Reliability and validity of assigning ultraprocessed food categories to 24-h dietary recall data

Vegan and omnivore diets in relation to nutrient intake and greenhouse gas emissions in Iceland

Plant-rich diets have gained recognition for their environmental sustainability. However, relatively few studies have compared dietary habits of vegans and omnivores in terms of compliance with nutritional recommendations and dietary greenhouse gas (GHG) emissions, which this study aimed to assess. We used data on 651 omnivores and 68 vegans from the Icelandic National Dietary Survey (2019-2021) and a comparable survey on vegans (2022-2023), respectively. The median dietary GHG emissions was substantially lower among vegans than omnivores (2.6 vs. 5.3 kg CO2-eq/day). Compared to omnivores, vegans had a proportionally higher intake of energy from carbohydrates (48% vs. 39%) but a lower intake from fat (35% vs. 40%) and proteins (12% vs. 18%). More vegans compared to omnivores fell within the dietary recommendations for fiber (74% vs. 8%) and saturated fat (56% vs. 7%) while vegans were less likely to have protein intake in line with the recommended ≥ 0.83 g/kg body weight (52% vs. 79%). Despite frequent use of dietary food supplements among vegans (97%) and omnivores (72%) the prevalence of those reaching the recommended intake of iodine, calcium and vitamin D, was low (40-60%) in both groups. In conclusion, vegans were overall more compliant with macronutrient recommendations and had substantially lower dietary GHG emissions compared to omnivores. In terms of meeting dietary recommendations, room for improvements was observed in both groups.

Fifteen Years of NOVA Food-Processing Classification: "Friend or Foe" Among Sustainable Diet Indicators? A Scoping Review

It has been 15 years since the introduction of the NOVA food-processing classification. While it was designed to identify ultra-processed foods linked to noncommunicable diseases, the NOVA system has a holistic concept that fits with sustainable nutrition. However, NOVA's connection to other sustainable diet indicators has not been thoroughly explored. The aim was to summarize the research and methodological context of using the NOVA system with other sustainable diet indicators and to investigate NOVA's synergies and discordance with them. A scoping review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Extension for Scoping Reviews (PRISMA-ScR). Studies published between 2009 and 2023 were collected from the Web of Science, Scopus, and PubMed databases. 1612 studies were initially screened; in the selected studies (n = 77), the NOVA system was applied in addition to other sustainable diet indicator(s). The studies were analyzed within a qualitative data analysis framework. 77 studies were analyzed in which healthiness (n = 66), environmental pressure (n = 9), affordability (n = 11), other processing classifications (n = 6), and other sustainable diet indicators (n = 10) were applied with NOVA. Among them, the identified relationships between the NOVA system and other healthfulness indicators were synergistic in the majority of studies (n = 70/93). For environmental pressure indicators, a mixed picture was observed; the NOVA classification was predominantly synergistic with greenhouse gas emissions (n = 8/13), while it was mostly discordant with fresh water use (n = 8/12). Economic affordability was also found to be discordant with the NOVA classification in the majority of studies (n = 10/16). To complete the NOVA classification with nutrient profiling would be beneficial to identify healthy diets. In the case of the integration of NOVA into sustainable nutrition research, environmental pressure and economic affordability indicators should be controlled to reach optimal trade-offs for more sustainable diets. The application of NOVA is gaining relevance; thus, its methodological adaptation to sustainable nutrition research is necessary.

Association of ultra-processed foods with phenotypic age acceleration in US adults: a mediation analysis of body mass index in the NHANES

Background

The rising intake of ultra-processed foods (UPFs) has been linked to adverse health outcomes, yet its impact on aging acceleration remains unclear.

Objective

This study aimed to examine the association between the percentage of total daily calories (%Kcal) and grams (%Gram) from UPFs and phenotypic age acceleration (PhenoAgeAccel).

Methods

Data from 12,079 adults in the NHANES 2005-2010 cycles were analyzed. The relationship between UPFs intake and PhenoAgeAccel was assessed using multivariable linear regression and restricted cubic splines, with adjustments for relevant covariates. The mediating role of body mass index (BMI) was also explored.

Results

A significant positive linear association was observed between UPFs intake (%Gram) and PhenoAgeAccel, with the highest quartile showing an increase of 0.60 (95% CI: 0.15, 1.05; p for trend = 0.039), but no association was found between UPFs intake (%Kcal) and PhenoAgeAccel. Mediation analysis indicated that BMI mediated 27.5% of the association between UPFs intake (%Gram) and PhenoAgeAccel. Sensitivity analyses confirmed the robustness of the results.

