Salt

In the 1980s, a low-sodium diet was seen as the gold standard for healthy behavior. In 2026, salt has been repackaged as “electrolytes” and is now cast as a core component of wellness. How did we get here?

Also, an important correction: One pound of butter to one pound of potatoes is Joel Robuchon’s recipe.

Support us:

• Hear bonus episodes on Patreon
• Watch Aubrey's documentary
• Buy Aubrey's book
• Listen to Mike's other podcast
• Get Maintenance Phase T-shirts, stickers and more

Links!

• The 25 Saltiest Restaurant Meals in America 
• Facts, Issues, and Controversies in Salt Reduction for the Prevention of Cardiovascular Disease 
• Salt Wars 
• The INTERSALT Study: background, methods, findings, and implications
• Sodium reduction
• Sodium Intake Reduction: An Important But Elusive Public Health Goal
• Effects of Diet and Sodium Intake
• Salt intake, stroke, and cardiovascular disease
•  Racial and Ethnic Differences in Sodium Sources and Sodium Reduction Behaviors Among US Adults
• The Great Salt Debate: So Bad?
• Salt guidelines draw heavy backlash
• Sodium Reduction in US Households’ Packaged Food and Beverage Purchases
• Blood pressure lowering efficacy of angiotensin converting enzyme (ACE) inhibitors for primary hypertension

Thanks to Doctor Dreamchip for our lovely theme song!

Transcript

[Maintenance Phase theme]

Michael: Welcome to Maintenance Phase, the podcast. Wait, why can't I do this? Oh, yeah. [Aubrey laughs] Welcome to Maintenance Phase, the podcast that will finally make an episode that other people will call salty.

Aubrey: There we go.

Michael: See.

Aubrey: you did it. 

Michael: It's okay. It's like 6 out of 10.

Aubrey: We're doing the episodeium.

Michael: I'm Michael Hobbes.

Aubrey: I'm Aubrey Gordon. If you would like to support the show, you can do that at patreon.com/maintenance phase. You can also subscribe through Apple Podcasts. It's the same audio content.

Michael:  Same stuff, Aubrey.

Aubrey:  We're talking about salt today, Mike.

Michael: This was like the anxiety around diet growing up.

Aubrey: Yep.

Michael: It was like low fat and low salt were the two things you need to strive for.

Aubrey: This came up in our bonus episode about “80s diets” that a ton of them were extremely low salt. It is a thing that came up for me with my mom called me and said that a friend of hers invited her over to taste her cooking and make sure that it had the right amount of salt because her friend does not use salt ever.

Michael: This is a decade’s long fight that I've been having with my mom. She does not put salt in foods. And she says if you want salt, you can just salt it at the end. Like if you're eating chili, you could salt it at the end. And I keep trying to explain that that's not how it works. [laughs] So sorry mom. [Aubrey laughs] She can't-- she can’t overcome her heritage.

Aubrey: That's right.

Michael: Everyone's white mom grew up like this.

Aubrey: Right. We're all products of our time. So, I think the central question that I wanted to explore here is how did we get from this idea in the '70s and '80s that reducing your salt as much as possible was one of the most important things that you could do for your health, to the point now where many folks have just dropped that guidance altogether and folks are generally not paying attention to their salt intake, and even some folks are even opting for electrolyte beverages to up their salt intake? So, how do we get from point A to point Z?

Michael: Because it's fallen off the radar, the wellness radar. You don't hear about salt in the way that you used to.

Aubrey: People have this idea that you're not going to be able to salt your food at the table if we talk about salt. That's not true. According to the research, depending on which study, between 3 and 7% of American salt is added in home cooking or at the table.

Michael: Oh, interesting. Okay.

Aubrey: So, we're talking about a vanishingly small amount of the salt is what you decide to add to your food.

Michael: Right.

Aubrey: We're talking much less about individual decisions and policing individual decisions than we are talking about food supplies, and ways in which you might be consuming salt that you don't really know is consuming salt or you don't really think about is consuming salt.

