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. 2011 Jan 1;24(1):34-42.
doi: 10.1016/j.niox.2010.10.002. Epub 2010 Oct 15.

Acute Effect of a High Nitrate Diet on Brain Perfusion in Older Adults

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Free PMC article

Acute Effect of a High Nitrate Diet on Brain Perfusion in Older Adults

Tennille D Presley et al. Nitric Oxide. .
Free PMC article

Abstract

Aims: Poor blood flow and hypoxia/ischemia contribute to many disease states and may also be a factor in the decline of physical and cognitive function in aging. Nitrite has been discovered to be a vasodilator that is preferentially harnessed in hypoxia. Thus, both infused and inhaled nitrite are being studied as therapeutic agents for a variety of diseases. In addition, nitrite derived from nitrate in the diet has been shown to decrease blood pressure and improve exercise performance. Thus, dietary nitrate may also be important when increased blood flow in hypoxic or ischemic areas is indicated. These conditions could include age-associated dementia and cognitive decline. The goal of this study was to determine if dietary nitrate would increase cerebral blood flow in older adults.

Methods and results: In this investigation we administered a high vs. low nitrate diet to older adults (74.7±6.9 years) and measured cerebral perfusion using arterial spin labeling magnetic resonance imaging. We found that the high nitrate diet did not alter global cerebral perfusion, but did lead to increased regional cerebral perfusion in frontal lobe white matter, especially between the dorsolateral prefrontal cortex and anterior cingulate cortex.

Conclusion: These results suggest that dietary nitrate may be useful in improving regional brain perfusion in older adults in critical brain areas known to be involved in executive functioning.

Conflict of interest statement

Conflicts of Interest

Dr. Kim-Shapiro is listed as a co-author on a patent application entitled "USE OF NITRITE SALTS FOR THE TREATMENT OF CARDIOVASCULAR CONDITIONS".

Figures

Figure 1
Figure 1
Timeline of study design for the larger study that included MRI scans.
Figure 2
Figure 2
Plasma nitrate (A) and nitrite (B) levels prior to and at 30-minutes, 1-hour, 2-hours, and 3-hours following a high nitrate breakfast in the time course study. Plasma nitrite and nitrate were measured after consumption of a high nitrate breakfast following overnight fast. Averages and standard deviations are shown (n=5). * indicates significantly different than fasting values # indicates significantly different than at 30-minutes
Figure 3
Figure 3
Plasma nitrate (A) and nitrite (B) levels in the perfusion study. The levels reflect measures on days and 2 and 4 of the study, either before (Pre) or one hour after (Post) consuming breakfast on the high or low nitrate diet. Subjects consumed either a high or low nitrate diet starting on days 1 and 3 that continued through the breakfast before and after which blood was drawn. Values plotted are averages ± one standard deviation. * indicates significantly different than fasting values
Figure 4
Figure 4
Group cerebral blood flow maps (in ml/100g tissue/minute) for the 14 subjects on the high nitrate diet (left) and low nitrate diet (right). Both images are from a coronal slice through the frontal lobes. There is subtle increased perfusion within the frontal lobe gray matter and at the gray-white junction and within the white matter itself (smaller blue and purple regions). The cross-hairs were placed to illustrate those regions in Figure 5 where statistically significant increases in CBF were present on the high nitrate diet.
Figure 5
Figure 5
Cerebral blood flow (CBF) differences between the high nitrate diet and low nitrate diet states. Statistical maps show significant differences in regional blood flow for the n=14 subjects on the high nitrate diet versus on the low nitrate diet. Note the increased CBF (ml/100g/min) within the bilateral white matter of the frontal lobes, areas known to be at risk for chronic ischemia in the elderly. The bottom left image is a coronal slice at the level of genu of the corpus callosum. The diagonal stacked images are axial slices extending from the uppermost portions of the lateral ventricles superiorly to the basal ganglia/mid-body of the lateral ventricles inferiorly. Although there are some asymmetries to the findings, the effects on CBF from the high nitrate diet clearly manifest bilaterally within the white matter. Statistical analyses were performed at p<0.005, extent corrected at 180 voxels. Color scale represents the t-score from a voxel-wise paired-samples t-test.

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