Conclusion

Higher intake of UPFs intake (%Gram) is positively associated with PhenoAgeAccel, with BMI playing a significant mediating role.

The association between ultra-processed food consumption and low-grade inflammation in childhood: A cross-sectional study

This study aimed to investigate the relationship between the amount of ultra-processed food (UPF) in the diet and low-grade inflammation in children. This cross-sectional study was conducted in 50 healthy children recruited from children attending the Social Paediatrics Outpatient Clinic for follow-up of normal developmental stages. Low-grade inflammation was calculated by INFLA-score, dietary intake by three 24-h dietary recalls and dietary content analyses by BeBiS™ software. The mean age of the 50 children included in our study was 10.18 ± 3.98 years (5-17 years). UPF accounted for 24.5% of the total daily energy intake of children. In children with higher inflammation scores (INFLA-score ≥ 2), the amount in grams of UPF and the percentage of total energy from UPF were found to be significantly higher (p = 0.030 and p = 0.015, respectively). A weak positive correlation was found between the INFLA-score and the percentage of daily dietary energy intake coming from UPFs (r = 0.350, p < 0.01), the average daily energy intake from UPFs (r = 0.313, p < 0.05), and the average daily amount of UPF consumed (r = 0.260, p < 0.05). The linear regression model revealed that every one-unit increase (1%) in the percentage of total daily energy intake coming from UPF caused an increase in β = 0.154-unit in the INFLA-score. It was found that obesity was not a mediator in the association between the percentages of total energy intake from UPF on the INFLA-score, instead, the energy intake from UPF had a significant direct association with the INFLA-score. The average amount of UPF consumed daily showed an increasing pattern in parallel with inflammation-score quartile classes (Q1 to Q4) with 33.3% in Q1, 38.5% in Q2, 53.8% in Q3 and 66.7% in Q4 (p = 0.049). In conclusion, a positive association was found between low-grade inflammation and UPF consumption in children, independent of obesity.

Validation of a Food Frequency Questionnaire: VioScreen-Allergy

BACKGROUND/OBJECTIVES

An adapted version of an online pictorial food frequency questionnaire (FFQ), VioScreen-Allergy, assesses total dietary intake and intake of allergens and foods in the maternal diet index (MDI), linked to offspring allergy. This study assessed intermethod reliability, test-retest reliability, and external validity of the VioScreen-Allergy.

METHODS

Females of childbearing age were recruited at Denver Health and Children's Hospital, Colorado, USA, and were asked to complete four 24 h recalls and two VioScreen-Allergy FFQs over the course of a month. All those with at least two 24 h dietary recalls and both VioScreen-Allergy assessments were analyzed. Energy-adjusted and non-adjusted linear mixed models (1) compared MDI scores and intake of nutrients and allergens as measures of intermethod reliability; (2) evaluated VioScreen-Allergy test-retest reliability as differences between repeated measurements; and (3) assessed external validity by modeling associations between VioScreen-Allergy-derived intake of beta-carotene and orange vegetables and Veggie Meter®-assessed skin carotenoids. Bonferroni corrections controlled multiple comparisons within the assessment.

RESULTS

Of 53 participants enrolled, 25 demographically dissimilar participants were included in the analysis. There were no significant differences between 24 h recall and VioScreen-Allergy mean intakes of macronutrients, micronutrients, allergens, or MDI, except for Vitamin C, niacin, and cashew allergen protein. There were no significant differences between repeated measurements of VioScreen-Allergy, either energy-adjusted or unadjusted. Both beta-carotene and orange vegetable servings were significantly associated with Veggie Meter®.

CONCLUSIONS

Although non-significance could have been due to low power, clinical as well as statistical assessments of intermethod reliability, test-retest reliability, and external validity suggest that VioScreen-Allergy has reasonable utility for trials assessing food allergens and MDI in the context of overall intake. The VioScreen questionnaire can also be used in future studies to assess macro- and micronutrient intake. Additional validation studies assessing different portion sizes and foods eaten by infants and young children are currently undergoing.

