Wild Blueberry Extract Intervention in Healthy Older Adults: A Multi-Study, Randomised, Controlled Investigation of Acute Cognitive and Cardiovascular Effects

BACKGROUND

Circadian and homeostatic declines in cognitive performance are observed during the day, most commonly at 14:00. Additionally, postprandial reductions in cognitive ability have been widely demonstrated 1 h after lunch consumption, affecting domains of executive functioning (EF), episodic memory (EM), and attention. Existing evidence shows that anthocyanin-rich foods such as berries may improve or attenuate the decline in EF and EM in ageing adults. Further research is required to assess whether extracts such as wild blueberry extract (WBE) may be beneficial for cognitive function across an acute timeframe, including known periods of reduced functioning.

OBJECTIVES

(1) Study 1: ROAB: To investigate the efficacy of WBE in maintaining EF and EM throughout the day alongside measures of cardiovascular outcomes in healthy older adults. A range of WBE doses were utilised to identify the optimal dose at which cognitive and cardiovascular effects occur. (2) Study 2: BEAT: To replicate alleviation of cognitive decline during a predicted post-lunch dip whilst also improving cardiovascular outcomes following acute WBE 222 mg supplementation.

METHODS

Both studies employed a randomised, double-blind, cross-over, placebo-controlled design to explore the effects of WBE intervention versus placebo on several outcomes, including EM, EF, blood pressure, and heart rate in a healthy older adult population (aged 68-75). In ROAB, 28 participants received a single dose of WBE 111 mg, 222 mg, 444 mg, or 888 mg or placebo over a 5-week period, each separated by a 1-week washout. Outcomes were measured at 0 h, 2 h, 4 h, and 6 h post intervention, with intervention occurring immediately after baseline (0 h). In BEAT, 45 participants received WBE 222 mg and placebo (1-week washout). Outcomes were measured at 0 h and 6 h (14:00) when a post-lunch dip was anticipated. This was further enhanced by consumption of lunch 1 h prior to cognitive testing. The WBE 222 mg intervention aligned with known peaks in plasma blueberry polyphenol metabolites at 2 h post dosing, which would coincide with a predicted drop in post-lunch performance.

RESULTS

ROAB: A significant dip in executive function was apparent at the 4 h timepoint for placebo only, indicating attenuation for WBE doses. Strikingly, WBE 222 mg produced acute reductions in both systolic and diastolic blood pressure compared with placebo. BEAT: EF reaction time was found to be significantly faster for WBE 222 compared to placebo at the predicted post-lunch dip (14:00), with no other notable benefits on a range of cognitive and cardiovascular outcomes.

CONCLUSION

These two studies indicate that WBE may have cardiovascular benefits and attenuate the natural cognitive decline observed over the course of the day, particularly when a decline is associated with a circadian rhythm-driven postprandial dip. However, it is important to acknowledge that effects were subtle, and benefits were only observed on a small number of outcomes. Further research is required to explore the utility of WBE in populations already experiencing mild cognitive impairments.

Blueberry extract alleviated lipopolysaccharide-induced inflammation responses in mice through activating the FXR/TGR5 signaling pathway and regulating gut microbiota

BACKGROUND

Blueberry extract (BE) is rich in phenols, especially anthocyanins. Anthocyanins regulate the inflammatory response in mice and may be related to gut microbiota and bile acid receptors. The aim of the present study was to explore the effects of BE on the inflammatory response by regulating gut microbiota and bile acid receptors in mice administered Escherichia coli lipopolysaccharide (LPS).

METHOD

Thirty male KM mice were randomly divided into three groups: CON (control diet) group; LPS (LPS stimulation) group; and LPS + BE (LPS stimulation, 5% BE intervention) group.

RESULTS

our results showed that, compared with the LPS group, the addition of BE decreased the level of inflammatory factors in serum and tissues, inhibited the TLR4/MyD88 signaling pathway, protected the intestinal barrier and activated FXR/TGR5, which was related to gut microbiota (especially Akkermansia). The active component (e.g., cyanidin 3-O-glucoside, C3G) in BE may be an important factor in regulating gut microbiota.

CONCLUSION

BE alleviated the inflammatory response mainly by activating bile acid receptor expression and regulating the gut microbiota; this effect may be related to the composition of bioactive substances in BE. © 2023 Society of Chemical Industry.

Selective Activity of an Anthocyanin-Rich, Purified Blueberry Extract upon Pathogenic and Probiotic Bacteria

Blueberry extracts have been widely recognized as possessing antimicrobial activity against several potential pathogens. However, the contextualization of the interaction of these extracts with beneficial bacteria (i.e., probiotics), particularly when considering the food applications of these products, may be of importance, not only because their presence is important in the regular gut microbiota, but also because they are important constituents of regular and functional foodstuffs. Therefore, the present work first sought to demonstrate the inhibitory effect of a blueberry extract upon four potential food pathogens and, after identifying the active concentrations, evaluated their impact upon the growth and metabolic activity (organic acid production and sugar consumption) of five potential probiotic microorganisms. Results showed that the extract, at a concentration that inhibited L. monocytogenes, B. cereus, E. coli and S. enteritidis (1000 μg mL^-1), had no inhibitory effect on the growth of the potential probiotic stains used. However, the results demonstrated, for the first time, that the extract had a significant impact on the metabolic activity of all probiotic strains, resulting in higher amounts of organic acid production (acetic, citric and lactic acids) and an earlier production of propionic acid.

