A recent study published in the January 2025 issue of Nutrients has cast doubt on the health benefits of popular juice cleanses. Researchers found that individuals who participated in a three-day juice cleanse exhibited higher markers of inflammation in their oral and gut microbiomes compared to those adhering to a plant-based diet. This revelation raises questions about the efficacy and safety of these widely adopted health fads.
The study, which involved dividing 14 adults into three distinct groups, aimed to explore the effects of juicing on human health. Participants either consumed only a juice cleanse of fruits and vegetables, supplemented their juice intake with whole foods, or followed a plant-based diet with equivalent calorie content to the juice-only group. The results revealed significant microbiome changes, particularly in those who adhered strictly to the juice cleanse.
"We collected saliva, cheek swabs, and stool samples from participants before, during, and after they followed the three diets," said Maria Luisa Savo Sardaro, PhD, a research associate in the Department of Anthropology at Northwestern University.
"DNA was then extracted from these samples, and a specific bacterial gene was sequenced to identify the bacteria present—similar to scanning a barcode to identify a product," she added.
"We found that the exclusive juice group had the most significant increase in bacteria linked to inflammation and gut issues," she concluded.
Juice cleanses have surged in popularity, driven by societal pressures and trends.
"I believe diet culture significantly drives the popularity of juicing in the U.S.," noted Lisa Froechtenigt, RD, a senior program management associate in the Baylor College of Medicine Bariatric Surgery Program.
"This culture is heavily influenced by celebrities, social media, and the behaviors of friends and family," she explained.
Juicing typically strips fruits and vegetables of around 90% of their fiber content, according to Amy Moyer, RD, director of culinary medicine at the University of North Carolina, Greensboro. This loss of fiber is crucial because fiber feeds beneficial bacteria that produce anti-inflammatory compounds like butyrate.
"Fiber is essential for feeding beneficial bacteria that produce anti-inflammatory compounds like butyrate," remarked Maria Luisa Savo Sardaro.
The absence of fiber not only impacts gut health but also increases the sugar and carbohydrate concentration in juices, posing additional health concerns. Decreasing fiber effectively alters the nutritional balance by raising sugar levels, which can be detrimental if consumed excessively or in isolation.
In contrast to juice cleanses, incorporating juice as part of a balanced diet appears more beneficial. A 2018 study found improvements in fecal microbiota when a juice regimen was added to a normal diet over three weeks. Similarly, a 2022 study observed decreased gut microbe diversity following a juice fast but noted increased bacterial diversity when participants supplemented with fiber.
The latest study suggests that while juices provide hydration and essential vitamins and minerals, they should complement rather than replace whole foods. Experts recommend enjoying juices alongside meals rather than as standalone beverages. This approach ensures that individuals receive adequate fiber and maintain nutritional balance.
"Think of juice as an addition to your daily diet, not a replacement for foods as part of a 'cleanse,'" advised Froechtenigt.
Experts agree that fruits and vegetables are crucial for a healthy diet but emphasize consuming them whole for optimal microbiome health. These findings reinforce that while juicing is not inherently harmful, it may not support a healthy microbiome as effectively as previously believed.
"The Nutrients study isn’t the first to look at the effects of juicing on oral and gut microbiota, but it provides further evidence that juicing may not be the best way to support a healthy microbiome," noted experts in the field.
Leave a Reply