The results, published in the journal Nitric Oxide suggest, reportedly for the first time, that dietary nitrate may help to improve blood flow in critical areas of the brain known to be involved in executive functioning.
"There have been several very high-profile studies showing that drinking beet juice can lower blood pressure, but we wanted to show that drinking beet juice also increases perfusion, or blood flow, to the brain …There are areas in the brain that become poorly perfused as you age, and that's believed to be associated with dementia and poor cognition," said Prof. Daniel Kim-Shapiro, of Wake Forest University in North Carolina.
“We demonstrated the ability of oral nitrate to increase plasma nitrite and to increase cerebral blood flow within white matter in older adult humans,” write the researchers in their paper.
The authors noted that poor blood flow contributes to the development of many disease states and may also be a factor in the decline of physical and cognitive function in aging.
Reduced blood flow to the brain contributes to cognitive impairment, such as a reduction in information processing speed, and to the progression of dementia, however research suggested that nitrites could help to open up the blood vessels in the body, increasing blood flow and oxygen specifically to places that are lacking oxygen.
Previous studies have shown nitrates to act as a vasodilator, which when taken in through the diet have been observed to decrease blood pressure and improve exercise performance.
According to the researchers, a major feature of nitrite’s ability to increase blood flow is that it acts preferentially in conditions of low oxygen, “allowing nitrite to increase blood flow precisely in the areas where it is needed most.”
“Several groups have shown that ingesting diet sources high in nitrate leads to substantial increases in plasma nitrite …We hypothesized that we could use this feature to increase cerebral blood flow in older adults,” stated the researchers.
Prof. Kim-Shapiro and colleagues reported that the high nitrate diet did not alter global cerebral blood flow, but did lead to increased regional blood flow in the frontal lobe white matter – the areas of the brain commonly associated with degeneration that leads to dementia and other cognitive conditions
The authors observed the effects of dietary nitrate on plasma nitrite and nitrate levels were sustained after the overnight fast, suggesting that the effects of dietary nitrate may be prolonged.
“Our results support the proposal that oral nitrate therapy may be beneficial in treating cognitive decline that is often observed with aging. Towards that end, we show a direct effect of dietary nitrate on cerebral blood flow within the subcortical and deep white matter of the frontal lobes,” concluded the researchers.
They added that nitrite had been shown to “not only increase blood flow to certain areas of the body, but also acts preferentially in hypoxic conditions, allowing nitrite to increase blood flow precisely in the areas where it is needed.”
“Based on this notion, our data suggest that a diet high in nitrate might allow increased [blood flow] to those areas of the brain known to be at risk in the elderly and important for cognitive function—the deep white matter in the frontal lobe,” added Kim-Shapiro and co workers.
Source: Nitric Oxide
Published online ahead of print, doi: 10.1016/j.niox.2010.10.002
“Acute effect of a high nitrate diet on brain perfusion in older adults”
Authors: T.D. Presley, A.R. Morgan, E. Bechtold, W. Clodfelter, R.W. Dove, J.M. Jennings, et al.