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Comment by Herodotus38 | Hacker News Reader

This study looked at a stricter sodium goal than is typically advised (<1500 mg/day). Usually I counsel pts on less than 2000 mg a day which is what the control group targeted and seemed to achieve. This study is useful in that it shows being more restrictive isn’t necessary, but those with heart failure should still try to avoid excess salt. It is very easy to hit double the recommended intake with a typical American diet. The average American salt intake is about ~3400 mg/day from some studies.

Edit: after reading some of the replies I think there’s confusion about who the target population is in this study: it’s people who already have heart failure. I could have added in my comments that I was also referring to ppl with heart failure.

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I don't know much about this subject, but this information has been on the wikipedia page for years.

https://en.wikipedia.org/wiki/Health_effects_of_salt#Dietary...

As of 2009 the average sodium consumption in 33 countries was in the range of 2,700 to 4,900 mg/day. This ranged across many cultures, and together with animal studies, this suggests that sodium intake is tightly controlled by feedback loops in the body. This makes recommendations to reduce sodium consumption below 2,700 mg/day potentially futile.[39] Upon review, an expert committee that was commissioned by the Institute of Medicine and the Centers for Disease Control and Prevention reported that there was no health outcome-based rationale for reducing daily sodium intake levels below 2,300 milligrams, as had been recommended by previous dietary guidelines; the report did not have a recommendation for an upper limit of daily sodium intake.[27][40]

There's also this: https://en.wikipedia.org/wiki/Health_effects_of_salt#Dietary...

Studies found that excessively low sodium intake, below about three grams (3,000 mg) of salt per day, is associated with increased mortality and higher risk for cardiovascular disease.[6][7]

But.. maybe it depends on the population.

I know that if you're outside in the heat, insufficient salt is far more dangerous.

Agreed. The title of the post is misleading. A strict restriction of sodium versus usual care (a recommended low sodium diet) was tested. There was no benefit to a strict low sodium diet. As a cardiologist, it doesn't not change my advice regarding usual care -- recommending a low sodium diet in patient with heart failure.

If the goal is lowering blood pressure, why would you put people on an insane low salt diet instead of a low carb diet?

The measured goal in the study was to reduce heart failure exacerbations, which included ER visits and admissions to the hospital, not blood pressure per se.

Low carb diets can be really unhealthy for your heart. Sure if you do low carb with mostly salad you're probably fine. But many people start eating red meat, bacon and other things that cause heart disease.

Isn't that just clinging to the old advice without evidence? This study shows it has no effect. A lesser restriction would logically also have no effect.

Let's give up on the old urban legend that salt has f-all to do with heart health.

> A lesser restriction would logically also have no effect.

How can you "logically" come to that conclusion?

Salt raises blood pressure. That's just simple chemistry. High blood pressure causes all sorts of problems. That's medicine.

The ratio of sodium to potassium is what matters for blood pressure, not sodium intake.

Eating a lot of salt raises it a point or two for an hour or so.

Let's get our 'simple chemistry' right.

> Salt raises blood pressure

Which is why your body has means to get rid of salt.

> That's just simple chemistry

sure, but biology is what we are talking about here, and biology is more complex.

I feel that this sort of simplification is common to our mis-understanding of health and nutrition. I also heard similar myths like: Calories in = Calories out, you are what you eat (meaning if you eat high fat you'll gain fat), etc.

Can you explain why you think salt raises blood pressure?

It's a very well understood effect -- as your body absorbs salt, it also retains more water to maintain osmotic pressure. This additional fluid in your circulatory system necessarily causes your blood pressure to increase.

That's the very simple chemistry behind salt increasing blood pressure. The biology is more complex and the effect isn't necessarily long lasting or linear, but there is indeed a direct relationship between sodium intake -> blood pressure.

It would seem to make sense, until biology gets in the way. Mammals have several exquisite mechanisms for regulating sodium. Unless you're very sick, they work fine. So there is no 'direct' relationship at all.

It should also be noted this is a study evaluating a reduced sodium diet (standard treatment for those having heart failure) vs. an even further reduced sodium diet. Further reduction yielded little difference in results. That is to say reducing your intake below 1,500 mg per day doesn't present any net benefits. The study should not be interpreted as salt intake has no effect whatsoever on your blood pressure.

The problem with this is the assumption that dietary sodium is bad.

People had this weird rage boner against cholesterol. Cholesterol in the blood is bad. So cholesterol in food must be bad too. This is based on the ridiculous assumption that your body just dumps the cholesterol in your body with no processing or regulation of cholesterol in the blood. Suddenly, there is this relevation that cholesterol in eggs is no longer harmful and you can eat as many eggs as you want. In fact, science has progressed so far that total cholesterol levels predict nothing if you adjust for oxidized cholesterol. If you are in a hurry to oxidize your cholesterol just smoke cigarettes or eat heat processed fats/transfats. The saturated fat scare also feels completely pointless. Saturated fats are solid at room temperature and they are harder to oxidize which means all the supposed harmful effects are overshadowed by the fact that they extend your lifespan. People care about avoiding specific causes of death but if your cells simply get damaged slower because they are less reactive? Nobody gives a damn.

How far away are we from reaching that understanding for salt?

You do know we have kidneys, right? They are amazing organs, they conserve the 0.9% salinity of your blood, roughly 40 grams in total. When you take in too much, the kidneys simply excrete it in urine. When you take in too little, they hold on to as much as they can.

Salt without water would do that. But what if you drink water with salt and thus increase your sodium without increasing the osmotic pressure?

So can you eat a lot of salt if you drink a gallon or more of water with it?

It seems the control group was following the current advice while the experimental group went beyond it, which would mean this study has nothing to say about the efficacy of the former.

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