Neuroprotective effect of wild lowbush blueberry (Vaccinium angustifolium) on global cerebral ischemia/reperfusion injury in rats: Downregulation of iNOS/TNF-α and upregulation of miR-146a/miR-21 expression

This study aims to investigate the neuroprotective effect of wild lowbush blueberry on CIRI in rats. Accordingly, CIRI and reperfusion were induced in rats for 60 min and 24 h, respectively. Then, the mechanisms of the neuroprotective effects of BBE were investigated in the injury through evaluating miR-146a, miR-21, and their targets in a CIRI rat model. After that, the BBE (30, 60, and 120 mg/kg b.wt) was intraperitoneally injected for 14 days, then CIRI was induced by BCCAO for 60 min for ischemic stroke and reperfusion for 24 h. Several parameters including the oxidative stress levels in the hippocampus and serum were measured 24 h after the CIRI. The findings showed that the BBE significantly decreased the levels of malondialdehyde (MDA) and nitric oxide (NO) and increased ferric ion reducing antioxidant power (FRAP) levels in the hippocampus and serum following the stroke. The BBE also maximized the miR-146a and miR-21 expressions and moderated iNOS and TNF-α expressions in the hippocampus. Likewise, the BBE enlarged the CA1 and CA3 domains of the post-stroke pyramidal cell layers of the hippocampus. Overall, the results revealed that BBE had potent neuroprotective efficacy against CIRI via the effective modulation of neuroinflammatory cascades and protected neurons against ischemic death.

Chlorogenic Acid Improves Symptoms of Inflammatory Bowel Disease in Interleukin-10 Knockout Mice

Inflammatory bowel disease (IBD) is a chronic intestinal inflammation that is highly prevalent worldwide. Interleukin (IL)-10 can effectively inhibit negative cascades such as the production of inflammatory mediators (inducible nitric oxide synthase [iNOS], cyclooxygenase-2), accumulation of inflammatory infiltrates (macrophages, eosinophils, neutrophils), toxicity (lower T cell subsets), and secretion of pro-inflammatory cytokines (IL-1β, TNF-α) in tissues such as the spleen, mesenteric lymph nodes (MLN), Peyer's patch (PP), and colon. In this study, we investigated whether chlorogenic acid (CHA) can regulate inflammation in IL-10 knockout (KO) mice used as an IBD animal model. CHA significantly increased the ratio of CD4⁺/CD8⁺, T cell subsets in PP, and MLN of IL-10 KO mice. In addition, CHA also morphologically attenuated colon inflammation in IL-10 KO mice. We demonstrated that CHA significantly reduced the expression levels of iNOS, IL-1β, TNF-α, which were highly expressed in IL-10 KO mice. Therefore, CHA may provide beneficial effects for improving IBD by decreasing inflammations.

Sex Modulates Lactobacillus johnsonii N6.2 and Phytophenol Effectiveness in Reducing High Fat Diet Induced mTOR Activation in Sprague-Dawley Rats

Metabolic syndrome (MetS) is the underlying cause of some devastating diseases, including type 2 diabetes and cardiovascular disease. These diseases have been associated with over-activation of the mechanistic Target of Rapamycin (mTOR) pathway. This study utilizes a high fat diet (HFD) to induce MetS and to dissect the effects of a beneficial bacterium, L. johnsonii N6.2, and natural phenolics on mTOR complex 1 (mTORC1) expression compared to a reduced energy density diet (REDD). HFD significantly elevated MetS markers in males, as noted through an increase in weight, glucose levels, and triglyceride levels. Treatments were effective in reducing mTORC1-activating phosphorylation of pAKT-T308 and pAKT-S473 (p = 0.0012 and 0.0049, respectively) in HFD-fed females, with the combined treatments of L. johnsonii and phytophenols reducing phosphorylation below REDD-fed control levels, and significantly below HFD-fed control levels. Meanwhile, diet was the significant factor influencing male mTORC1-activating phosphorylation (p < 0.0001), as treatments were only effective in reducing phosphorylation in REDD-fed animals. Downstream analysis of mTORC1 activated genes phosphogluconate dehydrogenase (pgd) and phosphofructose kinase (pfk) followed this similar trend, enforcing the significant effect sex has on a treatments’ ability to modulate diet induced abnormalities. Analyzing mTORC1 stimulators such as insulin, inflammatory cytokines, and tryptophan, revealed no significant differences among groups. These results indicate that the effects observed on mTORC1 are a direct consequence of the treatments, and not exerted indirectly via the modulation of stimuli. This study highlights the potential use of commensal microorganisms and natural compounds in reducing the onset of metabolic diseases through mTORC1.

The protective effects of a polyphenol-enriched protein powder on exercise-induced susceptibility to virus infection

Prolonged and intensive exercise induces transient immunosuppression and is associated with an increased risk and severity of infections. The goal of this study was to characterize the antiviral and antibacterial properties of the bioactive metabolites of a blueberry-green tea-polyphenol soy protein complex (PSPC) in the serum of supplemented subjects during a 3-day intensified training period. Long-distance runners, randomly divided into two groups, ingested 40 g/day PSPC or placebo (soy protein and colorings) for 17 days, with a 3-day running period inserted at day 14. Blood serum samples were collected pre-14 days and post-14 days supplementation, and immediately and 14 h after the third day of running. The post-exercise serum from both groups significantly promoted the growth of Escherichia coli and Staphylococcus aureus in culture by 20-70%, but returned to normal levels following recovery. Furthermore, the serum from subjects ingesting PSPC did not display antibacterial properties at any time point. In contrast, there was a significant difference in the ability of serum from PSPC-supplemented versus placebo-supplemented athletes to protect cells in culture from killing by vesicular stomatitis virus following strenuous exercise. In addition, the serum of subjects who ingested PSPC significantly delayed an exercise-induced increase in virus replication. These results indicate that polyphenol complexes containing blueberry and green tea have the potential to protect athletes from virus infections following rigorous exercise.