A comprehensive guide to salt
“The salt of the earth.” “Worth one’s salt.” “Salt away” savings. These age-old expressions illustrate the value humans have placed on salt for eons.
More recently, however, salt has gone from something treasured to something feared. Health authorities have been encouraging us for decades to cut back on this once-prized substance, especially for lowering blood pressure and decreasing heart disease risk.
But are low-sodium diets necessary — or even safe — for everyone? Read on to learn more about salt and how much of it we should be eating, based on the best current evidence.
This guide is written for adults eating a low-carb diet and who are concerned about salt intake and health.
Discuss any lifestyle changes with your doctor. Full disclaimer
1. What is salt?
When you hear the word “salt,” you probably picture a typical salt shaker filled with the white, crystalline substance that’s added to food for seasoning purposes. Originating from seawater, evaporated lakes, or mines deep beneath the earth, salt not only brings out flavors in foods, but it’s also used as a preservative and plays an important role in curing, smoking, pickling, and processing food.
For centuries, salt was a precious commodity that was traded for gold. In fact, the term “salary” comes from salarium, the Latin word for salt.
Salt vs. sodium: What’s the difference?
Although frequently used interchangeably, salt and sodium aren’t the same thing — an important distinction when discussing daily intake. Sodium is a mineral that is found naturally in small amounts in many foods such as meat, milk, yogurt, certain tropical fruits, and vegetables like artichokes, celery, beets, and seaweed.
Salt is sodium combined with chloride, another mineral. Since sodium chloride is roughly 40% sodium, 5 grams of salt (about 1 teaspoon) contains about 2 grams of sodium. According to one study, salt added to processed foods accounts for about 70% of our daily sodium intake.3
Some sodium also comes from baking soda (sodium bicarbonate) in baked goods, crackers and cookies.
In short, sodium is the essential mineral our body uses, but salt (sodium chloride) is the dominant way we take that mineral in.
Different types of salt
Salt is found on every continent, and edible forms are available in dozens of varieties. Here are a few of the most popular:
- Table salt: Known as rock salt, or halite, it is mined from underground deposits resulting from the evaporation of ancient seas. Rock salt can be used for curing meat or pulverized to a fine texture to create table salt. To prevent goiter and other problems caused by iodine deficiency, manufacturers typically add iodine and label their salt as iodized.
- Sea salt: Coarser-grained, flakier, and more subtly flavored than table salt, sea salt comes from evaporated present-day seawater. It may sometimes contain natural traces of iodine.
- Himalayan salt: Harvested from salt caves in the Himalayan mountains of Pakistan, this colorful salt ranges from off-white to deep pink and contains minuscule amounts of trace minerals despite common claims for larger amounts.
- Kosher salt: Its large size and coarse texture is used in the koshering process to draw fluids out of meat. Kosher salt is never iodized.
Although some forms are less processed than others and differ slightly in taste and trace mineral content, from a nutritional point of view, salt is salt, or sodium chloride (NaCl). Most salt substitutes are a mix of sodium chloride and potassium chloride (KCL).
2. Why do we need salt?
Sodium is an essential nutrient that must come from your diet because your body can’t make it on its own. As the most concentrated electrolyte in your blood, sodium helps:4
- maintain the delicate chemical and fluid balance in and around your cells
- maintain blood pressure
- contract muscles
- conduct nerve impulses
Sodium in your body is tightly regulated by your kidneys, central nervous system, and adrenal glands to make sure it doesn’t go too high or too low.5
If you eat too little salt, your adrenal glands release more aldosterone, a hormone that prompts your kidneys to retain sodium. However, this can potentially have adverse effects on other hormones and potassium levels as your body makes adjustments in order to stay balanced and stable at all times.6
The sodium your body loses through urine and sweat must be replaced. This amount can vary considerably from day-to-day depending on weather, the intensity and duration of any physical activity performed, how much water you have consumed, your overall state of health, and other factors.
Indeed, drinking far too much water without replacing lost sodium can have devastating consequences. Hyponatremia is a potentially dangerous condition in which there is too little sodium in the bloodstream. Symptoms of hyponatremia include headache, weakness, vertigo, muscle spasms, nausea, and vomiting.
