The notion that hypertension is caused by a high-salt diet is more than 100 years old, but much of its history is punctuated by controversy. The earliest study that reported a positive correlation between salt intake and blood pressure in humans was published in 1904 and was refuted just 3 years later. A half-century later, Dr. Lewis Dahl conducted a study on rats that were bred to have differing susceptibility to developing hypertension. Dahl induced hypertension in the rats by feeding them 500 grams of sodium per day. Unsurprisingly, the rats developed hypertension......quickly. By reducing their sodium intake, Dahl proposed that there was a link between hypertension and salt intake. While there’s no dispute that Dahl’s research was well-intended, it was significantly flawed. For instance, the average American’s salt intake is roughly 8.5 grams of salt per day — compared to the 500 grams given to the rats in the study. Furthermore, hundreds of studies conducted since Dahl’s work have conclusively shown that reducing sodium intake alone does not significantly relieve hypertension. Reducing our salt intake isn’t necessarily a bad idea, except when it is. Simply cutting salt out of your diet completely can actually cause more harm than not cutting it out at all. When salt intake is reduced, your body responds by releasing aldosterone and renin which increase blood pressure. If the sodium levels in your blood are too low, you could develop hyponatremia – a condition that causes the water levels in your blood to rise and the cells to swell. As with the now-debunked recommendations on dietary cholesterol and fat, the sodium-hypertension myth appears to be on the way out. History, and consumers, will not look kindly on organizations that continue to cling to their unjustified war on salt.