Ultraprocessed Food Intake during the Transition to Adulthood Varies According to Sociodemographic Characteristics and Maternal Intake in Cebu, Philippines

BACKGROUND

Ultraprocessed foods (UPFs) are associated with elevated risk of noncommunicable disease, but little is known about UPF intake and the individual-, household-, and community-level factors associated with it among adolescents in low- or middle-income countries.

OBJECTIVES

We estimated the association of UPF intake across adolescence with sociodemographic characteristics and maternal UPF intake in a Filipino cohort.

METHODS

Data were from 4 waves (1994-2005) of the Cebu Longitudinal Health and Nutrition Survey (n = 2068); participants were aged 11, 15, 18, and 21 y. Foods from 24-h recalls were classified using NOVA. We used two-part multilevel models to estimate time-varying associations of the odds and amount (percentage daily kilocalories) of UPF intake with sociodemographic characteristics and maternal UPF intake (none, below median among UPF-consuming mothers ["low"], at or above median ["high"]).

RESULTS

Median UPF intake (interquartile range [IQR]) among adolescents was 7.3% (IQR: 0, 17.2%) of daily kilocalories at age 11 y and 10.6% (IQR: 3.6, 19.6%) at 21 y. The odds and amount of adolescent UPF intake were positively associated with female sex, years of schooling, and household wealth and inversely associated with household size. The odds-but not amount-of adolescent UPF intake was positively associated with maternal education and urbanicity and inversely associated with the distance from a household's primary store/market. The association between odds of adolescent UPF intake and school enrollment was positive in adolescence but disappeared in early adulthood. Compared with offspring whose mothers did not consume UPFs, the odds of UPF intake among those whose mothers had low or high UPF intake was greater in adolescence, but there was no association once offspring became adults. At all ages, maternal UPF intake was positively associated with the amount of offspring intake.

CONCLUSIONS

Adolescent UPF intake varied across sociodemographic characteristics and was positively associated with maternal UPF intake, but not after adolescents entered adulthood.

Hedonic hunger, ultra-processed food consumption, and the moderating effects of impulsivity in pregnant individuals with body mass index ≥ 25

Evidence suggests higher hedonic hunger (preoccupation with/desire to consume food for pleasure) is associated with greater ultra-processed food (UPF) consumption in non-pregnant individuals with higher, but not lower, self-report impulsivity or delay discounting. The current study tested the association between hedonic hunger and UPF consumption, and the moderating effects of self-report impulsivity and delay discounting, during pregnancy. Individuals (N = 220) with body mass index (BMI)≥25 completed the Power of Food Scale, 24-h dietary recalls, and Barratt Impulsiveness Scale-Version 11 in early-mid pregnancy. A subset enrolled in an ancillary study (n = 143) completed a Delay Discounting Task. Linear regression and moderation models covaried for age, gestational age, pre-pregnancy BMI, and socioeconomic status. The association between hedonic hunger and UPF consumption was nonsignificant (p = 0.47). Self-report impulsivity was not a significant moderator (p = 0.11), but delay discounting was (p = 0.01). Simple slopes analysis revealed a one-unit increase in hedonic hunger was associated with 7% lower UPF intake among participants with lower (M+1SD) delay discounting (p = 0.01) and 1% higher UPF intake among those with higher (M-1SD) delay discounting (p = 0.57). Findings contrast those from research with non-pregnant samples and indicate lower delay discounting may serve as a protective factor, associated with reduced UPF consumption at higher levels of hedonic hunger, during pregnancy.

Ultra-processed foods consumption and health-related outcomes: a systematic review of randomized controlled trials

Introduction

The increase in ultra-processed foods (UPFs) intake has raised concerns about its impact on public health. Prospective observational studies have reported significant associations between higher intake of UPFs and adverse health outcomes. The aim of this study is to determine whether these associations could be confirmed in randomized controlled trials (RCTs).

Methods

We conducted a systematic review to analyze the evidence on the effects of UPFs intake on health. A systematic search was conducted in Medline, Embase, Web of Science, Scopus, LILACS, and CENTRAL up to April 22, 2024. RCTs in English, Spanish, and Portuguese evaluating the health effects of interventions to modify UPFs intake were included. The certainty of evidence was determined using the GRADE methodology.

