Association of the dietary phytochemical index with general and central obesity in a sample of Iranian adults

Effect of Phytochemical-Rich Food Intake on Respiratory and Muscle Function in Middle-Aged Patients with COPD: A Cross-Sectional Study

Background: It is known that the consumption of single phytochemicals improves respiratory function in chronic obstructive pulmonary disease (COPD) patients. Since phytochemicals have a synergistic effect on health, a more comprehensive analysis is needed. The aim of this study was to estimate the intake of phytochemicals using the dietary phytochemical index (DPI) and assess their association with respiratory function, inspiratory muscle strength and function, and peripheral muscle strength. Methods: This study was conducted at the Special Hospital for Pulmonary Diseases in Zagreb (September 2023 to May 2024). The DPI was assessed using three 24 h recalls from 71 COPD patients (66.5 ± 8.4 years; 53.5% men). Anthropometric measurements, respiratory function, inspiratory muscle function and strength, and peripheral muscle strength were assessed during pulmonary rehabilitation following standard protocols. Results: Patients were divided into DPI tertiles with mean values of 7.3 ± 3.0, 16.0 ± 3.0, and 32.2 ± 8.8, respectively. After controlling for confounding factors, a significant association was found between DPI tertiles and FEV1 (p-trend < 0.001), FVC (p-trend = 0.002), FEV1/FVC (p-trend < 0.001), MIP (p-trend = 0.012), and MSUE (p-trend = 0.002). In addition, an inverse association was found between DPI tertiles and diaphragm thickness during inhalation (p-trend = 0.012) and exhalation (p-trend = 0.013). Conclusions: This study suggests that a higher intake of phytochemicals could be beneficial in dietary interventions for COPD therapy. Future prospective studies are needed to confirm these findings.

Dietary Total Polyphenol, Flavonoid, and Lignan Intakes Are Associated with Obesity and Diabetes-Related Traits: A Case-Control Study

Purpose: Dietary phytochemicals have been under examination as adjuvants for the prevention and treatment of obesity and diabetes. This study aimed at examining the potential associations of dietary "Phytochemical Index" (PI) and polyphenol intake with obesity and diabetes-related parameters. Materials and Methods: The case-control study involved 331 participants (156 overweight/obese and 175 normal weight), aged 18-50 years. Dietary intake was assessed using the 24-hr dietary recall method, and the PI score was calculated as the percentage of energy intake provided by phytochemical-rich foods. Polyphenol intakes were calculated using Phenol-Explorer and U.S. Department of Agriculture databases. Anthropometrical measurements were taken, serum glucose, insulin, and lipid profiles were analyzed, homeostatic model assessment for insulin resistance (HOMA-IR) was calculated, and blood pressure was measured. Linear regression analyses were used to examine the potential associations. Results: Participants with higher PI scores had higher total and some sub-classes polyphenol intakes compared with lower ones (P < 0.05, for each). Dietary PI score was not associated with any of the anthropometrical measurements; however, total polyphenol and flavonoids intakes were inversely associated with body mass index (β = -0.269, P = 0.049; β = -0.262, P = 0.048; respectively), waist circumference (β = -0.127, P = 0.021; β = -0.130, P = 0.016; respectively), and waist-to-hip ratio (β = -20.724, P = 0.032; β = -22.199, P = 0.018; respectively) after adjusting for potential confounders. Either dietary PI score or total and sub-class polyphenol intakes were not associated with a better metabolic profile, except for the lignan intake, which was inversely associated with HOMA-IR (β = -0.048, P = 0.011). Conclusions: Higher dietary polyphenol intake may have potential in the prevention of obesity and diabetes, and validated practical tools are essential for the assessment of polyphenol intake in clinical practice.

