Cardiovascular Health Trajectories in Adolescence and Their Association With Sociodemographic and Cardiometabolic Outcomes in Spain

PURPOSE

To determine cardiovascular health (CVH) trajectories and their association with sociodemographic and cardiometabolic outcomes in adolescence.

METHODS

One thousand eighty adolescents attending 24 secondary schools enrolled in the SI! Program for Secondary Schools trial in Spain were assessed at approximately 12, 14, and 16 years of age. CVH was assessed according to American Heart Association criteria based on seven metrics (smoking status, body mass index, physical activity, diet, blood pressure, total cholesterol, and blood glucose), and CVH trajectories were identified by latent class trajectory modeling. Associations between CVH trajectories, sociodemographic characteristics, and cardiometabolic outcomes were analyzed using generalized linear and Poisson models.

RESULTS

Five CVH trajectory groups were identified: poor-stable (27 adolescents [2.5%]), intermediate-substantial rise (79 [7.3%]), intermediate-substantial decline (63 [5.8%]), intermediate-mild decline (403 [37.3%]), and intermediate-mild rise (508 [47.1%]). Boys and adolescents from families with low-average income, low-intermediate educational attainment, and a migrant background more frequently belonged to groups with lower baseline CVH and poor or declining trajectories. The intermediate-substantial decline group had the highest prevalence ratio for overweight/obesity (3.84; 95% confidence interval: 2.86-5.16) and metabolic syndrome (4.93; 95% confidence interval: 1.21-20.04) at age 16, whereas prevalence was lowest in the intermediate-mild rise group.

DISCUSSION

Adolescent CVH trajectories differ according to socioeconomic characteristics and are associated with cardiometabolic outcomes. Primordial prevention interventions should be implemented early in life, taking into account CVH trajectories and with a particular focus on vulnerable populations.

Metabolic syndrome, adiposity, diet, and emotional eating are associated with oxidative stress in adolescents

Background

Metabolic syndrome (MS), a condition related to adiposity and oxidative stress, can develop in adolescence, a critical stage in life that impacts health in adulthood. However, there is scarce scientific research about the relationship between lifestyle factors, emotion management, and oxidative stress in this phase of life.

Aim

To analyze whether nutritional parameters, lifestyle factors, emotion management, and MS in adolescents are associated with oxidative stress measured by the biomarker 8-isoprostane.

Methods

A cross-sectional study was carried out in 132 adolescents (48.5% girls, aged 12 ± 0.48 years) and data were collected on nutritional parameters (anthropometric measurements, biochemical analyzes, and blood pressure), lifestyle factors (physical activity, sleep, and diet), and emotion management (self-esteem, emotional eating, and mood). 8-isoprostane was analyzed in spot urine samples. The study population was categorized in three groups (healthy, at-risk, and with MS) using the International Diabetes Federation definition of MS in adolescents. To capture more complex interactions, a multiple linear regression was used to analyze the association between 8-isoprostane and the aforementioned variables.

Results

Urinary 8-isoprostane levels were significantly higher in the MS group compared to the healthy group (1,280 ± 543 pg./mg vs. 950 ± 416 pg./mg respectively). In addition, univariable analysis revealed positive significant associations between 8-isoprostane and body mass index, waist circumference, waist-to-height ratio, body fat percentage, blood lipid profile and glucose, emotional eating, and refined cereal intake. Conversely, a negative significant association was found between 8-isoprostane and sleep duration and fish intake. The multiple linear regression analysis revealed associations between 8-isoprostane and LDL-c (β = 0.173 value of p = 0.049), emotional eating (low β = 0.443, value of p = 0.036; high β = 0.152, value of p = 0.470), refined cereal intake (β =0.191, value of p = 0.024), and fish intake (β = -0.187, value of p = 0.050).

Conclusion

The MS group, LDL-c, emotional eating, and high refined cereals and low fish intakes were associated with higher levels of oxidative stress in an adolescent population.

Sleep duration and its association with adiposity markers in adolescence: a cross-sectional and longitudinal study

AIMS

Large studies linking adolescents' objectively measured sleep duration and adiposity markers are lacking. We characterized sleep duration and its cross-sectional and longitudinal associations with adiposity markers in adolescence.

