Restricting Sodium in your diet.

[Guy_Incognito]

My wife had a recent checkup and has been found to have high blood pressure and cholesterol. We’re not talking astronomical numbers on either figure: BP was measured at 146 / 108, cholesterol was 278. Granted, this isn’t exactly great, but it’s not a death sentence either. I’ve just turned 40 and haven’t had a physical in awhile, but I wouldn’t be surprised if my cholesterol count didn’t match or exceed hers. My blood pressure usually doesn’t stray much above 120 / 80, so I feel pretty good about that. Anyway, my wife now is taking medicine for her BP and cholesterol.

We’re planning on getting a membership at the local YMCA or other fitness center so that we can shed a few pounds and get some much needed exercise, so hopefully that might help us both out all around. The tricky part for us now is our diet.

I’ve had good luck in steering us away from foods with higher cholesterol and have been trying to buy foods which are supposed to aid in lowering cholesterol. The trick for me right now is finding foods that are low in sodium. I know that processed foods are usually high in sodium, as are other convenience and snack foods.

I guess my question is this: has there been any overwhelming proof that consuming more than the US RDA of sodium contributes greatly to high blood pressure? I’m not talking about eating a box of kosher salt for breakfast here. I’m talking about going 10 - 20% over the RDA. If my wife takes her medications as directed and we go on a moderate exercise plan, shouldn’t that offset the effects of a little extra sodium in our diet? If we’ve gotta cut the salt, we will. We just won’t like it very much.

[KarlGauss]

For any given individual, the effect is likely to be modest, perhaps a 3 or 4 mm drop. However, even small reductions in BP when considered over a large population translate into a significant net benefit (reduced cardiovascular disease) for the population. Indeed, given that there are some people who achieve rather large blood pressure reductions by restricting salt intake, and very, very few if any who suffer consequences from salt restriction, it makes sense to recommend decreased salt intake for all people with high BP.

This quote is from The New England Journal of Medicine 2003:

Restriction of sodium intake to 2 g per day lowers systolic pressure, on average, by 3.7 to 4.8 mm Hg and lowers diastolic pressure, on average, by 0.9 to 2.5 mm Hg, although the reductions vary from person to person beyond these ranges. Salt sensitivity is common in elderly patients with hypertension. Despite concern that salt restriction for all patients with hypertension might have adverse consequences, moderate sodium restriction appears to be generally safe and effective and is particularly effective in elderly persons

Here is an abstract from a 1997 review article in The American Journal of Clinical Nutrition which analysed all “good” studies on salt restriction:

REVIEW ARTICLES
Randomized trials of sodium reduction: an overview
JA Cutler, D Follmann and PS Allender
Division of Epidemiology and Clinical Applications, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA. cutlerj@gwgate.nhlbi.nih.gov

We updated a previously published overview of randomized clinical trials testing the effects of reducing sodium intake. We excluded trials that had confounded designs, enrolled preadolescent study populations, tested intakes outside the usual range for the US population, or reported neither systolic nor diastolic blood pressure. Thirty-two trials with outcome data for 2635 subjects were included. Two reviewers abstracted information independently and differences were reconciled. Pooled blood pressure differences between treated and control groups were highly significant for all trials combined and for trials in hypertensive and normotensive subjects pooled separately. The effects on blood pressure of lowering sodium in hypertensive and normotensive subjects, respectively (each trial weighted according to sample size), were -4.8/-2.5 and -1.9/-1.1 mm Hg (systolic/diastolic). Median differences in sodium excretion between sodium-reduction and control groups in these subgroups were -77 and -76 mmol/24 h, respectively. Weighted linear-regression analyses across the trials showed dose responses, which were more consistent for trials in normotensive subjects. These associations were, per 100 mmol Na/24 h, - 5.8/-2.5 and -2.3/-1.4 mm Hg in hypertensive and normotensive subjects, respectively. There is no evidence that sodium reduction as achieved in these trials presents any safety hazards. The blood pressure reduction that would result from a substantial lowering of dietary sodium in the US population could reduce cardiovascular morbidity and mortality.

[Guy_Incognito]

KarlGauss,

Thanks for the info! I guess I wasn’t sure of how much of a drop in blood pressure that my wife could expect. It sounds to me like there are definite advantages to reducing sodium intake and little likelihood of any risks. Like anything else, I can appreciate that the results will differ among individuals.

Has anybody on the SDMB experienced a measurable reduction in their high blood pressure strictly by limiting their salt intake? Just curious.