The health effects of salt are the conditions associated with the consumption of either too much or too little salt. Salt is a mineral composed primarily of sodium chloride (NaCl) and is used in food for both preservation and flavor. Sodium ions are needed in small quantities by most living things, as are chloride ions. Salt is involved in regulating the water content (fluid balance) of the body. The sodium ion itself is used for electrical signaling in the nervous system. [1]
Salt is usually high in ultra-processed and hyperpalatable foods. [2] In 2020, the World Health Organization (WHO) recommended that adults consume no more than 5 grams (0.18 oz) (just under a teaspoon) of salt per day, an amount providing about 2 grams (0.071 oz) of sodium per day. [3] [4] The WHO further recommends that salt intake be adjusted for those aged 2 to 15 years old based on their energy requirements relative to those of adults. [3] High sodium consumption (5 g or more of salt per day) and insufficient potassium intake (less than 3.5 grams (0.12 oz) per day) have been linked to high blood pressure and increased risk of heart disease, stroke, and kidney disease. [5] [6]
As an essential nutrient, sodium is involved in numerous cellular and organ functions. Several national health organizations recommend limiting sodium consumption to 2.3 g per day. However, some studies have found that sodium intake that is below 3 g per day (equivalent to about 7.5 g of salt) may increase the risk for cardiovascular disease and early death. [5] [7] [8] The cardiovascular benefits of reducing salt consumption are similar to reductions in obesity, cholesterol, and tobacco use. [9]
Hypernatremia (high blood sodium level, above 145 mEq/L) causes thirst, and due to brain cell shrinkage may cause confusion, muscle twitching, or spasms. With severe elevation, seizures and comas may occur. [10] [11] Death can be caused by ingestion of large amounts of salt at a time (about 1 g per kg of body weight). [12] Deaths have also been caused by the use of salt solutions as emetics, typically after suspected poisoning. [13]
Hyponatremia, or blood sodium levels below 135 mEq/L, causes brain cells to swell; the symptoms can be subtle and may include altered personality, lethargy, and confusion. In severe cases, when blood sodium falls below 115 mEq/L, stupor, muscle twitching or spasms, seizures, coma, and death can result. [14]
Major health organizations and recent reviews state that high consumption of salt increases the risk of several diseases in children and adults. [15] [16] [17] [18]
Excess sodium consumption increases blood pressure. [15] [18] Some studies suggest a U-shaped association between salt intake and mortality, with increased mortality associated with both excessively low and excessively high salt intake. [7] [8] [19] Larger reductions in salt intake lead to larger decreases in blood pressure. [18]
Normotensive overweight/obese patients who were salt restricted for six weeks showed an endothelin 1 (ET-1) decrease of 14% associated with a 45% increase in flow-mediated dilation (FMD). [20] ET-1 has autocrine action on endothelial cells causing the release of nitric oxide. [20] Another study using middle-aged or older adults with moderately elevated blood pressure taking sodium chloride tablets or placebo tablets for a few weeks showed that sodium restriction increased nitric oxide and tetrahydrobiopterin (BH4) resulting in improved FMD without affecting blood pressure. [21] The suppression of endothelium production of nitric oxide is the result of oxidative stress on the vasculature. [22]
Health effects associated with excessive sodium consumption include:
A meta-analysis investigated the association between sodium intake and health outcomes, including all-cause mortality and cardiovascular disease (CVD) events. [8] Low sodium intake level was a mean of <115 mmol (2645 mg), usual sodium intake was 115-215 mmol (2645–4945 mg), and a high sodium intake was >215 mmol (4945 mg), concluding: "Both low sodium intakes and high sodium intakes are associated with increased mortality, consistent with a U-shaped association between sodium intake and health outcomes".
