Too much salt may harm more than blood pressure

University of South Australia researcher Dr Jennifer Keogh will investigate how a diet high in salt can harm more than your blood pressure.

She has published a preliminary study showing high salt intake adversely affects blood vessel function, which may lead to serious health problems such as atherosclerosis (stiffening and narrowing of the arteries) and heart disease.

"This study was the first time anyone had shown that if you reduce your salt intake, you get benefits on the blood vessel or endothelial function," she says.

"When we conducted this preliminary study, we found people on a lower salt diet had much better blood vessel response than those on a high salt diet.

"We cut off blood supply in the participants' arms for a short time using a blood pressure cuff and then measured how well the blood vessel relaxed to allow increased blood to flow to the extremities by measuring blood vessel size with ultrasound equipment following either a reduced or normal salt diet.

"If the blood vessel can't increase in size, it suggests it's not as healthy as it should be."

Dr Keogh has recently been awarded $246,355 funding in the National Health and Medical Research Council's 2010 Project Grants Scheme to investigate sodium intake and endothelial function in a longer six-week study at UniSA's City East campus.

Dr Keogh, who contributed to the CSIRO's Total Wellbeing Diet, hopes the study will provide an understanding of how salt has an effect beyond blood pressure.

"The NHMRC suggests the population intake for sodium should be around six grams per day. However, most people are taking around nine to 12 grams per day," she says.

"However, this high salt intake is not discretionary. Most people don't add salt to their food and they don't add salt to their cooking, but salt is abundant in our manufactured foods.

"In this wider study I'll be taking blood samples to see what changes are taking place in the blood. We believe salt could be affecting nitric oxide, a substance produced by the endothelial cells which helps the blood vessels relax.

"I'd like to see this work help to inform public health policy in the area and to contribute to health authorities and state and federal governments changing their policies in relation to salt."

(Source: University of South Australia)