Holy f*@$*#g s@#t. “Urinary Sodium and Potassium Excretion, Mortality, and Cardiovascular Events“:
BACKGROUND: The optimal range of sodium intake for cardiovascular health is controversial.
METHODS: We obtained morning fasting urine samples from 101,945 persons in 17 countries and estimated 24-hour sodium and potassium excretion (used as a surrogate for intake). We examined the association between estimated urinary sodium and potassium excretion and the composite outcome of death and major cardiovascular events.
Researchers got more than 100,000 people in 17 countries to pee in a cup. Then they checked the levels of potassium and sodium in it, as a measure of how much salt they were eating. Then they looked at a whole bunch of outcomes.
Another study in the same journal looked at blood pressure. Yes, salt intake was associated with higher blood pressures. For each 1g (not mg, mind you, but grams) of salt intake, systolic blood pressure went up 2.1 mm Hg and diastolic went up 0.8 mm Hg. Statistically significant, but I’m not sure about clinically. Remember, it’s recommended by the American Heart Association that we eat less than 1.5 g of salt a day (the FDA says 2.3 g), so a 1g difference in consumption is huge. The average US consumption is 3.4 g.
But this study looked at death and cardiovascular events like stroke, heart attack, or heart failure .
The average sodium excretion was 4.9 g per day, and posassium was 2.1 g. They followed people for 3.7 years on average. They used people excreting 4 to 5.99 g of sodium a day as the baseline for comparison.
Compared to them, people with a higher excretion (more than 7 g a day) had significantly higher rates of death or cardiovascular events (odds ratio 1.15). Ok, so far so good. This association was even stronger if people had high blood pressure. So really high salt intake is a bad idea, especially if you have hypertension.
But here’s where things go off the rails. Compared to those who excreted the baseline amount, those who had low excretion (below 3 g per day) also had an increased risk of death and cardiovascular events (odds ratio 1.3). In fact, this association appeared even stronger.
In other words, people who consume between 3 g and 6 g of sodium per day had a lower risk of death or cardiovascular events than people who eat a low salt diet. Yeah, this is an observational study, and it’s not a randomized controlled trial. I’m not saying this is advice for everyone to go out and increase their salt intake. Everyone, including this study, agrees that excess salt consumption is a bad idea. But we’re getting a ton of pressure to decrease our salt intake to very low levels. There’s no RCT for that. The available observational evidence says it’s a bad idea. Yet it’s the recommendation of the AHA, the WHO, the FDA, and I’m sure more. The IOM warned us that there wasn’t good evidence to support this. Here’s what they said:
However, the evidence on health outcomes is not consistent with efforts that encourage lowering of dietary sodium in the general population to 1,500 mg/day. Further research may shed more light on the association between lower—1,500 to 2,300 mg—levels of sodium and health outcomes.
This study is that research. What are we doing?