Some people turn to juice cleanses hoping to boost their health, lose weight, or “reset” their gut. While these plans can lead to quick weight loss, even short juice cleanses have been linked to potential downsides, including adverse effects on gut health. Here are the ways a juice cleanse may backfire, especially for gut health.
Unlike whole foods, juices lack fiber, which helps fuel bacteria in your digestive tract. “Juicing is not nutritionally equivalent to eating whole fruits and vegetables,” Ritu Saluja-Sharma MD, told Health. “Juicing removes most of the fiber from foods, which plays a critical role in slowing glucose absorption, regulating insulin response, supporting gut microbiome health, and promoting fullness,” she explained.
The fiber in your diet supports the growth of beneficial bacteria in your large intestine, keeping your gut in balance. Fiber is also needed for the production of short-chain fatty acids (SCFAs), which play essential roles in health, including the regulation of intestinal inflammation.
Studies show that even short-term juice fasts, such as those lasting just a few days, can increase gut bacteria associated with inflammation, gut permeability, and cognitive decline. This is likely due to juices’ low fiber and high sugar content.
“Juice cleanses can cause hunger, fatigue, and weakness due to their low calorie load and lack of protein and fat, which the body needs for normal function and repair,” David D. Clarke, MD, a board-certified gastroenterologist, told Health.
When you severely restrict calories and underconsume protein, fiber, and fat, your body is unable to regulate hunger, leading to hunger pangs and symptoms such as fatigue and dizziness.
Longer juice cleanses are riskier because the lack of calories and essential macronutrients can further strain your health, leading to low energy, cravings, sleep disturbances, and other issues.
The lack of fiber and high sugar content of juices can cause digestive issues in many people. Some may experience constipation due to the lack of fiber, while others may develop loose stools as large amounts of sugar move quickly through the digestive tract.
Additionally, some juices are high in compounds that some people don’t tolerate. For example, juices made with apples, pears, and mangos are high in Fermentable Oligo-, Di-, Mono-saccharides, And Polyols (FODMAPs). “These are fermentable carbohydrates found in plant foods that are known to cause gut symptoms, including bloating, pain, excess gas, and diarrhea,” Erin Judge, RDN, LDN, CPT, told Health.
Juices are high in natural sugars and low in fiber, a combination that can cause spikes in blood sugar.
While healthy people are often able to regulate blood sugar even after consuming a high-sugar load, people with blood sugar concerns, such as those with prediabetes or diabetes, may experience sharper rises and drops during a juice cleanse.
Studies show that high blood sugar can harm gut health by disrupting the intestinal barrier and altering gut bacteria.
Many juices, such as orange, lemon, and pineapple, are highly acidic and can worsen symptoms in people with acid reflux.
During a juice cleanse, frequent, large intake of acidic juices without solid food can increase irritation and trigger heartburn or discomfort.
Juice cleanses can be especially problematic for people with existing digestive conditions, such as IBS or inflammatory bowel disease (IBD).
People with these conditions are more likely to experience symptoms, like bloating and diarrhea, after consuming high-FODMAP foods, like fruits and vegetables, which are commonly found in juices.
Additionally, people with IBS and IBD are more sensitive to changes in fiber in their diet and may already be experiencing constipation and/or diarrhea, which are common side effects of juice cleanses.
While adding juices to a well-balanced diet can be an effective way to boost your intake of essential vitamins, minerals, and antioxidants, juice cleanses generally aren’t a good idea.
“Juice cleanses can cause a variety of serious side effects not just for the gut but the whole body, such as dangerous fluid and electrolyte shifts, kidney stones leading to kidney damage, nutrient deficiencies, microbiome alterations, and hypoglycemia,” explained Adam B. Gluskin, MD, a board-certified gastroenterologist.
For these reasons, most doctors advise against juice cleanses, especially those lasting more than 24 hours.
While a short juice cleanse may not pose serious risks for otherwise healthy adults, it can be unsafe for certain groups, including people with:
- IBS or IBD
- Acid reflux
- Diabetes or hypoglycemia
- A history of eating disorders
Additionally, people who are underweight, pregnant, breastfeeding, or malnourished should not partake in juice cleanses.
If your goal is to improve your gut health, evidence-based habits, such as eating a balanced, fiber-rich diet, maintaining a healthy weight, and managing underlying health conditions, are far more effective and sustainable than a juice cleanse.
