Effects of a Brazil nut‐enriched diet on oxidative stress and inflammation markers in coronary artery disease patients: A small and preliminary randomised clinical trial

Effect of nuts on lipid profile and inflammatory biomarkers in atherosclerotic cardiovascular disease: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Nut-enriched diets are related to improve lipid and inflammatory biomarkers in meta-analyses in the context of primary cardiovascular prevention. However, primary studies on secondary cardiovascular prevention are scarce and controversial. This systematic review and meta-analysis aimed to evaluate the effect of nut supplementation on lipid and inflammatory profiles in individuals with atherosclerotic cardiovascular disease, and the frequency of adverse events.

METHODS

Six databases were used for research: PubMed, EMBASE, BVS, Cochrane Library, Web of Science, and ClinicalTrials.gov, until February 2023, with no language restrictions. We performed random-effects meta-analyses to compare nut-enriched diets vs. control diets for pre-post intervention changes. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system assessed the evidence's certainty.

RESULTS

From the 5187 records identified, eight publications containing data referring to five randomized clinical trials involving 439 participants were included in the final analyses. The nuts evaluated were almonds, pecans, Brazil nuts, and mixed nuts, with doses ranging between 5 g and 85 g (median: 30 g/day). The intervention time varied between 6 and 12 weeks. Compared to nut-free diets, nut intake did not have a statistically significant effect on lipid profile biomarkers, except on the atherogenic index (MD: -0.32 [95% CI -0.58 to -0.06], I2 = 0% - moderate certainty of the evidence). Similarly, there was no effect of nuts on inflammatory profile biomarkers. It was not possible to aggregate data on adverse events.

CONCLUSIONS

Nut supplementation did not change lipid and inflammatory profiles in the secondary cardiovascular prevention setting.

Effects of Regular Brazil Nut (Bertholletia excelsa H.B.K.) Consumption on Health: A Systematic Review of Clinical Trials

The Brazil nut (BN) is a promising food due to its numerous health benefits, but it is still necessary to systematically review the scientific evidence on these benefits. Thus, we examined the effects of regular BN consumption on health markers in humans according to the health state (with specific diseases or not) of the subjects. PubMed, Embase^®, and Scielo databases were used to search for clinical trials. The PRISMA guideline was used to report the review, and the risk of bias for all studies was assessed. Twenty-four studies were included in the present review, of which fifteen were non-randomized. BNs were consumed in the context of a habitual free-living diet in all studies. Improvement in antioxidant status through increased levels of selenium and/or glutathione peroxidase activity in plasma, serum, whole blood, and/or erythrocytes was observed in all studies that evaluated antioxidant status, regardless of the health state of the sample. In addition, healthy subjects improved lipid markers and fasting glucose. Subjects with obesity had improvement in markers of lipid metabolism. Subjects with type 2 diabetes mellitus or dyslipidemia improved oxidative stress or DNA damage. Subjects undergoing hemodialysis benefited greatly from BN consumption, as they improved lipid profile markers, oxidative stress, inflammation, and thyroid function. Older adults with mild cognitive impairment improved verbal fluency and constructional praxis, and controversial results regarding the change in a marker of lipid peroxidation were observed in subjects with coronary artery disease. In conclusion, the benefits of BN consumption were found in different pathways of action and study populations.

Brazil nut supplementation does not affect trimethylamine-n-oxide plasma levels in patients with coronary artery disease

The purposes of this study were to assess the effect of Brazil nut supplementation on trimethylamine N-oxide (TMAO) levels and glutathione peroxidase (GPx) activity in patients with coronary artery disease (CAD). Patients with CAD were randomly assigned to two groups, Brazil nut group (23 patients, 48% male, 62.7 ± 6.8 years, 29.4 ± 5.8 kg/m² ), which received one Brazil nut per day for 3 months, and the control group (14 patients, 43% male, 63.7 ± 8.7 years, 28.4 ± 4.2 kg/m² ) who did not receive any supplementation. After 3 months, TMAO levels and their precursors did not change in either group. Although not significant, GPx activity increased by 41% in the Brazil nut group. TMAO levels were negatively associated with total fiber intake (r = -0.385 and p = .02). A 3-month Brazil nut supplementation did not change TMAO levels and GPx activity in CAD patients. PRACTICAL APPLICATIONS: Trimethylamine N-oxide (TMAO) has been associated with oxidative stress and cardiovascular disease risk. Thus, the increase in antioxidants enzymes production could be a promising strategy to reduce TMAO-mediated oxidative stress. In this context, nutritional strategies are well-known as activators of cellular antioxidant responses. As Brazil nuts have a known role in reducing oxidative stress by increasing glutathione peroxidase (GPx) activity (a selenium-dependent antioxidant enzyme), this study hypothesized that Brazil nuts could be a strategy that, via antioxidant capacity, would reduce TMAO plasma levels. Although no changes in TMAO levels and GPx activity can be observed in this study, it is believed that other results can be obtained depending on the dosage used. Thus, this study can open new paths and direct other studies with different doses and treatment times to evaluate the effects of Brazil Nuts on TMAO levels.

Brazil Nut Supplementation Does Not Regulate PPARβ/δ Signaling Pathway in Peripheral Blood Mononuclear Cells from Coronary Artery Disease Patients

BACKGROUND

Peroxisome proliferator-activated receptor (PPAR)β/δ activation is a potential target for modulation of inflammation in cardiovascular disease. PPARβ/δ activation depends on the presence of a ligand, which may be pharmacological or natural, such as bioactive compounds and nutrients. Due to its composition, rich in selenium and unsaturated fatty acids, Brazil nuts have been related to reduced oxidative stress and inflammation in chronic non-communicable diseases and could regulate PPARβ/δ. This study aimed to evaluate the effects of Brazil nut supplementation on PPARβ/δ mRNA expression in patients with Coronary Artery Disease (CAD).

METHODS

A secondary analysis of a randomized controlled clinical trial was performed with 36 CAD patients. Patients were randomly assigned to either the Supplementation group or the control group and followed up for three months. The Supplementation group consumed 1 Brazil nut/day; the control group did not receive any intervention. At the baseline and after three months, analysis of gene expression and biochemical parameters linked to inflammatory biomarkers and oxidative stress was carried out.

RESULTS

In the supplementation group, no significant change was observed in PPARβ/δ (0.9 ± 0.5 vs 1.2 ± 0.6; p = 0.178) and NF-κB (1.6 ± 1.5 vs 0.8 ± 0.30, p = 0.554) mRNA expression. There were no significant changes in both groups concerning all the other biochemical parameters.

CONCLUSION

One Brazil nut per day for three months was not able to increase the PPARβ/δ expression in CAD patients.