The myth that salt increases blood pressure has been around for a while – likely at least as far back as 1904 when some doctors in France found that six subjects who had high blood pressure also happened to eat a lot of salt. Then in the 1940s, a researcher named Kemper was able to show that reducing salt intake in some people led to drops in blood pressure.
Studies continued and in the 1970s, a man named Dahl fed rats what would amount to more than a pound of salt for an adult human and cited that as proof that salt causes high blood pressure.
As a result of the myth that salt causes high blood pressure, many people have been advised to limit their salt intake. Ironically, many people who have high blood pressure actually crave salt. Nonetheless, many obey the orders and restrict salt. The question is, is there a payoff? Does salt substantially increase blood pressure? And if so, is that associated with any increase in diseases?
The conclusions from the rather extensive studies that have been conducted in this matter are categorical. In no way does salt restriction offer any benefits to blood pressure or offer protection from disease. In fact, some studies conclude that increased salt intake correlates to decreased risk of various diseases, including heart disease!
The Cochrane Collaborative, a non-for-profit research organization, published two reviews of trials – one in 2004 and one in 2011 – both of which concluded that there is no benefit in reducing salt intake. In 2011, Cochrane wrote that “cutting down on the amount of salt has no clear benefits in terms of likelihood of dying or experiencing cardiovascular disease.”
The Journal of the American Medical Association published a paper in 2011 concluding that “systolic blood pressure, but not diastolic pressure, changes over time aligned with change in sodium excretion, but this association did NOT translate into a higher risk of hypertension or cardiovascular disease complications.”
(Katarzyna Stolarz-Skrzypek, et al., 2011)
These reports are not alone. There are more than 10 such reports that I have found that draw the same conclusions: increased sodium intake does not cause high blood pressure or higher rates of disease. In fact, some of the studies conclude that reducing sodium intake is correlated to higher rates of health problems in some populations.
The body maintains a balance between sodium and potassium. Too little sodium leads to a condition known as hyponatremia. This condition can be brought about in a variety of ways, the most common of which is excessive water intake following prolonged physical exertion, and in some rare cases it can even prove fatal.
Unfortunately, a lot of people may be producing mild hyponatremia by greatly reducing or eliminating salt intake coupled with increasing potassium intake (through ingesting more things like green smoothies).
Both sodium and potassium are essential nutrients for human health. Too little of either can cause serious problems. Many people eat too little potassium, creating an imbalance in the sodium to potassium ratio. The ratio can be corrected by limiting sodium intake, of course. But doing so results in deficiencies of both nutrients rather than correcting the existing potassium deficiency.
Different people respond differently to salt. Some people are more sensitive to salt than others. But by and large, the evidence suggests that modest salt intake (up to 6 grams of sodium per day) does not cause high blood pressure or diseases.