Although it’s often triggered by certain medications or an underlying illness, hyponatremia can also occur due to overhydration (“water intoxication”) and inadequate sodium repletion during exercise, especially in hot weather, or in elderly adults who consume low-sodium, restrictive diets.7
3.The controversy over salt intake
What is a “healthy” daily sodium intake? It seems like a simple question, yet it’s one that’s generated quite a bit of controversy over the past several decades.
According to major health organizations in the US and Europe, nearly all of us consume too much sodium on a regular basis, mainly from processed foods.8 They recommend that we sharply reduce our sodium consumption in order to prevent high blood pressure and decrease the risk of heart disease and kidney disease, down to the equivalent of just 1 teaspoon a day.
- For instance, the 2015-2020 Dietary Guidelines for Americans specify that people should eat no more than 2.3 grams (2,300 mg) of sodium per day — the equivalent of about 1 teaspoon.
- The American Heart Association goes even further, saying that everyone should ideally consume less than 1,500 mg of sodium (approximately ¾ of a teaspoon) daily. Most people would consume that much by just eating a bowl of soup or a Caesar salad.
- The World Health Organization (WHO) recommends that we cap our salt intake at 5 grams of salt per day, which at first glance seems quite a bit higher than the amounts above. However, remember that salt is only 40% sodium. Therefore, the WHO’s guidelines call for limiting sodium to 2,000 mg per day.
Other experts have also been saying that too-low sodium intake may have unintended adverse health consequences.10 Let’s dive deeper into this controversy, by reviewing the evidence.
The salt guidelines are too restrictive, say experts
News Is it really necessary to lower your salt intake as much as the current guidelines advise, in order to lower your blood pressure? According to a new expert paper, the guidelines are way too restrictive and not based on enough evidence.
4. Research on salt intake in healthy adults
Is there any evidence that following a low-sodium diet, when healthy, can help decrease your risk of developing future chronic disease? The answer may surprise you.
Systematic reviews and meta-analyses of randomized controlled trials (RCTs) — considered the strongest type of evidence — have found variable results.
Systematic reviews of RCTs from 1996, 2011, and 2017 all showed no benefit for salt restriction among people with normal blood pressure.11 A 2014 Cochrane review likewise showed no mortality benefit from salt restriction.12
In contrast, a 2019 meta-analysis of RCTs from the Annals of Internal Medicine concluded there is “moderate certainty evidence” that reduced salt intake “mildly reduced the risk for all-cause mortality” in those with normal baseline blood pressure.13 The inconsistent data makes it difficult to draw strong conclusions, and makes definitive recommendations to lower sodium intake suspect for the general population.
Part of the concern is understanding the baseline diet. For instance, would the small cardiovascular benefit seen in the RCTs have been different if people instead ate a low carb, real-foods diet? We don’t have the answer to that based on RCTs.
Observational studies, a lower level of evidence, show no evidence that higher sodium intake increases the risk of future cardiovascular disease in those currently without the disease.14
Again, we, unfortunately, need more information about the quality of the underlying diets they ate.15
Could limiting salt actually harm healthy individuals?
Once again, the data is mixed.
One group of researchers conducted a review of both observational studies and RCTs and concluded that sodium restriction has no detrimental effects in healthy people and could potentially benefit some people. Therefore, they feel a low-salt diet is advisable for all.16
This finding was questioned by the recent PURE study which reviewed data on sodium intake from over 100,000 people living in 17 countries. This study found that consuming less than 3,000 mg of sodium per day (7,500 grams of salt or 1.7 teaspoons) was associated with increased risk of heart attack and death in people whether or not they already had elevated blood pressure.17 The lowest risk was between 3,000mg and 7,000mg daily intake.
In earlier analyses by the same researchers, consuming between 3 and 6 grams of sodium daily was linked to the lowest risk of heart disease and early death.18
While observational data like this cannot prove that sodium intake is either a risk factor or a protective factor for heart disease, it does suggest that diets with 3 to 6 grams of salt a day could be part of a healthy lifestyle. For more discussion about this, listen to cardiologist and Diet Doctor’s medical director Dr. Bret Scher discuss the PURE study findings with one of its principal investigators Professor Andrew Mente.