Results

Three educational intervention studies and one controlled feeding trial were included, evaluating the effect of reducing the consumption of UPFs (455 participants, median follow-up, 12 weeks). No significant effects were observed in 30 out of the 42 outcomes evaluated. The controlled feeding trial in adults with stable weight showed a reduction in energy intake, carbohydrates, and fat (low certainty of evidence), as well as in body weight, total cholesterol, and HDL cholesterol (moderate certainty of evidence). In the educational intervention studies, a reduction in body weight and waist circumference was observed (low certainty of evidence) in women with obesity, as well as improvement in some dimensions of quality of life (very low certainty of evidence). No significant changes were observed in children and adolescents with obesity, while in overweight pregnant women, the consumption of UPFs was not reduced, so the observed benefits could be attributed to other components of the intervention.

Conclusion

Interventions aimed at reducing the consumption of UPFs showed benefits on some anthropometric and dietary intake outcomes, although significant effects were not observed for most of the evaluated outcomes. The limited number and significant methodological limitations of the studies prevent definitive conclusions. Further well-designed and conducted RCTs are needed to understand the effects of UPF consumption on health.Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023469984.

Ultra-Processed Foods: A Narrative Review of the Impact on the Human Gut Microbiome and Variations in Classification Methods

Ultra-processed foods (UPFs) are foods that are industrially processed and are often pre-packaged, convenient, energy-dense, and nutrient-poor. UPFs are widespread in the current Western diet and their proposed contribution to non-communicable diseases such as obesity and cardiovascular disease is supported by numerous studies. UPFs are hypothesized to affect the body in multiple ways, including by inducing changes in the gut microbiome. This review summarizes the available research on the effect of UPFs on the gut microbiome. We also review current usage of the NOVA food classification system in randomized controlled trials and observational studies and how its implementation effects UPF research. Despite some differences in methodology between studies, results often associate UPF consumption with a number of negative health consequences. There are attempts to standardize a UPF classification system; however, reaching and implementing a consensus is difficult. Future studies focusing on the mechanisms by which UPFs effect the body, including through the microbiome and metabolome, will be essential to refine our understanding of the effects of UPFs on human health.

A high consumption of ultra-processed foods is associated with higher total mortality in an adult Mediterranean population

BACKGROUND & AIMS

The consumption of ultra-processed foods (UPF) has been associated with higher all-cause and cardiovascular disease (CVD) mortality, although this association has not been sufficiently investigated in Mediterranean populations. We aimed to evaluate the association between UPF consumption and all-cause, CVD and cancer mortality in an adult population in Spain.

METHODS

We analysed data from 1,538 participants aged 20 years and above in the Valencia Nutrition Survey in 1995. Diet was assessed at baseline using a validated food frequency questionnaire and the consumption of UPF was calculated using the NOVA system. Information on socio-demographic characteristics, lifestyles, and presence of diseases was also collected at baseline. Cause of death was ascertained during an 18-year follow-up period. We used Cox regression and competing risk models as proposed by Fine and Gray's to estimate adjusted hazard ratios (HR) and 95 % confidence intervals (95 %CI).

RESULTS

After 18 years of follow-up, we documented 312 deaths (36.5 % of CVD and 25.6 % of cancer). Compared with participants in the lowest tertile of UPF consumption, those in the highest tertile showed 40 % higher risk of all-cause mortality, HR 1.40 (95 %CI: 1.04-1.90), and evidence of a higher CVD mortality, HR 1.39 (95 %CI: 0.80-2.41) and of cancer mortality, HR 1.53 (95 %CI: 0.83-2.82).

CONCLUSIONS

This study suggests that a high UPF consumption is associated with a higher all-cause mortality in a Mediterranean population after a long follow-up period. Considering the increase in UPF consumption and their detrimental health effects on mortality, these results should be confirmed by other studies in other populations.

Ultra-processed Food and Obesity: What Is the Evidence?

PURPOSE OF REVIEW

Obesity is a growing global healthcare concern. A proposed driver is the recent increase in ultra-processed food (UPF) intake. However, disagreement surrounds the concept of UPF, the strength of evidence, and suggested mechanisms. Therefore, this review aimed to critically appraise the evidence on UPF and obesity.

RECENT FINDINGS

Observational studies demonstrate positive associations between UPF intake, weight gain, and overweight/obesity, more clearly in adults than children/adolescents. This is supported by high-quality clinical data. Several mechanisms are proposed, but current understanding is inconclusive. Greater UPF consumption has been a key driver of obesity. There is a need to change the obesogenic environment to support individuals to reduce their UPF intake. The UPF concept is a novel approach that is not explained with existing nutrient- and food-based frameworks. Critical analysis of methodologies provides confidence, but future observational and experimental research outputs with greater methodological rigor will strengthen findings, which are outlined.

Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses

OBJECTIVE

To evaluate the existing meta-analytic evidence of associations between exposure to ultra-processed foods, as defined by the Nova food classification system, and adverse health outcomes.

DESIGN

Systematic umbrella review of existing meta-analyses.

DATA SOURCES

MEDLINE, PsycINFO, Embase, and the Cochrane Database of Systematic Reviews, as well as manual searches of reference lists from 2009 to June 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Systematic reviews and meta-analyses of cohort, case-control, and/or cross sectional study designs. To evaluate the credibility of evidence, pre-specified evidence classification criteria were applied, graded as convincing ("class I"), highly suggestive ("class II"), suggestive ("class III"), weak ("class IV"), or no evidence ("class V"). The quality of evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) framework, categorised as "high," "moderate," "low," or "very low" quality.

RESULTS

The search identified 45 unique pooled analyses, including 13 dose-response associations and 32 non-dose-response associations (n=9 888 373). Overall, direct associations were found between exposure to ultra-processed foods and 32 (71%) health parameters spanning mortality, cancer, and mental, respiratory, cardiovascular, gastrointestinal, and metabolic health outcomes. Based on the pre-specified evidence classification criteria, convincing evidence (class I) supported direct associations between greater ultra-processed food exposure and higher risks of incident cardiovascular disease related mortality (risk ratio 1.50, 95% confidence interval 1.37 to 1.63; GRADE=very low) and type 2 diabetes (dose-response risk ratio 1.12, 1.11 to 1.13; moderate), as well as higher risks of prevalent anxiety outcomes (odds ratio 1.48, 1.37 to 1.59; low) and combined common mental disorder outcomes (odds ratio 1.53, 1.43 to 1.63; low). Highly suggestive (class II) evidence indicated that greater exposure to ultra-processed foods was directly associated with higher risks of incident all cause mortality (risk ratio 1.21, 1.15 to 1.27; low), heart disease related mortality (hazard ratio 1.66, 1.51 to 1.84; low), type 2 diabetes (odds ratio 1.40, 1.23 to 1.59; very low), and depressive outcomes (hazard ratio 1.22, 1.16 to 1.28; low), together with higher risks of prevalent adverse sleep related outcomes (odds ratio 1.41, 1.24 to 1.61; low), wheezing (risk ratio 1.40, 1.27 to 1.55; low), and obesity (odds ratio 1.55, 1.36 to 1.77; low). Of the remaining 34 pooled analyses, 21 were graded as suggestive or weak strength (class III-IV) and 13 were graded as no evidence (class V). Overall, using the GRADE framework, 22 pooled analyses were rated as low quality, with 19 rated as very low quality and four rated as moderate quality.

CONCLUSIONS

Greater exposure to ultra-processed food was associated with a higher risk of adverse health outcomes, especially cardiometabolic, common mental disorder, and mortality outcomes. These findings provide a rationale to develop and evaluate the effectiveness of using population based and public health measures to target and reduce dietary exposure to ultra-processed foods for improved human health. They also inform and provide support for urgent mechanistic research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023412732.

From dearth to excess: the rise of obesity in an ultra-processed food system

More people now have obesity than suffer from starvation thanks to our modern food system. Agriculture was transformed over the 20th century by a variety of technological advancements that relied heavily on fossil fuels. In the United States, government policies and economic incentives led to surplus production of cheap inputs to processed food industries that produced a wide variety of heavily marketed, convenient, rewarding, timesaving, and relatively inexpensive ultra-processed foods. The energy available in the food supply increased by much more than the population needs, albeit with large inequities in nutrition security. While most of the rise in per capita food availability during the late 20th and early 21st centuries in the United States resulted in increased food waste, a variety of mechanisms have been proposed by which changes in the increasingly ultra-processed food environment resulted in excess energy intake disproportionately in people genetically susceptible to obesity. As populations continue to grow, substantial investments in coordinated nutrition and agricultural research are needed to transform our current food system to one that relies less on fossil fuels, preserves biodiversity, ensures environmental health, and provides equitable access to affordable, safe and nutritious food that reduces the prevalence of chronic diet-related diseases like obesity. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

Industrial Use of Phosphate Food Additives: A Mechanism Linking Ultra-Processed Food Intake to Cardiorenal Disease Risk?

