OBJECTIVES: To investigate the in¯uences of inactivity and dietary macronutrient composition on energy and fat balance and to look for interactions between them. DESIGN: Two-day measurements of energy expenditure and substrate oxidation on ®ve occasions; ad libitum food intake from diets of 35% and 60% energy as fat, with and without imposed activity, and a ®xed overfeeding at 35% fat with free activity. SUBJECTS: Eight normal-weight male volunteers. MEASUREMENTS: Energy expenditure and substrate oxidation by indirect whole-body calorimetry, and macronutrient intakes from food consumption on ad libitum regimens. RESULTS: Subjects consumed the same energy, mean 11.6 MJad, regardless of activity level, on the 35% diet. Subjects consumed more energy on the 60% than the 35% diet, mean 14 vs 11.6 MJad. Inactivity induced a strong positive energy balance: 5.1 (60% diet), and 2.6 MJad (35% diet). Energy balance with activity was not signi®cantly different between diets, nor signi®cantly different from zero: 1.1 MJad (60% diet), and 7 0.2 MJad (35% diet). When intentionally overfed, subjects failed to compensate by raising voluntary activity. CONCLUSION: Energy intake was not regulated over a 2-day period in response to either imposition of inactivity or a high-fat diet. Activity proved essential to the avoidance of signi®cant positive energy balance.

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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. Carbohydrate: Glycaemic load: Glycaemic index: Cognitive performanceThe principle that foods can reliably modulate cognitive performance is receiving validation and experimental support (1 -3) . As a consequence, the link between nutrition science and cognitive psychology is developing rapidly. Since glucose is the primary breakdown product of carbohydrate and the primary source of energy for the brain, its influence on cognitive performance has been the focus of much of the research in this area (1,4 -6) . The majority of studies investigating the link between glucose and cognitive performance have employed placebo-controlled oral glucose drink interventions followed by performance measures on behavioural tests (for example, memory, attention) with or without accompanying blood glucose measures (7 -9) . Administration of cognitive test batteries is commonly accompanied by measures of subjective states using visual analogue rating scales (1,3) . Although the evidence is not consistent, a number of studies have reported beneficial effects of glucose on performance measures, in particular on delayed verbal memory (10) . More recently, studies have investigated the effect of different carbohydrates on cognitive performance rather than just pure glucose drinks. Food interventions are typically described using terms such as glycaemic index (GI), glycaemic load (GL), the ratio of slowly to rapidly available glucose, the proportion of simple to complex carbohydrate, or the amount of rapidly v. slowly digested carbohydrate. Although more ecologically valid than pure glucose manipulations, different expressions used for the glycaemic potency of interventions render a direct comparison of results between studies difficult.Both the quality (for example, type, nature, source) and quantity of a carbohydrate are important determinants of its glycaemic r...

Previous research suggests that glucoregulation and nutrient interventions, which alter circulating glucose, impact cognitive function. To examine the effect of modulating glycemic response using isomaltulose on cognitive function 24 healthy male adult participants consumed energy and macronutrient-matched milk-based drinks containing 50 g isomaltulose, 50 g sucrose or a water control in a counterbalanced within-subject design. Interstitial glucose was measured continuously in 12 subjects and all provided 9 capillary measures on each test day. A 30-min cognitive test battery was administered before and twice (135 and 1 115 min) after drink ingestion. Immediate, delayed, recognition, verbal and working memory, and psychomotor performance were assessed. Glycemic profiles induced by the drinks differed significantly during the first but not the second post-drink test battery. Neither administration of the sucrose nor isomaltulose drinks produced consistent effects on verbal or working memory, or psychomotor performance. This study used isomaltulose as an investigative tool to lower glycemic response. Importantly, it demonstrates a lack of effect of modulating glucose on cognitive performance based on reliable, continuously measured glycemia. It refutes the hypothesis that glycemia is associated with cognitive performance and questions the suggestion that isomaltulose has an effect on cognitive performance.

Patterns of food additive usage in the Irish food supply and changes in patterns of usage between 1995-97 and 1998-99 were assessed by means of an Irish National Food Ingredient Database (INFID). Of the 300 additives permitted for use according to the European Union food additives Directives, some 54% were recorded in foods in INFID. Colours, emulsifiers and acids were the most frequently used additive categories, representing 18, 13 and 12% of the total additives used, respectively. Colours were most commonly recorded in sauces (n = 182 brands, 26% of sauces), emulsifiers were most commonly recorded in biscuits (n = 181 brands, 47% of biscuits) and acids were most commonly recorded in sauces (304 brands, 43% of sauces). Carotenes (E160a), Annatto (E160b), mono- and diglycerides of fatty acids (E471) and citric acid (E330) were the most commonly used colour, emulsifier and acid, respectively. All diet soft drinks (n = 37), low-fat spreads (n = 25) and liver pâtés (n = 10) recorded the use of at least one additive. When expressed in terms of the number of brands that contain additives, sauces (n = 522, 73% of sauces), biscuits (n = 323, 84% of biscuits) and preserves (n = 321, 85% of preserves) were ranked highest. For most categories of additive (n = 24), there appeared to be a minimal change in qualitative additive usage between 1995-97 and 1998-99. However, there was a significant increase in the frequency of use of emulsifiers (p < 0.001), acids (p < 0.01), sweeteners (p < 0.05) and acidity regulators (p < 0.05), and a significant decrease in the frequency of use of antioxidants (p < 0.05) during the period 1998-99 compared with 1995-97. Despite changes in additive usage patterns, it appeared that changes in the types of brands on sale between both periods were more apparent than actual changes in qualitative ingredient formulations across brands, as some 17% of brands that were on sale in 1995-97 were no longer on sale in 1998-99.