Other experts have suggested that blanket low-sodium recommendations may have unintended health consequences in many people.19This includes increased insulin resistance, which has been shown in several salt restriction trials in healthy adults.20
In 2017, a coalition of three European health organizations recommended an upper limit of 5,000 mg of sodium per day for most people — more than twice as much as the 2,300 mg guidelines that come from other major health organizations.21
As you can see, the data on salt is far from unanimous.
How do we sum it up? The highest level of evidence, reviews of RCTs, show a small increased risk of cardiovascular mortality with higher salt diets in the general population. Thus, when following a standard Western diet, it seems reasonable to limit salt intake.
Would this also apply to real-food, low-carb diets? That is unknown, and we will address that further in the next section.
With decreased carb intake, insulin levels fall significantly. It’s been known for decades that when insulin levels drop, the kidneys excrete more sodium and water.22
If sodium isn’t replaced, you’re likely to develop the unpleasant symptoms of “keto flu,” which include headache, fatigue, and weakness.
What’s more, a keto or low-carb diet composed of mainly whole foods doesn’t have a lot of sodium to begin with, especially compared to processed foods. Thus some may want to add more salt to avoid side effects.23
How can we reconcile advising increased salt intake when we just mentioned some RCTs showing small mortality benefit with salt reduction? This is where we need to consider the subtle nuances of studies.
In a standard Western diet, much of the sodium comes from processed foods.24 On a low carb, real foods diet, however, we believe that we respond differently to salt.25 Since we don’t have long term data showing safety, we are cautious in our recommendation to increase salt intake, especially for those with underlying medical conditions.
See our section below for more information regarding salt and co-existing medical issues.
Ways to increase salt intake – more info
Consuming about 4,000 to 7,000 milligrams of sodium (about 2 to 3 teaspoons of salt) is usually sufficient to get through keto-adaptation and can often be maintained beyond the transition period, depending on individual needs.26
Here are a few ways to boost sodium intake. However, if you have elevated blood pressure, kidney disease or congestive heart failure, talk to your doctor first before increasing your sodium intake, especially if you take medication.27
- Drink 1 or more cups of salty broth every day
- Add 1-2 teaspoons of salt in daily food preparation or at the table
- Eat olives, pickles, sauerkraut, and other salty keto foods regularly
- Choose standard rather than “low-sodium” sauces and seasonings for cooking
- Shake salt into a glass of water a couple of times a day.
5. What about salt intake in people with medical conditions?
Recommendations to reduce sodium intake are so pervasive that we could assume there must be high-quality supporting research. But we would be wrong.
In truth, much of the evidence has been contradictory or inconclusive.28
Let’s take a closer look at the mostly weak research evidence for salt restriction as it relates to common chronic diseases:
Hypertension is the medical term for high blood pressure. It currently affects almost one in three people and is especially common in older, overweight or obese individuals.29 See our guides on high blood pressure and what you can do about it for more information.
Is there overwhelming evidence that salt restriction significantly lowers blood pressure for everyone? No, not really, for a few reasons:
- Not everyone is salt sensitive. Eating a lot of sodium doesn’t significantly raise blood pressure in everyone, including those with hypertension. A person whose blood pressure increases after eating salt is said to have “salt-sensitive hypertension.”30
It’s estimated that about 50% of those with hypertension and 25% of individuals with normal baseline blood pressure are salt sensitive, meaning their blood pressure increases by at least 5 points following a high-sodium diet compared to a low-sodium diet.31Therefore, higher sodium intake may not increase blood pressure in about half of all people with hypertension. As we discuss next, salt restriction will also not lower blood pressure in this population.
- Reducing sodium intake may decrease blood pressure, but only slightly. The highest quality data have found that for most hypertensive adults, sodium restriction doesn’t lead to a dramatic decrease in blood pressure.32 In practical terms, going from 3,500 mg to 1,500 mg of sodium per day might reduce blood pressure by an average of 5 points. Although this modest change may be viewed as a statistically significant reduction in risk by researchers, individuals may question if sustaining this level of sodium restriction is worth the effort and inconvenience.
Could this small reduction in blood pressure explain the small reduction in cardiovascular mortality seen in two meta-analyses of RCTs? It is possible. It is also possible that the smaller percentage of people who are salt sensitive had a greater effect, and thus saw an improvement in mortality. Unfortunately, the data do not specify with this degree of detail.