The consumption of ultra-processed food (UPF) keeps rising, and at the same time, an increasing number of epidemiological studies are linking high rates of consumption of UPF with serious health outcomes, such as cardiovascular disease, in the general population. Many potential mechanisms, either in isolation or in combination, can explain the negative effects of UPF. In this review, we have addressed the potential role of inorganic phosphate additives, commonly added to a wide variety of foods, as factors contributing to the negative effects of UPF on cardiorenal disease. Inorganic phosphates are rapidly and efficiently absorbed, and elevated serum phosphate can lead to negative cardiorenal effects, either directly through tissue/vessel calcification or indirectly through the release of mineral-regulating hormones, parathyroid hormone, and fibroblast growth factor-23. An association between serum phosphate and cardiovascular and bone disease among patients with chronic kidney disease is well-accepted by nephrologists. Epidemiological studies have demonstrated an association between serum phosphate and dietary phosphate intake and mortality, even in the general American population. The magnitude of the role of inorganic phosphate additives in these associations remains to be determined, and the initial step should be to determine precise estimates of population exposure to inorganic phosphate additives in the food supply.

Ultra-processed food consumption and BMI-Z among children at risk for obesity from low-income households

OBJECTIVE

To evaluate the association between baseline ultra-processed food consumption in early childhood and child BMI Z-score over 36 months.

METHODS

We conducted a prospective cohort analysis as a secondary data analysis of the Growing Right Onto Wellness randomised trial. Dietary intake was measured via 24-h diet recalls. The primary outcome was child BMI-Z, measured at baseline and at 3-, 9-, 12-, 24- and 36-month timepoints. Child BMI-Z was modelled using a longitudinal mixed-effects model, adjusting for covariates and stratifying by age.

RESULTS

Among 595 children, median (Q1-Q3) baseline age was 4.3 (3.6-5.0) years, 52.3% of the children were female, 65.4% had normal weight, 33.8% were overweight, 0.8% were obese and 91.3% of parents identified as Hispanic. Model-based estimates suggest that, compared with low ultra-processed consumption (300 kcals/day), high ultra-processed intake (1300 kcals/day) was associated with a 1.2 higher BMI-Z at 36 months for 3-year-olds (95% CI = 0.5, 1.9; p < 0.001) and a 0.6 higher BMI-Z for 4-year-olds (95% CI = 0.2, 1.0; p = 0.007). The difference was not statistically significant for 5-year-olds or overall.

CONCLUSIONS

In 3- and 4-year-old children, but not in 5-year-old children, high ultra-processed food intake at baseline was significantly associated with higher BMI-Z at 36-month follow-up, adjusting for total daily kcals. This suggests that it might not be only the total number of calories in a child's daily intake that influences child weight status, but also the number of calories from ultra-processed foods.

Association between ultra-processed foods and risk of cancer: a systematic review and meta-analysis

Background

Despite increasing evidence that has shown the association of ultra-processed foods (UPFs) with cancer risk, the results remain inconclusive. We, therefore, conducted the meta-analysis to clarify the association by including recently published studies.

Methods

A comprehensive search was conducted in PubMed, Embase, and Web of Science to identify all relevant studies from inception to January 2023. To pool data, fixed-effects or random-effects models were used where appropriate. Subgroup analyses, sensitivity analyses, and publication bias tests were performed.

Results

A total of 13 studies (4 cohort studies and 9 case-control studies) were included in the analysis, with a total of 625,738 participants. The highest UPFs consumption was associated with increased risk of colorectal cancer (OR = 1.23, 95% CI: 1.10-1.38), colon cancer (OR = 1.25, 95% CI: 1.14-1.36), and breast cancer (OR = 1.10, 95% CI: 1.00-1.20) but not rectal cancer (OR = 1.18, 95% CI: 0.97-1.43) and prostate cancer (OR = 1.03, 95% CI: 0.93-1.12). In addition, the subgroup analyses showed that a positive association between UPFs consumption and colorectal cancer was observed among men (OR = 1.31, 95% CI: 1.15-1.50), whereas no significant association was observed among women (OR = 1.10, 95% CI: 0.94-1.29).

Conclusion

The present meta-analysis suggests that high UPFs consumption is associated with a significantly increased risk of certain site-specific cancers, especially the digestive tract and some hormone-related cancers. However, further rigorously designed prospective and experimental studies are needed to better understand causal pathways.