Michael: Although I am policing your behavior, you should salt food when you're cooking it. If you don't do that, I'm bringing a protein bar when I come to your house.

Aubrey: In order to get the conversation going, I think we got to do a little bit of myth busting up top.

Michael: Okay.

Aubrey: And the way that we're going to do that is a salt quiz.

Michael: I thought you were going to say we need to do a taste test where we each just eat a teaspoon of salt.

Aubrey: Go get your salt shaker. How does it taste? Fucking delicious.

Michael: Let's both get grounded here and just eat a bunch of salt. Just the sound of me puking in the background.

Aubrey: So, question number one, Michael.

Michael: Aubrey.

Aubrey: The WHO maintains a ranking of estimated sodium consumption across over 150 nations. Where in that ranking do you think the United States falls? Do you think we are in the top 25, the top 100, or the bottom 25?

Michael: I think we're in the top 100, but not particularly high.

Aubrey: We're number 50.

Michael: Okay, who's the highest?

Aubrey: The highest consumption once you learn-- So lowest consumption is Samoa. They consume about a teaspoon of salt a day. 5 g of salt, so that's 2 g of sodium. The highest is China with 17 g of salt a day.

Michael: But are you sure this wasn't a survey of which country is the saltiest, like the most irritable?

Aubrey: You think China is the most irritable country and we're number 50?

Michael: I can't argue with statistics, Aubrey.

Aubrey: So, Samoa at 5 g of salt is much, much closer to the actual WHO recommendations, FDA recommendations, all of that kind of stuff.

Michael: Wait, so what is the WHO recommendation in teaspoons?

Aubrey: It's about a teaspoon is the what we should be aiming for. That's the goal. 

Michael: Okay.

Aubrey: Next question. We're going to do a little salt-Mortal Kombat. Finish him. Which of these has the most salt? We're going to do one teaspoon of each of these things. Which one do you think has the most salt? And which one do you think has the least salt? The options are a teaspoon of table salt, a teaspoon of MSG, a teaspoon of Marmite, a teaspoon of soy sauce, and a teaspoon of grated Parmesan.

Michael: From context clues, I think the answer is soy sauce. But also, Marmite is pure fucking salt. On your tongue, it's so unbelievably salty. So, I'm going to say Marmite and soy sauce is a close second. Am I wrong? I'm sure I'm wrong.

Aubrey: You're very wrong.

Michael: Okay. [laughs]

Aubrey: Marmite contains less sodium than a teaspoon of salt.

Michael: Really? It's so salty, though, on my mouth.

Aubrey: So, here's the story. One teaspoon of salt contains 2300 mg of sodium. A teaspoon of soy sauce has 3000 mg of sodium. So, considerably more, right? Like, almost 50% more sodium.

Michael: Yeah.

Aubrey: A teaspoon of Marmite has 340 mg of sodium.

Michael: Wait, what? One tenth?

Aubrey: Almost one tenth the amount as soy sauce.

Michael: Was I the wrongest it's possible to be? Was that the lowest one?

Aubrey: No, you were not the wrongest it's possible to be? Okay, here's the other one that I found fascinating. Grated Parmesan has about 25 mg of sodium in one teaspoon.

Michael: Wait, 2500 or 25?

Aubrey: 25.

Michael: But it tastes so salty. Aubrey, what's happening? What's going on?

Aubrey: Right, so all of this is to say, if you're counting on things tasting salty to determine what has sodium in it, we're almost all getting it wrong.

Michael: Wait, I did exactly the thing. I did exactly the concept that you wanted to illustrate. I'm putty in your hands. I've been puppeteered.

Aubrey: So, the last question that I have for you for our salt pop quiz--

Michael: This is so fun.

Aubrey: Are you enjoying it?

Michael: This is so fun.

Aubrey: Which of the following is the highest sodium dish at an American chain restaurant?

Michael: Ooh, okay.

Aubrey: A, the Wendy's Triple Baconator. That's three beef patties and six strips of bacon. [laughs]

Michael: I got to go to Wendy's more. Okay.

