Sodium and salt have long been connected with high blood pressure and heart disease. With high blood pressure and heart disease being so endemic in the United States, the call for low-sodium diets and healthier eating have followed. Low-sodium diets like the DASH diet have been developed to help lower our intake of salt, but is it all necessary? Is salt that bad for you that we should just avoid it or is it time to end the war on salt? Is there even a war on salt to begin with?
The Good
Let’s start out with the good. There has to be some benefit to adding salt to your food. That’s why foods taste good, because they have some nutritional value that our body recognizes. The same is true here. Salt tastes good because it is rich in sodium and chloride (among other reasons), which are both important electrolytes. This makes them essential in providing fluid and pH balance in the blood, along with helping our muscles and nervous system function properly.
Clearly, salt is pretty healthy for you, at least in the right amounts.
Beyond that, there’s evidence that having too little salt in our diets can be extraordinarily bad for us. Several studies have linked low-salt diets to increased levels of insulin resistance, especially if the salt restriction is severe. Low salt intake has also been linked with an increase in all-cause and cardiovascular mortality in type-2 diabetes patients. Other studies have noted an increase in LDL cholesterol (the bad kind) in low-sodium diets. Clearly, salt is pretty healthy for you, at least in the right amounts.
The Bad
That last statement is important here. The proportions of sodium in your diet can be where things turn unhealthy. Unfortunately, nine out of ten Americans eat too much sodium on a daily basis, ingesting around 3,400 mg of sodium — over double the daily recommendation of 1,500 mg. This where the trouble lies. There is an undeniable relationship between sodium-intake and blood pressure, which is where the majority of the health concerns are. If you have a high blood pressure, also called hypertension, it can lead to a host of health complications, not all dealing with the heart. Of course, hypertension can lead to heart attacks, heart failure, strokes, aneurysms, and weakened blood vessels, but it can also cause kidney problems and possibly even dementia.
By having excess sodium, our blood vessels absorb more water, increasing the total volume of fluid in them and the pressure on the vessel walls.
So, how does salt cause high blood pressure? Sodium is important in helping your body balance out water levels in our bodies. By having excess sodium, our blood vessels absorb more water, increasing the total volume of fluid in them and the pressure on the vessel walls. As we know, the measurement of this is what we call blood pressure. Over time, this pressure on the walls can cause the issues we mentioned above for blood pressure.
The 2017 Boston University Study and Others
In last decade and a half, there have been a few studies that have challenged the general understanding of sodium and blood pressure. Perhaps the best known of these is a 2017 Boston University study led by Dr. Lynn Moore that threw into question how responsible salt is for high blood pressure. The study found “no evidence that a diet lower in sodium had any long-term beneficial effects on blood pressure.” These findings joined a litany of others that have taken issue with the current dietary advice. Some studies even claim that low-salt diets may actually increase your risk of cardiovascular death, though each study responsibly highlights the need for further research.
That means salt is in the clear, and we can eat it without worry now, right? Not so fast. Part of the problem has to do with the reporting on this issue. Where one story highlights the no evidence that low-sodium diets help with blood pressure, you have to dig a bit to find that the study isn’t claiming that sodium has no effect on blood pressure, just that there’s what’s called a J-curve for sodium intake. In other words, they found that people with very low sodium diets and people with very high sodium diets experienced similar rates of cardiovascular disease. This meshes well with other studies that found that light reductions in salt have little difference for hypertension, though long-term moderate changes do. The study also noted that potassium may be more influential than we originally thought.
The American Heart Association is backed up by the Centers for Disease Control and Prevention and the Food and Drug Administration for their recommended sodium totals.
In 2018, the American Heart Association reflected on these studies to address the questioning of their dietary guidelines. In it, they discuss issues found in the methodology of some of these studies, such as inaccurate measurements of sodium and researching sick patients instead of healthy ones. These concerns can cause false correlations if used to explain relationships for all people. Ultimately, the American Heart Association is backed up by the Centers for Disease Control and Prevention and the Food and Drug Administration for their recommended sodium totals.
Part of the problem with finding a catch-all recommendation for sodium intake is that sodium may influence us differently. What we’ve found is that salt sensitivity can greatly alter how salt and sodium influences your blood pressure. For those that are salt-sensitive (estimated to be roughly 60 percent of people with hypertension), increasing or decreasing the amount of salt ingested can have a similar effect on blood pressure. If you’re not, there is a much more muted response. This can make finding a singular suggestion for dietary sodium very difficult to make.
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So, what does this all mean for you? Is salt good for you or bad for you? Well, as with all things in health, it’s both. Salt is the main source of sodium, which is an essential nutrient for our bodies. It’s healthy for us until we have too much of it, which is true for many of us. While the results found in the 2017 Boston University study and others are interesting, when a study has such novel findings that challenge such a well-established connection like sodium and blood pressure, more research and discussion are needed before recommendations are changed. For that reason, it seems that it’s a wise choice to stick with the recommended 1,500 mg of sodium a day, though not exceeding 2,300 mg per day. Just remember that it’s usually a good idea to discuss your diet with a dietician or your doctor, who can help give you personalized advice (especially if you’re thinking about changing your diet). While you may not need to cut back on salt right now, if your doctor suggests trying out a low-sodium diet, listen to them.
