The Salty Truth
Updated: Oct 23, 2019
Nearly every cell in your body auto regulates its contents. The body as a whole regulates its fluid levels in different compartments (blood, intracellular, extracellular) primarily through sodium (salt). In addition, sodium is a very common carrier of electric charge. Therefore, two crucial functions of dietary salt in the body are:
1. Regulate osmolarity. Regulation of osmolarity is achieved by balancing the intake and excretion of sodium with that of water.
2. Regulates charge (this refers to whether something is positively or negatively charged.) Sodium is a positive charge.
Scientific evidence showing detrimental health effects from the consumption of salt is complicated and weak at best. In 2013 the prestigious Institute of Medicine (IOM) found there was no good evidence that lowering salt intake to under 2000 mg/day, as the World Health Organization recommends, will result in better health outcomes. The main author of the study, Brian Strom, stated: “There is not a single study, not one, showing [such a] benefit for having a sodium intake of fewer than 2,300 milligrams.” The science is mixed on this issue and has been for the last 40 years. One confounding factor is that we all react to dietary salt in differing ways. It is true that some people display a greater degree of sensitivity to salt but it is unclear why. Salt’s relationship to health is modulated by many dietary and non-dietary factors, including the interaction and balance of a range of essential minerals. More evidence is being uncovered, from studies published over the past decade, which actually suggests salt restriction may increase our likelihood of dying prematurely. It may be that we’re better off with more salt than less. The NYTimes wrote:
One 2008 study the committee examined, for example, randomly assigned 232 Italian patients with aggressively treated moderate to severe congestive heart failure to consume either 2,760 or 1,840 milligrams of sodium a day, but otherwise to consume the same diet. Those consuming the lower level of sodium had more than three times the number of hospital readmissions — 30 as compared with 9 in the higher-salt group — and more than twice as many deaths — 15 as compared with 6 in the higher-salt group.Another study, published in 2011, followed 28,800 subjects with high blood pressure ages 55 and older for 4.7 years and analyzed their sodium consumption by urinalysis. The researchers reported that the risks of heart attacks, strokes, congestive heart failure and death from heart disease increased significantly for those consuming more than 7,000 milligrams of sodium a day and for those consuming fewer than 3,000 milligrams of sodium a day.
The New England Journal of Medicine published the results of a massive research study (2014) called the PURE study. It included more than 100,000 adults sampled from the general population of 17 countries. It concluded: ‘… that people who conform to the U.S. recommended limits (under 2300mg/day) actually have more heart trouble’. However, and as per usual, there are many scientists who disagree with the methodology of this study. A meta-knowledge analysis of the literature on salt intake and health outcomes (analyzing 269 recent research reports) in The International Journal of Epidemiology’ found “a strong polarization of scientific reports on the link between sodium intake and health outcomes, and a pattern of uncertainty in systematic reviews about what should count as evidence”. They found that 54% were supportive of the hypothesis, 33% were contradictory and 13% were inconclusive. The hypothesis, in this case, is that population-wide reduction of sodium intake results in a reduction in cerebrocardiovascular disease or all-cause mortality. Basically, a coin flip. There is no scientific agreement.
Gary Taubes wrote an article in the New York Times excoriating low salt diets:
“The idea that eating less salt can worsen health outcomes may sound bizarre, but it also has biological plausibility and is celebrating its 40th anniversary this year, too. A 1972 paper in The New England Journal of Medicine reported that the less salt people ate, the higher their levels of a substance secreted by the kidneys, called renin, which set off a physiological cascade of events that seemed to end with an increased risk of heart disease. In this scenario: eat less salt, secrete more renin, get heart disease, die prematurely.“With nearly everyone focused on the supposed benefits of salt restriction, little research was done to look at the potential dangers. But four years ago, Italian researchers began publishing the results from a series of clinical trials, all of which reported that, among patients with heart failure, reducing salt consumption increased the risk of death. “Those trials have been followed by a slew of studies suggesting that reducing sodium to anything like what government policy refers to as a ‘safe upper limit’ is likely to do more harm than good.”
Despite the vast uncertainty of the scientific evidence surrounding dietary salt intake and health, public officials in the U.S. and many other countries have decided to enact laws, put forth recommendations and guidelines regulating salt intake. Why? And is this a good or bad thing? I am all for transparency but enacting laws that are based on questionable science hurts all of us. Putting a warning label on salt may get some people to lower their intake to the point of impairing their health and increasing their risk of death. It also devalues legitimate warning labels. We don’t have good data on the population-wide health effects of dietary salt intake. It may just come down to moderation. Like most things, everyone responds differently and too much or too little is likely unhealthy.
Facts About Dietary Salt: The Salty Truth
Salt is a necessary element of the human diet. Humans die without the adequate salt intake. Just don’t drink salt water when you are dying of thirst.
Perspiration is the biggest source of variability in an individual’s requirement for salt. Given that our need for salt varies widely with exercise and with ambient temperature.
For most people, consuming a moderate amount of salt daily (3000-5000 mg) has no adverse effects.
For nearly everyone, eating more salt causes an increase in blood pressure, but the increase is temporary and not clinically important.
About 10-15% of the population can be labeled “salt sensitive”. The people in this group who also have high blood pressure may need to stay away from too much salt.
A diet too low in salt increases the risk of cardiovascular events and increase a risk of all-cause death for many people.
The science to quantify what constitutes “too low”, “moderate”, and “too high” regarding salt intake is best characterized as “somewhat uncertain”.
Individuals vary widely in how they respond to dietary salt.
Average daily sodium intake in the US is about 3400 mg per day.
The majority of the salt we get in our diets does not come from the salt shaker. It comes from processed and prepared foods, especially things like bread, crackers, cereals, desserts, etc…
When we consume a lot of salt, our bodies retain more water to dilute the sodium in the bloodstream.
All of us have an individualized healthy dietary salt range. Our innate preference for saltiness will direct much of our appetite for sodium rich or sodium free foods. Listen to your body and really pay attention to your true cravings. Keep in mind that many overly processed foods can destroy your carefully calibrated appetite for the right amount of salt. Stick with whole foods, mostly plants, and it will be easy to follow your natural tastes and mediate your salt intake.