Lowering sodium intake doesn’t help heart patients
thelancet.com
thelancet.com
They have compared a diet with a sodium intake close to the lower limit of the recommended intake, with a diet including an even lower sodium intake, slightly less than normally recommended.
A daily sodium intake in a relatively wide range around the recommended daily intake (which is of about 4 to 6 grams of salt per day) is not expected to cause any differences, so the results of the study are not surprising.
The recommendation to eat less salt is only for the people who eat mostly industrially-processed food, which always includes excessive quantities of salt and sugar, because they are among the cheapest ingredients, while enhancing the taste of the food.
Such people typically eat 2 to 3 times more salt than recommended, and only for them it may be expected that lowering the sodium intake can reduce the risk of diseases. However, lowering the sodium intake is not easy for them, because they must begin to eat something different, since the excessive salt is not added by them to the food.
Otherwise, lowering the salt intake much under 4 grams per day is a serious risk, especially for older women, and especially when they also take medication against high blood pressure.
Hyponatremia, i.e. having a too low sodium content in the body, manifests initially with symptoms like muscular weakness, constipation, lack of appetite and problems with the equilibrium, which may result in falls.
Such symptoms may be difficult to distinguish from just consequences of old age. If hyponatremia is not diagnosed in time, the consequences can be extremely severe, including the loss of life.
So the real conclusion is that a modest reduction of salt from the recommended low levels likely does not drop the odds of a repeat heart attack by more than 20%.
This is a very, very long ways from the headline that lowering sodium doesn't help heart patients.
And yet, this crap passes as science???
The science itself seems fine though! Testing, measuring, experimenting. Yes. But either there ought to be an onus on us as readers or them as publishers to make clear what has been done. Otherwise, as I believe you can surmise, there’s no benefit to doing at all!
Therefore the science we encounter goes through a selection bias that picks out the most surprising results. But far too often, "surprising" translates into "unlikely to be true". And so we get a constant stream of intellectual junk food wrapped up in the language of science.
Take this result. It is surprising that low sodium would not help with cardiovascular problems. Why is it surprising? It is because we know two facts:
1. High sodium intake increases blood pressure: https://www.cdc.gov/salt/research_reviews/sodium_potassium_b...
2. High blood pressure is bad for your cardiovascular system: https://www.cdc.gov/bloodpressure/about.htm
And therefore we EXPECT that high sodium intake is bad for your cardiovascular system. Which is why we constantly tell people to reduce salt.
Now we see this research that has a variety of limitations in what it could detect, saying that it found no correlations. We're surprised because we expect a correlation. But now people will walk around saying that science says that salt doesn't matter, ignore salt, and they're probably causing a problem for themselves.
And this brings us to another problem with the research. The known mechanism by which salt is bad for you involves blood pressure. However if you've had a heart attack, your blood pressure is going to be monitored and medications adjusted until your blood pressure is under control. The benefit of less salt will be that you need less medication and will have less side effects. It won't be lower blood pressure and a reduced risk of heart attack! So the primary outcome that should be measured isn't adverse events, it is how much medicine was required!
It was sad to see him struggle with food that was less and less appetizing. Salt tastes great :(
For some reason, salt stops my blood pressure medication from working. (Several possible diagnoses were explored without success.) This was discovered after I checked in to the ER feeling terrible with a blood pressure around 190/120 and then had to stay for a week. So I'm now on a low salt diet and my blood pressure is now fine.
I don't cheat. And after a while my taste buds kind of reset. What tastes normal to most tastes insanely salty to me, and I get to enjoy the taste of low salt food.
It does suck that I can't simply eat out though.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5179550/. “Graudal et al. (40) observed that sodium restriction (sodium reduction of 42–341 mmol/24 h in studies lasting 4–90 days) was independently associated with increased heart rate in healthy individuals and individuals with hypertension.”
> Given the discrepancy in results, more studies in this area are required to investigate the relationship between dietary sodium intake and heart rate.
You're cherry picking one small part from a section not really related to the topic at hand and also ignoring the conclusion the study authors draw.
The sentence literally before the one you quote is
> Studies that demonstrated the effects of dietary sodium on heart rate have shown conflicting results.
