A few days of just the wet stuff can start to mess with your 'biomes.
Juices are generally regarded as a health food, whether as a way to sneak in fruit and vegetables you can’t be bothered to eat, or to “cleanse” your filthy body from evils that your perfectly functional liver can’t handle.
Side note: “Juice/s” is up there with “moist” as a word the Back Page avoids whenever possible, so I’d better get some clicks for putting myself through this.
I was always baffled as a child by the prevalence of orange juice at Other People’s breakfast times, usually not just squeezed but from a bottle and with all the joy pasteurised out of it. Also missing was any sort of fibre or resemblance to fresh fruit.
The bafflement continued when the first Vroom Juice* franchises began opening around Sydney, with such queues you’d think they were serving holy communion in pureed form, when really, under all that healthy green branding, their offerings were about as nutritious for body and soul as a cherry sundae.
Plenty of companies stand ready to take hundreds of dollars for packaged juices to “help you cleanse from the inside”, spare you “the need for heavy digestion”, “support your immune system and improve overall wellbeing”, and even “ignite your inner essence”, which sounds a bit like heartburn.
A small study published in Nutrientssought to measure the effects of substituting juices for a normal human diet for a few days, citing a report (which the Back Page could not retrieve) from last year finding that “26% of consumers have tried a juice cleanse or detox program for perceived benefits like detoxification, weight loss, and improved digestion”.
While the Italian/US team has no quarrel with the many health benefits of fruits and vegetables, they suspect juicing may compromise them, especially by removing fibre. They were especially interested in the effects on gut and oral microbiota.
So they randomised 23 students to follow one of three intervention diets for three days following a three-day elimination diet: a typical “juice fast” consisting of 800–900Kcal of cold pressed juice a day; cold pressed juice plus regular diet ad libitum; and 800–900Kcal plant-based whole foods per day.
Saliva, cheek and faecal samples were taken before and after the elimination diet, and immediately after and 14 days after the intervention diet.
The results of the juice fast and juice+diet were less pronounced, especially in the gut, than the authors had hoped – limited by the small sample size and short duration – but they “tended to suggest negative health effects”.
Some of the taxa that increased in abundance are associated with inflammation, colorectal cancer, cardiovascular disease, gingivitis, periodontal disease and neurological and psychological problems.
“For example, the overrepresentation of taxa belonging to the Porphyromonadaceae and Odoribacteraceae families have been identified in an aging mouse study to induce memory deficits and increase anxious behaviour with progression toward neurodegenerative disorder. Also, the Alcaligeneceae family has been positively correlated with cognitive impairment”, while others have been linked in animal studies to stress, depression, anxiety and increased gut permeability.
“These findings suggest that short-term juice consumption may negatively affect the microbiota, likely due to reduced fibre and the higher sugar and carbohydrate content, underscoring the need for further research on diet-microbiome-disease interactions, as juice products are also often considered a fruit substitute in children’s daily diets.”
The Back Page is no nutritionist. I was reminded of this fact by this Conversation piece listing the vegetables that are and are not high in fibre – several entries on both lists were a big surprise.
But it seems safe to conclude that an array of food including rather than limited to fruit and vegetables’ wet bits (hey, I found something worse than “juices”) is best for good health.
Send heavily digested story tips to penny@medicalrepublic.com.au.
*Names have been changed
