Nutrition Reviews

Vajdi, Mahdi; Hassanizadeh, Shirin; Hassanizadeh, Reza; Bagherniya, Mohammad

doi: 10.1093/nutrit/nuad166pmid: 38213188

ContextClinical evidence from investigations of the effects of curcumin on liver enzymes in patients with nonalcoholic fatty liver disease (NAFLD) have led to inconsistent results.ObjectiveThe aim of this systematic review and meta-analysis was to investigate the overall effects of curcumin and curcumin plus piperine supplementation on liver enzymes such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) in patients with NAFLD.Data SourcesThe Scopus, Web of Science, PubMed, and Cochrane Library databases were searched from inception through July 2023, using search terms representing NAFLD and liver enzymes. Articles were screened independently by 2 researchers based on PICOS inclusion criteria.Data ExtractionThe following data were extracted: first author’s name, study location, year of publication, mean age, study duration, study design, participants’ sex, number of participants in each group, dose of curcumin supplementation, and ALT, ALP, and AST concentrations. Risk of bias was assessed using the Cochrane Collaboration’s modified risk-of-bias tool.Data AnalysisFixed- or random-effects meta-analysis was performed to estimate the effects of curcumin on liver enzymes, considering heterogeneity across studies. The I2 and Cochran’s Q tests were used to assess heterogeneity between studies.ResultsOverall, 15 randomized controlled trials comprising 905 participants were eligible for this meta-analysis. Curcumin supplementation significantly reduced ALT (weighted mean difference [WMD], –4.10, 95%CI, –7.16 to –1.04) and AST (WMD, –3.27; 95%CI, –5.16 to –1.39), but not ALP (WMD, –0.49; 95%CI, –1.79 to 0.82). Curcumin plus piperine supplementation had no significant effect on ALT (WMD, –3.79; 95%CI, –13.30 to 5.72), and AST (WMD, –1.1; 95%CI, –3.32 to 1.09).ConclusionsCurcumin supplementation improved AST and ALT levels compared with the control group. However, better-designed randomized controlled trials with larger sample sizes and of higher quality are needed to assess the effects of curcumin on ALP.Systematic Review RegistrationPROSPERO registration no. CRD42023448231.

Behzadi, Mehrdad; Akbarzadeh, Marzieh; Mohammadi Sartang, Mohsen; Rabiee, Mohammadreza; Bideshki, Mohammad Vesal

doi: 10.1093/nutrit/nuad172pmid: 38219250

ContextHypertension (HTN) is regarded as a serious public health issue throughout the world. High blood pressure (BP) may be improved by carotenoid supplementation; however, randomized controlled trials (RCTs) provide conflicting evidence.ObjectiveThe aim of this study was to evaluate the effects of carotenoid supplementation on BP in RCTs by systematically review and meta-analysis.Data SourcesA comprehensive literature search was performed in the Scopus, PubMed, and Web of Science databases until October 2023, with no limitation on the date or language of publication.Data ExtractionStudies that evaluated the net effects of carotenoids in the form of supplements on BP in adults were selected. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated on the basis of a fixed or random-effects model. Sensitivity analysis, meta-regression, publication bias, and heterogeneity were assessed using standard methods. Cochrane quality assessments were used to evaluate the included studies' bias risks. Evidence certainty was calculated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework).Data AnalysisReports on a total of 19 RCTs involving 1151 participants were included in this review. Carotenoid supplementation significantly reduced the systolic BP (SBP) (WMD, –2.492 mmHg; 95%CI, –4.52, –0.47; P = 0.016) and diastolic BP (DBP) (WMD, –1.60 mmHg; 95%CI, –2.73, –0.47; P = 0.005). Greater effects were observed in Asian participants, those aged >50 years, nonhealthy participants, and participants with a baseline SBP ≥130 mmHg and DBP ≥80 mmHg, at dose >10 mg. Dose–response analysis showed that carotenoid supplementation decreased SBP and DBP levels at doses of, respectively, 0–25 and 0–20 mg/d. Evidence for all SBP, DBP, and heart rate values was high quality.ConclusionsCarotenoid supplementation had a beneficial effect on BP parameters, especially in nonhealthy study participants with high BP baseline levels.PROSPERO registration noCRD42023402740.

