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Nitrate-rich beetroot juice modulates cerebral blood flow and cognitive performance in humans
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K.M. Appleton, S. Higgs / Appetite 57 (2011) 553–569
Nitrate-rich beetroot juice modulates cerebral blood flow and cognitive performance in humans C.F. HASKELL ∗ , K. THOMPSON, A.M. JONES, J.R. BLACKWELL, P.G. WINYARD, J. FORSTER, D.O. KENNEDY Brain, Performance and Nutrition Research Centre, School of Life Sciences, Northumbria University, Newcastle-upon-Tyne NE1 8ST, UK E-mail address: [email protected] (C.F. Haskell). Dietary nitrate, which is most often consumed in vegetables, is converted to nitrite in the body and thereafter to nitric oxide (NO). Nitrate has been shown to improve endothelial function, reduce blood pressure and the oxygen cost of sub-maximal exercise, and increase regional perfusion in the brain. The most abundant supply of dietary nitrate is found in beetroot. In this double blind, placebo controlled, parallel-groups study, 40 healthy young adults received either 450 ml of beetroot juice (∼5.5 mmol nitrate) or a fruit flavoured placebo drink. Following a 90-min drink/absorption period participants performed the Cognitive Demand Battery (Serial 3 and Serial 7 subtractions—2 min each; Rapid Visual Information Processing—5 min) six times in succession (i.e. 54 min of task performance). Cerebral blood-flow (CBF) and haemodynamics, as indexed by concentration changes in oxygenated and deoxygenated-haemoglobin, were assessed in the frontal cortex throughout using Near Infrared Spectroscopy (NIRS). The bioconversion of nitrate to nitrite was confirmed in plasma by ozone-based chemi-luminescence. Dietary nitrate increased levels of nitrite, and modulated the haemodynamic response to task performance, with an initial increase in CBF at the start of the task, followed by consistent reductions during the RVIP task. Cognitive performance was improved on the Serial 3 s subtraction task. CBF was also modulated during the 30-min drink consumption period, most likely as a consequence of the sensory properties of the drinks. Dietary nitrate can enhance cognitive performance and modulate the CBF response to tasks. These effects on brain function may well be predicated on increased synthesis of NO. doi:10.1016/j.appet.2011.05.076 Rhythm in food intake: The effects of the intake of others on young women’s food intake in micro-perspective R.C.J. HERMANS ∗ , A. LICHTWARCK-ASCHOFF, J.K. LARSEN, C.P. HERMAN, R.C.M.E. ENGELS Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands E-mail address: [email protected] (R.C.J. Hermans). Numerous experimental studies have already demonstrated that people adjust their food intake to that of their eating companions. Until now, these studies have mostly used a normative framework to explain why people eat more or less when their eating companions eat more or less. Another possibility, however, is that social modeling processes may be caused by behavioral mimicry, whereby the food intake of one person triggers a mimicked response by the other person. In the current study, we investigated whether young women synchronize their intake (in bites) to that of their same-sex eating companion, a process that may be linked to behavioral mimicry. We observed and coded both the participant’s and confederate’s timing of bites taken during a 20-min eating opportunity. Synchronization was operationalized as participant’s bite within 5 s after a confederate’s bite. A total of 72 young women (mainly university students) participated. Analyses reveal that participants’ synchronize their intake to that of their eating companion. That is, they are likely to take a bite directly after their eating companion has done so. This may suggest that people not only model the overall intake of their eating companion, but also synchronize their intake patterns (in bites) to that of their eating companion. doi:10.1016/j.appet.2011.05.077
Flavour–flavour learning in children: Encouraging liking for a novel vegetable M.M. HETHERINGTON ∗ , S. AHERN, K. DOWNIE, D. MCSORLEY, S. CATON Institute of Psychological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom E-mail address: [email protected] (M.M. Hetherington). Habitual consumption of vegetables has known health benefits, however children across the EU fail to consume the recommended amounts. Several experiments have attempted to increase liking and intake of vegetables in children using flavour–flavour (FFL) or flavour nutrient learning (FNL). These have shown variable levels of success. A recent failed FNL study attributed lack of effect to the strong intensity of the flavour of vegetables; whereas FFL in which a sweet taste was paired with vegetable juice produced an increase in liking. Adding even small amounts of sugar to vegetables contravenes health messages to reduce sugar intake. The present study set out to pair a novel flavour (cinnamon) with a sweet taste (apple sauce) and then to offer a novel (target) vegetable (parsnip) with the flavour paired with the sweet taste to determine whether vegetable liking could be improved by association with a liked flavour. 15 children aged 14–49 m completed the study. Intake of the target vegetable was measured before repeated exposure to apple and cinnamon for at least 7 sessions. Then intake of the target vegetable plus cinnamon was measured. Intake of the target did not increase significantly (15.2 ± 5 g; 17.3 ± 7 g) although intake of apple sauce with cinnamon increased from 48.5 ± 10 g to 76 ± 7 g (p < 0.01). A forced choice task at 6 weeks after the last exposure demonstrated a strong liking for both forms of apple sauce. Clearly, sweet taste is a more potent stimulus than a novel flavour associated with sweet taste in promoting vegetable liking. Funding: EU (FP7/ 2007-2013) no. FP7-245012-“HabEat” doi:10.1016/j.appet.2011.05.078
