People who followed a low-salt diet for just one week experienced a reduction in systolic blood pressure of about 6 mm Hg, according to a new study.[1]
The CARDIA-SSBP trial involved 213 people aged 50 to 75 years, both hypertensive and non-hypertensive, and it was shown that the decrease in blood pressure produced by a low-salt diet was independent of hypertension status and the use of antihypertensive drugs. . There was also general consistency between subgroups and no excess of adverse effects.
“The blood pressure reduction we observed here is significant and equivalent to that produced by an antihypertensive drug,” he told Medscape Medical News lead researcher Dr. Deepak Gupta of Vanderbilt University Medical Center in Nashville, Tennessee.
Dr. Gupta presented the CARDIA-SSBP study on November 11 at the American Heart Association (AHA) Scientific Sessions 2023 meeting in Philadelphia, United States. The study was also published electronically on November 11 in JAMA.[1] The exact menus used in the study are available in a supplement to the article. JAMA.
“To lead a healthy lifestyle, understanding what we eat has important effects on health. Increased blood pressure contributes to 1 in 8 deaths worldwide,” said Dr. Gupta. “If people want to lower their blood pressure, paying attention to dietary sodium is one part of that. If individuals can follow a low-sodium diet, they will be able to stop taking one of their antihypertensive drugs, and those who are normotensive will have less likely to suffer from hypertension.
Commenters stated that the study had important implications for public health, but noted that maintaining a low-sodium diet long-term is difficult, given the high salt content of generally available foods.
Dr. Gupta added that the study used commercial products in the low-sodium diets and that the menus are available for people to follow, making them more accessible than some diets used in previous studies.
“What may also be attractive to people is that you don’t have to wait months to see an effect. If you start eating a low-sodium diet, you can see blood pressure results quickly, within a week,” he said.
The diet in this study involved a large reduction in sodium, but Dr. Gupta emphasized that any reduction in sodium in the diet is likely beneficial.
“If you reach the level we reached, you could expect a reduction of about 6 mm Hg. But it’s like walking: you don’t need to take 10,000 steps a day. Any walk or physical activity is beneficial. The same can be said for salt : Any reduction is beneficial.”
For the study, participants’ blood pressure was measured by ambulatory monitoring for 24 hours while they followed their usual diet. They were then randomized to a high- or low-sodium diet for one week. Participants were then switched to the opposite diet for a week and had their blood pressure measured over a 24-hour period on the final day.
Based on 24-hour urinary excretion, participants’ usual diet was already high in sodium (median: 4.45 g/d). This figure increased to a median of 5.00 g/d when they followed the study’s high-sodium diet and decreased to 1.27 g/d when they followed the low-sodium diet.
The results revealed that participants had a median systolic blood pressure of 125 mm Hg on their usual diets. This figure increased to 126 mm Hg with the high-sodium diet and decreased to 119 mm Hg with the low-sodium diet.
The researchers also reported that 75% of individuals showed a reduction in blood pressure on the low-sodium diet and were therefore defined as “salt sensitive.” This is a higher percentage than that found in previous studies.
“Those who did not show a reduction in blood pressure on a low-sodium diet in this study did not appear to adhere to the diet as much as those who did have lower blood pressure,” Dr. Gupta said.
He stressed that hypertension is the most common chronic disease worldwide, with some 1.3 billion people affected, and although dietary sodium has long been known to affect blood pressure, there have been some gaps in previous studies.
For example, many previous studies have excluded people already taking antihypertensive medications and patients with diabetes, and have generally not included many older people. In the current study, it was observed that all of these groups also showed significant reductions in blood pressure when dietary sodium was decreased.
Great effect on people with diabetes
Subgroup analyzes showed largely consistent results across the population, regardless of age, sex, race, and body mass index and whether or not participants were taking antihypertensive drugs, but there were a couple of exceptions. Individuals with higher blood pressure at the start of the study appeared to experience a greater effect of reducing dietary sodium, although for those who were normotensive at the start of the study there was also a significant reduction in blood pressure, Dr. Gupta reported.