And then you cherrypick the one example that agrees with your point while ignoring the examples that refute your point.
If you want to say the science is still unsettled, sure. But to pretend that it is settled in the way you want and quote one sentence out of context in a meta-study who's entire point is that the debate is not settled? Come on.
I agree studies give conflicting results and there is isn’t a clear winner here.
I agree more studies are perfectly reasonable.
However, the default when faced with conflicting information isn’t to put forth effort into changing behavior. That requires justification, which isn’t available.
Consider if millions where micro-dosing Tylenol to avoid dementia and the results where inconclusive, what messaging would you provide? (Stop your wasting money), (do it it’s probably worth it), (might help, might not, we don’t know do what you want). The temptation is to say ‘do it’, the costs are low and the benefits could be significant. However, when there are known useful things people could be doing it’s probably best to stick with the third option.
PS: Ok you could jump on the latest study and constantly flip flop on recommendations, but that just confuses people and erodes trust in the process.
The statement you picked made it out that there is no correlation between sodium intake and heart rate. The study you took that statement from was making the point that we can't draw such conclusions either way.
I didn't say anything about whether or not people should flip flop recommendations. But don't irresponsibly cite studies. It defeats your entire argument when you do so.
“was independently associated with increased heart rate in healthy individuals and individuals with hypertension.”
Cherry picking would have been linking to the study that suggested lower salt intake was unhealthy directly. Instead I linked to the meta study to give better context.
This is literally how the null hypothesis / statistical significance works; how is this crap science? If the measured effect is too tiny, you cannot conclude that it's a real effect.
The title as presented here is Lowering sodium intake doesn’t help heart patients.
The impression that people will walk away from that title with is, "If you have heart problems, there is no need to eat a low sodium diet."
This is not a hypothetical interpretation. I first saw this study at https://twitter.com/EricTopol/status/1510292643292491779, and that is exactly the impression that a well-known cardiologist drew. Many others came to the same conclusion.
Now what should we expect?
Their intervention reduced sodium consumption by 415 mg of sodium per day. (According to the least accurate method of measurement - self-reporting. The actual reduction was probably smaller.) If all else was equal, the correlation found at https://www.cdc.gov/salt/research_reviews/sodium_potassium_b... we should expect that to reduce systolic blood pressure by 1.9 mmHg. However not all else is equal, these are all patients receiving medical care. If your blood pressure is too high, you receive more medication. So all else is not equal, and we should expect blood pressure to be approximately equal between the groups, and medication not.
Therefore, to a first approximation, we should expect small differences in blood pressure, larger differences in required medication, and little difference in adverse events.
They designed a study that did not report on average blood pressure between the groups, or what levels of medication were required, and would only notice a large difference in adverse events. And so they failed to find a result that they should not have expected to see, failed to look for the result that they should have expected, and it wound up being reported in a way that undermines public health messaging around sodium reduction.
You may consider this quality scientific research. I don't.
Yes, though this is the title posted to HackerNews, so I blame the poster. In the actual link, it's just : Reduction of dietary sodium to less than 100 mmol in heart failure (SODIUM-HF): an international, open-label, randomised, controlled trial
The study looked for a large effect size. That’s totally fine. I think it is good that non-pharmacological interventions are being studied. Calling it crap is quite unfair.
https://my.clevelandclinic.org/health/diseases/17072-heart-f....
Having patients suffer through this diet for little changes in outcome is important to know.
Have you ever looked at the papers that support the hypothesis that lowering salt consumptions helps heart patients?
Interesting. So the study produced no news at all. Just a click bait title...
Such a logical argument, but I could never get it across to my relative with congestive heart failure. Poor guy was terrified of food and what he did eat was almost flavorless (steamed plain proteins and veg, no fat). He was plainly malnourished. Not sure how the doctors didn’t see it.
Hold the phone....4000 to 6000mg? I've never seen anything that high as a recommendation. Maybe I'm an outlier, but if I get close to 4000mg I'll feel bloated the next day and my BP will be elevated.
https://www.nhs.uk/live-well/eat-well/food-types/salt-nutrit...
