High salt intake may have immediate effects on circulation: Study

[Guest guest]

Consuming highly salty foods may begin to impair the functioning of blood

vessels within 30 minutes, according to new research published in the *American

Journal of Clinical Nutrition.*

The study suggests that 3.8 grams of

salt<http://www.foodnavigator-usa.com/content/search?SearchText=salt & FromNews>–

an amount similar to commonly eaten meals – can reduce the ability of

blood vessels to widen after a meal when compared with a lower salt meal.

The researchers found raised levels of salt from the diet can significantly

reduce flow mediated dilation (a measure of blood vessels ability to widen)

within 30 minutes.

Researchers from the Commonwealth Scientific and Industrial Research

Organization (CSIRO), Australia report that when a high salt meal was

consumed blood vessels widened about half as much as for low salt meal,

though they noted that these effects passed after around two hours when

normal functioning was restored.

*“What surprised us was that this is similar to responses seen after a meal

high in saturated fats, which we know can be damage blood vessels in the

long-term,”* said the study’s lead author, Kacie Dickinson.

*“These results suggest that high salt intakes have acute adverse effects on

vascular dilatation in the postprandial *[post meal]* state,”* said the

researchers.

*Salt risks*

Dickinson and her colleagues said that there is *“compelling evidence”* to

show a link between salt intake, increased blood pressure, and risk of

cardiovascular disease

(CVD<http://www.foodnavigator-usa.com/content/search?SearchText=CVD & FromNews>).

The researchers said that impaired blood vessel functioning (endothelial

dysfunction) is considered to be an initial step in the development of

atherosclerosis, which has been previously shown to be induced by metabolic

factors – through an increase in oxidative stress and a reduction in the

bioavailability of nitric oxide. The endothelium is the layer of cells

lining blood vessels.

High salt intakes, even over a short period of time, are known to lead to

similar reduction in nitric oxide, and increases in oxidative stress –

however Dickinson and her co- workers said that whether blood vessel

functions are impaired after a high salt meal have not been studied.

*“Determining whether a high salt meal has a detrimental effect on

endothelial function in the postprandial *[post meal]* state is of interest

given the high levels of nondiscretionary salt consumed in foods and typical

meals,”* they said.

The new study investigated the vascular responses of a group of healthy

adults to a high-salt meal containing 65 mmol

sodium<http://www.foodnavigator-usa.com/content/search?SearchText=sodium & FromNew\

s>and

low-salt control meal containing 5 mmol sodium.

*Study details*

The researchers studied the impact of short-term salt intake in sixteen

healthy volunteers. The postprandial effect of dietary salt on endothelial

function was measured by flow-mediated dilatation (FMD) and blood pressure.

FMD is often used by scientists to assess endothelial function: Impaired FMD

response is a CVD risk factor and can precede clinically symptomatic CVD by

many years.

Flow mediated dilation was found to decrease after both the high and low

salt meals, but was significantly more impaired after the high salt meal

than the low salt.

The authors reported that measures of FMD were significantly reduced after

30 minutes and one hour for the high salt meal – with the greatest

impairment in function occurring one hour after the meal was ingested.

The impairment in flow mediated dilation in response to the high salt meal

was said to be of a similar magnitude to that shown in healthy subjects

after a meal high in saturated fats.

Despite the differences in salt intake and observed changes in FMD,

Dickinson and colleagues did not observe any significant changes blood

pressure between the high and low salt meals.

They added that they found no evidence to suggest that blood pressure is

involved in the mechanism by which salt impairs the endothelial functioning.

*Mechanisms*

*“It may be plausible that the 65-mmol sodium load (3.8 g salt) in the

current study induced changes in endothelial function via alterations in

plasma sodium …A repeat of the current study including plasma sodium samples

and other parameters of endothelial function, such as nitric oxide and eNOS

would confirm this,” *suggested the authors.

They said that the study suggests that high salt intakes may have acute,

adverse effects on the ability of blood vessels to widen after in the post

meal phase.

Dickinson and colleagues added that it is unclear whether the observed

effects have long-term consequences on the risk of atherosclerosis and

cardiovascular disease, but said that the results contribute to a body of

research showing non blood pressure related effects of high salt intakes.

Source: *American Journal of Clinical Nutrition*

Published online ahead of print, doi: 10.3945/ajcn.110.006155

*“Endothelial function is impaired after a high-salt meal in healthy

subjects”*

Authors K.M. Dickinson, P.M. Clifton, J.B. Keogh

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--

Ortiz, MS, RD

*The FRUGAL Dietitian* <http://www.thefrugaldietitian.com>

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