The researchers also observed that the blood pressure of patients with diabetes (21% of the total cohort) decreased significantly as their sodium intake decreased. Their mean reduction in systolic blood pressure between the high- and low-sodium diet was nearly 17 mm Hg, instead of 7-8 mm Hg for the entire cohort.
Dr. Gupta assured that the results are applicable to the majority of the population.
“The people who will be most motivated to follow a low-sodium diet are those with hypertension, but even normotensive individuals are likely to benefit.”
To help people follow a low-sodium diet, Dr. Gupta emphasized that educational campaigns are needed “to show people that they can do it and that it works.” But there are larger structural issues that need to be addressed at the political and governmental level.
“Most foods available in stores and restaurants are high in salt. We now have overwhelming evidence that what is offered in the food supply needs to change,” he said. Spain, Mexico, Uruguay, Chile and Brazil are included in a list of only 9 countries in the world that have a comprehensive set of policies to reduce sodium intake, rated with the best evaluation (score of 4) by the World Health Organization. Health (WHO); The body recommends a consumption of less than 2,000 mg/day (equivalent to one teaspoon).
Difficult to maintain long term
Dr. Paul Whelton, professor of global public health at Tulane University School of Medicine, told Medscape Medical News that sodium reduction is known to lower blood pressure, and that further sodium reduction leads to greater lowering of blood pressure, and that some people are more sensitive to the effects of sodium than others.
He described CARDIA-SSBP as a “well-done study”: “They got a very low sodium intake and a big difference between the two groups, which translated into a big reduction in systolic blood pressure,” Dr. Whelton noted. “However, the problem with these types of trials where diets are provided to participants is that, although they show preliminary evidence, it is difficult to generalize because we usually cannot provide patients with their meals. In this type of study ‘feeding’ we find it difficult to keep people on their behavioral intervention long term.
Dr. Whelton said he was more excited about this trial knowing that the foods being given were commercially available. “That makes it more practical, but you still have to be quite motivated to follow a diet like this. Buying low-sodium products at the supermarket requires a lot of work to read the labels and sometimes low-sodium foods are specialty products and are more expensive. expensive.”
He noted that older people from higher socioeconomic classes are more likely to try and have better results from behavioral interventions overall. “Unfortunately, the people who do not do well with behavioral interventions of this type are those from lower socioeconomic groups, who are most at risk for cardiovascular disease.”
Dr. Whelton added that the food industry has been reluctant to reduce sodium content because foods high in salt sell better. “Unfortunately, foods high in saturated fat and salt taste good to most people. In general, we are used to high salt consumption. But by the time people have been following a low-salt diet for a while, they usually already They don’t like foods rich in salt. They get used to a low-sodium diet,” he added.
Salt is ubiquitous in food
Cheryl Anderson, PhD, master of public health, University of California, San Diego, and presenter of the CARDIA-SSBP study at the conference, said the results were important and consistent with previous studies.
“These studies have global implications because salt is ubiquitous in the food supply in much of the world,” he noted, adding that “Americans consume nearly 50% more sodium than recommended, and there has been a persistent lack of adherence.” to healthy diet recommendations to reduce salt, sugar and fat.
Anderson noted that in 2021, the U.S. Food and Drug Administration (FDA) issued guidance for voluntary sodium reduction, which uses a graduated approach, with goals to reach a population goal of 3,000 mg/d sodium for 2023 and 2,300 mg/d by 2031.
“These objectives apply to 150 sales-weighted food categories to focus on the dominant sellers of each category. They apply to food manufacturers, restaurants and food services,” he concluded. “These objectives serve as a basis for continued dialogue. The research community looks forward to the review of population-based data to help refine this approach and objectives.”
This study was funded by grants of National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, American Heart Association, and National Center for Advancing Translational Sciences. The authors have declared that they have no relevant financial conflicts of interest..
This content was originally published in the English edition of Medscape.