Researchers link salt intake and high blood pressure

Kelsey Misbrener

Physicians have been unable to explain the exact cause of high blood pressure, but researchers at Kent State and Case Western Reserve University School of Medicine came one step closer to solving the mystery.

Salt-sensitive people experience high blood pressure when they consume salt, but salt-resistant people’s blood pressure is unaffected by salt, said Robert Blankfield M.D., M.S., clinical professor of family medicine at Case Western Reserve University School of Medicine and director of a recent study about salt-induced high blood pressure.

When salt-sensitive people ingest salt, their blood pressure increases while body temperature remains the same, said Matthew D. Muller, postdoctoral researcher at the Penn State College of Medicine and the first author of the study. When salt-resistant people ingest salt, their blood pressure remains the same while their body temperature decreases.

“When you eat salt, your blood vessels should get bigger, and that’ll normalize blood pressure,” Muller said. “But in the process of your blood vessels getting bigger, or dilating, then you lose heat.”

The Kent State and Case Western Reserve study looked at:

22 college-aged males, half were salt-sensitive and half were salt-resistant

The study found:

a salt sensitive person experiences high blood pressure when they consume salt

a salt resistant person’s blood pressure is unaffected by salt consumption

Muller worked with Blankfield and Ellen Glickman, professor of Health Sciences at Kent State, to find the reason some individuals are salt-sensitive has to do with the way each person’s body regulates temperature.

For a long time, doctors have known a person can be either salt-resistant or salt-sensitive, Blankfield said. Though scientists knew the two types existed, they never knew how it related to hypertension until the recent study.

Researchers recruited 22 male college students with healthy blood pressure. The subjects went to a physiology lab on two occasions and took a pill each time with varying amounts of salt. They measured participants’ blood pressure, rectal temperature, cardiac index and urine output each time.

About half of the subjects were salt-sensitive, while the other half were salt-resistant, Muller said.

The study didn’t focus on whether it’s healthier for a body to increase in blood pressure or decrease in temperature, but Muller said a decrease in temperature is probably the better option.

Since only one age group was tested, Blankfield said the researchers can’t make any generalizations about salt sensitivity in college students. However, if they can get funding, they plan to extend the experiment to other ages, ethnicities and sexes.

Salt sensitivity isn’t just genetic.

“If a college age person ingests a lot of salt, they can become salt sensitive, even if they were initially salt resistant,” Blankfield said. “So college-aged students, as well as middle aged adults, should ideally adopt healthy lifestyles.”

Contact Kelsey Misbrener at [email protected]