The influence of fat co-administration on the glucose memory facilitation effect

Memory for a list of 20 words can be enhanced when learning is preceded by consumption of 25 g of glucose, compared with consumption of an equally sweet aspartame solution. The present study examined whether memory performance is also enhanced when glucose is administered in conjunction with another food constituent, in particular fat. Four groups of healthy young participants were tested under one of four conditions: (a) glucose + full-fat yoghurt; (b) glucose + fat-free yoghurt; (c) aspartame + full-fat yoghurt; (d) aspartame + fat-free yoghurt. The groups were compared on measures of blood glucose and cognitive performance. Participants receiving a glucose drink in conjunction with a fat-free yoghurt displayed higher blood glucose levels (BGL) and better performance on short- and long-delay recall of the word list compared with (a) individuals who consumed the glucose drink in conjunction with a full-fat yoghurt and (b) individuals who consumed the aspartame drink. The glycaemic data indicated that the presence of fat slows down glucose absorption. The findings suggest that only foods with a relatively fast glucose absorption rate are able to significantly enhance the encoding and long-term retention of novel memory materials in healthy young adults.