Published in the Journal of the American Heart Association, the results are from an observational study that followed 4,523 normotensive people in the general population of Japan.
"Both relatively high levels of dietary sodium intake and gradual increases in dietary sodium are associated with future increases in blood pressure and the incidence of hypertension in the Japanese general population," reads the study's conclusion.
Almost a quarter of the healthy study population developed high blood pressure over a 3-year period - and those who ate the most salt were the most likely to develop hypertension.
People who gradually increased their sodium intake also showed gradually higher blood pressure.
Dr. Tomonori Sugiura - lead author and an assistant professor in the cardio-renal medicine and hypertension department at the Nagoya City University Graduate School of Medical Sciences in Nagoya, Japan - says:
"In our study, it did not matter whether their sodium levels were high at the beginning of the study or if they were low to begin with, then gradually increased over the years - both groups were at greater risk of developing high blood pressure."
Dr. Sugiura has a warning for Americans, who are just as relevant to the study findings as Japanese:
"Americans consume an average of nearly 3,500 milligrams of sodium a day, which is about 1,000 milligrams more than any public health group recommends.Reducing sodium intake can save lives, save money and improve heart health - no matter what background or nationality a person is."
AHA helping Americans reduce their salt intake
In fact, the American Heart Association (AHA) recommend a lower daily limit for salt intake - consuming no more than 1,500 milligrams of sodium a day.
The organization is providing a number of ways to help people cut salt intake at its Sodium Breakup website.
The study researchers estimated the amount of salt being consumed by analyzing the amount of sodium in the urine of people getting a routine check-up from their health care provider. Follow-up urine analysis continued for about 3 years.
At the conclusion of the study, the people consuming the least amount of sodium had a daily intake of 2,925 milligrams, while those with the highest intake were consuming 5,644 milligrams a day.
The AHA say over three quarters of sodium in the US diet is found in the salt added to processed food.
About 9 in every 10 Americans consume too much sodium, and there are six salty foods that contribute the leading sources of overall sodium: breads and rolls, cold cuts and cured meats, pizza, poultry, soup and sandwiches.
Discussing the study's findings, the authors say: "Taking into consideration previous experimental and clinical studies that showed dietary sodium to be one of the most important keys to the development of hypertension, the present results showed that mild reduction in dietary sodium intake may be useful for preventing new onset of hypertension and reducing age-dependent increase in blood pressure."
"An effort not to increase dietary sodium as well as an effort to reduce dietary sodium intake may be effective for the primary prevention of hypertension or reduction of blood pressure in the population at large," they add.