Microplastic contamination in sea salt has been confirmed in all areas of the world, ranging from zero to 1,674 particles per kilogram. [34] The most common particles are polypropylene, followed by polyethylene and nylon. [35] Microplastic particles per kg sea salt tend to be higher when sourced from Asian countries. [34] Salt sourced from India ranged from 115 to 560 particles/kg. [36] Sea salt sourced from China reported more than 400/kg. [37] Microplastics also accrue in shellfish grown or harvested in regions with microplastic contamination of seawater, and are a significant contributor to human exposure. [38] The extent to which humans are exposed to microplastics in foods and beverages can be assessed via measuring microplastics content in feces, but the health effects, if any, are poorly understood. [39]
Recommended intakes of salt are usually expressed in terms of sodium intake as an Adequate Intake (AI) and a Tolerable upper intake level (Upper Limit or UL). Salt (as sodium chloride) contains 39.3 percent of sodium by weight.
Country | Description | Sodium intake mg per day | Salt intake mg per day | Authority | Remarks |
---|---|---|---|---|---|
United Kingdom | The Reference Nutrient Intake (RNI) defined for a typical adult | RNI: 1600 | RNI: 4000 | Scientific Advisory Committee on Nutrition (SACN) (2003) [40] | However, average adult intake is two and a half times the RNI. SACN states, "The target salt intakes set for adults and children do not represent ideal or optimum consumption levels, but achievable population goals." The Food Safety Authority of Ireland endorses the UK targets. [26] |
Canada | An Adequate Intake (AI) and Upper Limit (UL) recommended for persons aged 4 years or more. | AI: 1200–1500 UL: 1900–2300 | AI: 3000–3750 UL: 5500–5750 | Health Canada (2017) [6] | "Canadians are consuming too much sodium without understanding the risks to their health. Canadians should lower their sodium intakes, as part of maintaining a healthy lifestyle, to reduce the risk of high blood pressure, stroke and heart and kidney disease." (2017) [6] |
Australia and New Zealand | An Adequate Intake (AI) and an Upper Level of intake (UL) defined for adults | AI: 460–920 UL: 2300 | AI: 1150–2300 UL: 5750 | NHMRC (2006) [41] | Not able to define a recommended dietary intake (RDI) |
United States | An Adequate Intake (AI) and Upper Limit (UL) defined for adults. A different UL defined for the special group comprising people over 51 years of age, African Americans and people with hypertension, diabetes, or chronic kidney disease (regardless of age). [5] | UL: 2300 UL for special group: 1500 | UL: 5750 UL for special group: 3750 | Department of Agriculture and Department of Health and Human Services (2010) [42] [43] | The Food and Drug Administration itself does not make a recommendation, but refers readers to the dietary guidelines given by this authority. [44] |
Sweden | An Adequate Intake (AI) and Upper Level of intake (UL) defined for adults | AI: 2000 UL: 2400 | AI: 5000 UL: 6000 | Swedish Food Agency (2023) [45] | An excessive intake of sodium increases the blood pressure, which in turn can lead to increased risk of cardiovascular diseases and kidney failure. It is estimated that one forth of the adults in Sweden have high blood pressure, and almost half of all over 65 years of age. The Swedish recommendations are based on the Nordic Nutritional Recommendations (2012). [46] |
Nordic countries | An Adequate Intake (AI) and Chronic disease risk reduction (CDRR) | UL: 1500 CDRR: 2300 | UL: 2500 CDRR: 5750 | The Nordic Nutritional Recommendations (NNR) (2023) [47] | Adverse effects of high intake are high blood pressure and increased mortality. [48] [47] |
As of 2009 the average sodium consumption in 33 countries was in the range of 2,700 to 4,900 mg/day. This ranged across many cultures, and together with animal studies, this suggests that sodium intake is tightly controlled by feedback loops in the body. This makes recommendations to reduce sodium consumption below 2,700 mg/day potentially futile. [49] Upon review, an expert committee that was commissioned by the Institute of Medicine and the Centers for Disease Control and Prevention reported that there was no health outcome-based rationale for reducing daily sodium intake levels below 2,300 milligrams, as had been recommended by previous dietary guidelines; the report did not have a recommendation for an upper limit of daily sodium intake. [28] [50]
