> Note that I am not a doctor, though, so take this information with the proper grain of salt.
In moderation though, too much sodium is bad for you
In moderation though, too much sodium is bad for you
[1] https://www.scientificamerican.com/article/its-time-to-end-t...
This is a well-understood process with much data to back it up and it will take a lot more than one meta-analysis of 6k people to provide evidence against it.
Note also a common mistake of studies that test correlations between a factor such as salt and a health outcome like CVD or death: often, the people at most high risk are already cutting down on the substance.
For example (I can't find the reference now, sorry) a study that reported that moderate drinking had better health outcomes than not drinking at all included in its study population individuals who had cut alcohol consumption completely because of pre-existing (at the time of the study) disease. So obviously those people had worse health outcomes than the ones that drank moderately.
This can skew results something bad. If you're testing whether cutting down on salt correlates with a reduction to CVD and some of your study population have cut down on salt because they already have CVD, the association between cutting down on salt and good outcomes will appear reduced in your data. In the first study reported in Scientific American in the link you provide it's hard to know whether this is the case because they don't link to the study (typical). The next study reported by SA, where the amount of sodium in urine was measured, seems to have suffered from this error: it found that cutting down on salt increased risk of dying from heart disease. Not benefitting from reducing salt intake is one thing, but dying more of it? That takes hellalot of explaining!
The point is that just because a study found one result doesn't mean everything changes overnight.
It is important to understand that when there is a large body of evidence supporting one hypothesis ("too much salt is not good for you") it takes an equally large body of evidence to reject that hypothesis. A single study, even a meta-analysis, doesn't cut it. It will take many years and a lot of work before the evidence SA presents is credible enough to change our understanding. And this is as it should be.
[1] https://bmccardiovascdisord.biomedcentral.com/articles/10.11...
The meta-analysis results are very confusing: low salt intake is associated with a relative risk of cardiac death, but moderate and high salt intake is associated with a relative risk of stroke death. Now what?
Some of the studies analysed controlled for various groups, e.g. with high BMI, or, indeed, with previous CVD. Some followed patients up for 10 or more years, some had 10,000 or more subjects, some had more or less than 60% male subjects- and all these factors seem to have afffected outcomes.
So perhaps a tentative conclusion should be that salt intake doesn't have a significant effect on healthy individuals, but it does seem to affect those with underlying conditions.
The question is- how do you know what underlying conditions you have, given that our interest in the study is probably to decide how much we should cut back on our salt consumption as individuals, according to dietary advice from basically all major health bodies, etc.
Well, I have a single data point on this. A relative of mine recently found out she has kidney disease. The news came out of the blue. She had a blood test for something unrelated and there was a worying signal. She was referred to a nephrologist, had an ultrasound to check the state of her kidney and discovered that she's missing one kidney from birth. It turns out that people with a single kidney from birth have an increased risk to develop kidney disease, higher than people who lose a kidney later in life, who in turn have a higher risk than the general population. It seems also that my relative's liberal salt consumption (until now) has played a role in her developing kidney disease, because the most likely course of events is that her blood pressure was elevated, which damaged her kidney, which raised her blood pressure, which further damaged her kidney, etc.
Like I say, this came out of the blue. Kidney disease is like that: it sneaks up on you, when you don't expect it. My relative was lucky to find out before she found herself on a hospital bed, strapped to a dialysis machine, but others have not been so lucky.
This whole affair made me realise I have no idea what might be going on in my body, that may affect me very suddendly a few years down the line. Perhaps I have some underlying condition I don't know of, myself. Maybe I'll find, when I'm older, that I have a high blood pressure and that I need to take medication, and cut back on salt, to control it.
Current guidelines are to limit salt intake and those are based on numerous studies carried out over many years, and, I think, clinical experience. Perhaps there were confounding factors not controlled for, in those studies- like high BMI, previous CVD, smoking (!) etc etc. But, if those confounding factors caused a significant jump in the relative risk for things that can easily kill anyone, then maybe the message is that there are many things that can increase the risk from high salt intake- and that many people are affected by those things. In which case the wise thing is to not assume that you can eat as much salt as you want, and that you have to be a little bit careful with it, now, so you that don't have to make huge, very difficult changes, later.
My relative has had to cut back entirely on the salt that she eats: no cheese, no cured meats, no eating out unless she can be entirely sure the food she eats is unsalted (which means steak and fries pretty much every time, because there's nothing else that most restaurants can guarantee is salt-free). That is a big pain in the ass, and she might have been able to avoid it if she had been more careful earlier on.
For the record- I'm suggesting everyone should do as I say, not as I do. I salt my food liberally, still. Incorrigible :)
Edit: On the other hand, you can always monitor your blood pressure. If you're eating "too much salt" that's how you'd find out. But, who monitors their blood pressure when without a good reason?