METHODS AND RESULTS

Seven-day accelerometry was performed in a cohort of adolescents enrolled in the SI! Program for Secondary Schools trial in Spain at approximately ages 12 (1216 adolescents, 49.6% girls), 14 (1026 adolescents, 51.3% girls), and 16 (872 adolescents, 51.7% girls) years. Participants were classified as very short sleepers (VSS; <7 h), short sleepers (SS; 7-<8 h), or recommended-time sleepers (RTS; 8-10 h). Adjusted associations between sleep duration and adiposity markers were analysed using generalized linear and Poisson models. At ∼12 years, 33.7% of adolescents met sleep recommendations, and this percentage decreased with advancing age (22.6% at ∼14 and 18.7% at ∼16 years). Compared with RTS, overweight/obesity prevalence ratios at ∼12, 14, and 16 years among SS were 1.19 [95% confidence interval (CI): 1.09-1.30], 1.41 (95% CI: 1.34-1.48), and 0.99 (95% CI: 0.77-1.26) and among VSS were 1.30 (95% CI: 1.28-1.32), 1.93 (95% CI: 1.41-2.64), and 1.32 (95% CI: 1.26-1.37). Compared with adolescents who always met sleep recommendations, the prevalence of overweight/obesity was ∼5 times higher in those never meeting recommendations or meeting them only once. Similar trends were observed for the waist-to-height ratio (P = 0.010) and fat mass index (P = 0.024).

CONCLUSION

Most adolescents did not meet sleep recommendations. Shorter sleep duration was independently associated with unfavourable adiposity markers, and such adverse impact was cumulative. Health promotion programmes should emphasize the importance of good sleep habits.

School-Based Cardiovascular Health Promotion in Adolescents: A Cluster Randomized Clinical Trial

Importance

School-based interventions offer an opportunity for health promotion in adolescence.

Objective

To assess the effect of 2 multicomponent educational health promotion strategies of differing duration and intensity on adolescents' cardiovascular health (CVH).

Design, Setting, and Participants

The SI! Program for Secondary Schools is a 4-year cluster randomized clinical intervention trial conducted in 24 secondary schools from Barcelona and Madrid, Spain, from September 7, 2017, to July 31, 2021. Eligible participants were adolescents enrolled in the first grade of secondary school.

Interventions

Schools and their participants were randomized to receive a health promotion intervention (SI! Program) over 4 school years (long-term intervention [LTI], 8 schools, 412 adolescents) or 2 school years (short-term intervention [STI], 8 schools, 504 adolescents) or to receive the standard curriculum (control, 8 schools, 441 adolescents).

Main outcome and Measures

The primary end point was the between-group difference at 2 and 4 years in the change from baseline of the overall CVH score, as defined by the American Heart Association (range, 0-14 points, with a higher score indicating a healthier CVH profile). Intervention effects were tested with multilevel mixed-effects models. A complete-case intention-to-treat analysis was performed as the primary analysis.

Results

Of the randomized students, the study enrolled 1326 adolescents (684 [51.6%] boys, mean [SD] age, 12.5 [0.4] years at recruitment) with a study completion rate of 86.0%. Baseline overall CVH scores were 10.3 points in the LTI group, 10.6 points in the STI group, and 10.5 points in the control group. After 2 years, at halfway through the LTI and at the end of the STI, the difference in the CVH score change was 0.44 points (95% CI, 0.01-0.87; P = .04) between the LTI group and the control group and 0.18 points (95% CI, -0.25 to 0.61; P = .39) between the STI group and the control group. At 4 years, differences for the LTI and STI groups vs control were 0.12 points (LTI: 95% CI, -0.19 to 0.43; P = .42) and 0.13 points (STI: 95% CI, -0.17 to 0.44; P = .38). No adverse events were reported.

Conclusions and Relevance

Overall, the tested school-based health promotion strategies in this randomized clinical trial had a neutral effect on the CVH of the adolescents. Although there was evidence of a marginal beneficial effect at a point halfway through implementation in the LTI group, such a benefit was not noted at 4 years. Further research is warranted into the efficacy of school-based health promotion programs.

Trial Registration

ClinicalTrials.gov Identifier: NCT03504059.

Clustering of lifestyle behaviors and adiposity in early adolescents in Spain: findings from the SI! Program for Secondary Schools

BACKGROUND

Several unhealthy lifestyle behaviors in adolescence are often linked to overweight/obesity. Some of them may be present simultaneously, leading to combined effects on health. Therefore, the clustering of several unhealthy behaviors in adolescents might be associated with adiposity excess.

