Oral processing of hydrogels: Influence of food material properties versus individuals' eating capability.

Food material properties play an important role in sensory perception and consumer acceptance of foods. However, the actual oral processing behavior may depend on both the material properties of the food that is being consumed and individuals' oral capabilities. This study aimed to examine the relationships between intrinsic (oral capabilities of healthy participants) and extrinsic (food material properties of a set of hydrogels) variables to the real oral processing behavior. Three κ-carrageenan hydrogels (κC), differing in fracture mechanics and oral tribology properties, were prepared: native κC, κC with added Na-alginate, and a κC matrix with added Ca-alginate beads of 300 µm. A composite score of eating capability (EC) was measured with non-invasive techniques (maximum bite force and tongue pressure) using a panel of 28 untrained consumers. The oral processing behaviors (number of chews, oral residence time, and chewing rate) were analyzed with the same participants using frame-by-frame video analysis. It was found that the EC scores did not correlate with any of the oral processing behaviors. The number of chews and oral residence time showed a strong correlation with the fracture force and friction force at orally relevant speeds (10-100 mm/s), whereas chewing rate did not vary with these properties. The results from this study indicate that oral processing in healthy adults seems mainly motivated by food material properties, and the chewing rate seems to relate more to individual differences and EC than to food properties. Insights from this study, using model hydrogels, have helped to promote knowledge on oral processing behavior in healthy individuals; could bridge the gap between consumer science, psychology, and food science; and may be of interest to product developers in designing foods with pleasant texture properties.

A systematic review and meta-analysis of the effects of mastication on sustained attention in healthy adults.

The aims of this paper are to conduct: 1) a systematic review of the effects of mastication on sustained attention, and 2) a meta-analysis of the effects of mastication on the performance of participants undertaking cognitive tests. Papers were obtained from MEDLINE and PsycInfo using a systematic approach incorporating defined inclusion and exclusion criteria. Twenty-one papers linking mastication and sustained attention were reviewed. Meta-analysis detected a weak, but statistically significant, improvement in levels of sustained attention when chewing with low between-study heterogeneity (mean Cohen's d = -0.1479 standard deviations, 95% CI [-0.2913, -0.0045], p = 0.043 & I2 = 0.00%), and a tendency for feelings of alertness to decrease less during cognitive demanding tasks when chewing (mean Cohen's d = 0.3797 standard deviations, 95% CI [-0.0053, 0.7647], p = 0.052 &I2 = 70.94%). To better understand the effects of mastication on sustained attention and alertness, further research is required which refines existing protocols, eliminates confounding effects such as gum formulation and constituents, and investigates the effects of contiguity, rate, and intensity of chewing.

Does reduced mastication influence cognitive and systemic health during aging?

There is a growing body of literature which suggests that oral health and mastication can influence cognitive and systemic health during aging. However, it is currently unclear whether oral health, masticatory efficiency, cognitive health and systemic health merely deteriorate independently with age, or whether mechanisms exist linking mastication to cognitive and systemic health directly. The aim of this paper is to review the extent to which reduced mastication influences cognitive and systemic health during aging because this knowledge may underpin future interventions that improve quality of life. Current evidence suggests that a deterioration in mastication and oral health during aging can have: 1) direct effects on systemic health through mechanisms such as the migration of the oral microbiota into the systemic environment, and 2) indirect effects on systemic health through changes nutrient intake. A loss of teeth and reduction in masticatory efficiency during aging can have: 1) direct effects on cognitive performance and potentially impact cognitive health through mechanisms such as enhanced adult hippocampal neurogenesis, and 2) indirect effects on cognitive health through changes in nutrient intake. It is concluded that oral health and masticatory efficiency are modifiable factors which influence the risk poor cognitive and systemic health during aging, although it is currently premature to propose chewing-based interventions to slow the rate of cognitive decline and improve cognitive health during aging. Future research should include large-scale longitudinal studies which control for the types of confounding factors which concurrently influence the association between mastication and cognitive and systemic health.

Influence of oral processing on appetite and food intake - A systematic review and meta-analysis.

Food delivers energy, nutrients and a pleasurable experience. Slow eating and prolonged oro-sensory exposure to food during consumption can enhance the processes that promote satiation. This systematic review and meta-analysis investigated the effects of oral processing on subjective measures of appetite (hunger, desire to eat) and objectively measured food intake. The aim was to investigate the influence of oral processing characteristics, specifically "chewing" and "lubrication", on "appetite" and "food intake". A literature search of six databases (Cochrane library, PubMed, Medline, Food Science and Technology Abstracts, Web of Science, Scopus), yielded 12161 articles which were reduced to a set of 40 articles using pre-specified inclusion and exclusion criteria. A further two articles were excluded from the meta-analysis due to missing relevant data. From the remaining 38 papers, detailing 40 unique studies with 70 subgroups, raw data were extracted for meta-analysis (food intake n = 65, hunger n = 22 and desire to eat ratings n = 15) and analyzed using random effects modelling. Oral processing parameters, such as number of chews, eating rate and texture manipulation, appeared to influence food intake markedly but appetite ratings to a lesser extent. Meta-analysis confirmed a significant effect of the direct and indirect aspects of oral processing that were related to chewing on both self-reported hunger (-0.20 effect size, 95% confidence interval CI: -0.30, -0.11), and food intake (-0.28 effect size, 95% CI: -0.36, -0.19). Although lubrication is an important aspect of oral processing, few studies on its effects on appetite have been conducted. Future experiments using standardized approaches should provide a clearer understanding of the role of oral processing, including both chewing and lubrication, in promoting satiety.

Poor cognitive ageing: Vulnerabilities, mechanisms and the impact of nutritional interventions.

BACKGROUND: Ageing is a highly complex process marked by a temporal cascade of events, which promote alterations in the normal functioning of an individual organism. The triggers of normal brain ageing are not well understood, even less so the factors which initiate and steer the neuronal degeneration, which underpin disorders such as dementia. A wealth of data on how nutrients and diets may support cognitive function and preserve brain health are available, yet the molecular mechanisms underlying their biological action in both normal ageing, age-related cognitive decline, and in the development of neurodegenerative disorders have not been clearly elucidated. OBJECTIVES: This review aims to summarise the current state of knowledge of vulnerabilities that predispose towards dysfunctional brain ageing, highlight potential protective mechanisms, and discuss dietary interventions that may be used as therapies. A special focus of this paper is on the impact of nutrition on neuroprotection and the underlying molecular mechanisms, and this focus reflects the discussions held during the 2nd workshop 'Nutrition for the Ageing Brain: Functional Aspects and Mechanisms' in Copenhagen in June 2016. The present review is the most recent in a series produced by the Nutrition and Mental Performance Task Force under the auspice of the International Life Sciences Institute Europe (ILSI Europe). CONCLUSION: Coupling studies of cognitive ageing with studies investigating the effect of nutrition and dietary interventions as strategies targeting specific mechanisms, such as neurogenesis, protein clearance, inflammation, and non-coding and microRNAs is of high value. Future research on the impact of nutrition on cognitive ageing will need to adopt a longitudinal approach and multimodal nutritional interventions will likely need to be imposed in early-life to observe significant impact in older age.