The United States Centers for Disease Control and Prevention (CDC) states that excess sodium can increase blood pressure and the risk for heart disease and stroke in some individuals. [51] Therefore, health authorities recommend limitations on dietary sodium. [52] [53] [54] [55] The United States Department of Health and Human Services recommends that individuals consume no more than 1500–2300 mg of sodium (3750–5750 mg of salt) per day. [51] [42]
Although sea salt is sometimes promoted as being healthier than table salt, both forms have the same sodium content. [56]
UK: The Food Standards Agency defines the level of salt in foods as follows: "High is more than 1.5 g salt per 100 g (or 0.6 g sodium). Low is 0.3 g salt or less per 100 g (or 0.1 g sodium). If the amount of salt per 100 g is in between these figures, then that is a medium level of salt." In the UK, foods produced by some supermarkets and manufacturers have 'traffic light' colors on the front of the packet: red (high), amber (medium), or green (low). [57]
USA: The FDA Food Labeling Guide stipulates whether a food can be labeled as "free" "low," or "reduced/less" in respect of sodium. When other health claims are made about a food (e.g., low in fat, calories, etc.), a disclosure statement is required if the food exceeds 480 mg of sodium per 'serving'. [58]
In Australia, the "Drop the Salt! Campaign" aimed to reduce the consumption of salt by Australians to 6g per day over the course of five years ending in 2012. [59]
In 2016, South Africa was the first country to legislate the maximum amount of salt in processed food. [60] The legislation was aimed at addressing the fact that 60% of salt in the diet was contributed to by processed foods, with 65% of all ethnic groups consuming sodium in excess of 6g/day, and 40% of young adults in excess of 9g/day. [61]
Consensus Action on Salt and Health (CASH) [62] established in the United Kingdom in 1996, actively campaigns to raise awareness of the negative health effect of high intake of salt. The 2008 focus includes raising awareness of high levels of salt hidden in sweet foods that are marketed towards children. [63] In 2004, Britain's Food Standards Agency started a public health campaign called "Salt – Watch it", which recommends no more than 6 g of salt per day; it features a character called Sid the Slug and was criticised by the Salt Manufacturers Association (SMA). [64] The Advertising Standards Authority did not uphold the SMA complaint in its adjudication. [65] In March 2007, the FSA launched the third phase of their campaign with the slogan "Salt. Is your food full of it?" fronted by comedian Jenny Eclair. [66]
Since 2010, as part of the Sodium Reduction in Communities Program (SRCP), the United States Centers for Disease Control and Prevention funded local communities across the United States to implement a variety of policy, systems, and environmental change strategies focused on increasing access to lower sodium in foods in a variety of settings such as hospitals, congregate meal sites, and university settings. [67]
In January 2010, New York City launched the National Salt Reduction Initiative (NSRI). [68] It was the only coordinated, voluntary effort to reduce sodium in the United States, an effort supported by the Institute of Medicine as an interim goal in advance of federal action on sodium reduction.
As of 2013, over 90 state and local health authorities and health organizations had signed on as partners of the NSRI. Together, the NSRI partnership encouraged food manufacturers and chain restaurants to voluntarily commit to NSRI sodium reduction targets for 2012 and 2014. The NSRI aimed to reduce sodium in the food supply by 25 percent in five years and reduce population sodium intake by 20 percent in the same time, thereby reducing risk for heart attacks and strokes. [68]
In the United States, taxation of sodium has been proposed as a method of decreasing sodium intake and thereby improving health in countries where typical salt consumption is high. [69] Taking an alternative view, the Salt Institute, a salt industry body based in North America, is active in promoting the use of salt, [70] and questioning or opposing the recommended restrictions on salt intake. [71]
In 1989 the Swedish Food Agency launched the symbol Nyckelhålet [72] (The Green Keyhole). The symbol is a public health campaign that aims to help consumers to find healthier food alternatives, and the requirements for using the symbol differs between food categories. Apart from salt, the requirements include fat content, fat quality, fibre content and sugar. It is voluntary for food manufacturers to apply for the symbol on food items that fulfill the requirements, and the application is usually reviewed by the municipal environment and health protection board. Since June 2009, the symbol is also used in Norway and Denmark.