Bizzozero-Peroni, Bruno; Martínez-Vizcaíno, Vicente; Fernández-Rodríguez, Rubén; Jiménez-López, Estela; Núñez de Arenas-Arroyo, Sergio; Saz-Lara, Alicia; Díaz-Goñi, Valentina; Mesas, Arthur Eumann

doi: 10.1093/nutrit/nuad176pmid:

Ji, Jiawei; Fotros, Danial; Sohouli, Mohammad Hassan; Velu, Periyannan; Fatahi, Somaye; Liu, Yinghao

doi: 10.1093/nutrit/nuad175pmid: 38219223

ContextDespite the important role of inflammation-related factors on the occurrence of chronic diseases, there is still conflicting evidence about the effects of the ketogenic diet (KD) on these factors.ObjectiveIn order to obtain a better viewpoint, this study aimed to comprehensively investigate the effects of a KD on inflammation-related markers.Data SourcesTo find pertinent randomized controlled trials up to August 2023, databases including PubMed/Medline, Web of Science, Scopus, Cochrane Library, and Embase were searched.Data ExtractionThis study included all randomized controlled trials investigating the effects of a KD on C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-8, and IL-10 levels. Pooled weighted mean difference (WMD) and 95% confidence intervals (CIs) were achieved by random-effects model analysis for the best estimation of outcomes.Data AnalysisForty-four studies were included in this article. The pooled findings showed that a KD has an effect on lowering TNF-α (WMD: −0.32 pg/mL; 95% CI: −0.55, −0.09; P = 0.007) and IL-6 (WMD: −0.27 pg/mL; 95% CI: −0.52, −0.02; P = 0.036) compared with control groups. However, no significant effect was reported for others inflammation marker–related levels. The results of the subgroup analysis showed that, in trials following the KD for ≤8 weeks and in people aged ≤50 years, the reduction in TNF-α levels was significantly higher than in other groups. In addition, in people with a body mass index greater than 30 kg/m2 compared to a body mass index ≤30 kg/m2, IL-6 levels decreased to a greater extent after receiving the KD.ConclusionsConsequently, adherence to a KD appears to improve some markers associated with inflammation, including TNF-α and IL-6.

Poon, Eric Tsz-Chun; Tsang, Jaclyn Hei; Sun, Fenghua; Zheng, Chen; Wong, Stephen Heung-Sang

doi: 10.1093/nutrit/nuad168pmid: 38193357

ContextIntermittent dieting incorporated with break periods (INT-B) has recently been promoted as an alternative dietary approach for optimal weight management.ObjectiveThis study assessed the effectiveness of INT-B compared with that of conventional continuous energy restriction (CER) for improving body composition and attenuating metabolic adaptation.Data SourcesA systematic search was conducted on 6 databases using all available records until July 2023.Data ExtractionThe extracted data included the lead author, year of publication, population characteristics, intervention protocols, duration, and adherence.Data AnalysisRandom-effects meta-analyses were conducted for within-group and between-group comparisons of anthropometric and metabolic outcomes. Subgroup moderator analysis was performed for the types of INT-B, intervention duration, and population characteristics.ResultsOf the 1469 records, 12 randomized trials (with 881 participants) were included. Within-group analyses demonstrated significant improvements in body mass, fat mass, body mass index, body fat percentage, and waist circumference following both INT-B and CER, with no significant group differences. However, resting metabolic rate (RMR) was significantly reduced following CER only. The compensatory reduction in RMR was significantly smaller following INT-B compared with CER, suggesting a lesser degree of metabolic adaptation. INT-B had a more significant effect on RMR retention in individuals with overweight/obesity compared with resistance-trained individuals.ConclusionThis review provides up-to-date evidence for INT-B as a viable dietary strategy to improve body composition and attenuate metabolic adaptation.Systematic Review RegistrationPROSPERO registration no. CRD42023448959.

Zhao, Shilin; Liang, Suisha; Tao, Jun; Peng, Ye; Chen, Siqi; Wai, Hogan K F; Chung, Feng-Ying; Sin, Zhen Y; Wong, Matthew K L; Haqq, Andrea M; Chang, Wing C; Ni, Michael Y; Chan, Francis K L; Ng, Siew C; Tun, Hein M

Hashemi Javaheri, Fatemeh Sadat; Karbin, Karim; Senobari, Mohammad Amin; Hakim, Hakime Ghadiri; Hashemi, Mohammad

doi: 10.1093/nutrit/nuad174pmid: 38273741

ContextBreast milk composition is influenced by many factors, ranging from maternal nutritional status to infant sex. Previous studies have explored the relationship between maternal body mass index (BMI) and breast milk composition; however, the findings have been inconsistent and controversial.ObjectiveTo systematically review the evidence on the association of maternal weight and BMI with breast milk composition.Data SourcesThe PubMed and Scopus databases were searched up to May 3, 2023, using the following search strategy: (“maternal weight” OR “maternal BMI” OR “mother’s weight” OR “mother’s BMI”) AND (“maternal milk” OR “human milk” OR “breast milk”).Data ExtractionA total of 83 publications, involving data from more than 11 310 lactating women, were identified. All extracted data were compiled, compared, and critically analyzed.Data AnalysisOverall, maternal BMI was associated with higher levels of leptin and insulin, and the ratio of omega-6 to omega-3 polyunsaturated fatty acids in breast milk. However, no conclusive associations were found between maternal BMI and the levels of energy, macronutrients, micronutrients, and other components of breast milk.ConclusionsThis systematic review provides robust evidence supporting a positive correlation between maternal BMI and breast milk concentrations of leptin, insulin, and the omega-6 to omega-3 polyunsaturated fatty acid ratio. Nevertheless, disparities in findings are noticeable for other constituents of breast milk. To comprehensively grasp the influence of maternal weight and BMI on breast milk composition, further research endeavors are imperative.Systematic Review RegistrationPROSPERO registration no. CRD42023458667.