Association of dietary phytochemical index with cardiometabolic risk factors

Objective(s): Cardio-metabolic risk factors are becoming a global health concern. To address this problem, one of the proposed ways is to focus on phytochemical-rich foods consumption. Therefore, we aimed to summarize the results of observational studies (cohorts, case-control, and cross-sectional) that investigated the association between dietary phytochemical index (PI) as a new index for evaluating phytochemical-rich food intake and various risk factors of cardio-metabolic disorders. Methods: We conducted a comprehensive systematic review through PubMed, Scopus, and Web of Science databases. The literature search was performed up to August 2021 with no publication year restriction on observational studies investigating the association between PI and cardiometabolic risk factors on adults and children. A random-effect meta-analysis was used. Results: Overall, 16 articles (cross-sectional, case-control, cohort) were eligible for this systematic review and 8 studies with 99771 participants were included in the meta-analysis. Random effect meta-analysis showed that adherence to higher dietary PI decrease the odds of abdominal obesity (OR: 0.73, 95% CI: 0.58, 0.88, I2: 84.90), generalized obesity (OR: 0.84, 95% CI: 0.69, 0.98, I2: 68.10), hypertriglyceridemia (OR: 0.81, 95% CI: 0.73, 0.89, I2: 0.00), hypertension (OR: 0.86, 95% CI: 0.73, 0.99, I2: 7.02), and MetS (OR: 0.79, 95% CI: 0.69, 0.88, I2: 84.90). However, results considering the associations between dietary PI with glycemic indices, and low high-density lipoprotein cholesterol (HDL-C) were not significant (p<0.05). Conclusion: Evidence showed adverse associations between dietary PI and some cardio-metabolic risk factors such as obesity, hypertriglyceridemia, hypertension and metabolic syndrome.

Association between dietary phytochemical index, cardiometabolic risk factors and metabolic syndrome in Switzerland. The CoLaus study

BACKGROUND AND AIMS

Plant-based diets are associated with reduced cardiometabolic risk factors (CRFs) and lower risk of metabolic syndrome (MetS), probably via phytochemicals acting synergistically. However, dietary phytochemical content estimation is challenging; therefore, the dietary phytochemical index (DPI) was proposed as a practical way to assess total dietary phytochemical content from phytochemical-rich foods (PRFs). We evaluated the association between DPI with CRFs and MetS and its components.

METHODS AND RESULTS

Cross-sectional analysis of 2009-2012 data of Colaus cohort study (Lausanne, Switzerland), including 3879 participants (mean age 57.6 ± 10.4 years, 53.5% women). Dietary intake was assessed via a validated food frequency questionnaire. DPI was calculated as the total energy intake percentage obtained from PRFs consumption and assessed as quartiles. Associations were determined using multivariable linear and logistic regression for CRFs and MetS, respectively. Median DPI value was 25.5 (interquartile range: 17.7-34.6). After multivariable-adjusted analyses, significant inverse associations were observed between the last two highest DPI quartiles and waist circumference (WC), body mass index (BMI), insulin, leptin, and hs-CRP. No significant associations were observed for MetS or its components except for central obesity, as subjects in the highest DPI quartile had lower odds (OR: 0.78; 95% CI: 0.62, 0.97) than those in lowest quartile.

CONCLUSION

A diet high in PRFs assessed via DPI is associated with lower WC, BMI, insulin, leptin, hs-CRP values, and lower odds of central obesity, indicating a potential protective effect of phytochemical intake on these CRFs and highlighting the importance of high PRFs intake in promoting cardiometabolic health.

The association of dietary phytochemical index and nonalcoholic fatty liver disease

Consumption of phytochemical-rich foods relates to the prevention of chronic diseases. In this study we assessed the dietary phytochemical index (PI) in metabolic parameters, liver enzymes, and severity of fibrosis among nonalcoholic fatty liver disease patients. This cross-sectional study was conducted on 210 patients with NAFLD. Fibrosis-4 index (FLB4), nonalcoholic fatty liver disease fibrosis score (NFS), FBS, lipids profile, AST, ALT, ALP, and GGT were measured. PI was calculated through the information obtained from a validated semi-quantitative food frequency. Multiple regression models were used to estimate mean difference changes in the evaluated variables associated with various dietary PI. Participants' mean ± SD of age and BMI were 39.23 ± 10.52 and 24.40 ± 2.64, respectively. We found that DPI is inversely associated with serum TG, TC, and LDL-C and directly associated with serum HDL-C and a higher score in DPI is associated with lower scores in NFS and FIB-4. Multivariate linear regression showed that there is an inverse association between DPI and AST, ALT, ALP, GGT, NFS, and FIB-4. Higher dietary PI could impact on reduction of NAFLD progression and improvement of metabolic parameters.