Aubrey: [laughs] B, Long John Silver's Footlong Chili Cheese Dog. C, Bob Evans Steakhouse Salad. D, Outback Steakhouse's Bloomin' Onion, or E, the Cheesecake Factory's Chicken and Broccoli Pasta.

Michael: Well, with these questions, the surprising answer is always the correct answer.

Aubrey: How dare you?

Michael: So, you shouldn't be thinking about what is correct. You should be thinking about what the surprising answer will be.

Aubrey: You should hack my brain, and I don't appreciate it.

Michael: The most surprising answer would be one of the salads or probably the Bob Mackie salad whatever.

Aubrey: [laughs] Bob Mackie, The Bob Fosse.

Michael: I've never heard of this restaurant, but okay.

Aubrey: Bob Evans Steakhouse Salad is number one.

Michael: Okay.

Aubrey: It is 7700 mg of sodium in a salad? 

Michael: Three times your daily recommended in a salad.

Aubrey: Correct.

Michael: Is lettuce secretly really salty?

Aubrey: No. Salad dressing.

Michael: It's the dressing, right? Yeah, yeah, yeah.

Aubrey: Absolutely. The lowest sodium of those is the Triple Baconator.

Michael: Wait, really?

Aubrey: Yep.

Michael: Okay,

Aubrey: That one's just shy of 1800 mg of sodium.

Michael: Right. Because I heard recently that just because things taste salty doesn't mean that they're high in sodium.

Aubrey: Oh, interesting. Where did you hear that one?

Michael: So, just letting you know.

Aubrey: You could just eat one Triple Baconator in a day and be like, “I nailed it by the FDA guidelines.”

Michael: That's technically an electrolyte. A triple bacon cheeseburger is an electrolyte.

Aubrey: You're just getting hydrated. [laughs]

Michael: That's your recovery drink. My recovery cheeseburger.

Aubrey: The question here is, if we're not getting it from foods that taste salty, if we're not getting super high levels of sodium from the Baconator, but we are from a salad, where the fuck is the salt coming from?

Michael: The Cheesecake Factory. It's all coming from the Cheesecake Factory.

Aubrey: Salt is used in food in ways that go way beyond palatability. The big one is that salt is overwhelmingly used as a preservative.

Michael: Right.

Aubrey: Cured foods, especially things like lox, bacon, ham, prosciutto, salami, really high in sodium. Pickled foods are pickled with a mixture of salt and sugar, so they have quite a bit of both. Canned foods use salt both to preserve and to inhibit bacteria growth. Salt is also heavily used in meat production, not just as seasoning, but as a way to increase profits.

Michael: Okay.

Aubrey: Because salt helps retain moisture, saline is often added generously to meat before it is sold.

Michael: Okay.

Aubrey: Meat with more moisture weighs more.

Michael: Right.

Aubrey: And meat is sold by the pound. So, it's a way to make more money from the same amount of livestock. So, I'm going to send you a quote. This is from a book called Salt Wars, written by Michael Jacobson, who is the former director of the Center for Science in the Public Interest.

Michael: “According to the USDA, 21% of beef, 78% of chicken, and 57% of pork is bulked out in this way. Such products are far higher in sodium than plain natural meat. Judging by a 2006 study of poultry, consumers nationwide were paying $2.6 billion, adjusted for inflation, annually for the added solution. Add in the beef and pork products that are watered down, and it appears that consumers are now being cheated out of at least $4 billion annually and possibly much more.” This is why I kind of hate it at the grocery store, how they spritz the produce with water, you know, and they have the cute little thunder sound now and then, the little spray comes on. I'm like, I'm paying by the pound for these apples. I don't want little drops of water on them.

Aubrey: I want them shriveled as God intended.

Michael: Do you know how much water a head of broccoli will soak up? I'm like, shaking it out at the store as if I'm opening a sugar packet.

Aubrey: I'm like, your cheapskate tendencies really are boundless.

Michael: I'm not paying for water.

Aubrey: The other thing that is related to a profit motive is that high sodium foods trigger a thirst response. So, whether by design or by happenstance, serving high-sodium foods can encourage people to order more drinks, which, as anybody who's worked in the restaurant biz knows, is where your bread and butter comes from, so to speak.