PURPOSE

To identify lifestyle patterns and analyze their association with adiposity in early adolescents.

METHODS

A cross-sectional cluster analysis was performed in 1183 adolescents (50.5% girls) with a mean age of 12.5 (0.4) years included in the SI! Program for Secondary Schools in Spain to identify lifestyle patterns based on healthy diet, step counts, sleep time, and leisure screen time. Generalized mixed models were applied to estimate the association between lifestyle patterns and adiposity indices.

RESULTS

Four lifestyle patterns were derived: Cluster 1-higher screen time and poorer diet (n = 213), Cluster 2-lower activity and longer sleepers (n = 388), Cluster 3-active and shorter sleepers (n = 280), and Cluster 4-healthiest (n = 302). Except for the number of steps (12,008 (2357) day), the lifestyle behaviors in our sample presented levels far below the recommendations, especially for sleep duration. Cluster 4 included the largest proportion of adolescents from high socioeconomic status families (47.7%) and the lowest prevalence of overweight/obesity (23.1%). Compared to Cluster 4-healthiest, adolescents in the remaining clusters presented a higher prevalence of overweight/obesity and central obesity, showing Cluster 3 the highest prevalences (PR:1.31 [95%CI: 1.31, 1.31] and PR:1.40 [95%CI: 1.33, 1.47]).

CONCLUSIONS

Clustering of lifestyle patterns in early adolescence allows the identification of individuals with excess adiposity, in whom health promotion strategies should be stressed, especially in socioeconomically disadvantaged groups.

TRIAL REGISTRATION

Clinical Trial Registry, NCT03504059. Registered 20/04/2018-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03504059 .

Microbial Phenolic Metabolites in Urine Are Inversely Linked to Certain Features of Metabolic Syndrome in Spanish Adolescents

(1) Background: To explore the association between microbial phenolic metabolites (MPM) and metabolic syndrome (MetS) and its clinical features in adolescents aged 12.02 ± 0.41 years. (2) Methods: a cross-sectional study was conducted in 560 participants at baseline in the SI! Program for Secondary Schools trial. The following MPM, coumaric acids (m-, o-, p-coumaric acids), dihydroxyphenylpropionic acid, dihydroresveratrol, enterolignans, gallic acid, hydroxybenzoic acids, hydroxyphenylacetic acid, hydroxytyrosol, protocatechuic acid, syringic acid, urolithins (A, B), and vanillic acid, were analyzed by HPLC-LTQ-Orbitrap-HRMS. MetS and its clinical features were defined in accordance with the International Diabetes Federation. (3) Results: Out of all MPM, urolithin A was inversely associated with the diastolic blood pressure z-score. Urolithin B was inversely associated with the MetS score and waist circumference z-score. Additionally, higher levels of gallic acid were associated with lower odds of presenting MetS (OR = 0.85, 95% CI: 0.77; 0.93) and abdominal obesity (OR = 0.93, 95% CI: 0.89; 0.98). Higher urolithin B levels were inversely associated with abdominal obesity (OR = 0.94, 95% CI: 0.89; 0.98) and high blood glucose (OR = 0.92, 95% CI:0.88; 0.96); (4) Conclusions: gallic acid, urolithin A and B were associated with lower odds of presenting MetS or some of its clinical features in adolescents. This is the first study that evaluates several MPM with MetS in adolescents, highlighting the importance of MPM on cardiometabolic health at early life stages.

Urinary Nitric Oxide Levels Are Associated with Blood Pressure, Fruit and Vegetable Intake and Total Polyphenol Excretion in Adolescents from the SI! Program

Nitric oxide (NO) is important to cardiovascular health (CVH), and its bioavailability could be regulated by the antioxidant effect of polyphenols, improving endothelial function and consequently blood pressure (BP). However, scant research has been carried out on NO and CVH correlates in adolescent populations. Therefore, our aim was to investigate the association between NO and the CVH status and other health factors in adolescents. NO, total polyphenol excretion (TPE), anthropometric measurements, BP, blood lipid profile, blood glucose, diet, physical activity, and smoking status were recorded, while CVH score was classified as ideal, intermediate, and poor. Negative associations were observed between NO and body mass index, body fat percentage, BP, and triglycerides; and positive associations between NO and skeletal muscle percentage, HDL-cholesterol, fruit and vegetable intake, and TPE was observed. To capture more complex interactions among different factors, multiple linear regression was performed, obtaining a significant association between NO and fruit and vegetable intake (β = 0.175), TPE (β = 0.225), and systolic BP (β = -0.235). We conclude that urinary NO levels are positively associated with the consumption of fruits and vegetables rich in antioxidants such as polyphenols and negatively associated with systolic BP.