K.M. Appleton, S. Higgs / Appetite 57 (2011) 553–569
Nitrate-rich beetroot juice modulates cerebral blood flow and cognitive performance in humans C.F. HASKELL ∗ , K. THOMPSON, A.M. JONES, J.R. BLACKWELL, P.G. WINYARD, J. FORSTER, D.O. KENNEDY Brain, Performance and Nutrition Research Centre, School of Life Sciences, Northumbria University, Newcastle-upon-Tyne NE1 8ST, UK E-mail address: [email protected] (C.F. Haskell). Dietary nitrate, which is most often consumed in vegetables, is converted to nitrite in the body and thereafter to nitric oxide (NO). Nitrate has been shown to improve endothelial function, reduce blood pressure and the oxygen cost of sub-maximal exercise, and increase regional perfusion in the brain. The most abundant supply of dietary nitrate is found in beetroot. In this double blind, placebo controlled, parallel-groups study, 40 healthy young adults received either 450 ml of beetroot juice (∼5.5 mmol nitrate) or a fruit flavoured placebo drink. Following a 90-min drink/absorption period participants performed the Cognitive Demand Battery (Serial 3 and Serial 7 subtractions—2 min each; Rapid Visual Information Processing—5 min) six times in succession (i.e. 54 min of task performance). Cerebral blood-flow (CBF) and haemodynamics, as indexed by concentration changes in oxygenated and deoxygenated-haemoglobin, were assessed in the frontal cortex throughout using Near Infrared Spectroscopy (NIRS). The bioconversion of nitrate to nitrite was confirmed in plasma by ozone-based chemi-luminescence. Dietary nitrate increased levels of nitrite, and modulated the haemodynamic response to task performance, with an initial increase in CBF at the start of the task, followed by consistent reductions during the RVIP task. Cognitive performance was improved on the Serial 3 s subtraction task. CBF was also modulated during the 30-min drink consumption period, most likely as a consequence of the sensory properties of the drinks. Dietary nitrate can enhance cognitive performance and modulate the CBF response to tasks. These effects on brain function may well be predicated on increased synthesis of NO. doi:10.1016/j.appet.2011.05.076 Rhythm in food intake: The effects of the intake of others on young women’s food intake in micro-perspective R.C.J. HERMANS ∗ , A. LICHTWARCK-ASCHOFF, J.K. LARSEN, C.P. HERMAN, R.C.M.E. ENGELS Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands E-mail address: [email protected] (R.C.J. Hermans). Numerous experimental studies have already demonstrated that people adjust their food intake to that of their eating companions. Until now, these studies have mostly used a normative framework to explain why people eat more or less when their eating companions eat more or less. Another possibility, however, is that social modeling processes may be caused by behavioral mimicry, whereby the food intake of one person triggers a mimicked response by the other person. In the current study, we investigated whether young women synchronize their intake (in bites) to that of their same-sex eating companion, a process that may be linked to behavioral mimicry. We observed and coded both the participant’s and confederate’s timing of bites taken during a 20-min eating opportunity. Synchronization was operationalized as participant’s bite within 5 s after a confederate’s bite. A total of 72 young women (mainly university students) participated. Analyses reveal that participants’ synchronize their intake to that of their eating companion. That is, they are likely to take a bite directly after their eating companion has done so. This may suggest that people not only model the overall intake of their eating companion, but also synchronize their intake patterns (in bites) to that of their eating companion. doi:10.1016/j.appet.2011.05.077
Flavour–flavour learning in children: Encouraging liking for a novel vegetable M.M. HETHERINGTON ∗ , S. AHERN, K. DOWNIE, D. MCSORLEY, S. CATON Institute of Psychological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom E-mail address: [email protected] (M.M. Hetherington). Habitual consumption of vegetables has known health benefits, however children across the EU fail to consume the recommended amounts. Several experiments have attempted to increase liking and intake of vegetables in children using flavour–flavour (FFL) or flavour nutrient learning (FNL). These have shown variable levels of success. A recent failed FNL study attributed lack of effect to the strong intensity of the flavour of vegetables; whereas FFL in which a sweet taste was paired with vegetable juice produced an increase in liking. Adding even small amounts of sugar to vegetables contravenes health messages to reduce sugar intake. The present study set out to pair a novel flavour (cinnamon) with a sweet taste (apple sauce) and then to offer a novel (target) vegetable (parsnip) with the flavour paired with the sweet taste to determine whether vegetable liking could be improved by association with a liked flavour. 15 children aged 14–49 m completed the study. Intake of the target vegetable was measured before repeated exposure to apple and cinnamon for at least 7 sessions. Then intake of the target vegetable plus cinnamon was measured. Intake of the target did not increase significantly (15.2 ± 5 g; 17.3 ± 7 g) although intake of apple sauce with cinnamon increased from 48.5 ± 10 g to 76 ± 7 g (p < 0.01). A forced choice task at 6 weeks after the last exposure demonstrated a strong liking for both forms of apple sauce. Clearly, sweet taste is a more potent stimulus than a novel flavour associated with sweet taste in promoting vegetable liking. Funding: EU (FP7/ 2007-2013) no. FP7-245012-“HabEat” doi:10.1016/j.appet.2011.05.078