Michael: There's also, I think this is probably an urban legend, but when I was living in London, there's a thing where you go to nightclubs, drink whatever, like 2:00 in the morning, you're walking home and they have not quite food trucks, but booths on the street that will sell hot dogs and French fries and stuff. And they call it mistake away because it's always bad. You feel like shit the next day. But the explanation of these was that if you're at a bar, you're drinking a ton of liquid. So, your body's salt balance is out of whack at the end of a night of drinking. And so, your body craves super salty foods because you're low in sodium. So that's why you want French fries and a shawarma or whatever at the end of the night. It's like at a subconscious level, you're just like, “Oh, I want terrible food.”

Aubrey: Absolutely.

Michael: I don't know whether that's true, but I did eat those hot dogs all the time for my health.

Aubrey: The main thing we're going to talk about today as we start to chart the path of how we got here is something called the salt-hypertension hypothesis.

Michael: Yes.

Aubrey: The idea is that because salt helps retain moisture, it increases your blood volume and the more blood volume you have, the harder your heart has to work. The harder your heart has to work, the greater the likelihood of high blood pressure, the bigger your heart gets. It can contribute to an enlarged heart. Presumably, then the inverse would be true, that cutting out salt would decrease blood volume and blood pressure.

Michael: And when you say that someone has a big heart, you're implying that they're at risk of a stroke.

Aubrey: The idea that sodium intake is linked to heart health stretches back centuries. There is a classic text in Chinese medicine called Huangdi Neijing, estimated to be written sometime between 400 BCE and 200 CE. And it noted that, "if too much salt is used for food, the pulse hardens." That is the first mention that we see of relating salt to your blood pressure or to your heart health.

Michael: I love that phrase.

Aubrey: The pulse hardens.

Michael: Yeah.

Aubrey: Empirical testing of this question of the link between sodium and blood pressure and heart health started very early in the 20th century. In 1904, two French researchers reported that treating hypertensive patients with a low-salt diet reduced blood pressure. So that starts to kick off a series of other little studies. They're mostly small sample sizes. They're mostly working with patients that already have hypertension. Most of those studies seem to largely bear out the hypothesis that, “Oh, yeah, when you cut down on salt for people who already have high blood pressure, it appears to improve their blood pressure either a little bit or a fair amount.”

Michael: I thought you were going to tell me that people with hypertension also eat a lot of salt and it would be these correlational studies. But these sound fine. They're actually doing interventions and finding that changing your diet reduces your blood pressure.

Aubrey: That is an overwhelming majority of the studies that we're going to talk about.

Michael: Cool.

Aubrey: In 1939, there is what is seen at the time as a big breakthrough in salt. Research physician at Duke University, Walter Kempner is his name, creates the Kempner rice diet.

Michael: Okay.

Aubrey: Kempner believed that salt was a "waste byproduct" of the kidney.

Michael: Okay.

Aubrey: And that reducing sodium intake would protect kidney function. You're giving your kidneys less salt to have to contend with and filter out. And he thought that if you could devise a super low-sodium diet, that that would help folks with kidney function and heart function.

Michael: It was the Marmite and Parmesan cheese diet. [Aubrey laughs] Just spoonfuls.

Aubrey: So, the diet that Dr. Kempner devised is a fucking wild one, Mike. It's not heavy on the calorie restriction. The maximum was 2,000 calories, which is not as unhinged as we get and is pretty normal.

Michael: Yeah.

Aubrey: It had a maximum of 5 g of fat. One chicken thigh has more than 5 g of fat. It had a maximum of 20 g of protein. It had a maximum of 150 mg of sodium which is-

Michael: Oh, wow.

Aubrey: -nothing.

Michael: So, what you're saying is it's just three Wendy's Baconators per day?

Aubrey: No, it's unlimited rice. [laughs]

Michael: Is that what it is?

Aubrey: It's called the Kempner rice diet.

