Red raspberry improves postprandial metabolic indices and cognitive function in older adults who are overweight or have obesity

Metabolic dysregulation increases the risk of cognitive and motor deficits, exacerbated by diets high in refined carbohydrates and fats. Polyphenol-rich berries, such as red raspberries (RRB; <i>Rubus idaeus</i>), may offer protective benefits. This randomised, single-blinded, controlled crossover study evaluated the acute metabolic and cognitive effects of RRB intake in older adults (55-70 years) with overweight/obesity. Thirty-six adults (61 (sd 5) years, BMI: 30·0 (sd 2·8) kg/m²; 19 females: 17 males) consumed a high-carbohydrate, moderate-fat meal (56 % carbohydrate, 33 % fat) containing 0 g (control) or 25 g of freeze-dried RRB powder. Plasma was collected at baseline and postprandially over 7·5 h to assess glucose, insulin, triacylglyceride (TAG) and IL-6. <i>In vitro</i>, fasting and postprandial serum samples were applied to lipopolysaccharide (LPS)-stimulated microglial cells to assess neuroinflammatory responses (nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) expression). Cognitive and vascular function were assessed at baseline and postprandially. The RRB meal significantly reduced peak glucose (by 8 %), insulin concentrations at 0·5 h and overall insulin response compared with control (<i>P</i> < 0·05). Serum from RRB consumers attenuated LPS-induced NO, iNOS and COX-2 expression in microglial cells (<i>P</i> < 0·001). Cognitive performance improved following the RRB meal, with fewer attempts in the CANTAB (Cambridge Neuropsychological Test Automated Battery) Paired Associates Learning task (<i>P</i> < 0·05) and fewer errors with better strategy use in the Spatial Working Memory task (<i>P</i> < 0·05). No significant differences were observed in vascular function. These findings suggest that acute RRB supplementation attenuated postprandial metabolic stress, reduced markers of neuroinflammation and improved cognitive performance, supporting RRB's potential role in a dietary strategy for ageing populations.