When you eat home-made food, there is some small quantity of sodium in meat and other animal-based food, but most of the sodium comes from the salt you add to food, which you should measure.
The sodium recommended intake is useful only when reading the labels of industrially-processed food, to see how much you could eat daily. However, if such food makes the bulk of what you eat, then there is not much point in reading the labels, as it is unlikely that you can achieve the recommended intake.
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.
Let's give up on the old urban legend that salt has f-all to do with heart health.
How can you "logically" come to that conclusion?
Let's get our 'simple chemistry' right.
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.
Can you explain why you think salt raises blood pressure?
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.
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?
So can you eat a lot of salt if you drink a gallon or more of water with it?
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.
> In ambulatory patients with heart failure, a dietary intervention to reduce sodium intake did not reduce clinical events.
Ambulatory = walking around, e.g. not hospitalized. The patients were already diagnosed with chronic heart failure and were followed for a year to see if a low-sodium diet would prevent further cardiac events. There wasn't statistical evidence that the low-sodium diet did so. Tada!
> Between baseline and 12 months, the median sodium intake decreased from 2286 mg/day (IQR 1653–3005) to 1658 mg/day (1301–2189) in the low sodium group and from 2119 mg/day (1673–2804) to 2073 mg/day (1541–2900) in the usual care group.
They did not find (or even try to find) whether a low-sodium diet helps in comparison to a normal, average diet.
Anecdotally, I put salt in everything I cook - sometimes to the point where others find it salty. My blood pressure has always been firmly in the healthy range (low 30s Male).
Apparently the average American has a diet that has 1.5 times the recommended level, so what this study is looking at isn’t anything like that, let alone an even higher-salt diet. So you can’t take the study as saying anything about preventing heart disease generally.
The one conclusion you perhaps could extrapolate from it is to say that the recommended limit is probably pretty good since it doesn’t seem to help going lower.
I don't have a source but I vaguely remember reading about how salt is no different than fat or cholesterol in terms of how it correlates to your body. Fat does not make you fat. Cholesterol doesn't raise your cholesterol. Salt doesn't raise your sodium levels. Excess calorie consumption combined with lots of fat (high in calories), will indeed, make you fat. Excess calorie consumption combined with lots of cholesterol, will raise cholesterol levels. Salt is no different.
This is an interesting read about salt from a 2011 article.
"Intersalt, a large study published in 1988, compared sodium intake with blood pressure in subjects from 52 international research centers and found no relationship between sodium intake and the prevalence of hypertension. In fact, the population that ate the most salt, about 14 grams a day, had a lower median blood pressure than the population that ate the least, about 7.2 grams a day."
[1] https://www.scientificamerican.com/article/its-time-to-end-t...
EDIT:
The above referenced article has been discussed here on HN a few times over the years for anyone who wants to read previous comments.
Speculatively, i.e... your body has a greater need to use the sodium-potassium pump more when you're stressed, which makes you crave salt, and eat more sodium. The high stress is what causes bad health outcomes, the high sodium levels just happen to correlate with it.
The study is decreasing sodium intake even further from the current guideline for patients with heart failure.
The effect of sodium intake is very different for people who need to maintain very tight tolerances to survive. And a ton of effort is spent keeping people with heart failure out of the hospital.
I have heart failure and have an implant that measures electrical conductivity of heart tissue and will warn if I am approaching fluid overload due to too much sodium.
https://peterattiamd.com/rickjohnson2/
Genetics are also a huge factor.
https://www.frontiersin.org/articles/10.3389/fnut.2021.80122....
This explains the higher incidence of stomach cancer in many E. Asian countries. Stomach cancer is the fourth most common cancer last time I checked.
So, if you create an experiment that can subtly select for the 75% of the population doesn't experience high blood pressure, then you can show that sodium doesn't raise it. I don't if that's what's going on here but a lot interested parties will try to go this route in order to show that salt is harmless.
Perhaps part of the obesity epidemic is due to the vilification of salt?
I'm not saying either are correct, I'm saying this hypothetical is a bad one.