Michael: Oh, it's not named after a researcher named Rice. I thought it was like two researchers and one of their last names was rice.

Aubrey: No, it's a guy and a food. Kempner rice. [laughs]

Michael: You're just eating unsalted rice, three meals a day.

Aubrey: Unlimited rice and unlimited fruit juice and you could have white sugar.

Michael: That's the most '80s-ass diet. I know this isn't the '80s, but it's the most '80s-ass diet I've ever heard in my life.

Aubrey: It's 1939, but we're getting a head start on the '80s. [Michael laughs] Absolutely. To be clear, that 150 mg sodium ceiling is almost impossible to manage. Five stalks of celery has over 150 mg of sodium.

Michael: No way.

Aubrey: Two unseasoned eggs has over 150 mg of sodium. Sodium is a mineral. It exists in soil, which means it exists in almost every fruit and vegetable. A stiff breeze will get you to 600 mg of sodium. Like, what the fuck? As a result, because this diet is so extreme, the adherence rate to the diet hovers between 25% and 30%.

Michael: Yeah, miserable.

Aubrey: Part of what you're trying to get at is, what's our treatment recommendation for people who have hypertension? How should they be eating in perpetuity? It's not functional to say you pretty much can't eat vegetables. There's too much salt in them.

Michael: The only thing you have to do is never derive any pleasure from food the rest of your life.

Aubrey: Never have a slice of cake at a birthday party. Never eat another sandwich.

Michael: You will get scurvy, but think of how small your blood will be.

Aubrey: The people who did experience improvement, whether Kempner was studying it or others were studying it, they saw improved blood pressure, they saw improved electrocardiograms. Like, they're seeing significant improvements in heart health across measures.

Michael: All right, clip it and ship it. Let's start giving everybody the rice diet.

Aubrey: Please enjoy only rice, nothing else.

Michael: We solved it.

Aubrey: There aren't really blood pressure meds on the market at this point, so the Kempner rice diet is one of the only treatments on offer. This is a little bit like the keto diet story, where we didn't have anticonvulsant medications on the market yet. So, when people were using the keto diet as a treatment for epilepsy, it was the only game in town.

Michael: Yeah, yeah, yeah.

Aubrey: So, in the 1940s and '50s, the research around sodium and heart health continued largely in animal studies, rats and chickens and American researchers observed an increase in high blood pressure in those rats and chickens during those animal studies.

Michael: But then if we eat those rats and chickens, do we also have high blood pressure? Is that the real problem?

Aubrey: No. Then we have superpowers. 

[laughter]

This research was generally received as a confirmation of the salt-hypertension hypothesis. But there are a couple of significant challenges with the research. One, rats and chickens don't display significant variants in blood pressure response to salt intake. Humans do. And two, the doses were nutso. The human equivalent of the dose that these rats got would have been 40 g of salt per day.

Michael: You're basically preserving yourself.

Aubrey: That's right.

Michael: Like an Iberian ham.

Aubrey: You're pickled now.

Michael: Yeah. [laughs] 

Aubrey: So, like, yes, hypothetically, if humans quadrupled their salt intake, that would have a bigger effect, but that's not especially helpful in terms of guiding whether or not our current much lower levels of salt intake should be cut down from there. That is the data that is available to the U.S. government when it starts making large scale nutritional recommendations about salt. We've got the Kempner rice diet, we've got this early French research, and we've got a number of animal studies. So, 1969 is the point at which the U.S. federal government starts talking about reducing salt intake.

At that point, again, the data is definitely imperfect, but all of it seems to point to sodium reduction as a strategy worth pursuing. And there's certainly nothing outperforming sodium reduction as a treatment strategy for hypertension.

Michael: Right.

Aubrey: In 1977, a Senate select committee published Dietary Goals for Americans. It's the predecessor to the Dietary Guidelines for Americans, which are published for the first time in 1980. Both of those include broad recommendations to reduce sodium intake, but they don't have specific goals just yet.

