Should you try a juice detox or fast in 2025? I delve into this growing trend and discuss what science says about juice cleanses, especially how they impact the microbiome. Are juice fasts safe or effective? Not interested in juicing? Five practical ways to improve your natural detox processes are provided.
Juice cleanses or fasts are more popular than ever with more than 25% of US adults having tried a juice cleanse or detox program at least once in their lifetime. The perceived benefits of such programs, which are often used on a short-term basis (usually less than 2 weeks), include detoxing the liver, weight loss, and improved digestive health.
The juicing market is projected to grow to almost $10 billion USD by 2032 due to improvements in juicing technology, adding health-benefiting bioactives like adaptogens and probiotics, and specific formulations targeting improved digestion, immunity, and energy. Cold-pressed juices are one example of how innovative technology is used to help preserve nutrients and extend shelf life.
Studies have shown that juicing can provide certain nutrients, such as the antioxidants vitamin C and beta-carotene, as well as other non-nutritive compounds like polyphenols. However, there are some concerns regarding the reduction in calories combined with high sugar found in juice detoxes that might influence health outcomes that may be attributed to changes in the oral and gut microbiome. Juice cleanses are also devoid of essential nutrients involved in metabolic and immune health, like omega 3 fats, protein, fiber, and B12
Juicing Influences the Oral and Gut Microbiome
A healthy oral microbiome is linked to lower chronic inflammation, and reduced risks of developing conditions like cardiovascular disease and insulin resistance. For example, an unhealthy oral microbiome may contain Porphyromonas species linked to periodontal disease, as well as other pro-inflammatory and auto-immune disorders. The Porphyromonas species promote plaque formation when the bacteria are exposed to excessive sugar and starches.
A recent study published in Nutrients (1) gave healthy subjects a typical juice fast consisting of 800-900 kcal/d for 3 days. Juicing can be high in sugar and low in fiber, thus the purpose of the study was to understand how the oral (and gut) microbiome changes at the end of the juice intervention. Both the saliva and cheek microbiome found significant increases in Proteobacteria that quickly break down simple sugars and allows the bacteria to grow very rapidly. These changes were observed in just 3 days, highlighting how quickly dietary changes can impact the relative abundance of oral bacteria specific to macronutrient composition.
In addition, many of the taxa increased during the juice fast have been attributed to increased pro-inflammatory markers and the development of periodontal disease. Just as important, one nitrate-producing taxa decreased. Nitrate inhibits the growth of the bacteria that contributes to the development oral diseases.
Similar, but less pronounced, changes also occurred in the gut microbiome following the juice fast where increased pro-inflammatory taxa were observed. Such taxa have been linked to neurodegenerative disorders, anxiety, and leaky gut. Leaky gut is a condition where the lining of the gut is compromised and allows pathogens from the gut to cross into the bloodstream that causes inflammation and infection.
While rapid shifts in the microbiome are observed within days of starting a juice fast, this study also found that the microbiome tends to shift toward baseline within two weeks. Eating prebiotic fibers, like resistant starch, are necessary to shift the microbiome to a more anti-inflammatory, immune-boosting profile.
Does Juicing Actually Work?
Limited research has been conducted on the practice of juicing and health-related outcomes. One review (2) examined popular weight loss strategies and found that some juice detoxes are so low in calories that cortisol levels rise and stimulate appetite, which can cause binge eating. Some detox juices have been linked to severe hyponatremia (low sodium) and even cardiovascular events.
Low caloric intake for a short period of time can also cause muscle protein to be broken down to be used as an energy source, which can reduce metabolic rate over time. This adaptation occurs usually within 1-2 days of the body being “starved” of energy and glycogen stores are no longer available. Then around day 3, ketone body production increases as an adaptive measure to help slow muscle tissue break down. The initial body weight loss that is often observed within the first few days of juicing are likely due to water weight that was stored alongside glycogen.
In summary there is very little clinical evidence (3) showing juice fasts indeed eliminate toxins and promote weight loss. Eating plenty of plant-based foods, especially those rich in mono- and poly-unsaturated fats (e.g., nuts and seeds, avocados, and extra virgin olive oil), and drinking plenty of liquids, especially water, will naturally improve the detoxification processes in the liver. Therefore, juice detox programs are not necessary.
Detox Deception on TikTok
A recent study conducted a trend analysis on common weight loss and detox hashtags associated with TikTok videos (4). These TikTok detox trend videos promoting weight loss and/or detox programs featured feminine engaging (70.5% and 71%, respectively) and thin (35.9% and 44.9%, respectively) individuals. Over 93% did not disclose credentials and 97% did not provide any scientific backing weight loss or health claims. Unfortunately, these TikTok videos made false health claims that can cause health risks to uninformed users, as well as disordered eating practices. This is especially harmful to the 2/3 US adolescent female users of the platform. In 2024 TikTok did crack down on its policy stating that it does not allow the promotion of dangerous weight loss behaviors or disordered eating. Only time will tell if these policies are enforced and advantageous.
What to Do Instead: A Smarter Way to Support Health
Instead of restrictive juice fasts devoid of several key nutrients, these are my recommendations on how to naturally support your body’s detoxification processes and are backed by clinical evidence:
- Fuel Your Gut with Prebiotic Fibers: High fiber foods can feed the beneficial microbes in your gut, especially those naturally rich in resistant starch. Such foods include just-ripe bananas, cooked then chilled potatoes, oats, legumes and beans, and colorful fruits and vegetables that contain polyphenols.
- Support Liver Detoxification with Foods: Adding cruciferous vegetables, such as broccoli, kale, and cauliflower, as well as garlic and onions will support the liver detox enzymes.
- Stay Hydrated: Swapping juice for water aids in flushing waste out of the body and supports healthy liver and kidney function.
- Add Healthy Fats: Nuts and seeds, extra virgin olive oil, avocados, and fatty fish contain fats are linked to proper liver function and reinforce metabolic health.
- Limit Ultra-Processed Foods and Added Sugars: Limiting these in your diet allows your microbiome to re-set to an immune-boosting profile.
The best reset is not a juice fast or cleanse, but instead, eating high-quality, nutrient-dense foods that naturally detox the body every day.
References:
(1) Sardo MLS et al., 2025, Nutrients
(2) Obert J et al., 2017 Curr Gastroenterol Rep
(3) Klein AV & Kiat H., 2015 J Hum Nutr Diet
(4) Raffoul A et al., 2024 Eat Behav