A role for dietary saccharide intake in cognitive performance

Considerations in selection of diet assessment methods for examining the effect of nutrition on cognition

Older adults are the most rapidly growing age group in the United States, and it is estimated that 22.2 % of U.S. adults over 71 years of age have cognitive impairments without dementia and 13.9% have dementia. Cognitive impairment is associated with reduced quality of life, increased risk of hospitalization, inability to live independently, and increased health care costs; therefore, identification of modifiable risk factors for prevention and delay of cognitive decline is of increasing importance. There is a growing body of research and interest in the relationship between diet and cognitive function. Epidemiologic studies suggest that cognitive function may be improved and cognitive decline prevented as a function of a particular nutrient, food group or dietary pattern; however, results from these trials have failed to be replicated in randomized controlled trials. One possible reason for the equivocality of findings in the diet and cognitive function literature may be the methodological issues and limitations in the assessment of dietary patterns and nutritional intake. Self-reported dietary data can be biased by many factors such as age, gender, socioeconomic status, and education; yet, there is limited research on the impact of cognitive function on the integrity of self-reported dietary data. Cognitive function itself may bias diet assessment methods, subsequently obscuring the evaluation of the nutrition-cognition relationship. The present review summarizes methodological validation studies that provide insight into potential errors of diet assessment methods due to cognitive function, identifies research gaps and provides recommendations for improving diet assessment accuracy in studies of individuals with cognitive impairments.

Saccharide effects on cognition and well-being in middle-aged adults: a randomized controlled trial

The current study used a randomized, double-blind, placebo-controlled design to investigate the effects of saccharide supplementation on cognition and well-being in middle-aged adults. Participants (N = 109; 45-60 years) took a teaspoon of a combination of saccharides or a placebo twice daily for 12 weeks (3.6 g per day). Before and after this supplementation period, participants completed alternate forms of standardized tests of cognition and self-report measures of well-being. Significant beneficial effects of saccharide supplementation were found for memory performance and indicators of well-being. The potential for these nutrients to optimize cognitive function and well-being in older adults warrants ongoing investigation.

The influence of carbohydrate on cognitive performance: a critical evaluation from the perspective of glycaemic load

Links between nutrition and cognition are widely acknowledged. Within the context of short-term cognitive performance, carbohydrate has been the dietary component most commonly investigated. The majority of studies investigating the influence of carbohydrate on cognitive performance have employed oral glucose drink interventions followed by measures of performance on cognitive tests. More recently, studies have investigated the effect of different carbohydrates on cognitive performance rather than just pure glucose drinks. To date, studies have not been evaluated based on a standardised measure of glycaemic response, such as glycaemic load. The present review provides a critical evaluation of eight studies that have explored the relationships between food carbohydrate and cognitive performance and allow glycaemic load to be used as a basis for comparison. The key finding is that these provide insufficient evidence to support a consistent effect of glycaemic load on short-term cognitive performance. Future studies should employ consistent test methodologies and describe food interventions in more detail to facilitate meaningful comparisons and interpretations of results.

Association between dietary saccharide intake and self-reported memory performance in middle-aged adults

The aims of the present study were to assess dietary intake of saccharides in middle-aged adults, and to determine whether intakes of these sugar nutrients were related to self-reported memory performance. A population-based sample of 1183 men and women (aged 40–60 years) completed questionnaires assessing everyday memory function. Dietary intake status of saccharides was estimated using a self-completed, quantified FFQ. After controlling for demographic and health measures (for example, time spent exercising, smoking and alcohol consumption), saccharide intake was related to better self-reported memory functioning. Thus, longer-term intakes of saccharides through the usual diet may be positively related to perceived memory performance in mid-life.