- Sodium restriction may have adverse effects. Cutting back on salt may have a negative impact on other health markers in hypertensive adults.
In a very large review of 185 clinical studies, people with hypertension who followed a sodium-restricted diet for two or more weeks experienced a 3.5% decrease in blood pressure, on average.33However, this came at the expense of an increase in triglycerides and in the adrenal hormones aldosterone, adrenaline and noradrenaline, which could potentially lead to health problems over time.
Noting the study’s short time frame the authors concluded: “we do not know if low-salt diets improve or worsen health outcomes.” What’s more, the response to sodium restriction in hypertensive individuals seems to include increased insulin resistance, regardless of whether they are salt sensitive or not.34
Thus, rather than simply measuring small changes in blood pressure, what we really need to know is if long-term health outcomes improve or not. Unfortunately, we don’t have that data.
- Overall diet may affect blood pressure as much as salt does. Other researchers have suggested that rather than restricting sodium intake, those who are salt sensitive should be provided with tools to improve the quality of their diet, promote weight loss and decrease insulin resistance, which could help make them less salt sensitive and reduce their disease risk.35
While it may not be the only beneficial approach, a very-low-carbohydrate, ketogenic diet may significantly decrease blood pressure in those who are overweight or have metabolic syndrome regardless of sodium content.36
How to normalize your blood pressure
GuideElevated blood pressure is a common health issue today. Almost a third of U.S. adults have high blood pressure – perhaps you or someone in your family does? High blood pressure isn’t necessarily something you can feel, but it increases the risk of serious conditions such as strokes and heart attacks.
Heart disease, also known as cardiovascular disease (CVD), is a broad term that includes several disorders. People with CVD are generally advised to reduce their salt consumption as part of a “heart healthy diet,” but here is what the research evidence has found:
A recent systematic review and meta-analysis of 11 randomized controlled trials (RCTs) concluded that reducing sodium by an average of 3,000 mg per day improved arterial elasticity.38 By contrast, several large observational studies have found that very low sodium intake is associated with worse cardiovascular outcomes.39
While this associational data does not prove cause and effect, the study authors hypothesize the poor outcomes are due to the aldosterone and adrenaline increases discussed previously. At a minimum, this data should trigger a reevaluation of current recommendations and a call for higher-quality evidence.
- Congestive heart failure:40 Individuals with CHF are usually told to minimize sodium intake in order to prevent fluid overload.
However, this is based mostly on clinical recommendations without the backing of strong research.
In fact, in 2018, researchers performed a systematic review and analysis of nine RCTs and concluded that a lack of high-quality evidence exists in support of current low-sodium guidelines for CHF.41
As a result, some in the medical community are rethinking whether patients with CHF benefit from very-low-sodium diets.42
Based on the inconsistent results across the studies, it’s possible that some people may be more sensitive to sodium’s fluid-retaining effects than others. Although more research is needed, individualized sodium recommendations, as opposed to generalized guidelines, may be most appropriate for managing CHF.
Diabetes and prediabetes
Since people with diabetes are at increased risk for both heart and kidney disease, they are usually advised to limit their salt intake. At one time, the American Diabetes Association recommended that individuals with diabetes aim for less than 1,500 mg of sodium per day; however, this was modified to 2,300 mg per day in the 2019 Standards of Care in Diabetes based on the lack of evidence supporting a further restriction.
Overall, the evidence to date seems to suggest that salt restriction doesn’t improve diabetes outcomes.