Total urinary polyphenols and ideal cardiovascular health metrics in Spanish adolescents enrolled in the SI Program: a cross-sectional study

To study the relationship between urinary total polyphenol excretion (TPE) in adolescents and ideal cardiovascular (CVH) metrics. 1151 adolescents aged 12.04 (0.46) years participating in the SI! Program for Secondary Schools were selected based on the availability of urine samples and information required to assess CVH metrics. Data on health behaviours (smoking status, body mass index, physical activity, and healthy diet) and health factors (blood pressure, total cholesterol, and blood glucose) were used to calculate the CVH metrics. TPE in urine was analysed by a Folin-Ciocalteu method after solid-phase extraction. Associations between TPE (categorized into tertiles) and CVH metrics (total and separate scores) were assessed using multilevel mixed-effect regression models. Higher TPE levels were associated with higher (healthier) CVH scores and ideal smoking status (OR 1.54, 95% CI 1.10; 1.87, p value = 0.007), physical activity (OR 1.12, 95% CI 1.02; 1.23, p value = 0.022) and total cholesterol (OR 1.78, 95% CI 1.16; 2.73, p value = 0.009) after multivariate adjustment. An association between TPE and total CVH scores was observed only in boys. Girls with higher TPE had higher rates of ideal total cholesterol and blood pressure. According to our findings, higher urinary TPE is related to better CVH scores, with relevant differences in this association by gender.

Flavonoid Intake From Cocoa-Based Products and Adiposity Parameters in Adolescents in Spain

Background

Cocoa-based products are a good source of flavonoids, which may have beneficial effects on metabolic health.

Objective

The aim of this study is to assess the relationship between flavonoids from cocoa-based products and adiposity parameters in adolescents.

Methods

A cross-sectional study was conducted involving 944 adolescents aged 11-14 years enrolled in the SI! Program for Secondary Schools trial in Spain with available baseline data from food frequency questionnaires and anthropometric measurements [weight, height, waist circumference (WC), and fat mass percentage (% FM) by bioimpedance analysis]. Fat mass index (FMI) and waist-to-height ratio (WHtR) were obtained by dividing fat mass by height and WC by height, respectively. Body mass index (BMI), WC, and FMI for age and gender z-score were calculated. Overweight/obesity was defined as BMI ≥ 85th percentile and excess adiposity as %FM or FMI ≥ 75th percentile. WC ≥ 90th percentile and WHtR with a 0.5 threshold were considered as criteria of abdominal obesity. Multilevel mixed-effect regressions were used to evaluate the association between flavonoids from cocoa-based products and adiposity parameters. Municipalities and schools were considered random effects.

Results

Participants with a higher flavonoid intake from cocoa-based products had lower WC z-score [B = -0.04, 95% CI (-0.07; -0.01), P-for trend = 0.045] and WHtR [B = -0.01, 95% CI (-0.02; -0.01), P- for trend < 0.001]. They also had lower probability of having abdominal obesity [OR 0.66, 95% CI (0.52; 0.85), P- for trend = 0.001]. Inverse associations were observed between flavonoids from cocoa powder and BMI z-score [B = -0.08, 95% CI (-0.12; -0.05), P < 0.001], WC z-score [B = -0.06, 95% CI (-0.11; -0.02), P = 0.003], WHtR [B = -0.01, 95% CI (-0.01; -0.00), P < 0.001], %FM [B = -1.11, 95% CI (-1.48; -0.75), P < 0.001], and FMI z-score [B = -0.18, 95% CI (-0.20; -0.17), P < 0.001]. Regarding dark chocolate, an inverse association only with WC z-score [B = -0.06, 95% CI (-0.08; -0.05), P < 0.001] was found. However, no association was observed between flavonoids from milk chocolate intake and anthropometric parameters.

Conclusions

A higher intake of flavonoids from cocoa-based products was associated with lower adiposity parameters and a lower probability of presenting abdominal obesity.

