Sodium[1] constitutes the major cation present in the extracellular fluid (ECF) of the human body. Half of the mean body sodium content is present in the ECF and the remaining is present in the skeleton and the intracellular fluid (ICF). The activity of the sodium-potassium pump is responsible for the maintenance of the sodium concentration gradient across ICF and ECF. This pump transfers sodium to the outside and potassium to the inside of the cell.
The concentration and balance of sodium in the body are closely associated with water homeostasis, which is maintained by the kidneys. Sodium is lost from the body in the form of sweat and feces, however, the losses are further increased with the increase in the intake of sodium. The importance of sodium is reflected by its role in many bodily processes. This includes the regulation of blood pressure, fluid balance, electrolyte balance, and normal cellular homeostasis.
Does Sodium Make You Fat?
Another explanation to support the association between salt intake and weight gain is the observation that higher salt intake or the consumption of high-sodium diets can be associated with the consumption of carbohydrates, protein, fats, and saturated fatty acids. Furthermore, high salt intake in the form of intake of high sodium foods can lead to addiction to high sodium diet. Excess sodium intake may stimulate the dopamine receptors located in the reward and pleasure centers in the brain. Withdrawal of sodium consumption can cause individuals to gain weight by an increase in calorie intake, appetite, and incidence of obesity.
Another mechanism that may underlie the relationship between too much sodium intake and weight gain is water retention. As the body retains water, the weight gain in the affected individuals increases. Animal experiments have confirmed that excess sodium intake is related to obesity, based on high levels of glucose, which is converted into fat.
Therefore, it is established that high sodium intake is associated with increased weight gain, which is influenced by several body mechanisms such as water retention, increased energy and calorie intake, and greater deposition of body fat.
How Sodium Intake Affects Weight
The following mechanisms explain the weight gain resulting from high sodium intake in the form of consumption of a high-salt diet or the addition of excess sodium chloride or table salt into prepared food. Weight gain is also associated with the consumption of processed foods that contain too much sodium, adding to the total sodium intake of an individual.
Excessive intake of sodium is observed during the preparation of food in households and during the manufacturing of processed food products. Therefore, the deficiency of this essential mineral is not usually observed in normal circumstances. True depletion of sodium and water is observed in different pathologic conditions including kidney diseases, chronic diarrhea, prolonged sweating, or uncontrollable vomiting.
Dietary intake of sodium is constituted by the small quantities of sodium found in natural food substances such as vegetables. This is complemented by excessive amounts of salt additionally incorporated in foods during preparation and at the table. Greater quantities of sodium are added during the industrial processing of foods.
Higher intake of sodium tends to be associated with obesity[2], as indicated by various studies. According to these studies, the increased risk of obesity associated with an increase in the intake of sodium was found to be accompanied by a rise in the intake of energy. The intake of high-energy salt foods such as cheese and their relationship with an increase in obesity indicate that individuals consuming higher quantities of salt may also consume more food. However, salt intake and weight gain can be independent of the quantity of food or energy intake.
Water Weight
Weight indicates that the excess weight of the body is attributed to the body fluid levels and the body retains water, causing an individual to gain weight. Intake of salty foods causes the body to produce a physiological response. Under this response, the body tends to manage the water and osmolyte balance. Hence, high salt intake causes the body to conserve water and prevent dehydration. Increased salt tends to induce thirst mechanisms, stimulating increased fluid intake. This is paralleled by how more sodium affects water and salt elimination by the kidneys. The hormone responsible for fluid retention in response to extra salt in the body is aldosterone.
Processed Foods
There is a high concentration of salt in processed foods[3]. The food-related products containing excess salt include color enhancers, preservatives, and stabilizers. The greater consumption of such foods correlates with high salt intake, which is also implicated in the development of high blood pressure. High salt content also causes weight gain by the mechanisms described above.
Is Sodium Harmful to Weight Loss?
The discussion of the role of salt intake in increasing the fat content and excess water concentration in the body explains that higher levels of sodium may hinder weight loss[4] in individuals. Research has demonstrated that adaptation to a reduces the body mass index. According to research, the reduction in the body is attributed to reduced total body water coherent with reducing salt instead of reducing visceral fat or body fat mass.
How Much Sodium Should You Eat Per Day?
Concerning the amount of salt intake, the recommended intake[5] is 1.5-2.3 grams per day for those who are looking forward to consuming less sodium in their diet. Overweight or obese individuals suffering from borderline high blood pressure are required to consume less salt and consume a healthy diet. Reducing the salt intake by eating healthy foods and limiting the addition of extra salt into foods helps mitigate the risk of heart diseases.
Effects of High Salt Intake on Health
Fresh foods such as fresh vegetables and fruits contribute a negligible amount of sodium concentration in the total dietary intake of salt. The major sources of dietary salt include bread, cereal and cereal products, meats, eggs, milk and dairy products, and fish.
Pre-existing pathologic conditions such as decompensated liver cirrhosis, renal failure, and heart failure can have severe outcomes in patients due to a dangerous rise in the ECF volume. The common practice of adding table salt during the preparation of food and at the table is considered a recognized etiological factor in the development of diseases affecting the heart and blood vessels, resulting in the onset of cardiovascular events and hypertension. Other outcomes of high salt intake include gastric cancer, osteoporosis, chronic kidney disease, and calcium nephrolithiasis.
In Addition
Sodium is also integral to the nerve cell function. Excessive salt intake disrupts the balance of intestinal homeostasis, which may lead to cognitive impairment. This is represented by impaired memory ability and disrupted learning. High salt intake also triggers apoptosis and an inflammatory environment in the brain[6].
To limit the dietary intake of excess salt, it is suggested that individuals may consume whole foods instead of processed foods which contain high levels of salt and sodium added during industrial preparation. In addition to dietary recommendations[7], the stakeholders and other relevant authorities shall improve food labeling to assist individuals in identifying salt content by reading food labels before purchase or consumption. Another way to implement modest dietary salt reduction is limiting the intake of processed canteen, supermarket, and restaurant foods.
A simple yet effective measure to limit excess salt intake is to remove the salt shaker from the kitchen and table. The combination of low sodium intake with the Dietary Approaches to Stop Hypertension (DASH) is effective in reducing blood pressure and improving the health of hypertension patients. The DASH includes low levels of cholesterol and saturated fat and high levels of magnesium, protein, carbohydrates, calcium, and potassium.
Conclusion
Sodium is an essential mineral found in the human body and is integral to several processes including the regulation of fluid and electrolyte balance and nerve conduction. The increase in the consumption of processed foods and the addition of excess salt during food preparation has made humans prone to excess sodium content in the body. Not only it affects the renal, nervous, gut, and cardiovascular health of individuals, but it also increases the risk of weight gain. The increase in body weight is explained by several mechanisms including water retention, fat volume, and simultaneous energy intake.
It is recommended that individuals refrain from adding excess salt during food preparation and remain mindful when purchasing processed foods by reading labels.
Frequently Asked Questions
Sodium is an essential mineral and a cation found in the ECF of the human body. Its concentration across the ECF and ICF is maintained by the sodium-potassium pump. Important functions of sodium in the body include the regulation of fluid and electrolyte balance, nerve conduction, and blood pressure.
The recommended intake of salt for the adult population is 1.5-2.3 grams per day.
Meats, cheese, and processed foods available at restaurants and supermarkets have high concentrations of salt. Further, the addition of table salt during food preparation such as making pasta increases the dietary sodium content.
Fresh fruits and vegetables along with cereal and cereal products contain relatively low levels of sodium and do not pose a risk of excess sodium in the body if consumed in moderate amounts.