- Observational studies suggest potential increase in heart disease and mortality risk. One 2011 study found that people with type 2 diabetes who consumed the least sodium had an increased risk of early death from heart disease or other causes compared to those who consumed the most sodium.43 Another 2011 study in people with type 1 diabetes reported that both the highest and lowest intakes of sodium were linked to an increased risk of early death and developing kidney disease.44
- Experimental study outcomes are mixed. Of the few RCTs available, some have found that sodium restriction may lead to small improvements in blood pressure and kidney function in people with type 2 diabetes.45 High-quality research on salt restriction in type 1 diabetes is even more scarce, but two small studies suggest that restricting salt may have adverse effects on kidney health.46
Although a meta-analysis of RCTs in people with type 1 and type 2 diabetes found that sodium restriction helped reduce blood pressure, the largest effects were seen in people with normal blood pressure, for whom further blood pressure reduction might be of limited or no value.47
- Health risks of high sodium intake may depend on blood sugar control. One study in Japanese men with type 2 diabetes found an association between higher sodium intakes and greater heart disease risk, but this only applied to those with extremely poor diabetes control (HbA1c of 9% or greater); no relationship was found between high salt intake and CVD in those with lower HbA1c’s.48
- Increased insulin resistance: Controlled studies have found that eating too little salt may worsen insulin resistance in adults with type 2 diabetes or exacerbate impaired glucose tolerance in people with prediabetes.49
Remember that sodium restriction may interfere with the body’s normal system of blood pressure regulation. It’s believed that low sodium intake triggers the adrenal glands to release aldosterone and noradrenaline, which may lead to reduced insulin sensitivity.50
In short, avoiding very high sodium intakes greater than 6 grams a day (15 grams of salt) may be beneficial for people with diabetes who have salt-sensitive hypertension. Severe sodium restriction in everyone else with diabetes, however, is less proven and has the potential to do more harm than good.
The National Kidney Foundation advises people with kidney disease to limit their sodium intake to less than 2,000 mg per day.51 However, the optimal sodium restriction for people with chronic kidney disease isn’t clear.
A recent systematic review and analysis of RCTs found that sodium restriction in people with early to end-stage kidney disease can significantly lower blood pressure and reduce urinary albumin.52
However, a controlled 4-week study found that the benefits of reducing salt were most pronounced in hypertensive people with kidney disease whose usual diets provided 5,700 mg of sodium per day (14 grams of salt).53 And an observational study found that consuming more than 4,500 mg of sodium daily (11 grams of salt) was associated with increased risk of CVD, heart attack, and stroke in people with chronic kidney disease. A wide range of sodium intakes below this level were all linked to lower risk.54
Therefore, for this group, moderate sodium restriction below four grams per day, may be beneficial and easier to sustain than extremely low salt intake. Unfortunately, these studies did not adequately control for the quality of food intake, thus leaving some questions about the applicability to a real-foods, low-carb diet.
6. Is salt the real culprit?
According to health organizations, high amounts of sodium in processed foods have played a major role in the epidemics of heart disease and other cardiometabolic conditions. In addition, analyses of RCTs suggest a benefit from reducing salt consumption.
However, what if it isn’t the sodium but rather the sugar and refined carbs that are responsible for most of the effects of highly-processed food? Unfortunately, the research does not do a great job of teasing this out.
Some researchers have suggested that sugar rather than sodium is the main driving force in hypertension, while others say that it’s a combination of sugar and salt.55 However, most studies have a hard time separating overall salt intake from consumption of these potentially unhealthy processed foods.
We know that reducing carbs can lower blood pressure, decrease CVD markers, help reverse diabetes, and promote weight loss — even with moderate to high sodium consumption.56 So the focus on the sodium content in processed foods alone may be somewhat misleading.
7. Summary: How much salt should you eat?
Both published research and anecdotal evidence have shown that the response to salt intake varies from person to person.57
If you have salt-sensitive hypertension, congestive heart failure, or kidney disease, it may be best to avoid eating more than four grams, of sodium. However, the amount that’s best for you may require some experimentation, in coordination with your medical provider. Also, keep in mind that eating a high-quality, carb-restricted diet may potentially improve blood pressure, cardiovascular function, and kidney health much more than restricting salt.
If you don’t have any of these conditions, there isn’t any convincing evidence that severe sodium restriction is beneficial when following a minimally processed low-carb or keto diet.
Consuming about 4 to 7 grams of sodium (about 2 to 3 teaspoons of salt) per day is where many people in the low-carb community will feel and perform the best.58 Occasionally, you may need to further increase sodium intake to replenish salt losses during the first few weeks of a ketogenic diet, during hot weather, or strenuous physical activity. Just keep in mind that if you have salt-sensitive hypertension, you will need to be more cautious than most.
Finally, remember that it’s always good advice to replace highly-processed, low-quality food with minimally-processed, nutritious food. On that, we can all agree.
