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Juice Fasts: Hype-Driven Fad Or Evidence-Based Health Habit?


Juice fasts, previously relegated to teams on the fringes of society, at the moment are embraced by mainstream tradition…

As soon as solely a ritual ceremony of passage for these embedded in pure drugs circles, juice fasts have now turn out to be ubiquitous, marketed by well being gurus, infomercials, and integrative medical docs alike.

Regardless of an abundance of anecdotal proof and the testimonies of numerous juicingenthusiasts, well-designed managed research on the topic have remained scant (1).

Intestine Microbiota: The Gateway to Good Well being

The intestine microbiota, or the 100 trillion commensal micro organism that inhabit our gastrointestinal tracts, stands out as the car via which juice fasts elicit their useful results. Not solely is a disturbed microbiota implicated within the pathogenesis of weight problems and metabolic issues, however weight discount has been reported to engender enhancements in ranges of bacterial species that contribute to inflammatory processes (2). Particularly, “Weight problems is related to decrease bacterial variety, phylum and genus-level modifications, and altered illustration of bacterial genes and metabolic pathways concerned in nutrient harvest” (2, p. 394).

One research carried out by Remely and colleagues (2015) examined the consequences of a standard weight-reduction plan in an Austrian monastery, comprised of small quantities of soup, cereal, fruit and vegetable juices, and natural teas (2). This intervention, carried out in overweight topics, considerably elevated microbial variety in addition to numbers of Bifidobacteria, Akkermansia, and Faecalibacterium prausnitzii. Mucin-degrading Akkermansia, which have excessive mucosal adherence and are correlated with a wholesome intestine microbial group, are depleted in inflammatory issues akin to Crohn’s illness and ulcerative colitis (three, four).

The researchers additionally reported that populations of Enterobacteria and Lactobacilli related to irritation declined after the intervention (2). The authors concluded, “Our outcomes present that caloric restriction impacts the intestine microbiota by proliferating mucin-degrading microbial subpopulations,” demonstrating that juice fasts might function by way of this mechanism (p. 394). Different fashions of caloric restriction have equally yielded decreases in Streptococcacae, which incite delicate irritation, and will increase in Lactobacillus species, which competitively inhibit pathogens and produce declines in inflammatory cytokine ranges (5).

Polyphenol-Induced Microbiome Modifications Favorably Affect Well being

Vegatables and fruits characterize the richest reservoir of phenolic compounds, which resist absorption within the small gut and as an alternative are metabolized by the colonic micro organism into compounds which modulate populations of intestine flora. Researchers speculate that the microbiota could also be a beforehand under-recognized avenue by means of which polyphenolspromote well being, enhance metabolic parameters, and mitigate irritation (6).

For example, when rats are given quercetin, a flavonoid present in plant meals resembling apples and onions, microbial dysbiosis induced by a high-fat high-sucrose food plan is inhibited (7, eight). The rats on this experiment likewise exhibited suppressed progress of bacterial species correlated with diet-induced weight problems, resembling Erysipelotrichaceae, Eubacterium cylindroides, and Bacillus, alongside an attenuated ratio of Firmicutes to Bacteroidetes (7). Additional, when administered in live performance, quercetin and trans-resveratrol prevented weight achieve in a rodent mannequin, whereas individually, they every improved insulin resistance (7). In isolation, supplementation with trans-resveratrol additionally modified expression of tight-junction proteins and inflammatory gene profiles, influencing intestinal permeability in methods probably mediated by the microbiota (7).

In one other research, mice receiving Harmony grape polyphenols with a high-fat eating regimen exhibited improved profiles of glucose tolerance, adiposity, and weight achieve, and had enhanced expression of fasting-induced adipocyte issue, which restricts triglyceride storage (6). The mice receiving grape polyphenols equally displayed decreased ranges of inflammatory markers, such because the inflammatory cytokines tumor necrosis issue (TNF)-α and interleukin (IL)-6, the endotoxin launched from gram-negative micro organism referred to as lipopolysaccharide (LPS), and inducible nitric oxide synthase (iNOS) (6). As well as, grape polyphenols improved intestinal barrier perform by up-regulating the genes for occludin and proglucagon, the previous of which is a decent junction architectural protein, and the latter of which is a precursor to proteins that keep mucosal barrier integrity and promote insulin manufacturing (6).

