The rats were fed on 8% sodium chloride enriched pellets and given tap water or diluted lingonberry juice for ten weeks. The research, published in the Journal of Functional Foods, sought to test whether lingonberry juice could beneficially affect salt-induced inflammation and hypertension.
The scientists saw that the salt-loaded diet impaired kidney function of rats without clear effect on blood pressure or vascular function. Within this, lingonberry juice was shown to moderately reduce biomarkers of low-grade inflammation.
The researchers said the anti-inflammatory effects of polyphenols could explain positive cardiovascular effects. “We have found that lingonberry, a northern berry rich in polyphenols, improves vascular endothelium-dependent relaxation and decreases blood pressure of spontaneously hypertensive rats,” the researchers said.
Thirty-two young male rats, aged six weeks, were randomised by weight and systolic blood pressure and housed four to a cage for the research. Each cage was assigned to receive either: a normal rodent diet and tap water; a normal diet and cold-compressed lingonberry juice with 1% of sucrose; high salt diet of standard rodent diet containing 8% sodium chloride and tap water; a high-salt diet and lingonberry juice with 1% of sucrose.
The researchers said: “The present study shows that high-salt diet aimed to induce hypertension for ten weeks induces slight renal dysfunction in young rats without clearly affecting blood pressure and vascular function. Low-grade inflammation caused by excess sodium is moderately lowered by lingonberry treatment in agreement with our previous studies in spontaneously hypertensive rats.”
The researchers said they were surprised to see that systolic blood pressure did not differ between the normal diet and high-salt diet groups although high salt diets of this kind in most studies have been shown to induce hypertension in different rat models.
They said the rats in their study appeared to be well protected against excess salt’s effect on blood pressure, and said steroid treatment to induce hypertensive effects could have strengthened results if used.
Source: Journal of Functional Foods
Published online ahead of print, http://dx.doi.org/10.1016/j.jff.2014.02.005
“Lingonberry juice negates the effects of a high salt diet on vascular function and low-grade inflammation”
Authors: A.S. Kivimäki, A. Siltari, P.I. Ehlers, R. Korpela and H. Vapaatalo