Rising blood pressure: are you consuming too much salt? The WHO recommends that adults consume no more than 5 g of salt per day, and 2 g for children. But “in France, women consume on average 7 g of salt per day and men 10 g,” reports Dr Hélène Lelong, general practitioner at the Hôtel-Dieu hospital in Paris and expert in hypertensiology. Consuming too much salt leads to water retention, which can lead to high blood pressure (or hypertension) and cause cardiovascular disease. But there was a lack of studies on the impact of a reduction in consumption in patients treated for hypertension. An American study carried out in adults over 50 confirms it: consuming less salt lowers blood pressure, whether or not one is treated for hypertension.
The two-week experiment, published in Jama, was carried out with 212 people aged 50 to 75 between April 2021 and February 2023 in two cities in the United States. Each week, a special diet was given to the participants, either high in salt (5.6g per day in addition to their usual diet) or low in salt (1.3g per day in total). For Dr Hélène Lelong, “the high-salt diet corresponds to the diet of adolescents fond of chips”. However, this protocol is questioned by the doctor, because in the salt-depleted diet “we gave less salt than to heart failure patients on a salt-free diet. I have never seen such a low dose, the protocol is difficult to maintain for a week for the study participants as evidenced by the urinary levels measured", specifying that "the quantity of 3g of salt per day corresponds to the consumption of human hunter-gatherers”, far from our current diet. Was the low-salt diet in the study rigorously followed by the patients, asks Dr Hélène Lelong?
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The results relate to measurements of cardiovascular parameters such as cardiac systolic pressure (at the time of heart contraction) and diastolic pressure (at the time of cardiac relaxation), measured at entry into the protocol and at the end of each week of experience. “We found that 70 to 75 percent of all people, whether or not they already take blood pressure medications, are likely to see a reduction in their blood pressure if they lower the sodium content of their diet,” one of the study’s authors, Norrina Allen, said in a statement.
On average, systolic blood pressure is reduced by 6 mm of mercury (mmHg) during a low-salt diet compared to a usual diet. Compared to a high salt diet, the drop is 7 to 8 mm Hg. This is far from negligible: Dr Hélène Lelong compares this with “a drop of 8 to 10 mmHg in systolic pressure for a person with hypertension treated with medication. However, this does not mean that you have to stop your antihypertensive treatment, but combine it with a balanced salt diet. And compared to the population, these few millimeters of mercury correspond to “thousands fewer cardiovascular events. So it’s interesting” says Dr Hélène Lelong. For the WHO, reducing salt consumption by 15% would prevent 8.5 million premature deaths in 10 years in low- and middle-income countries in the EU.
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According to health insurance, “in a doctor's office (…) to be considered normal, systolic blood pressure must be between 130 and 139 mmHg (millimeters of mercury) and diastolic pressure must be less than 90 mmHg. But checks can also be done at home by self-measurement of blood pressure or by ambulatory measurement of blood pressure, and the blood pressure must be less than 135/85 mmHg. In a 2017 publication, Inserm specifies that high blood pressure (or hypertension) is the leading cause of stroke in France; one in 3 adults is affected by this pathology, but only half know it. Finally, 10 to 30% of hypertensive patients are resistant to available treatments. This chronic disease, the most common in France, is generally silent, but uncontrolled hypertension is one of the main causes of cardiovascular pathologies (such as myocardial infarction), cerebrovascular (such as stroke) and neurovegetative diseases (such as myocardial infarction). Alzheimer's disease).
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WHO Europe states that “Member States have agreed to reduce salt consumption by 30% by 2025 as a priority intervention to combat noncommunicable diseases.” In France in particular, “this reduction would make it possible to make savings in high-income countries”, reports the WHO, specifying that “high salt consumption is one of the main causes of death in the WHO European Region ". How to adapt your diet? “You can learn to read labels, but it is complex. What I tell my patients is that the salt shaker is rarely the cause, unless you use a lot of broth. If you can make your own food with fresh or frozen vegetables, it's better, because canned foods contain a little salt. When eating prepared meals, you must use the Nutri-Score. The salt composition is taken into account, so we must favor Nutri-Scores rated higher (A).”