Dietary polyphenols, which are present in Aronia melanocarpa, have been associated with various beneficial effects on human health including antioxidant, antiviral, and anti-inflammatory activities. We aimed to investigate the immunomodulatory effects of aronia juice polyphenols in a randomized placebo-controlled human intervention study and cell culture experiments. A total of 40 females were asked to consume either 200 mL of aronia juice or a placebo drink for six weeks and were investigated again after a washout period of another six weeks. We observed that only half of the participants tolerated the aronia juice well (Vt) and the other half reported complaints (Vc). The placebo (P) was generally tolerated with one exception (p = 0.003). Plasma polyphenol levels increased significantly in Vt after the intervention (p = 0.024) but did neither in P nor in Vc. Regulatory T cell (Treg) frequencies remained constant in Vt and P during the intervention, whereas Tregs decreased in Vc (p = 0.018). In cell culture, inhibiting effects of ferulic acid (p = 0.0005) and catechin (p = 0.0393) on the differentiation of Tregs were observed as well as reduced activation of CD4-T cells in ferulic acid (p = 0.0072) and aronia juice (p = 0.0163) treated cells. Interestingly, a CD4⁺CD25⁻FoxP3⁺ cell population emerged in vitro in response to aronia juice, but not when testing individual polyphenols. In conclusion, our data strengthen possible individual hormetic effects, the importance of the food matrix for bioactivity, and the need for further investigations on possible impacts of specific physiological features such as the gut microbiota in the context of personalized nutrition.

With a constantly growing elderly population, incidences of neurodegenerative diseases are also rising and are expected to further increase over the next years, while costing health systems across the world trillions of dollars. Therefore, biomarkers to detect manifestations of brain aging early and interventions to slow down its pace are of great interest. In the last years, the importance of the neurotrophins brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the context of cognitive function and the aging brain has increased, besides the already well-established amyloid-beta (Aβ) and tau plaques. Due to their wide range of beneficial health effects as well as their antioxidant and anti-inflammatory properties, a class of secondary plant-metabolites, the so-called polyphenols, gained increasing attention. In this review, we discuss the roles of BDNF, Aβ, NGF, and tau proteins as biomarkers of brain aging and the effect of dietary polyphenol interventions on these biomarkers, assessed via blood analysis, magnetic resonance imaging (MRI), and positron emission tomography (PET).

Ageing is a process characterised by chronic low-grade inflammation and oxidative stress which could lead to increased prevalence of both physical and mental age-related chronic conditions. A healthy balanced diet, rich in fruit and vegetables as well as omega-3 polyunsaturated fatty acids (n3 PUFA), could reduce oxidative stress and improve markers of low-grade inflammation. Nonetheless, considering that a large part of the population struggles to meet current guidelines on fruit and vegetable and n3 PUFA recommendations, fruit and vegetable concentrate supplements and mixed omega fatty acid supplements could be an effective strategy to bridge the gap between actual and recommended intakes. In this randomised, controlled, open-labelled, parallel-grouped clinical trial, 112 participants will be allocated to one of four arms (n = 28 on each arm): an encapsulated juice powder concentrate, a plant-based omega fatty acid supplement, both or a control group. We aim to investigate whether long-term separate or combined ingestion of the two can affect biomarkers of cardiovascular health, low-grade inflammation and indicators of ageing, including cognitive function, in middle-aged and elderly people. We will additionally explore the effect of the different supplementations on plasma levels of vitamins, carotenoids and fatty acids. Intervention will last 2 years and participants will be assessed at baseline and at follow-up visits at 6, 12, 18 and 24 months. This study will provide evidence whether long-term, plant-based dietary supplementation can support cardiovascular health, anti-inflammatory processes, immunity and nutritional status in ageing. Trial registration This trial was registered at ClinicalTrials.gov (NCT04763291) on February 21, 2021.