Although it is well-known that consumption of fruit and/or vegetable juices only in the long term does not provide enough energy, carbohydrates, fats and proteins. It is widely recognised that these juices may be a good source of other important nutrients, such as vitamins and inorganic compounds (1, 3). Removal of fruit and vegetable pulp does not compromise delivery of the aforementioned compounds when pure vegetable and/or fruit juice is consumed (1, 3). Aside from these essential compounds, other phytochemicals are often present in fruit and vegetable juices which may change cellular function for other health benefits (3). Phytochemicals, such as polyphenols and/or flavonoids, may interact with certain metabolic pathways involved in development of lifestyle-related chronic diseases (3, 11).

Considering all of the aforementioned regulations and benefits of fruit and vegetable juicing, we present a summary of the most important benefits which have been documented to date of not only drinking this fruit and vegetable juices alongside other foods, but of juice fasting.

Important note: juice fasting is not meant to be a long term solution. It is better to use extended juice fasting occasionally every 3-6 months or on a yearly basis. Then add cold press vegetables juices into your diet daily to increase your intake of antioxidants, phytochemicals, polyphenols and nutrients.

What science says about juice fasting

Importance of juice cleansing or fasting is very much related to its very own capability to detoxify, reset and reduce gastrointestinal exposure to environmental factors which may harm correct intestinal functioning. This harmful exposure is mainly related to modern diet, which is often contaminated with toxins, heavy metals, pesticides and herbicides such as glyphosate, which have been shown to change intestinal microbial composition involved in the development of certain diseases (16-17).

A clinical trial showed particular concern in the possible benefits of fasting for rheumatoid arthritis (RA); this particular study, enrolled 16 patients with RA which underwent fasting for 7-10 days vs. 10 more patients which acted as controls and consumed a regular diet. 5 out of the 16 individuals in the fasting RA group, showed significant reduction of symptoms meanwhile in the normal diet RA group, only 1 patient showed significant improvement (12). It has been hypothesised that caloric restriction resulting from fasting may change the body’s response to inflammation and autoimmune reactions: lymphocytic behaviour may be altered during fasting, which may explain why patients with RA show significant improvement during fasting (12). Considering the important caloric restriction which occurs during juice fasting, these benefits may also manifest and further improve RA in a greater manner, considering the anti-inflammatory properties of fruits and vegetables (11-12).

Intestinal permeability and RA have also been linked and evaluated together in clinical trials (13, 15). Increased intestinal permeability is often referred to as “leaky gut”, which is a condition in which the normal lining of the intestines, designed for controlled absorption of nutrients and other molecules into the bloodstream, is compromised because of the presence of large cracks or holes which no longer allow for a controlled absorption of molecules, permitting other pathogenic compounds, such as bacteria, toxins and molecules, into the bloodstream (14). Increased intestinal permeability or “leaky gut”, allows the free pass of environmental factors to enter the bloodstream which (alongside genetic predispositions), trigger certain autoimmune diseases such as RA (15).

In a study, 5 patients with RA and increased intestinal permeability were recruited and underwent fasting for 10 days with the sole administration of 800 Kj derived from fruit and vegetable juices vs. other 5 control patients which followed a normal diet (13). The experimental group experienced an overall improvement in RA symptoms and reduced intestinal permeability (13). It is often recognised that dietary factors may alter the microbial composition which may allow for increased intestinal permeability (i.e., a higher count of Clostridium perfringens, has been documented to be present in patients with RA) (13). Benefits for RA might be clear in relation to juice fasting (11-13).

Juice fasting makes it easier for anybody to squeeze more fruits and vegetables into their everyday diet (CDC recommendation is for everybody to eat nine servings of fruits and vegetables per day) (1).

Juice fasting allows for an increased daily ingestion of antioxidants, soluble fibre, vitamins and minerals, which are all essential compounds needed for the correct functioning of the human body (1).

Depending on the different varieties of juices which can be mixed together, you can obtain different health benefits, such as the following (1, 2, 8):

Decreased oxidative stress from drinking carrot juice due to augmented ingestion of antioxidants (such as β-carotene).
Increased consumption of vitamin C (easily obtained from any fruits and vegetables), which further results in increased iron absorption.
Improved lipid levels (e.g., kale juice).

Juice fasting may augment the consumption of phenolic compounds which have been shown to possess anti oxidative, immunomodulatory and antimicrobial activities, all which may be beneficial for human health (3, 4).

Juice fasting increases the ingestion of soluble fibre which is often implicated in the overall improvement of gut microbiota (1, 5).
Increased consumption of fruit and/or vegetable juice may alter the human microbiota due to its high phenolic content, making it more similar to that of lean individuals (i.e., Increases the Bifidobacteria, Lactobacillus and Verrucomicrobia phyla and decreases the Firmicutes phyla) (3, 6).

Juice fasting allows for rapid short-term weight loss (e.g., reduced intake of overall calories which results in mobilisation and oxidation of fatty acids) (3, 7).
Juice fasting results in increased consumption of flavonoids, which in turn may help decrease the risk for cancer and heart disease (8).

Juice fasting has been linked to increased short-term satiety, due to its high water content, which in turn exerts a mechanical function in the stomach, expanding its walls and resulting in reduced hunger through the liberation of hormones, neurotransmitters and incretins (e.g., serotonin, Glucagon-Like Peptide 1 [GLP-1]) (9).

Juice fastings low caloric value may aid in weight reduction (7, 10).

CONCLUSIONS

Juice fasting may be beneficial for correcting increased intestinal permeability or “leaky gut”.
Juice fasting may be beneficial for reducing symptoms and severity of certain autoimmune diseases such as rheumatoid arthritis.
Juice fasting may be beneficial for reducing body weight through mechanical and metabolic pathways.
Juice fasting may be beneficial for cardiovascular health, because of its high phenolic content.
Juice fasting may be beneficial for improving the composition of gastrointestinal microbial species.

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