A tall glass of cold-pressed juice can be a refreshing way to refuel after a hard workout. All those vitamins and antioxidants go to work in fighting free radicals, plus those quick-digesting carbs refuel your muscles with glycogen so you can work out hard again tomorrow. While juice can be great before or after workouts, juice can quickly spike your blood sugar if you don’t include protein, fiber, or fat to slow down digestion.
Some people might go on juice fasts to cleanse their digestive system of toxins or shed a little bit of weight. A break from heavily processed food or consuming too many calories may seem like a good idea, but a 2025 study in Nutrients found that you could be doing more damage to your gut. Your gut microbiota feed on fiber so they can help your body support digestive and immune systems, reduce inflammation, and promote mental and physical health. When you do a juice cleanse, you could be allowing the harmful bacteria to flourish.
How juice cleanses affect your microbiome
You have billions of microbes living in your body, and they all don’t just live in your gut. You also have a microbiome in your mouth, and that not only affects your gut microbiome but also your overall health. Your oral microbiome can cause inflammation in your body and put stress on your immune system. The study looked at both the oral and gut microbiome of people when they followed a juice fast, adding juice to a regular diet, or a plant-based whole food diet for three days.
The juice fast increased Proteobacteria in the oral microbiome, which is linked to inflammation and disease if they grow out of control. Although there weren’t significant differences in the gut microbiome after the three diets, the researchers noticed that two types of bacteria increased in the gut during the juice fast diet and the juice plus food diet. These bacteria have been linked to inflammation, memory impairment, and mental health conditions. Those who followed the plant-based diet had slight but beneficial changes linked to improved gut health and reduced inflammation.
Are juice cleanses healthy?
Juice cleanses are still relatively popular, with many juice companies offering multi-day juice packs delivered to your home. If you’re concerned about toxins in your body, a juice fast might not be as effective as you think, according to a 2015 review in the Journal of Human Nutrition and Dietetics. Although clinical studies on commercial detox diets have shown some beneficial effects on health, the studies have their flaws. Besides, your liver naturally works to disarm any harmful substances, and you eliminate them through your sweat, urine, and poop.
Here’s what happens to your body when you follow a 7-day juice cleanse
A hearty beet juice might pack a good dose of vitamin C and potassium, but remember that some of these high-nutrient foods can also be high in oxalate. Oxalate can be toxic to humans, and diets high in oxalate can lead to kidney stones, especially if your diet is also low in calcium. Although your kidneys remove oxalate from your body, too many oxalates in your diet can lead to kidney issues, according to a 2020 study in Nutrients. If you would like to support your body’s natural detoxification process, it’s best to stick to a balanced or plant-based diet that focuses on minimally processed foods.
