Salt, the only rock we eat, has been one of the world’s most sought-after commodities. From keeping meat from spoiling, to financing of wars, to the establishment of trade routes and cities, salt courses through our veins and our history like no other substance on earth. But most physicians and health officials don’t care for it much – not for its ability to improve the taste of many foods, or its necessity to a properly functioning body – because we eat too much of it, and it causes hypertension (AKA high blood pressure). At least we are told.
How Hypertension came about
Hypertension is technically defined as a systolic blood pressure higher than 140 and a diastolic blood pressure higher than 90 — the old 140 over 90. Blood pressure is basically the force of blood exerted on the blood vessel walls. The systolic pressure is the peak pressure during contracting of the heart and diastolic is the pressure exerted during the relaxed phase. Oh, our beating hearts.
Snake oil salesmen and physicians started measuring blood pressure nearly 100 years ago. Why? Because they could. It was easy to do, and it provided concerned docs a quick “quantitative measure” of how we were doing. More importantly, high blood pressure soon became a risk factor for other diseases. Those with high blood pressure were more likely to be obese and or diabetic. And conveniently, if you were obese or diabetic, you had a pretty good chance of having high blood pressure. Nearly 80 percent of your risk for heart disease is said to be a result of being diabetic and suffering from hypertension. In other words, high blood pressure is not a good thing and should be avoided — and thus reduced — at all costs.
Interestingly, folks with “abnormally” elevated levels of insulin in their blood are more likely to be hypertensive, leading to the inclusion of hypertension in the spectrum of abnormalities collectively known as the metabolic syndrome (or Syndrome X Diseases). If you are obese, you are “more than likely” to have high blood pressure, and folks with high blood pressure are “likely” to be obese. In addition, the higher your blood pressure, so go your levels of cholesterol and triglycerides, and so your risk of diabetes and heart disease.
Despite the associations between obesity, heart disease, hypertension, diabetes, and high levels of cholesterol and triglycerides, public health officials blame salt. That’s like saying you’re an alcoholic because your drink too much. Something else is going on.
The salt-blood pressure link problem
The salt-hypertension hypothesis is what many would call a biological plausibility — seems to make sense, so that must be it. When we consume salt, our body retains that salt and more water at the same time. This increases the “pressure” in our blood vessels. Under “normal” intakes of salt (whatever that is), our kidneys will respond to the excess and excrete the salt in our urine, along with the additional water as well. It is thought that a “chronic” intake of salt disrupts this process in some way and thus we are “chronically” hypertensive.
Decades of pondering the obese-hypertensive-diabetes-heart disease-high cholesterol-and-triglycerides connection in clinical trial after clinical trial has resulted in what many have described as “inconclusive and contradictory” results with regards to the role of salt. Sure, you can get a spike in blood pressure if you slam back a large dose of salt, but that does not explain chronic hypertension. Systematic reviews of the evidence — whether you are a believer or not — demonstrate that if you have elevated blood pressure, say 40 mm Hg over healthy levels, cutting your salt intake by half will only result in a 4 to 5 mm Hg drop (i.e., not much).
It’s often said that high blood pressure is a natural part of aging and explains elevated levels as we clip along into our golden years. But as the British physician Cyril Donnison noted in the 1938 “Civilization and Disease,” societies eating traditional diets low in westernized fare of highly processed carbohydrates (sugar, refined grains, etc), consistently had lower blood pressure than the more “affluent” folks consuming more processed diets, regardless of the salt content. For example, Kenyan nomads in their sixties “had an average systolic blood pressure forty points lower than that of European men of the same age.” Similar patterns have been documented all over the world and as each of these traditional societies embraced the westernized diet of highly processed foods, their blood pressure — and weight, and risk of disease — went up.
Very little attention has been paid to the nutrition-related aspects of blood pressure. When was the last time your doctor said that processed carbs in the form of sugars and refined grains “may” play a role in your hypertension and that salt is a minor player? The laboratory evidence that salt raises blood pressure does not explain why blood pressure is raised in a given population in the first place. Until we come to the grips with the terrible connection between processed carbohydrates and elevated levels of insulin that are “almost always” associated with Syndrome X disease — including hypertension — we will only continue to suffer, both in our health and in the taste of our food.
Jeff Leach is the co-founder of New Orleans-based Naked Pizza. Jeff is currently completing his PhD in anthropology and has published widely in nutrition, medical and anthropological journals. Through Naked Pizza, Jeff hopes to influence public health policy in the U.S. and demonstrate that pizza can be part of the solution rather than part of the problem.