Since then, the recommended daily allowance has for quite some time now held steady at between 1500 and 2300 mg of sodium. The nutritional recommendation is now baked into the dietary guidelines and it becomes almost boilerplate language that just gets carried over and carried over and carried over. But that's when large scale human studies start to roll out and that's when the so-called "Salt Wars" begin.

Michael: Dude, is it fucked up that this is making me hungry for salty food and now I'm eating the smoked salmon that I have in the fridge? [laughs]

Aubrey: I feel like you now understand why I fucking burned through that jar of Gorgonzola olives.

Michael: I know.

Aubrey: So, there is a huge landmark study in the early 80s called “INTERSALT.”

Michael: Okay. [laughs]

Aubrey: It was a very ambitious global study of sodium consumption. There are different ways to measure sodium intake. One of the ways that you can do it is from self-report data, as we've discussed many times on the show. That's generally unreliable, but it's especially unreliable given how much people misunderstand where salt is in their diet. The other one you can do is you can look at consumer data about how much salt people are buying per capita. But dietary salt, like culinary salt, is such a small fraction of salt sales in the US. Salt is used in a bunch of medical equipment and treatments. You've got to have medical grade saline solution for a bajillion fucking things. You need salt to de-ice roads.

Michael: Yeah, yeah.

Aubrey: So, the gold standard for this kind of stuff are biomarkers, either blood work or urinalysis.

Michael: And it's like how much sodium I ate in the last 24 hours or something.

Aubrey: Yeah. It's how much is coming out in your pee. So, they're taking urine samples, they're measuring these sodium biomarkers and they're taking folks' blood pressure regularly. They ran a bunch of controls on the study. They found that across genders, across races, and across nationalities, people who consumed more sodium had higher blood pressure on average than people with the same demographics that consumed less.

Michael: Okay.

Aubrey: INTERSALT's results were released in the late 1980s and they made a huge splash that led to a huge wave of press. But neither the findings nor the press around them accounted for some really important variables. One is where the sodium was coming from, which varies pretty widely from one country's food system to the next. The other thing that the INTERSALT study didn't account for is what individuals should do as a result of these findings. That's not actually what the study was. It wasn't looking for, “Hey, what should most people do for their health?”

Michael: It's a descriptive study. They're just trying to find a phenomenon.

Aubrey: That's right. But it's released in the late 80s, which is exactly when certainly the U.S. is taking off in terms of health conscious behaviors.

Michael: Right.

Aubrey: So, a bunch of people hear this thing about salt consumption is associated with higher blood pressure, and they go, “Aha. Gotta take the salt shaker off the table.” In 1990, Congress passed the Nutrition Labeling and Education Act, which is what standardized our food labels to include X percent of your vitamin C for the day and Y percent of your sodium. And sodium is included in that labeling requirement. This is where we start to get the unhinged. I wrote this in my notes before your mom was the example, but I did write, this is where we get your unhinged, low-salt moms and uncles and whatever. [laughs] 

Michael: The white people took this and ran.

Aubrey: Following INTERSALT and the findings of INTERSALT, a bunch of nations around the world, including the U.S., launched national trials related to sodium and hypertension. In the US., ours was the DASH study, Dietary Approaches to Stop Hypertension.

Michael: Okay.

Aubrey: DASH was a randomized controlled trial of 459 adult participants that all had elevated blood pressure. So, we're once again looking at interventions for hypertension. All of the adherence stuff that we've talked about is a challenge when you're in the wild. So, what they decided to do was be like, “Cool, you're eating two of your three meals a day at the research center. And then you're getting a third one in a cooler to take home with you.”

Michael: So, it's super prescribed.

Aubrey: Study participants were cycled through three different diets, each for three weeks at a time. And they also answered a standard battery of questions about symptoms that they might be having, like the classic back-of-the-head hypertension headache or that kind of thing.

Michael: Every single one of them just said, “I'm hungry,”

Aubrey: I'm so hungry.

Michael:  I'm eating these terrible meals that the lab gives me. 

Aubrey: Please feed me. 

[laughter]

Michael: I've been living like this for six weeks.