The challenge of sustainability: Long-term results from the Fifty-Fifty peer group-based intervention in cardiovascular risk factors

BACKGROUND

The Fifty-Fifty trial demonstrated that a peer-group-based intervention was able to improve healthy behaviors in individuals with cardiovascular (CV) risk factors immediately post-intervention.

OBJECTIVES

To determine the long-term sustainability of a one-year peer-group-based intervention focused on CV health and behavior.

METHODS

A total of 543 adults aged 25 to 50 years with at least 1 CV risk factor were screened and recruited, received initial training through workshops, and were then randomized 1:1 to a peer-group-based intervention group (IG) or a self-management control group (CG) for 12 months. At a median of 52 months from baseline, 321 participants were re-assessed (~60% retention). The primary outcome was the mean change in a composite health score related to blood pressure, exercise, weight, alimentation, and tobacco use (Fuster-BEWAT score [FBS], range 0-15). Intervention effects were assessed using linear-mixed effects models.

RESULTS

The mean age of retained participants was 48.0 years (SD: 5.4), and 73% were female. Consistent with previous results, the change of overall FBS was significantly greater in the IG than in the CG at 12-month follow-up (between-group difference, 0.60 points; 95% CI, 0.08-1.12; P = .025). Assessment of long-term sustainability (52-month follow-up) showed that there were no between-group differences in the mean overall FBS (IG mean score, 8.52; 95% CI, 7.97-9.07 vs CG mean score, 8.51; 95% CI, 7.93-9.10; P = .972) or in the change of overall FBS from screening (IG mean change, 0.64; 95% CI, 0.00-1.28; CG mean change, 0.46; 95% CI, -0.20-1.12; P = .497).

CONCLUSIONS

A one-year peer-group-based intervention showed favorable results at immediate post-intervention but did not demonstrate significant differences between the IG and CG at 52 months. Combination of an initial training period (workshops) with the maintenance of peer-support groups or other re-intervention strategies may be required to achieve sustained effects on healthy behaviors.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT02367963. Registered (https://clinicaltrials.gov/show/NCT02367963).

Dietary Patterns and Cardiovascular Risk Factors in Spanish Adolescents: A Cross-Sectional Analysis of the SI! Program for Health Promotion in Secondary Schools

Previous studies on the association between dietary habits and cardiovascular risk factors (CVRF) in adolescents have generated conflicting results. The aim of this study was to describe dietary patterns (DP) in a large sample of Spanish adolescents and to assess their cross-sectional relationship with CVRF. In total, 1324 adolescents aged 12.5 ± 0.4 years (51.6% boys) from 24 secondary schools completed a self-reported food frequency questionnaire. DPs were derived by cluster analysis and principal component analysis (PCA). Anthropometric measurements, blood pressure, lipid profile, and glucose levels were assessed. Linear mixed models were applied to estimate the association between DPs and CVRF. Three DP-related clusters were obtained: Processed (29.2%); Traditional (39.1%); and Healthy (31.7%). Analogous patterns were obtained in the PCA. No overall differences in CVRF were observed between clusters except for z-BMI and z-FMI values, total cholesterol, and non-HDL cholesterol, with the Processed cluster showing the lowest mean values. However, differences were small. In conclusion, the overall association between DPs, as assessed by two different methods, and most analyzed CVRF was weak and not clinically relevant in a large sample of adolescents. Prospective analysis may help to disentangle the direction of these associations.

Rationale and design of the school-based SI! Program to face obesity and promote health among Spanish adolescents: A cluster-randomized controlled trial

Unhealthy habits in adolescents are increasing at an alarming rate. The school offers a promising environment in which to implement effective preventive strategies to improve adolescents' lifestyle behaviors. The SI! Program is a multilevel multicomponent school-based health-promotion intervention aimed at all stages of compulsory education in Spain. We present the study design of the SI! Program for Secondary Schools, targeting adolescents aged 12 to 16 years.

AIM

The main goal of this study is to evaluate the impact of the SI! Program educational intervention on adolescent lifestyle behaviors and health parameters.

