Q. In a recent interview, you mentioned cutting back on added sugar as one of the most important things you can do to improve your diet. I noticed you didn’t mention the importance of limiting sodium. Do you think the concerns over sodium are over-blown?
A. In a word, yes. In the recently released 2010 Dietary Guide for Americans, they really came down hard on salt, stressing the need for all Americans to reduce their sodium intake. Given all the things about the typical American diet that could use fixing, I thought it was a little odd how much emphasis they put on this. (Obviously, the salt lobby was asleep at the switch during the hearings…)
The rationale for universal sodium restriction rests a string of loosely related statistics:
- One in three American adults has high blood pressure–which is a major risk factor for stroke and death.
- The risk of high blood pressure goes up parallel to salt intake.
- Average intake of sodium is about 3500mg per day (Recommended intake is 2300mg for healthy individuals and 1500mg for those at risk.)
Based on this, the reasoning is that getting everyone to eat less salt will reduce the incidence of high blood pressure, thereby reducing strokes and death. But obviously, we’d be “treating” a lot of people who don’t need it in order to get at those who do. Even among those with high blood pressure, only about 60% are salt-sensitive. For the other 40%, reducing sodium does little to correct high blood pressure. (Black Americans are much more likely to be salt-sensitive.)
Where’s the Evidence?
So the question is, what benefit do the 66% of Americans with normal blood pressure get from restricting sodium? A commentary in the Journal of the American Medical Association argues that there have been no randomized clinical trials showing that reducing sodium reduces illness or death in otherwise healthy people. Observational studies on the relationship between sodium intake and health have been mixed. Some have found a relationship between high sodium intake and cardiovascular events; others found no relationship.
(Click here to read Richard Fogoros MD’s article, “Is salt restriction necessary.” )
Reducing Sodium Isn’t Always Harmless
Furthermore, the JAMA commentators point out, it’s not true that restricting sodium does no harm. Reducing sodium enough to lower blood pressure has also been shown to reduce insulin sensitivity, for example.
Is Reducing Salt the Best Way to Beat High Blood Pressure?
Here are some more statistics to consider:
- The risk of hypertension goes up steeply with age, even though sodium intake generally does not.
- The risk of hypertension goes up with body weight, independent of salt intake.
- Twice as many people are overweight as have high blood pressure.
- The overweight are also at risk of many other diseases, including Type 2 diabetes.
In the grand scheme of things, it would save a lot more lives to get people to lose weight rather than focusing on salt reduction. In fact, losing weight may reduce blood pressure more reliably than cutting salt. (Reference.) But that sort of brings us full circle…because cutting back on sodium might indirectly lead to weight loss.
Benefits of Salt Reduction May Be Indirect
Whether or not the sodium itself is a problem, salty foods stimulate appetite and lead to overeating. (Here’s an interesting study on this.) Imagine sitting down with a bowl of raw unsalted almonds. Now imagine sitting down with a bowl of roasted salted nuts. Which bowl gets emptied more quickly?
About 70% percent of the sodium in the American diet comes from packaged and prepared foods–foods which contribute a disproportionate amount of calories and anti-nutrients like trans fats without providing much meaningful nutrition. Foods that are literally engineered to promote over-consumption. Foods that push other more nutritious foods out of the diet.
How Reducing Salt Could Improve Diets and Health
If hammering everyone to reduce sodium results in people eating less processed junk food and more fresh food, we win on several counts. Not only does it reduce sodium intake, but a diet of fresh foods will likely be higher in potassium, which helps lower blood pressure. It’s also likely to promote healthier body weight.
Who Needs to Worry About Sodium?
About 10 to 25% of the general population are sodium sensitive; for these, people consuming too much sodium may increase their risk of cardiovascular disease and death, even if they have normal blood pressure. But in the context of a diet of mostly fresh foods, I think most people have little to fear from the salt shaker.