Aubrey: So, the three diets are this. One, there's a control diet. It was intended to reflect the standard American diet at the time. The fruits and vegetables diet was similar to the control diet but had just more fruits and vegetables in it, more fiber and then the DASH diet, which centered around fruits, vegetables, and low-fat dairy. That diet was high in calcium, high in magnesium, high in potassium, protein, and fiber. It was low in fat and saturated fat.

Michael: But it's not super low in salt.

Aubrey: No. Oh, so the first DASH trial is just “Can we look at just the foods that people eat.”

Michael: So, it's like low fat, careful eating, and Baconator. It's just comparing those three things. [Aubrey laughs]

Aubrey: The findings were significant and they were heralded as such. People who didn't have hypertension, but did have elevated blood pressure had a modest, but meaningful decrease in their blood pressure of 3 to 5 points-ish. And people who did have hypertension on average had a much larger decrease in blood pressure of 5 to 11 points. That's with the DASH diet.

Michael: So, the DASH diet worked to reduce blood pressure, which is the goal of the diet.

Aubrey: Absolutely. So, as a follow up to the DASH trial, those same researchers ran a second DASH study called the DASH-Sodium trial. Same kind of research design, but instead of cycling through these three different diets, they cycled through the DASH diet at different sodium levels.

Michael: Okay, cool.

Aubrey: The results this time were even more striking. The lower sodium diets yielded much more significant drops in blood pressure. We're now into the world of like double digit changes in your blood pressure, and that's genuinely huge.

Michael: Yeah. This actually sounds like a pretty good study or at least something promising as a biological mechanism that you should do more research to figure out but they found a real effect.

Aubrey: So, here's the challenge with the DASH diet. The DASH diet hinged on someone else preparing your food for you.

Michael: Right, right.

Aubrey: You also have the effect of being observed as part of a health study. So, people straighten up and fly right in a bunch of different ways.

Michael: And you're motivated. You know, it's a short-term thing.

Aubrey: Absolutely.

Michael: It's very different than doing it for the rest of your life.

Aubrey: Yes. You're having this quasi-celebrity experience of having a personal chef.

Michael: Or people asking you like, “What'd you eat today?” It's like dating someone.

Aubrey: When you put that in the real world and you ask folks to adhere to a low-sodium diet, the adherence rates out in the world are notoriously terrible. A 2024 study of patients in heart failure found that even in that group, folks who have really high stakes, adherence to a low-sodium diet was around 50%.

Michael: Oh, wow.

Aubrey: It goes down from there, with some studies of people with known hypertension putting the real-world adherence to a low-sodium DASH diet at 20%.

Michael: I'm assuming these are self-reported as well.

Aubrey: That's right. And as ever, Maintenance Phase is the diet. Like pretty explicitly—[crosstalk] 

Michael: Oh, she said the name of the show.

Aubrey: Oh my god. It is happening. [laughs] Pretty clearly the DASH diet is designed to be followed for life. If people are having this hard a time, even in short test periods, it doesn't bode well for how that translates in terms of a set of public practices.

Michael: I do think it's worth drawing the distinction between the adherence rates to a low-sodium diet versus adherence rates to other diets. With something like keto, it's like, you know what you're supposed to do, but it's joyless. It's really repetitive. Whereas the adherence to the DASH diet, it feels like it's more you don't even know what you're supposed to be doing. Just because sodium is in so many things, like saltiness of taste, as I learned an hour ago, is not the same as having high sodium levels. I think the adherence stuff can oftentimes get boiled down to a willpower issue. But this might really not be a willpower issue. It might just be like, we live in a world where you go to a restaurant and there's like two days' worth of sodium in your fucking salad dressing and you just didn't know.

Aubrey: Right. And you should have made the heart healthy choice of ordering a Baconator.

Michael: Exactly, yes. [Aubrey laughs]

Michael: I think it was like an Anthony Bourdain episode where he mentioned offhand that restaurant mashed potatoes are typically 50% butter.

Aubrey: That's the Jean-George ratio, famously, that he was like, one pound of potato to one pound of butter.