I find that salty processed foods such as Cheeze-Itz (flavored) are very addicting and not filling at all. My theory was always that anything with onion powder, salt and refined carbs is a craving that can't be satisfied easily.
If the goal for patients is not reduction of BP, then the presumption of this study is that sodium is affecting the heart and vessels in more complex ways than pressure alone, and such patients might suffer in a diverse multitude of complex ways that are much harder to attribute directly to the level of sodium.
The authors' conclusion seems to be only that the correlation between sodium intake and death in heart patients is not simple and linear.
Sodium is NOT the horrible evil it's portrayed as.
What is actually problematic is, if anything, an imbalance with potassium and sometimes calcium and/or magnesium.
That's a weird way to phrase it because this study has nothing to do with cardiovascular disease generally. It's specifically about non-hospitalized patients already diagnosed with heart failure.
This does nothing to disprove the very clear link between sodium intake above a certain level and heart disease in a previously healthy individual.
Is this actually well established? I’ve seen so many “war on salt” articles that I’d assumed it was still debated.
I know this is common knowledge but could you provide any recent studies or citations for curious readers? Anything from the past 5 years? I could never understand how they factor in body weight and physical activity, which should change the recommended levels. Someone who sweats a lot because of intense exercise might need sodium above that limit. Or if you drank more water than average, etc…
Spot on with a caveat: you cannot balance out to much sodium by consuming more potassium.
Let's be honest here, if you eat a bowl of food with no salt on it you will get bored and find the food hard to finish.
Don't know of its my opinion of the field or the journal but i don't rate the lancet highly after digging into most higher profile papers.
Lol. It’s every field! Unless you live under a rock you’ve heard terms like p hacking, publication bias, publish or perish and in and on. All a manifestation of the glaring problems in higher education.
If you uniquely don’t trust the lancet, you’re doing it wrong. Be skeptical of all research until it’s been replicated a bunch, ideally by your own research team.
This is a very narrow clinical result, and not evidence pro or con in the general sodium debate.
- higher chance to develop kidney stones
- increase in blood pressure
- hurt the liver
Study: States specific conditions and statistics.
Hacker News reaction post: Interprets the title as maximalists statement.
These studies are tiny information nuggets useful for researchers working in the field. Nobody should change their view based on studies posted here.
It's a mineral required for human life, it's only in our decadent modern society that too much has ever been an issue.
Too much is bad but heavily restricting it isn't as good as people think.
For reference, US Army regulations during the American Civil War called for soldiers to be given 3 pounds 12 ounces (1.7 kg) of salt every 100 days. Sprinkling a little bit of that onto a meal would not exactly have been opulent. Of course, those ration regulations were aspirational and soldiers were lucky to get what they were owed, but it gives an idea of how much salt people considered reasonable.
Even so, they surely ate a lot of salt.
At a certain level sodium does become excessive and can lead to high blood pressure and kidney issues (I believe the liver issues are blood pressure related). This is basically due to the kidneys not being able to process the extra minerals. As long as you stay within the kidneys limits of function, then you're fine.
I generally agree that too many of us eat too much for our own good and that of other life on the planet, but to reduce the issue solely to caloric intake seems off.
From my own experience, timing and order of what I eat matters more than total calories. If I eat a morning meal until I'm full, well that was fun but now I'm tired, and the day just started. If I start the evening meal with bread or a handful of chocolate chips and eat the greens and veggies and fruits last, I feel different than if I do it the other way around, a worse-different. I suspect there are reasons (some for health, some for economics) that multi-course meals include a salad early on. Since I'm not couting calories, and I am eating until I'm full (regardless of how many meals I eat in a day, which is part of my problem, and why I spend more time fasting these days), I don't actually know what the calorie difference would be if I mix up the order, but I've settled on starting with the plants and fats, then proteins, then carbs and that feels good. On days (thankfully not habitual, now) when I snacked all day, interspersed with full meals, I had acid reflux, low energy, was irritable, had teeth problems, and gained unwanted bodyfat. Lump all those calories into two full meals (a lunch and dinner, say) and I felt better. Bring it down to one meal a day and I feel better yet (and, to your point, I'm likely consuming fewer calories, so win-win?). If I was more physically active I might do it differently.