Importantly, grape polyphenols induced dramatic alterations locally of commensal microbes. This botanical decreased the ratio of Firmicutes and Bacteroidetes, which is critical since an elevated ratio of Firmicutes to Bacteroidetes, which is induced by a high-fat, excessive sugar food regimen, has been proven to extend host adiposity when transplanted into germ-free mice (9, 10, 11). The grape polyphenols additionally considerably augmented populations of Akkermansia muciniphila, an obligate anaerobic species which blooms after gastric bypass surgical procedure and promotes weight reduction when transplanted into germ-free recipients (11, 12). As well as, cross-sectional research have underscored that larger ranges of A. municiphila seem in lean people relative to overweight people (13). As a result of A. muciniphila is weak to reactive oxygen species, the free radical scavenging capability of grape polyphenols can create a extra hospitable setting for this species and different obligate anaerobes that profit well being (6).

Likewise, cranberry polyphenols induced comparable anti-diabetic results in mice fed a high-fat, excessive sucrose (HFHS) food regimen (14). Administration of cranberry extract improved insulin sensitivity and glucose dealing with, decreasing intestinal, plasma, and hepatic triglyceride ranges, and decreased intestinal and hepatic irritation and oxidative stress (14). Cranberry extract equally attenuated circulating ranges of LPS, successfully stopping the HFHS-induced metabolic endotoxemia that contributes to the pathophysiology of heart problems (14). Furthermore, like grape polyphenols, remedy with cranberry extract led to dramatic elevations in A. muciniphila, which confers safety towards metabolic syndrome options (14).

Different research have elucidated that dealcoholized purple wine polyphenols and cocoa-derived flavanols elicit comparable results on the intestine microbiota (15). Collectively, polyphenols “modulate the human intestine microbiota by reducing the abundance of Firmicutes and growing Bifidobacteria, Lactobacillus and Verrucomicrobia, which can also be a key distinction within the intestine microbiota present in overweight and lean people” (15, p.1).

Based mostly on the aforementioned findings, researchers recommend that myriad distinct polyphenols and bioactive compounds might exert comparable results, each immediately and not directly, on the intestine microbiome. They suggest that numerous courses of dietary antioxidants might engender well being advantages by conferring a survival benefit for sure commensal species (6). In line with Roopchand and colleagues (2015), “We suggest that this altered intestine microbiota is, partially, liable for the altered intestinal gene expression, epithelial integrity, and inflammatory markers, which then results in decreased fats deposition and glucose absorption, together with elevated insulin secretion” (6, p. 2857).

Modifications in Intestine Microbiota After a Juice Quick

Based mostly on the premise that modifications in microbial composition affect well being, researchers designed a research to look at whether or not a three-day juice quick, adopted by reversion to a customary eating regimen for 2 weeks, would favorably affect the microbiota composition of twenty wholesome topics with low fruit and vegetable consumption (15). A root juice combine was blended from beet, apple, ginger, and lemon, whereas a citrus juice combine consisted of apple, pineapple, mint, and lemon, and the inexperienced juice mixes contained romaine lettuce, apple, cucumber, celery, lemon, and small fractions of kale, parsley, and spinach (15). Additionally included was a mixture consisting of filtered water, lemon, cayenne, almond, vanilla bean, dates, and sea salt (15).

Whereas proportions of sure intestinal micro organism, resembling Fusobacteria, Actinobacteria, Verrucomicrobia, and Proteobacteria remained constant, a big lower in Firmicutes and will increase in each Cyanobacteria and Bacteroidetes have been noticed in topics present process the juice quick in comparison with baseline (15). Firmicutes and Bacteroidetes symbolize the 2 most plentiful bacterial phyla in human populations, representing 40-60% and 20-40% of the microbiota, respectively (16).

Elevated Firmicutes in relation to Bacteroidetes has been correlated with weight problems and physique mass index (BMI) in some human research (17). Based on researchers, “Comparisons of the distal intestine microbiota of genetically overweight mice and their lean littermates, in addition to these of overweight and lean human volunteers have revealed that weight problems is related to modifications within the relative abundance of the 2 dominant bacterial divisions, the Bacteroidetes and the Firmicutes” (18, p.1027). The microbiome attribute of the overweight phenotype, in flip, has been correlated with elevated harvesting of power from the weight loss plan, and produces weight problems when germ-free mice are colonized with the overweight microbiota (18).

This development, which has been supported by some research and refuted by others, was strengthened by the current juice quick, the place a big constructive correlation between weight at day 4 and Firmicutes proportion, and a big damaging correlation between weight at day 4 and Bacteroidetes proportion was noticed (13, 15, 18). These modifications in microbiota might mitigate or perpetuate metabolic syndrome options by regulating intestine barrier perform, as animal fashions have confirmed that a compromised intestine barrier allows translocation of micro organism and antigens, which evokes irritation from the gut-associated sub-mucosal lymphoid system (13).