A low sodium diet reduces the intake of sodium by the careful selection of food. The use of a salt substitute can provide a taste offsetting the perceived blandness of low-salt food; potassium chloride is widely used for this purpose. The World Health Organization (WHO) recommends daily potassium intake of not less than 3,510 mg. [17] Government interventions such as food product reformulation and food procurement policy have the potential to reduce the population salt intake. [73]
Studies found that excessively low sodium intake, below about three grams (3,000 mg) of salt per day, is associated with increased mortality and higher risk for cardiovascular disease. [7] [8]
A 2020 Cochrane systematic review [74] concludes that for white people with hypertension, reducing salt intake results in a decrease of about 4 mmHg (about 3.5%) of their blood pressure; for people with normal blood pressure, the decrease was negligible. Weak evidence indicated that these effects might be a little greater in black and Asian people. This review also indicates potential negative side effects on hormones and lipid levels, so that decreasing salt intake is not necessarily recommended for people with normal blood pressure.
In people with chronic kidney disease, including those on dialysis, there is high-certainty evidence that dietary salt restriction may help to lower systolic and diastolic blood pressure, as well as albuminuria. [75] The risk of hypotensive symptoms, such as dizziness, may also increase in some people, with moderate certainty. [75] It is unclear whether this affects the dosage required for anti-hypertensive medications. The effect of salt restriction on extracellular fluid, oedema, and total body weight reduction is also uncertain. [75]
Cholesterol is the principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitamin E, can cause nerve problems. Vitamin E is a fat-soluble antioxidant which may help protect cell membranes from reactive oxygen species. Worldwide, government organizations recommend adults consume in the range of 3 to 15 mg per day. As of 2016, consumption was below recommendations according to a worldwide summary of more than one hundred studies that reported a median dietary intake of 6.2 mg per day for alpha-tocopherol. Foods rich in vitamin E include seeds and nuts, seed oils, peanut butter, and vitamin E-fortified foods, such as margarine.
Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease, and dementia. Hypertension is a major cause of premature death worldwide.
A saturated fat is a type of fat in which the fatty acid chains have all single bonds between the carbon atoms. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched chain of carbon (C) atoms. Along the chain, some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). A double bond along the carbon chain can react with a pair of hydrogen atoms to change into a single -C-C- bond, with each H atom now bonded to one of the two C atoms. Glyceride fats without any carbon chain double bonds are called saturated because they are "saturated with" hydrogen atoms, having no double bonds available to react with more hydrogen.
In the U.S. and Canada, the Reference Daily Intake (RDI) is used in nutrition labeling on food and dietary supplement products to indicate the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of healthy individuals in every demographic in the United States. While developed for the US population, it has been adopted by other countries, such as Canada.
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases, heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, arrhythmia, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis.
Essential hypertension is a form of hypertension without an identifiable physiologic cause. It is the most common type affecting 85% of those with high blood pressure. The remaining 15% is accounted for by various causes of secondary hypertension. Essential hypertension tends to be familial and is likely to be the consequence of an interaction between environmental and genetic factors. Hypertension can increase the risk of cerebral, cardiac, and renal events.
Electrolyte imbalance, or water-electrolyte imbalance, is an abnormality in the concentration of electrolytes in the body. Electrolytes play a vital role in maintaining homeostasis in the body. They help to regulate heart and neurological function, fluid balance, oxygen delivery, acid–base balance and much more. Electrolyte imbalances can develop by consuming too little or too much electrolyte as well as excreting too little or too much electrolyte. Examples of electrolytes include calcium, chloride, magnesium, phosphate, potassium, and sodium.
