advertisement

Hypertension

17 May 2019

This may be why slashing salt lowers blood pressure

It is well known that reduced sodium intake reduces blood pressure and cardiovascular risk, and now, researchers may have found an underlying mechanism to explain why.

Slash sodium from your diet. That's the advice inevitably given to everyone.

Restricting sodium intake has been key to reducing blood pressure. Now researchers may have found an underlying mechanism to explain why.

Two specific metabolites

Scientists examined hundreds of metabolites substances produced during digestion from blood samples drawn in a study among 64 black British residents with high blood pressure, or hypertension. All participants were instructed to follow a reduced-sodium diet, but otherwise none were taking medication or receiving treatment for their condition.

The researchers discovered reducing sodium intake resulted in higher levels of two specific metabolites, both associated with lower blood pressure levels and arterial stiffness.

The study taps into the science of metabolomics, which examines how tiny molecules react to changes in their environment. In this case, the sodium levels altered the setting.

While everyone in the study was put on a low-sodium diet, half were given a slow-release sodium tablet for six weeks. The others received placebos. Researchers then switched the pills for an additional six weeks.

"We know reduced sodium intake reduces blood pressure and cardiovascular risk. However, the underlying biological mechanisms are not well established," said Dr Haidong Zhu, lead author of the study published in the American Heart Association's journal Hypertension.

Underlying biological pathway

Researchers examined the metabolites in blood samples to see which ones changed along with modification of sodium, she said.

They found that reduction of sodium intake resulted in the increase of two specific types of metabolites – beta-hydroxyisovalerate and methionine sulfone – along with a modest drop in blood pressure.

"The changes may represent some underlying biological pathway involved in this sodium regulation," said Zhu, an associate professor in the Department of Population Health Sciences at Medical College of Georgia at Augusta University.

The results were based on a sodium reduction of about 1 120mg a day, from 3 800mg to 2 680. That decline was associated with a decrease in both systolic blood pressure (the top number in a measurement) and diastolic pressure (the bottom number).

The AHA recommends less than 2 300 mg of sodium a day the equivalent of about 1 teaspoon of salt and ideally, no more than 1 500 mg per day for most adults. On average, Americans consume more than 3 400 mg of sodium each day.

Zhu said additional research would need to validate the study's results because of its small sample size. But she hopes further studies will lead to development of a drug that targets pathways altered by sodium intake levels.

Important group of people

The study focused on the black population "and the emphasis is highly warranted due to a higher prevalence of salt-sensitive hypertension in this group", said Casey Rebholz, an assistant professor in the epidemiology department of Johns Hopkins Bloomberg School of Public Health in Baltimore.

In the United States, the prevalence of high blood pressure among African Americans is among the highest in the world. More than 40% of black men and women have high blood pressure.

Rebholz pointed out that the landmark study Dietary Approaches to Stop Hypertension-Sodium showed a low-sodium diet was particularly effective in reducing blood pressure among black participants and among those with high blood pressure.

"That's an important group of people to continue studying," she said.

Rebholz said the new research backs up the standard advice doctors give many patients.

"It tells people that modifying and improving their diet, specifically by consuming less sodium, is important for reducing blood pressure."

Image credit: iStock

 

Ask the Expert

Hypertension expert

Dr Jacomien de Villiers qualified as a specialist physician at the University of Pretoria in 1995. She worked at various clinics at the Department of Internal Medicine, Steve Biko Hospital, these include General Internal Medicine, Hypertension, Diabetes and Cardiology. She has run a private practice since 2001, as well as a consultant post at the Endocrine Clinic of Steve Biko Hospital.

Still have a question?

Get free advice from our panel of experts

The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.

* You must accept our condition

Forum Rules