some juices used may be unpasteurized or treated to destroy harmful bacteria, which could expose people to toxigenic E coli, Salmonella, hepatitis A, and Cryptosporidium. 1, 2
Additionally, juice cleanses could be made from too many foods high in oxalates, including leafy greens and beets. Individuals at risk for kidney stones should limit their intake of foods high in oxalate to prevent them. 3
Dr Mir cites a case report of acute oxalate nephropathy related to a “green smoothie cleanse” made from juicing too many high-oxalate green leafy vegetables and fruits. 4
Recent negative press
A small randomized, three-arm intervention study with 14 healthy participants published in Nutrients discovered that, “a 3-day exclusive juice cleanse (800-900 kcal/d) led to shifts in the oral and gut microbiome, with increases in taxa linked to inflammation, gut permeability, and even cognitive decline after juice consumption,” according to principal author Melinda Ring, MD, executive director, Osher Center for Integrative Health at Northwestern University in Chicago. 5
Subjects followed one of three diets — juice only, juice plus food, or plant-based food — for 3 days. Samples of microbiota (stool, saliva, and inner cheek swabs) were collected at baseline, after a pre-intervention elimination diet, right after the juice intervention, and 14 days following the intervention. Gene sequencing was used to analyze microbiota composition.
Results showed that the juice-only group showed the most significant increase in bacteria associated with inflammation and gut permeability, in addition to changes in the saliva and cheek microbiota — significantly in the relative abundances of proinflammatory bacterial families. The authors believe these changes are likely due to the high sugar and low fiber intake of the juice-related products.
Ring notes the study “offers a reality check” on juice cleanses. “Whether a cleanse is ‘healthy’ depends on the individual and the intent behind it,” she told Medscape Medical News. “A short, structured cleanse, ideally lasting no more than 1-3 days, can be safe for many people if it focuses on polyphenol-rich, low-sugar vegetables rather than fruit, retains some fiber (as in blended rather than pressed juices), and avoids extreme calorie restriction.”
First author Maria Luisa Savo Sardaro, PhD, a professor of food microbiology at San Raffaele University in Rome, Italy advises pediatricians to be aware that low-fiber, high-sugar diets may encourage the growth of proinflammatory bacteria.
Savo notes, “Families often rely on juice boxes in lunch packs, believing they’re a healthy substitute for whole fruit, and school cafeterias frequently offer sugary drinks throughout the day. Together, these habits may contribute to an early-life increase of inflammation in children.”
Dietary Guideline Modifications
A recent study published in Nutrition Bulletin reviewed nutrient composition data on whole fruit and 100% fruit juice and how it impacted hunger and the link with chronic health issues. 6
Lead author Hemangi Mavadiya, a PhD candidate at the Joe C. Wen School of Population & Public Health, University of California Irvine, Irvine, California, said that, like the Nutrients study, the review of 83 studies found juicing removes most dietary fiber that has beneficial effects on the gut. Also, processing and/or storing 100% fruit juice reduces vitamins and other antioxidant contents and changes intrinsic sugars in the whole fruit into free sugars, which have minimal nutritional benefit. 7
The authors note that when fruit is eaten in its solid form, it offers greater satiety from delayed gastric emptying. Combined effects of polyphenols and fiber in whole fruit are also helpful to the gut microbiome because they act as prebiotics and make short-chain fatty acids, which lower inflammation.
The study also noted that consuming too much fruit juice is linked with increased risks of certain cancers, while results were inconclusive regarding type 2 diabetes and high blood pressure.
The authors suggest that the 2025 set of US Dietary Guidelines for Americans be updated to advise an amount of whole fruit and 100% juice that children and adults should have. 8
Right now, the guidelines recommend that at least half of the daily recommended fruit intake of two cups per day should be from whole fruits, which could allow the rest to come from 100% fruit juice.
How to handle your patients who want to juice cleanse
· Ring notes that a short cleanse may help as a motivational tool, but a diet of high-fiber, whole foods is more sustainable and beneficial in the long run. Remind patients that detoxification occurs naturally in the liver and kidneys and does not require juicing or detoxing.
· Patients should be advised that juice cleanses could alter the body’s natural microbial balance from their low-fiber, high-sugar content, and they may not improve long-term gut health. If continued long term, they are too low in protein and fiber, which may disrupt microbial diversity and nutritional status.
· Blending may be a better alternative to juicing as the fiber is kept intact. Juices could also be paired with whole foods, suggests Ring.
Mavadiya advises patients to read food labels, which can help differentiate between fruit juice and fruit drinks, since the latter “is loaded with added sugars,” and it’s easy to confuse them.
“Ultimately, the healthiest path forward is not a periodic cleanse, but a consistent, nutrient-dense, fiber-rich diet that supports gut and systemic health over the long term,” Ring concluded. Furthermore, clinicians should assess for underlying conditions such as diabetes, eating disorders, or frailty, which may make juice cleanses inadvisable.
I like to advise my clients, “If you have teeth and a small intestine, let your body do the digestion”!
Lisa Andrews, MEd, RD, LD
References:
1. https://www.nccih.nih.gov/health/detoxes-and-cleanses-what-you-need-to-know
3. https://www.sciencedirect.com/science/article/abs/pii/S0889157515002264?via%3Dihub
4. https://www.ajkd.org/article/S0272-6386(17)30863-6/abstract
5. https://www.mdpi.com/2072-6643/17/3/458
6. https://onlinelibrary.wiley.com/doi/10.1111/nbu.70009
7. https://www.nhs.uk/live-well/eat-well/food-types/how-does-sugar-in-our-diet-affect-our-health/
8. https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials
