A new study has found that reducing daily salt intake can decrease the need for medication to control high blood pressure. Researchers say that patients with resistant hypertension are those who take more than three medications to try to control their blood pressure, but it remains high. These patients benefit the most from a low-salt diet.
In the study, researchers from the University of Queensland in Australia studied 12 hypertension patients with an average age of 55, who were taking an average of 3.4 medications. The researchers had these patients eat a high-salt diet for a week, then take a two-week break to allow their bodies to clear it completely, before eating a low-salt diet.
Their average body mass index (BMI) was close to 33, which is considered obese. At the start of the study, despite taking medication, their average blood pressure was still 146/84 (ideal blood pressure is below 120/80, and blood pressure over 140/90 is considered high blood pressure). When participants ate a high-salt diet, they consumed about 7,000 milligrams of sodium per day; when they ate a low-salt diet, they consumed about 2,000 to 3,000 milligrams of sodium per day, which is below the U.S. dietary guideline for the general population of less than 2,300 milligrams or about one teaspoon of salt per day. According to the American Heart Association, people with high blood pressure are advised to consume 1,500 milligrams of sodium, while the average American consumes 3,436 milligrams per day.
The study results showed that compared to the high-salt diet, after one week of eating a low-salt diet, participants' systolic blood pressure (the upper number) decreased by an average of 22.7 mmHg, and diastolic blood pressure (the lower number) decreased by 9.1 mmHg. In another study, British researchers found that moderately reducing salt intake could lower blood pressure in Asians, Blacks, and Whites.
This study tested the effects of reducing salt on 169 men and women aged 30 to 75 with mild hypertension who were not taking blood pressure medication. Their salt intake was reduced from an average of 9.7 grams per day to 6.5 grams. This amount translates to a sodium intake of about 3,800 milligrams to 2,400 milligrams (salt is different from sodium; salt contains about 40% sodium, with the rest being chloride). The study results showed that at the beginning of the study, participants' average blood pressure was 147/91, and after eating the low-salt diet, it dropped to an average of about 141/88.
Researchers say that reducing salt, in addition to lowering blood pressure, has other benefits. For example: when eating a low-salt diet, there is less calcium in the urine, and in the long run, reducing the loss of calcium in the urine is expected to reduce the risk of osteoporosis. There is also less albumin in the urine; high albumin levels indicate kidney damage, suggesting a higher risk of cardiovascular disease. Researchers point out that reducing salt intake is beneficial for everyone, even if your blood pressure is very low and you are not at risk for osteoporosis. Although only 12 patients participated in this study on resistant hypertension, the effect on lowering blood pressure was significant. The degree of blood pressure reduction was equivalent to the effect of adding two more blood pressure medications. Not only can different ethnic groups benefit from reducing salt, but reducing salt is not only effective for blood pressure; it also has potential benefits for protecting the kidneys and heart.
■Translated by Cao Shufen