METHODS

The study was designed as a cluster-randomized controlled intervention trial and enrolled 1326 adolescents from 24 public secondary schools in Spain, together with their parents/caregivers. Schools and their students were randomly assigned to the intervention group (the SI! curriculum-based educational program over 2 or 4 academic years) or to the control group (usual curriculum). The primary endpoint will be the change from baseline at 2-year and 4-year follow-up in the composite Ideal Cardiovascular Health (ICH) score, consisting of four health behaviors (body mass index, dietary habits, physical activity, and smoking) and three health factors (blood pressure, total cholesterol, and glucose). Secondary endpoints will include 2-year and 4-year changes from baseline in ICH score subcomponents, the Fuster-BEWAT health scale, adiposity markers (waist circumference and body composition), polyphenol and carotenoid intake, and emotion management.

DISCUSSION

The overarching goal of the SI! Program is to instill healthy behaviors in children and adolescents that can be sustained into adulthood. The SI! Program for Secondary School is a comprehensive health-promotion intervention targeting 12-16-year-old adolescents and their immediate environment. The present study addresses the optimal timing and impact of the educational intervention on health in adolescence.

A Comprehensive Lifestyle Peer Group-Based Intervention on Cardiovascular Risk Factors: The Randomized Controlled Fifty-Fifty Program

BACKGROUND

Cardiovascular diseases stem from modifiable risk factors. Peer support is a proven strategy for many chronic illnesses. Randomized trials assessing the efficacy of this strategy for global cardiovascular risk factor modification are lacking.

OBJECTIVES

This study assessed the hypothesis that a peer group strategy would help improve healthy behaviors in individuals with cardiovascular risk factors.

METHODS

A total of 543 adults 25 to 50 years of age with at least 1 risk factor were recruited; risk factors included hypertension (20%), overweight (82%), smoking (31%), and physical inactivity (81%). Subjects were randomized 1:1 to a peer group-based intervention group (IG) or a self-management control group (CG) for 12 months. Peer-elected leaders moderated monthly meetings involving role-play, brainstorming, and activities to address emotions, diet, and exercise. The primary outcome was mean change in a composite score related to blood pressure, exercise, weight, alimentation, and tobacco (Fuster-BEWAT score, 0 to 15). Multilevel models with municipality as a cluster variable were applied to assess differences between groups.

RESULTS

Participants' mean age was 42 ± 6 years, 71% were female, and they had a mean baseline Fuster-BEWAT score of 8.42 ± 2.35. After 1 year, the mean scores were significantly higher in the IG (n = 277) than in the CG (n = 266) (IG mean score: 8.84; 95% confidence interval (CI): 8.37 to 9.32; CG mean score: 8.17; 95% CI: 7.55 to 8.79; p = 0.02). The increase in the overall score was significantly larger in the IG compared with the CG (difference: 0.75; 95% CI: 0.32 to 1.18; p = 0.02). The mean improvement in the individual components was uniformly greater in the IG, with a significant difference for the tobacco component.

CONCLUSIONS

The peer group intervention had beneficial effects on cardiovascular risk factors, with significant improvements in the overall score and specifically on tobacco cessation. A follow-up assessment will be performed 1 year after the final assessment reported here to determine long-term sustainability of the improvements associated with peer group intervention. (Peer-Group-Based Intervention Program [Fifty-Fifty]; NCT02367963).

The presence of Microlobius foetidus cause changes in the antioxidant defense of Urochloa decumbens?

Urochloa decumbens (Stapf) R. D. Webster (Poaceae) is an exotic species with has spread rapidly through the Cerrado area of Pantanal, Mato Grosso do Sul, Brazil. It has covered the soil aggressively turning it into cultivated pastures. Thus, it has become a challenge to protect native areas due its capacity of exclusion of native species. It has been observed that Microlobius foetidus (Jacq.) M.Sousa & G.Andrade species (Fabaceae) shows a dominant pattern over the development of U. decumbens. This work shows that M. foetidus interfere on the natural growth of U. decumbens within 10 m ratio. Between 15 and 20 m, it was observed an increase of Importance Value index (IVI) and Relative cover (RC) values. It was also observed a variation on the antioxidant defense system of U. decumbens within 10m ratio from M. foetidus. The enzymes superoxide dismutase, catalase and peroxidase present higher levels of activity then those found for glutathione reductase. This data indicates that M. foetidus may have an effect on U. decumbens, increase the activity of antioxidant enzymes. This effect probably happens as means to neutralize the toxic effects of the oxygen generated due to the presence of allelochemicals, which increases oxidative stress.