A Cochrane meta-analysis of RCTs show no clear benefit:
An earlier Cochrane review found a significantly increased risk of death from salt restriction in people with heart failure:
Electrolytes are minerals that form positive or negative electrical charges when dissolved in blood and other body fluids. The major electrolytes are sodium, potassium, calcium, magnesium, and phosphate. See Diet Doctor guide: Do you need electrolyte supplementation on a keto diet ↩
PLOS ONE: Excessively low salt diet damages the heart through activation of cardiac (pro) renin receptor, renin-angiotensin-aldosterone, and sympatho-adrenal systems in spontaneously hypertensive rats [mouse study; very weak evidence] ↩
Military Medicine 2018: Collapse in the heat – from overhydration to the emergency room – three cases of exercise-associated hyponatremia associated with exertional heat illness [case study series; weak evidence] ↩
Surveys show that adults in the US consume about 3-4 grams of sodium per day, on average, with almost 90% eating more than the recommended amounts.
We explore this further in our post:
Much of this concern comes from multiple studies showing an increase in the hormones renin and aldosterone and their potential negative downstream effects.
Cochrane Systematic Review 2017: Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride [systematic review of randomized trials; strong evidence]
The authors concluded, however, that there was “weak evidence” for improved cardiovascular mortality, although the data was inconclusive. The RRR was listed a 0.67, but with a wide confidence interval from 0.45-1.01. Since the confidence interval crossed one, this makes the data statistically insignificant. In this case, the more accurate conclusion is that the data did not show a significant difference in cardiovascular mortality. Regardless, it was clear there was no benefit for all-cause mortality
Annals of Internal Medicine 2019: Effects of nutritional supplements and dietary interventions on cardiovascular outcomes: An umbrella review and evidence map [systematic review of RCTs; strong evidence] ↩
A 2020 observation study from 181 countries reported higher salt intake correlated with greater life expectancy and less risk of dying.
The following study showed a weak association between sodium excretion and risk of cardiac death, but no association to the overall death rate, in all participants. When they studied only those without pre-existing hypertension, the findings were no longer significant.
Journal of the American Medical Association 2011: Fatal and nonfatal outcomes, incidence of hypertension, and blood pressure changes in relation to urinary sodium excretion [observational study with HR < 2; very weak evidence]
Even studies including people with and without hypertension at baseline, only show a very weak (HR 1.14) association between sodium intake and stroke and cardiovascular disease.
Therefore even if sodium intake had an impact on cardiovascular disease, it is likely to be very small and not clearly significant on an individual basis
However, they acknowledged that “There were insufficient randomized controlled trials to assess the effects of reduced sodium intake on mortality and morbidity.” Therefore they based their conclusions only on the observational cohort studies, a weaker level of evidence.
The study also found those who ate more than 7,000 mg of sodium (17.5 grams of salt, about 4 teaspoons) per day and had pre-existing high blood pressure had an increased risk of heart attack and death. This is referred to as a “U-shaped curve” where the risk increases at both high and low intake levels and is lower in the middle.
The Lancet 2016: Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies [observational study with HR < 2; very weak evidence] ↩
As discussed previously, sodium restriction signals the adrenal glands to release aldosterone, prompting the kidneys to hold on to sodium. Researchers have suggested that these higher aldosterone levels coupled with release of the stress hormone noradrenaline may be responsible for decreased insulin sensitivity in people who follow low-salt diets.
European Heart Journal 2017: The technical report on sodium intake and cardiovascular disease in low- and middle-income countries by the joint working group of the World Heart Federation, the European Society of Hypertension and the European Public Health Association [overview article; ungraded] ↩
As we mentioned above, practically all of the research on sodium has been conducted in people eating standard American diets or low-fat diets. That means most of the salt likely came from processed high carbohydrate food, not from minimally processed meats and vegetables with added sea salt.
We are not aware of any high-quality evidence that compares salt restriction on its own to carb restriction for improvements in health conditions.
And we do know that high-quality evidence has repeatedly demonstrated that low-carb and ketogenic diets — without salt restriction — can help reduce elevated blood pressure, waist circumference, and high blood sugar and insulin levels.
