Wednesday, May 04, 2011

Reducing Sodium Doesn't Reduce Deaths From Cardiovascular Disease, May Increase Them

Here's the new study:

Fatal And Nonfatal Outcomes, Incidence Of Hypertension, And Blood Pressure Changes In Relation To Urinary Sodium Excretion, JAMA, May 2011

From the accompanying summary:
"At a median of nearly 8 years later, participants in the group with the lowest sodium intake at the beginning of the trial were significantly more likely than the other 2 groups to die of cardiovascular disease."
- Author Insights: Questioning the Benefits Of Salt Restriction, JAMA News, May 3, 2011
Study author Dr. Jan Staessen, University of Leuven, Belgium:
"It's clear that one should be very careful in advocating generalized reduction in sodium intake in the population at large. There might be some benefits, but there might also be some adverse effects."
- Eating Less Salt Doesn't Cut Heart Risks: Study, Reuters, May 3, 2011
So, people (mostly healthy people) who ate more salt were not more likely to get high blood pressure. And the more sodium someone excreted (a gage of sodium eaten), the lower their incidence of death from heart disease. I'll be.

I've read studies pro and con and I'm on the fence about how detrimental a high sodium intake is. It really is a very individual call. While it may prove to be not so bad for heart disease (this study is far from conclusive, especially with only two measurements over 8 years), that may not hold true for other conditions. High sodium intake leads to greater calcium losses, which bodes poorly for bone. Also, the very efficient mechanism we have for getting rid of excess sodium may not work well if the kidney is compromised - as it is with diabetes, hypertension, or existing kidney and vascular disease.

Dumping too much salt into a person who can't get rid of it leads to extra fluid in the body (since sodium holds fluid). That fluid raises blood pressure even more, which damages the kidneys even more, in an unfortunate cycle.

Diabetes, hypertension ... these diseases are relatively silent in the early stages. If you're older, carrying excess weight, or have other chronic health conditions, it's probably not a good idea to require more from your kidneys when they may be dealing with silent maladies.

If you want to reduce your sodium intake, salt food just before you eat it. Try this experiment...

Make something wet like soup or porridge without any salt. When it's ready to eat, salt it to your liking. Stir it and let it rest for a minute or two. When you eat it, notice if it tastes less salty ... and if you're inclined to salt it more.

As salt dissolves and dissipates into the medium, we taste it less. This is one reason why processed and prepared foods can be high in sodium; manufacturers compensate for this. Also, salt added at subthreshold levels enhances sweet taste.
Photo of salt from LA Times


Matthew said...

If my maths is correct and assuming a stable sodium level so that intake was matching excretion:

The low sodium group were consuming 6 grams of salt per day.

The high sodium group were consuming a whole 14 grams. That is a lot of salt to get through each day.

It is a puzzling finding. I would be interested to know what kind of diet these different groups were eating.

preserve said...

the sodium intake issue is probably correlationary.

ie. most people with a high salt intake are probably eating junk food.

Bix said...

That's why the results are so curious, preserve. Those that ate more sodium, perhaps more junk food as you say, were less likely to die from CVD.

Dr. Mel said...

Geez Louise--it's all so confusing!