Cutting back on salt consumption can lead to a drop in blood pressure, but that health benefit could be offset in some people by a small increase in cholesterol levels. That’s the troubling finding of a new study published today in the American Journal of Hypertension, which analyzed evidence from 167 studies measuring the effects of sodium reduction.
And it adds to a growing body of research questioning the value of cutting back on salt if you’re otherwise healthy and don’t have high blood pressure. A study published last May in the Journal of the American Medical Association found that healthy people who ate the least amount of sodium didn’t have any health advantage over those who ate the most, and they actually had a slightly higher risk of dying from heart disease.
Another review analysis in July found that lowering salt intake led to lower blood pressure levels but not fewer deaths from heart attacks and strokes -- even in people who already had established heart disease.
This latest review of the current research points once again to the paucity of knowledge when it comes to predicting the benefits we’ll reap from putting down the salt shaker and buying low-sodium products. The researchers concluded that switching from a high-sodium to a low-sodium diet -- in those who are white and don’t have hypertension -- decreases blood pressure by less than 1 percent.
It also leads to a 2.5 percent increase in total cholesterol levels and a 7 percent increase in triglyceride levels -- which both elevate the risk of heart disease -- probably due to hormonal effects that occur from less sodium in the body. “These results do not support that sodium reduction may have net beneficial effects” in that group of individuals.
For those who have hypertension, as well as all blacks and Asians, reducing sodium intake led to greater drops in blood pressure -- perhaps enough to outweigh the cholesterol-raising effects. The researchers, though, pointed out that there weren’t enough data from the studies to determine this for certain.
And therein lies the rub: the lack of a large clinical trial to determine the long-term benefits and risks of lowering sodium in those who don’t have high blood pressure, as well as in those who do. In fact, other experts have been calling for bigger and better sodium studies for years, often criticizing the methodologies of individual studies that are included in review analyses.
For now, the federal government has chosen to rely on firm evidence that reducing sodium reduces blood pressure and last year recommended that people limit their daily sodium intake to less than 2,300 milligrams per day and that higher-risk individuals -- including all blacks, people over 50, and anyone with high blood pressure, diabetes, or chronic kidney disease -- to consider dropping their intake down to 1,500 mg. per day.
That’s a tall order, considering that the average American probably consumes about 3,400 mg. of sodium per day. (I'm curious to see whether US Food and Drug Administration officials take the latest research into account in a meeting tomorrow to discuss how to reduce sodium in various food products.)
What does all this mean for you?
If you’re in the government’s higher-risk category, you should certainly make efforts to lower your salt intake, and even if you’re not, you shouldn’t shake the salt to your heart’s content. If you aren’t carefully reading food labels, you’re probably getting far more sodium than your body needs because most processed foods have too much of it. And if you’re worried about high cholesterol, realize that you’ll probably benefit more from losing excess weight and reducing saturated fat in your diet than giving up any low-sodium diet you may be following to reduce your blood pressure.