Cardiovascular Diabetology 2018: Cardiovascular disease risk factor responses to a type 2 diabetes care model including nutritional ketosis induced by sustained carbohydrate restriction at 1 year: an open label, non-randomized, controlled study [non-controlled trial; weak evidence]
It may make sense then to question if we are better off restricting the sugar and carbs, not the salt, if we want to really improve these conditions. ↩
Blood pressure that remains elevated throughout the day can damage your arteries and increase the risk of heart attack, stroke, kidney disease, loss of vision, and other serious medical problems.
People with hypertension are usually put on medication and advised to minimize salt intake based on several studies suggesting that higher sodium intake may raise blood pressure.
British Medical Journal 1988: Intersalt: an international study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion. Intersalt Cooperative Research Group [observational study with HR < 2; very weak evidence] ↩
This is due to a combination of genetic and environmental influences on the complex systems that regulate the body’s sodium balance.
Physiological Genomics 2018: GNAI2 polymorphic variance associates with salt sensitivity of blood pressure in the Genetic Epidemiology Network of Salt Sensitivity study [mechanistic study; ungraded] ↩
Cochrane Database of Systematic Reviews 2017: Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride [systematic review of controlled trials; strong evidence] ↩
High Blood Pressure and Cardiovascular Prevention 2015: Middle and long-term impact of a very-low-carbohydrate ketogenic diet on cardiometabolic factors; a multi-center, cross-sectional, clinical study [non-randomized trial; weak evidence] ↩
The most common type of cardiovascular disease is coronary artery disease due to atherosclerosis, a process in which plaque builds up in the walls of the arteries, restricts blood flow, and increases heart attack risk. ↩
However, with the exception of one study in 169 hypertensive individuals, the studies were fairly small (between 6 and 40 participants), lasted only one to six weeks, and provided no data on clinical outcomes such as heart attacks and strokes. Therefore, the study did not address long-term effects of sodium restriction on arterial health.
Journal of the American Directors Association 2018: Association between sodium excretion and cardiovascular disease and mortality in the elderly: a cohort study [observational study with HR < 2; very weak evidence]
The Lancet 2016: Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies [observational study with HR < 2; very weak evidence]
In congestive heart failure (CHF), the heart’s ability to pump blood is impaired, leading to fluid buildup in the lungs and extremities. ↩
Although this does not prove it was the salt restriction that led to the increased risk, there was an association. At a minimum that should call for a higher scrutiny of evidence.
The Lancet 2018: Moderate salt restriction with or without paricalcitol in type 2 diabetes and losartan-resistant macroalbuminuria (PROCEED): a randomised, double-blind, placebo-controlled, crossover trial [moderate evidence]
Eventhough this was an analysis of multiple trials, they were very small trials and only included a total of 254 individuals
Cochrane Database of Systematic Reviews 2010: Altered dietary salt intake for preventing and treating diabetic kidney disease [sytematic review of randomized controlled trials; strong evidence] ↩
The Journal of Clinical Endocrinology & Metabolism 2014: Dietary sodium intake and incidence of diabetes complications in Japanese patients with type 2 diabetes: analysis of the Japan Diabetes Complications Study (JDCS) [observational study with HR < 2; very weak evidence] ↩
American Journal of Hypertension 1994: Dietary NaCl restriction deteriorates oral glucose tolerance in hypertensive patients with impairment of glucose tolerance [randomized trial; moderate evidence] ↩
When functioning properly, your kidneys reabsorb water, sodium, and other nutrients from your blood as needed and excrete whatever isn’t needed into your urine.
In chronic kidney disease, the kidneys become less efficient at eliminating excess sodium from the body. Additionally, hypertension is a leading cause of kidney failure because increased blood pressure can damage the delicate arteries that lead to the kidneys. ↩
Albumin is a protein normally present in blood, and its appearance in urine indicates that the kidneys aren’t functioning the way they should be.
Journal of the American Medical Association 2016: Sodium excretion and the risk of cardiovascular disease in patients with chronic kidney disease [observational study with HR < 2; very weak evidence] ↩
You can test your own blood pressure or look for signs of fluid retention (puffiness, tight rings) the day after you’ve eaten salty foods and compare these results to those following a day of eating less salt. In many cases, fluid retention and elevated blood pressure may be unrelated to sodium intake or only minimally influenced by it. ↩