Health effects of salt
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Single_grain_of_table_salt_%28electron_micrograph%29.jpg/220px-Single_grain_of_table_salt_%28electron_micrograph%29.jpg)
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
As an
Acute effects
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]
Long-term effects
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:
- Stroke and cardiovascular disease.[23]
- Left ventricular hypertrophy (cardiac enlargement): "Evidence suggests that high salt intake causes left ventricular hypertrophy. This is a strong risk factor for cardiovascular disease, independently of blood pressure effects."[24] "...there is accumulating evidence that high salt intake predicts left ventricular hypertrophy."[26]
- Edema (fluid retention): A decrease in salt intake has been suggested to treat edema.[11][27]
- renal disease.[11] A US expert committee reported in 2013 the common recommendation by several authorities "to reduce daily sodium intake to less than 2,300 milligrams and further reduce intake to 1,500 mg among persons who are 51 years of age and older and those of any age who are African-American or have hypertension, diabetes, or chronic kidney disease", but concluded that there was no health-outcome-based rationale for reducing intake below 2,300 mg, and did not have a recommendation for an upper limit.[28]
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".
Salt-preserved foods
Possible effects of microplastic contamination
Dietary recommendations
Recommended intakes of salt are usually expressed in terms of sodium intake as an
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.
The
Although sea salt is sometimes promoted as being healthier than table salt, both forms have the same sodium content.[56]
Labeling
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]
Campaigns
Australia
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]
South Africa
In 2016, South Africa was the first country to legislate the maximum amount of salt in
United Kingdom
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]
United States
Federal programs
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]
Voluntary initiatives
In January 2010, New York City launched the National Salt Reduction Initiative (NSRI).
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]
Taxation
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]
Sweden
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.
Dietary reduction
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
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Further reading
- Organization, World Health (2012). Guideline: sodium intake for adults and children. World Health Organization. ISBN 978-92-4-150483-6. Retrieved 10 May 2023.
- Neravetla SR, Neravetla SR (2012). Salt Kills. Springfield, OH: Health Now Books, LLC. ISBN 978-1938009006.
- Committee on Strategies to Reduce Sodium Intake (2010). Henry JE, Taylor CL (eds.). Strategies to Reduce Sodium Intake in the United States. Washington, DC: The National Academies Press. PMID 21210559.
- Panel on Dietary Reference Intakes for Electrolytes and Water (2005). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: The National Academies Press. ISBN 978-0-309-09158-9.