Cutting back on salt: Does it help?
Anyone who’s tried to reduce the amount of sodium in their diet knows how hard it can be to lower levels down to the government’s recommended limit of 1,500 milligrams a day for whites 51 and older, all African Americans and others with certain chronic health conditions such as hypertension and chronic kidney disease.
I’ve tried this, for kidney reasons. Heck, it’s hard to even get sodium levels down to the 2,300 mg recommended for other groups -- especially if you ever, ever eat out in a restaurant.
In the meantime, there’s been some debate among experts about what can be expected from cutting back on salt, which makes the matter confusing for the public.
Now a review just published in the American Journal of Hypertension suggests the blood pressure gains are minimal, at least for the general population -- and the body seems to fight back against the changes.
Pooling data from 167 studies, the scientists concluded that the average reductions in blood pressure were:
For whites with normal blood pressure: -1.27 points for systolic blood pressure (the higher, first number of a blood pressure reading) and -0.05 for diastolic pressure (the lower, second number).
For whites with high blood pressure: -5.48 (systolic) and -2.75 (diastolic).
The drops in blood pressure were higher for blacks and Asians, but the data were worse so the scientists are more tentative about the numbers.
That’s from eating a diet with an average of 2,760 mg of sodium (not exactly low if you go by the government limits listed above) compared with an average of 3,450.
At the same time, the studies noted changes in certain molecules in the blood. All of the following went up:
Renin (released by kidneys when blood pressure falls or blood salt levels fall low, to help constrict blood vessels and raise blood pressure again)
Aldosterone (made by the adrenal glands when salt levels fall low, triggering more salt to be reabsorbed by the kidneys)
Adrenaline (constricts blood vessels)
It’s almost as if the body is saying “salt / blood pressure levels falling – I’ll do what I can to ramp them up again.”
Blood cholesterol and triglyceride levels also rose.
The authors write: “Due to the relatively small effects and due to the antagonistic nature of the effects … these results do not support that sodium may have net beneficial effects in a population of Caucasians.” However, they did say that Caucasians with elevated blood pressure –as opposed to the population at large -- could benefit from sodium reduction “as a supplementary treatment.”
They add that the benefit might be greater in blacks and Asians, but the data weren’t firm enough to know that for sure.
If you’re interested in other options toward lowering blood pressure, check out a package of L.A. Times articles by freelancer Karen Ravn. She reviews the evidence for measures such as the DASH diet (rich in produce and low-fat dairy), cutting back on alcohol, reducing stress and upping the amount of potassium in your diet. The last one is based on a suggestion that the ratio between potassium and sodium may be more important than the exact level of sodium.
Oh, and don’t forget the blood-pressure-lowering power of owning a pet!