The world is far from achieving the global goal of reducing sodium consumption by 30% by 2025. The data are from an unprecedented report by the World Health Organization (WHO) on salt consumption.
Although it is an essential nutrient, sodium, when ingested in excess, increases the risk of heart diseases such as stroke (stroke), high blood pressure and premature death. The main source of sodium is table salt (sodium chloride), but other seasonings, such as sodium glutamate, also contain sodium.
The WHO report reveals that only 5% of countries have mandatory and comprehensive sodium reduction policies and that 73% do not fully implement such policies.
The association between salt and blood pressure has been the subject of studies for over a century. However, there are few answers to the association between high salt intake and changes in the central nervous system (CNS), which contribute to the so-called neurogenic hypertension.
Researchers from the University of São Paulo (USP) made progress in understanding this process. Studies have revealed that part of the salt consumed in excess is retained in the cerebrospinal fluid – called cerebrospinal fluid. The findings suggest a possible mechanism that triggers the disease and that involves the activation not only of neurons, but also of other glial cells, another type of cell present in the nervous system.
The research opens the way for understanding mechanisms and connections between neural cells involved in the formation of hypertension associated with high salt intake. The results were published in the scientific journals Molecular and Cellular Neuroscience and Experimental Physiology.
In the test, albino rats that were fed with excess salt were used. The animals were given a water solution with 2% sodium chloride for one week and developed hypertension. In addition to the increase in blood pressure, what caught the attention of the researchers was that the level of sodium in the blood of the animals remained normal, however, they noticed an accumulation of this ion in the brain, more precisely in the cerebrospinal fluid, a liquid that protects the central nervous system. .
“Animals exposed to high salt consumption showed hypertension and sodium accumulation in the CSF, but not in the blood. Thus, we can presume that the genesis of hypertension involves a neural component, which may be related to this excess of sodium retained in the CSF”, says Paula Magalhães Gomes, post-doctoral student at the Laboratory of Neural Circulation Control (LCNC) of the Department of Physiology and Biophysics at the Institute of Biomedical Sciences (ICB) at the University of São Paulo (USP), first author of one of the articles, in a statement.
“In theory, the sodium we consume in food is evenly distributed in the different compartments of our body, in a process that we call osmoregulation in physiology, but apparently this is not the case when the body is challenged with excessive salt consumption. Our future goal is to further investigate the physiological mechanisms behind the accumulation of sodium in the CSF and its relationship with hypertension”, he adds.
understand the process
Previous studies have already shown the involvement of the hypothalamus, a region of the brain, in the development of hypertension dependent on high salt intake. The neural cells of this nucleus, mainly the neurons, participate directly and indirectly in the regulation of blood pressure in response to an increase in circulating sodium in the body.
The researchers then sought to investigate the involvement of neural glial cells in this process. Experts noted that astrocytes, which are one of the most abundant cells in the central nervous system, were more activated in the brains of animals that were exposed to high salt intake.
“In general, astrocytes are cells that, in addition to supporting neurons, are also responsible for releasing several neurotransmitters, including ATP. [trifosfato de adenosina], a molecule that classically has always been known for its role in cellular energy metabolism, but which also acts as a neurotransmitter. Faced with a condition of high salt consumption, astrocytes are intensely activated”, explains Renato Willian Martins de Sá, doctor at LCNC, scholarship holder of the Research Support Foundation of the State of São Paulo (Fapesp).
Studies indicate that the accumulation of sodium in the cerebrospinal fluid may be related to the development of diseases not only of the cardiovascular system, but also neurodegenerative ones, including Alzheimer’s disease, considering that excess salt in the brain can alter the functions of neural cells , from its genetic and protein machinery to neurochemistry.
“Understanding these mechanisms may help in the development of new pharmacological therapeutic strategies for diseases associated with high salt consumption”, says Professor Vagner Roberto Antunes, laboratory coordinator, in a statement.
Changes can save lives
WHO recommends that daily salt consumption does not exceed 5 grams, with the aim of reducing hypertension and other cardiovascular diseases.
Implementing highly cost-effective sodium reduction policies could save an estimated 7 million lives worldwide by 2030. It is an important component of measures to achieve the Sustainable Development Goal target of reducing deaths from non-communicable diseases .
Currently, only nine countries (Brazil, Chile, Czech Republic, Lithuania, Malaysia, Mexico, Saudi Arabia, Spain, Uruguay) have a comprehensive set of recommended policies to reduce sodium intake.
“Unhealthy diets are among the leading causes of disease and death worldwide and excessive sodium intake is a major contributor,” said Tedros Adhanom, Director-General of the WHO.
“This report shows that most countries have yet to adopt any mandatory sodium reduction policies, leaving their populations at risk of heart attack, stroke and other health problems. The WHO calls on all countries to implement the “Best Investments” for reducing sodium and on manufacturers to implement the WHO benchmarks for sodium content in food”, he adds.
(With information from Jornal da USP and the Pan American Health Organization)
Source: CNN Brasil
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