As well as, Bacteroides species akin to B. ovatus, B. thetaiotaomicron, and B. uniformis can ferment a wide selection of indigestible complicated polysaccharides, corresponding to fruit- and vegetable-based xylan and pectin (19). These carbohydrates function fermentable substrates or prebiotics, that are metabolized into well being selling, intestine sealing, cardioprotective brief chain fatty acids. In accordance with Flint and colleagues (2012), “Sure dominant species, notably among the many Bacteroidetes, are recognized to own very giant numbers of genes that encode carbohydrate lively enzymes and may change readily between totally different power sources within the intestine relying on availability” (19, p. 289). The enrichment in Bacteroides species after the juice quick reinforces the prebiotic results of juice, since comparable will increase in Bacteroides species resembling B. acidifaciens, B. ovatus, and B. xylanisolvens have been witnessed in research of topics with metabolic syndrome who included resistant starch of their diets (20).

In a single specific research, flourishing of Bacteroides species was accompanied by vital decreases in fasting glucose, glycosylated hemoglobin, levels of cholesterol, physique fats, waist circumference, and pro-inflammatory markers, which speaks to the metabolic advantages incurred with methods that increase Bacteroides populations (20). As well as, one other rodent research confirmed that B. thetaiotaomicron mixed with probiotics decreased imply physique weight and decreased ranges of postprandial triglycerides in rats fed a excessive fats eating regimen, additional illustrating the good thing about these particular microbes (21).

After the juice quick, populations of Bacteroides, Odoribacteri, Paraprevotella, Barnesiella, and Halospirulina have been all enhanced at day 4 in comparison with baseline, whereas Eisenbergiella, Dialister, Ruminiclostridium, Subdoligranulum, and Streptococcus have been all suppressed at day 4 in comparison with baseline, illuminating the instant and dramatic impact that fruit and vegetable polyphenols can elicit on the microbiota (15). These different genera, nevertheless, in addition to Streptococcus, returned to baseline ranges at day seventeen, indicating the necessity for normal polyphenol consumption to take care of favorable microbiome modifications (15).

Impact of a Juice Quick on Irritation

Though plasma antioxidant capability remained unchanged after the juice quick, lipid peroxidation, as measured by urine malondialdehyde (MDA), considerably decreased by 40% at day 4 in comparison with baseline (15). The researchers attribute this to both the low-fat nature of the juice quick, such that fewer lipids can be found for oxidative degradation, or the antioxidant safety conferred by juice polyphenols for lipids throughout digestion (15).

This latter speculation is supported by analysis demonstrating that polyphenol-rich juices containing cyanidin glycosides and epigallocatechin gallate (EGCG) supplemented for 2 weeks led to decreases in plasma MDA (22). As well as, purple wine polyphenols have been proven to utterly forestall the rise in plasma MDA that happens resulting from oxidized fat (23). Equally, rosmarinic acid, a polyphenol in oregano, considerably reduces MDA focus in plasma and urine after burger consumption (24). Thus, the excessive polyphenol content material in juices might shield towards the carcinogenic and atherosclerotic results of lipid peroxidation.

As well as, after the juice quick, day 4 nitric oxide (NO) concentrations have been elevated by five-fold and three-fold, in urine and plasma, respectively, in comparison with baseline, indicating the vasodilatory impact of fruit and vegetable nitrate content material (15). Optimizing NO ranges might forestall heart problems, since disturbed exercise of endothelial nitric oxide synthase (eNOS) is implicated within the pathophysiology of endothelial dysfunction, impaired arterial compliance, and hypertension. That is in step with prior work which elucidated that nitrate-rich beet juice improves vascular perform in hypercholesterolemic sufferers, as illustrated by will increase in flow-mediated dilatation (FMD) and aortic pulse wave velocity and by decreases in platelet-monocyte aggregates in comparison with placebo (25). These modifications can also be mediated by the microbiome, and nitrate-reducing micro organism particularly, since in a single research, nitrate remedy modified the proportions of 78 bacterial taxa within the salivary microbiome in comparison with placebo (25).

Lastly, through the juice intervention, vital decreases in physique weight and physique mass index (BMI) occurred which endured after the two-week follow-up interval (15). Properly-being scores remained according to baseline at day three, however there was a big improve in well-being on the conclusion of the research (15). Nevertheless, each NO and MDA concentrations returned to preliminary baseline values at day seventeen, suggesting that continued consumption of polyphenols is required to take care of anti-inflammatory advantages (15).

Though the fiber is essentially faraway from juice, this research highlights that juicing nonetheless elicits a prebiotic impact on account of its polyphenol content material, and that it will probably subsequently favorably modify the microbiome by selectively stimulating the expansion of useful commensal micro organism. Thus, juicing, with an emphasis on decrease glycemic greens, could also be each a prudent adjunctive technique for individuals with gastrointestinal misery who can’t tolerate giant portions of fiber, and for people with metabolic derangements.


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