Nutritional Pearls: Salt Intake, Flavor, and Blood Pressures

John is a 40-year-old man who has struggled for many years to maintain a healthy blood pressure. He tells you that he tried switching to foods with reduced sodium, but he "might as well have been buying sodium-free" products because of how little salt he tasted in them.

How would you advise your patient?
 

(Answer and discussion on next page)

Dr. Gourmet is the definitive health and nutrition web resource for both physicians and patients with evidence-based resources including special diets for coumadin users, patients with GERD/acid reflux, celiac disease, type 2 diabetes, low sodium diets (1500 mg/d), and lactose intolerance.

Timothy S. Harlan, MD, is a board-certified internist and professional chef who translates the Mediterranean diet for the American kitchen with familiar, healthy recipes. He is an assistant dean for clinical services, executive director of The Goldring Center for Culinary Medicine, associate professor of medicine at Tulane University in New Orleans, and faculty chair of the Certified Culinary Medicine Specialist program.

Years ago, I shared a study performed in 1982 that looked at the relationship between the amount of sodium people were used to consuming and how salty they liked their food. In that study, those who were used to a higher amount of sodium in their daily diet went on a reduced-sodium diet.

They discovered that the amount of salt in crackers or soup that gave "maximum pleasantness" of taste was lower after reducing the amount of salt in their diet than it was before. It was clear, at least from this research, that those who habitually consumed more sodium found that foods tasted less salty than those who consumed less sodium.

Today's research supports that conclusion from a different direction—and links it to blood pressures.

The Research

Researchers in Japan recruited adult men and women from 2 regions in Japan: Osaka, in mid-western Japan (an urban area), and Akita, in northeastern Japan (a rural area), to submit to salt taste testing as part of an ongoing study known as the Circulatory Risk in Communities Study.

The 2223 men and women underwent their taste testing as part of an annual health checkup at which their height, weight, and blood pressures were measured.

The salt taste testing utilized multiple pre-made and validated test strips that the participant held in their mouth for 3 seconds. The initial strip was designed to be a control, with no sodium impregnated in the strip. Subsequent strips had increasing concentrations of sodium impregnated in each strip: 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%. and 1.6%.

Two measures were used: first, what the authors called a "perception" measure, which was the percentage where the participant noticed that the strip tasted different from the initial, no-salt strip. Then there was an "identification" measure—the percentage at which the participant could identify the flavor as "salty" as opposed to, say, umami or spicy. (All strips contained nothing but salty flavor and no other taste.)

After noting the participants' thresholds for both perception and identification, the authors correlated those scores with the participants' blood pressures as well as the amount of sodium-laden foods they reported consuming on a regular basis.

The Results

Interestingly, the outcomes were different by gender: about 61% of men and 79% of women could detect a difference between the no-salt strip and the strip containing 0.1% sodium. Yet those who could identify that the difference they tasted was a salty flavor was much smaller: between 15% and 24% for men and 24% and 32% for women.

On the other end of the spectrum were those who could detect a flavor difference but could not identify that flavor as "salty": between 30% and 34% of men could not identify a salt concentration of 1.6% sodium while between 16% and 21% of women could not, either.

The authors found that women were better able to detect salty flavors overall, and that for men between 30 and 59 years of age, blood pressures were positively linked with both detection (tasting a difference), perception (knowing the flavor was saltiness), and salt intake.

In short, those who consumed more salty foods were also those who failed to detect difference in flavor in general and salty flavors in particular. Those same people tended to have increasingly higher blood pressures as their minimum flavor detection and recognition levels increased.

What’s the Take Home?

To put this simply: Those who tended to consume more salt were less able to taste or identify salty flavors and had higher blood pressures than those who consumed less salt.

The United States' current recommended target is about 2400 mg of sodium per day. If you are used to consuming too much salt, it seems clear that in time your perception of salty flavor in foods will become accustomed to a lower level of intake: not only will your salt taste buds learn to recognize lower levels of sodium in foods, but it's likely that your blood pressures will adapt as well.

Reference:

Kudo A, Kitamura A, Imano H, et al. Salt taste perception and blood pressure levels in population-based samples: the Circulatory Risk in Communities Study (CIRCS). Br J Nutr. 2020 doi: 10.1017/S0007114520002640.