A healthy diet is a diet that maintains or improves overall health. A healthy diet provides the body with essential nutrition: fluid, macronutrients such as protein, micronutrients such as vitamins, and adequate fibre and food energy.
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as rock salt or halite. Salt is essential for life in general, and saltiness is one of the basic human tastes. Salt is one of the oldest and most ubiquitous food seasonings, and is known to uniformly improve the taste perception of food, including otherwise unpalatable food. Salting, brining, and pickling are also ancient and important methods of food preservation.
The European Prospective Investigation into Cancer and Nutrition (EPIC) study is a Europe-wide prospective cohort study of the relationships between diet and cancer, as well as other chronic diseases, such as cardiovascular disease. With over half a million participants, it is the largest study of diet and disease to be undertaken.
The Dietary Approaches to Stop Hypertension or the DASH diet is a diet to control hypertension promoted by the U.S.-based National Heart, Lung, and Blood Institute, part of the National Institutes of Health (NIH), an agency of the United States Department of Health and Human Services. The DASH diet is rich in fruits, vegetables, whole grains, and low-fat dairy foods. It includes meat, fish, poultry, nuts, and beans, and is limited in sugar-sweetened foods and beverages, red meat, and added fats. In addition to its effect on blood pressure, it is designed to be a well-balanced approach to eating for the general public. DASH is recommended by the United States Department of Agriculture (USDA) as a healthy eating plan. The DASH diet is one of three healthy diets recommended in the 2015–20 U.S. Dietary Guidelines, which also include the Mediterranean diet and a vegetarian diet. The American Heart Association (AHA) considers the DASH diet "specific and well-documented across age, sex and ethnically diverse groups."
A salt substitute, also known as low-sodium salt, is a low-sodium alternative to edible salt marketed to reduce the risk of high blood pressure and cardiovascular disease associated with a high intake of sodium chloride while maintaining a similar taste.
The Dietary Guidelines for Americans (DGA) provide nutritional advice for Americans who are healthy or who are at risk for chronic disease but do not currently have chronic disease. The Guidelines are published every five years by the US Department of Agriculture, together with the US Department of Health and Human Services. Notably, the most recent ninth edition for 2020–25 includes dietary guidelines for children from birth to 23 months. In addition to the Dietary Guidelines per se, there are additional tools for assessing diet and nutrition, including the Healthy Eating Index (HEI), which can be used to assess the quality of a given selection of foods in the context of the Dietary Guidelines. Also provided are additional explanations regarding customization of the Guidelines to individual eating preferences, application of the Guidelines during pregnancy and infancy, the USDA Nutrition Evidence Systematic Review, information about the Nutrition Communicators Network and the MyPlate initiative, information from the National Academies about redesigning the process by which the Dietary Guidelines for Americans are created, and information about dietary guidelines from other nations.
A low sodium diet is a diet that includes no more than 1,500 to 2,400 mg of sodium per day.
On October 25, 2007, the Minister of Health announced that the Government of Canada would establish an expert Sodium Working Group to explore options for reducing sodium intake and cardiovascular disease among Canadians.
Health Canada, the department of the Government of Canada responsible for national health, has allowed five scientifically verified disease risk reduction claims to be used on food labels and on food advertising. Other countries, including the United States and Great Britain, have approved similar health claims on food labels.
Salt consumption has been extensively studied for its role in human physiology and impact on human health. Chronic, high intake of dietary salt consumption is associated with hypertension and cardiovascular disease, in addition to other adverse health outcomes. Major health and scientific organizations, such as the World Health Organization, US Centers for Disease Control and Prevention, and American Heart Association, have established high salt consumption as a major risk factor for cardiovascular diseases and stroke.
A renal diet is a diet aimed at keeping levels of fluids, electrolytes, and minerals balanced in the body in individuals with chronic kidney disease or who are on dialysis. Dietary changes may include the restriction of fluid intake, protein, and electrolytes including sodium, phosphorus, and potassium. Calories may also be supplemented if the individual is losing weight undesirably.