Why Is Salt So Bad for You, Anyway?

You've probably been told that eating too much salt is bad for you, especially if you have high blood pressure. But what exactly does salt do to our bodies that can make it so hard on our hearts?

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[SciShow]

Since many of you have questions about this episode, here's some additional information, beyond what we included in the video.

Most people have probably heard that too much salt is bad, but they might not necessarily know why. That's all we really set out to explain in this episode: what researchers think salt does to the body, and why high blood pressure is unhealthy.

We didn't get into the controversies over the exact relationship between lowering salt intake and cardiovascular disease, because that relationship isn't totally settled yet, and there are many studies whose results seem to contradict each other.

One source of controversy in the research on salt and blood pressure is whether too little sodium is bad for you -- and how little is too little. But that's not what this episode was about, so I'm not going to get into it here.

Another major source of controversy is whether lowering salt intake actually lowers blood pressure and saves lives.


That led to a slew of articles saying that people don't actually need to decrease their salt intake, including the Scientific American article mentioned in one of the comments below.

It's worth noting, though, that the 2011 Cochrane review stated that "Our findings are consistent with the belief that salt reduction is beneficial in normotensive and hypertensive people." It went on to say that the methods used to reduce salt in the trials included in the review, and in other systematic reviews, didn't do enough. Their recommendation was that researchers find better ways to reduce salt intake, because clearly dietary advice isn't enough.


This time, they found weak evidence (meaning, some evidence, but not strong evidence) that reducing salt intake had some cardiovascular benefit. That led to another set of articles saying that people don't actually need to reduce their salt intake.

But the updated review's recommendations were the same as the earlier review's: we need to find better ways to help people reduce the salt in their diets.

Essentially, the problem is that just telling people to reduce the salt in their diets isn't enough. There's too much salt hidden in processed foods for people to be able to reduce their salt intake effectively just based on dietary advice.

It's telling that the study in the 2014 Cochrane review that showed the strongest effect of lowered salt intake on cardiovascular health was the one where the subjects had no control over the amount of salt in their diets. The study was done in a nursing home where kitchen staff prepared all the food.

It's hard enough for researchers to isolate the relationship between salt and cardiovascular disease because there are so many confounding factors. The fact that it's so hard for people to actually reduce their salt intake makes teasing out the relationship even more complicated. That's how we've ended up with a lot of inconclusive evidence.

None of this is saying that too much salt isn't a problem, or that high blood pressure isn't dangerous. It's saying, we still need to figure out how to help people lower their salt intake effectively, and then we need to figure out how much that will protect them against cardiovascular disease.

All we're saying in this episode is that salt can raise blood pressure, and that high blood pressure leads to all sorts of other health problems. That's the thinking behind the recommendations to limit salt intake.

So, that's the deal with the debates you might be seeing in the comments here.

[obsidianscale]

ironically not enough sodium ALSO causes kidney failure

[KenDBerryMD]

Salt is Good for people of all ages. Salt is NOT bad for you. Eat salt to taste...

[em]

Fun fact: A higher level of salt in your diet, or taking salt tablets, is used as part of treatment for Vasovagal Syndrome and similar illnesses. Weird how something we're generally told to avoid is a necessary part of treatment for some of us! :)

[niceguy]

League of Legends players must be dying left and right

[jarde]

FYI: High salt intake is far less dangerous than *low potassium* or *high sugar*

[Ishyona]

umm... I've been reading through your sources, and they all conclude there is insufficient evidence to say whether salt actually causes hypertension, or even if reducing salt intake relieves it. Given the large amount of research in this area, and the lack of consistent results, I think it's fair to conclude the culprit lies elsewhere. Especially when hypertension and sugar intake share a much stronger correlation.

[enotirab]

High blood pressure is no joke. I didn't realize I had high blood pressure until I suddenly started to lose vision in my right eye. I never even knew I was at risk.

[secondsuccess]

The takeaway from this video is that moderation is good. Don't eat too much salt, don't eat too little. In other news, man lands on moon!

[notstupidguitar]

hey sci show, you're information is not quite the whole story. recent studies punished by NIH and American journal of clinical nutrition are saying it's less about the raw value of sodium that's causing hypertensive episodes and more the imbalance of sodium and potassium in the diet. BP is largely regulated the rennin angiotensin aldosterone system and this hormone pathway excellent at dealing with sodium potassium and water balance, particularly potassium in the plasma/urine. We're finding that it's more the ratio of Na and K in the diet leading to much more sodium from the processed foods and much less potassium acting as the counter ion the glomerular filtration in the kiddy's to help with the Na excretion (Rather than the net Na alone) that's causing elevations in regulation of BP. check out the intersalt study in the journal of American and clinical nutrition (1997). that's the first study to really and directly show that its the Na and K ratio, not just that high Na is causative of hypertension. long story short, it's a bit more complicated than you let on.

[Scereyaha]

Can we also specify that if you don't have high blood pressure it's not a problem? Also that someone being over weight doesn't mean their blood pressure is high. And also that table salt in one of our main dietary intakes of iodine which is very essential for normal thyroid function...

Due to these attitudes, people get told to avoid salt because they are "over weight", which can actually deprive them of iodine and slow down their metabolism, often sabotaging any attempt to lose weight. [Though in some cases higher thyroid function can end up leading to weight gain too]

Moral of the story. Let your doctor voice concerns about your body, not other people, and certainly not popular opinion. Also make sure you know what your blood pressure is normally like, and have your thyroid checked periodically so you know what your levels are like.

[TheAkramCat]

Too much of anything is bad, what a shocker.

[corneliuswulpuswulpus]

Jokes on all y'all my blood pressures so low I faint if I run to much and my hands 'n' feet fall asleep in cold whether, so I can eat all the salt I want. I'd say it's a decent trade off.

[_Pyroon_]

For those concerned about consuming large amounts of salt, I would highly advise looking into your sugar (or more so, carbohydrate consumption) consumption habits before fearing your salt consuming habits. Sugar has heavily correlations with a multitude of different cardiovascular and metabolic issues.

[ethanalexander]

Normal people do not get high blood pressure from high salt intake. This only affects people who already have high blood pressure and people with hypertension. Healthcare Triage has multiple videos on this topic. I would recommend those.

I expected better from Scishow.

[mekkabon]

So what does SciShow think about the "Today I found Out" video about the studies done on salt?...and how the findings were essentially none, to faulty at best?

[Stoogie]

you need salt and calcium for your nerves to work, a salt free diet for a long time can make your nerves not work properly like having scintillating scotoma and temporary blindness, you need to eat salt for your nerves to work properly, rda of 2.3g a day or whatever, i had to ADD salt, not remove it

[CommanderWaddles]

Watching this as I eat diced tomatoes with a ton of salt in it

[KrazeeCain]

That moment when a SciShow video slightly contradicts a Healthcare Triage video...

[PatrickvonMassow]

Thanks for the explanations! However, I have some questions about this: Are there any negative aspects to eating too much salt, other than raising your blood pressure? In case you suffer from too low blood pressure, is it actually healthy to eat a little more than the recommended 2.3 grams of salt per day to slightly raise your blood pressure?