Fruit and vegetable intakes are major modifiable determinants of risk for non-communicable disease(1), yet intake levels remain low(2) and multiple barriers (cost, access, perishability, preparation skills) exist(3,4). 100% fruit and vegetable juices contain key micronutrients and bioactive compounds (5–7) and may help circumvent these barriers to consumption(6,7). However, their role in dietary guidelines and models of healthy eating remains controversial due to their free sugars and reduced dietary fibre content, relative to whole fruits and vegetables(6,7). Therefore, we conducted a systematic umbrella review of systematic literature reviews (SLRs) with meta-analyses assessing the relationships between 100% juice consumption and human health outcomes. Four databases (Medline, Cochrane Library, EMBASE, and CINAHL) were systematically searched for SLRs with meta-analyses of human prospective cohort, case-control, and intervention studies examining the relationship between 100% juice and any health outcome through to 20th October 2022. Screening (Covidence), quality (GRADE)(8), risk of bias (ROBIS)(9) and content overlap (corrected covered area(10)) tools were applied, and extracted data were narratively synthesised. The protocol was pre-registered (PROSPERO) and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklists. 15 SLRs on 100% fruit juice including 51 primary meta-analyses, 6 dose-response analyses, and 87 sub-analyses were eligible for inclusion. No eligible studies on vegetable juice were found. Included studies represented data from almost 2 million subjects with a range of doses (50-1200mL/day) and timeframes (hours to years). Significant improvements in health outcomes were found in 19.6% of included meta-analyses (blood pressure, flow-mediated dilation, IL-6, c-reactive protein, and stroke mortality), and increased disease risks were found in 5.9% of included meta-analyses (CVD mortality, prostate cancer, and type II diabetes). The remainder (74.5%) found no significant difference (blood lipids, weight, liver function, metabolic markers, colorectal and breast cancers, and multiple inflammatory markers). The ROBIS quality assessment rated nine SLRs as low risk of bias, three as unclear and three as high. Using GRADE, confidence in the body of evidence ranged from very low (27 primary and 79 secondary meta-analyses) to low (19 primary and 13 secondary meta-analyses), and medium (4 primary and one secondary meta-analyses.) Findings show 100% juice consumption has limited risks of harm and some potential benefits, over a broad range of doses, including some that are relatively high, and time periods. The positive associations between 100% juice consumption and specific health outcomes relevant to population health may be explained by multiple mechanisms, including the vitamin, mineral, and bioactive contents. The balance of evidence suggests that 100% may have a neutral or beneficial place in general, population-level dietary guidelines.

The health effects of 100% fruit and vegetable juices (FVJ) represent a controversial topic. FVJ contain notable amounts of free sugars, but also vitamins, minerals, and secondary compounds with proven biological activities like (poly)phenols and carotenoids. The review aimed to shed light on the potential impact of 100% FVJ on human subject health, comprehensively assessing the role each type of juice may have in specific health outcomes for a particular target population, as reported in dietary interventions. The effects of a wide range of FVJ (orange, grapefruit, mandarin, lemon, apple, white, red, and Concord grapes, pomegranate, cranberry, chokeberry, blueberry, other minor berries, sweet and tart cherry, plum, tomato, carrot, beetroot, and watermelon, among others) were evaluated on a series of outcomes (anthropometric parameters, body composition, blood pressure and vascular function, lipid profile, glucose homeostasis, biomarkers of inflammation and oxidative stress, cognitive function, exercise performance, gut microbiota composition and bacterial infections), providing a thorough picture of the contribution of each FVJ to a health outcome. Some juices demonstrated their ability to exert potential preventive effects on some outcomes while others on other health outcomes, emphasising how the differential composition in bioactive compounds defines juice effects. Research gaps and future prospects were discussed. Although 100% FVJ appear to have beneficial effects on some cardiometabolic health outcomes, cognition and exercise performance, or neutral effects on anthropometric parameters and body composition, further efforts are needed to better understand the impact of 100% FVJ on human subject health.

Major changes in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food packages that were implemented in 2009 included reductions in the amount of milk and 100% juices, as well as the removal of whole milk from food packages. In analyzing the effect of these changes on the beverage consumption of Texas WIC children ages two to four, we found a significant decrease in the amount of whole milk consumed, and this decrease was partially offset by the increase in the amount of lower-fat milks consumed. Intakes of both desirable and undesirable nutrients from milk were decreased.

Epidemiological studies indicate that diets rich in fruits and vegetables (F&V) are protective against CVD. Puréed F&V products retain many beneficial components, including flavonoids, carotenoids, vitamin C and dietary fibres. The present study aimed to establish the physiological effects of acute ingestion of a F&V purée-based drink (FVPD) on vasodilation, antioxidant status, phytochemical bioavailability and other CVD risk factors. A total of twenty-four subjects, aged 30–70 years, completed the randomised, single-blind, controlled, crossover test meal study. Subjects consumed 400 ml of the FVPD, or a fruit-flavoured sugar-matched control, after following a low-flavonoid diet for 5 d. Blood and urine samples were collected throughout the study day, and vascular reactivity was assessed at 90 min intervals using laser Doppler iontophoresis. The FVPD significantly increased plasma vitamin C (P= 0·002) and total nitrate/nitrite (P= 0·001) concentrations. There was a near significant time by treatment effect on ex vivo LDL oxidation (P= 0·068), with a longer lag phase after consuming the FVPD. During the 6 h after juice consumption, the antioxidant capacity of plasma increased significantly (P= 0·003) and there was a simultaneous increase in plasma and urinary phenolic metabolites (P< 0·05). There were significantly lower glucose and insulin peaks after ingestion of the FVPD compared with control (P= 0·019 and 0·003) and a trend towards increased endothelium-dependent vasodilation following FVPD consumption (P= 0·061). Overall, FVPD consumption significantly increased plasma vitamin C and total nitrate/nitrite concentrations, with a trend towards increased endothelium-dependent vasodilation. Puréed F&V products are useful vehicles for increasing micronutrient status, plasma antioxidant capacity and in vivo NO generation, which may contribute to CVD risk reduction.

High intakes of carotenoid-rich fruits and vegetables are associated with a reduced risk of various cancers including colon cancer. A human intervention study with carrot and tomato juice should show whether a diet rich in carotenoids, especially high in β-carotene and lycopene, can modify luminal processes relevant to colon carcinogenesis. In a randomised cross-over trial, twenty-two healthy young men on a low-carotenoid diet consumed 330 ml tomato or carrot juice per d for 2 weeks. Intervention periods were preceded by 2-week depletion phases. At the end of each study period, faeces of twelve volunteers were collected for chemical analyses and use in cell-culture systems. Consumption of carrot juice led to a marked increase of β-carotene and α-carotene in faeces and faecal water, as did lycopene after consumption of tomato juice. In the succeeding depletion phases, carotenoid contents in faeces and faecal water returned to their initial values. Faecal water showed high dose-dependent cytotoxic and anti-proliferative effects on colon adenocarcinoma cells (HT29). These effects were not markedly changed by carrot and tomato juice consumption. Neither bile acid concentrations nor activities of the bacterial enzymes β-glucosidase and β-glucuronidase in faecal water changed after carrot and tomato juice consumption. Faecal water pH decreased only after carrot juice consumption. SCFA were probably not responsible for this effect, as SCFA concentrations and profiles did not change significantly. In summary, in the present study, 2-week interventions with carotenoid-rich juices led only to minor changes in investigated luminal biomarkers relevant to colon carcinogenesis.