Dietary Phytochemical Index and the Risk of Breast Cancer: A Case-Control Study

High intakes of phytochemical-rich foods might have beneficial effects on reducing breast cancer risk. In this study, we assessed the association between the dietary phytochemical index (PI) and breast cancer risk in a sample of premenopausal Turkish women. This case-control study was conducted on 70 newly diagnosed breast cancer cases and matched 70 healthy controls. Dietary intake was assessed using a validated food frequency questionnaire and dietary phytochemical indexes were calculated with two different methods. The mean PI score of participants was 19.9 ± 9.52 and 23.0 ± 8.95 in cases and controls, respectively (p = 0.046). After adjusting for energy intake, the risk of breast cancer significantly increased by 29.5% in the third quartile as compared to the fourth quartile of dietary PI (OR = 0.295, 95%CI = 0.106-0.822). Higher dietary PI was negatively associated with breast cancer risk; therefore, dietary PI may be suggested as an important contributor to dietary intake for breast cancer.

The relationship between dietary phytochemical index and resting metabolic rate mediated by inflammatory factors in overweight and obese women: a cross-sectional study

Background

Unhealthy dietary patterns are the most important modifiable risk factors for obesity and overweight. This study aimed to examine the relationship between Dietary Phytochemical Index (DPI) and resting metabolic rate (RMR), mediated by inflammatory factors, in overweight and obese women.

Methods

A total of 404 women, aged 18–48 years, were included in the cross-sectional study. DPI was calculated using the 147-item food frequency questionnaire (FFQ). Anthropometric measurements, RMR, and blood biomarkers were assessed using standard protocols.

Results

There was marginally significant association between adherence to DPI and RMR status in the crude model (OR = 1.41, 95% CI 0.94–2.11, P = 0.09). After adjusting for potential confounders, a significant association was seen between the DPI and increase RMR.per.kg (OR = 2.77, 95% CI 0.98–7.82, P = 0.05). Our results indicated that plasminogen activator inhibitor-1 (PAI-1), transforming growth factor (TGF-β), and monocyte chemoattractant protein-1 (MCP-1) had a mediatory effect on the association between RMR and DPI (P > 0.05). Indeed, it was shown that, PAI-1, TGF-β, and MCP-1 destroyed the significance of this association and could be considered as mediating markers. However, no mediating effect was observed for high-sensitivity C reactive protein (hs-CRP).

Conclusions

Adherence to DPI can improve the RMR by reducing levels of inflammatory markers, and may be considered as a treatment for obesity. However, more long-term studies are recommended.

Association between the Phytochemical Index and Overweight/Obesity: A Meta-Analysis

Some studies suggest that a higher phytochemical index (PI) is associated with a lower risk of overweight/obesity. This meta-analysis is performed to summarize published studies on the relationship of PI and the risk of overweight/obesity. We searched on PubMed, Cochrane Library and Web of Science from the inception dates to February 2022. The random-effect model was used based on heterogeneity. Meta-regression was used to explore potential sources of between-study heterogeneity. Publication bias was evaluated using Begg’s and Egger’s tests. The dose–response relationship was assessed using a restricted cubic spline model. Nine studies were included in the meta-analysis, with a total of 100,753 participants. The meta-analysis showed that the phytochemical index was associated with a decreased risk of overweight/obesity. The pooled OR (95% CI) was 0.81 (0.74–0.90). The findings from dose–response analysis showed a nonlinear association between the phytochemical index and the risk of overweight/obesity. The results of the meta-regression showed that gender and area were significant covariates influencing the heterogeneity between studies. There was no publication bias in the meta-analysis of this study. In conclusion, although this meta-analysis indicates that a high phytochemical index is associated with a reduced risk of overweight/obesity, all the studies included in this meta-analysis were cross-sectional studies with high heterogeneity. As such, more data from randomized controlled trials are required to confirm the efficacy of PI in evaluating the risk of overweight/obesity.