Vresk, Laura; Flanagan, Mary; Daniel, Allison I; Potani, Isabel; Bourdon, Celine; Spiegel-Feld, Carolyn; Thind, Mehakpreet K; Farooqui, Amber; Ling, Catriona; Miraglia, Emiliano; Hu, Guanlan; Wen, Bijun; Zlotkin, Stanley; James, Philip; McGrath, Marie; Bandsma, Robert H J

doi:

O’Leary, John; Georgeaux-Healy, Chloé; Serpell, Lucy

doi: 10.1093/nutrit/nuad170pmid: 38263325

Research into the effects of calorie restriction continues to intrigue those interested in whether it may allow humans to live longer and healthier lives. Animal studies of continuous calorie restriction (CCR) and fasting have demonstrated substantial advantages to health and longevity. However, concerns remain about the impact of restricting calorie intake on human health and cognition. Given the emerging evidence of cognitive impairments in eating disorders, studies investigating restricted calorie intake in healthy humans (in an ethical way) may also have implications for understanding restrictive eating disorders. In this review, the published literature on the impact of CCR and fasting on cognitive function in healthy human participants is synthesized. Of the 33 studies of CCR and fasting in humans identified, 23 demonstrated significant changes in cognition. Despite variation across the cognitive domains, results suggest CCR benefits inhibition, processing speed, and working memory, but may lead to impairments in cognitive flexibility. The results of fasting studies suggest fasting is associated with impairments in cognitive flexibility and psychomotor abilities. Overall, the results of these studies suggest the degree (ie, the severity) of calorie restriction is what most likely predicts cognitive improvements as opposed to impairments. For individuals engaging in sustained restriction, this may have serious, irreversible consequences. However, there are mixed findings regarding the impact of CCR and fasting on this aspect of human functioning, suggesting further research is required to understand the costs and benefits of different types of calorie restriction.

Nguo, Kay; McGowan, Margaret; Cowan, Stephanie; Davidson, Zoe; Pirotta, Stephanie; Dordevic, Aimee L; Teede, Helena; Hajishafiee, Maryam; Carmichael, Mikaeli; Moran, Lisa J

doi: 10.1093/nutrit/nuad169pmid: 38345350

 Polycystic ovary syndrome (PCOS) occurs in 8%-13% of reproductive-aged women and is associated with reproductive, metabolic, and psychological dysfunction. Overweight and obesity are prevalent and exacerbate the features of PCOS. The aim of this review is to evaluate the extent of evidence examining the physiological factors affecting energy homeostasis, which may impact weight gain, weight loss, and weight maintenance in PCOS, and identify research gaps and recommendations for future research. Literature searches using MEDLINE, EMBASE, PsycInfo, AMED, CINAHL, and Cochrane Central Register of Controlled Trials were conducted up to June 22, 2022. Abstracts, non–English-language articles, and reviews were excluded. A total of n = 78 (n = 55 energy intake and n = 23 energy expenditure) primary research papers were included. Papers with multiple outcomes of interest were counted as separate studies. Energy-intake studies (n = 89) focussed on assessing food, nutrient, or supplements stimuli and were grouped into the outcomes of gastrointestinal appetite hormones (n = 43), adipokines (n = 34), subjective appetite (n = 9), functional brain imaging (n = 3), and neuropeptides (n = 0). Energy-expenditure studies (n = 29) were grouped into total energy expenditure (n = 1), resting energy expenditure (n = 15), meal-induced thermogenesis (n = 3), nutrient oxidation (n = 5), and metabolic flexibility (n = 5). Across both energy-intake and -expenditure papers, 60% of the studies compared outcome responses in women with PCOS with a control group. Results were inconsistent, with 57% reporting no differences and 43% reporting altered responses in PCOS compared with controls, including blunted appetite hormone responses, metabolic inflexibility, and reduced energy expenditure. The authors identified that there is inconsistent, yet preliminary, evidence of possible altered physiological factors, which may impact energy balance and weight management. Further work is needed to act on the identified clinical and research gaps to support women with PCOS and health professionals in informing and achieving realistic weight-management goals for women with PCOS.Systematic Review RegistrationThe protocol was prospectively registered on the Open Science Framework on February 16, 2021 (https://osf.io/9jnsm).