Michael: Yeah. Like, restaurant food's hella good because part of it is they don't care how much sugar, fat, salt, whatever they put in the food.

Aubrey: So, one of the problems with the DASH diet and with any low-sodium diet recommendations is adherence rates. The other is that, as we learn as the research continues to unfold, different people respond really differently to sodium. As you can imagine, following the release of the DASH trials and the DASH-Sodium trials, there is an explosion in sodium intake and heart health research because there is this sense of, “Okay, we're onto something. Let's dig in. Let's figure out how those DASH diets impact normotensive people. People who don't have hypertension.”

Michael: Normotensive.

Aubrey: That is the term of art, Michael.

Michael: TERFs would call that a slur. [Aubrey laughs] They think cisgender is a slur.

Aubrey: In the process of calling it a slur, they become hypertensive. 

[laughter]

So, there is this giant wave of new salt research that hits in the 2000s and 2010s. So, we learn a bunch of things that sort of flesh out the picture and add a lot of light and shading to what we know.

Michael: As a member of the normotensive community, [Aubrey laughs] I need to know what I can take from this now that you I'm normotensive, you changed.

Aubrey: Among other things, we learned that not everyone has the experience of increased sodium intake increasing their blood pressure.

Michael: Oh.

Aubrey: Some people have no real response to added sodium. Some people have the opposite reaction where they cut out salt and their blood pressure goes up.

Michael: Your heart expands, expecting salt.

Aubrey: We don't really know how many people have each kind of response. And at this point, most of our research, and I think rightly so, has been on people who have hypertension and heart disease, because we're trying to stop those people from dying.

Michael: Right, right.

Aubrey: All of that means that the public health question then starts to shift. If a significant portion of the population has hypertension and sodium reduction can help prevent heart attacks, strokes, and death, is it worth reorganizing our food systems to keep those folks alive? Or do we need to do a bunch more research on people who are at less risk in order to make those kinds of food systems level decisions?

Michael: And also, the problem of adherence is not a minor problem.

Aubrey: No.

Michael: Giving people food in this very structured way is actually very different from telling people to eat differently.

Aubrey: Totally. And again, this is all research on people who have high blood pressure and who have heart disease.

Michael: And are supermotivated.

Aubrey: And are supermotivated and have high stakes sitting right in front of them and the question is what do we do for everybody.

Michael: Also, I just looked up hypertension prevalence, and it's fucking 47%.

Aubrey: It's really fucking high, Mike.

Michael: It's a massive deal. If this is useful for people with hypertension.

Aubrey: In that way, we're kind of doing a trolley problem.

Michael: Right, right.

Aubrey: We also find out that there are some downsides to sodium reduction, that a low-salt diet may increase production of some hormones and can increase cholesterol levels.

Michael: Okay.

Aubrey: So, we're just getting more and more and more nuance, more and more light and shading to the salt data.

Michael: Right.

Aubrey: There are some broader limitations to the research as a whole. We talked about the ways to measure salt intake, like how much salt do people buy versus how much do they excrete in their urine versus how much shows up in their blood. All that kind of stuff. For the US, our primary sodium intake data per capita comes from NHANES, which is a long running nutrition research study where researchers ask folks to recall just what they've eaten in the last 24 hours and then those researchers run analysis.

Michael: Highly problematic methodology, but there's not a lot of other methodologies available because people cannot remember what they ate. And then also if somebody says like, “I had a pizza yesterday,” it's not totally clear how much sodium that had. 

Aubrey: 100%.

Michael: It depends on the pizza. Depends on how much pizza.

Aubrey: You're going to have to make some assumptions in NHANES world, one of those assumptions that they make in terms of sodium data is that when people say that they ate rice, they assume that folks have salted the water in which their rice is cooked.

Michael: Interesting. But these are boomers. They're not doing it.

Aubrey: It's actually less relevant about findings across age and much more relevant around findings around race.

Michael: They do have race data. So, they should assume that the white people are not salting their rice.

Aubrey: Incorrect. Michael.

Michael: Wait, really?

Aubrey: The white people are salting their rice water? But some studies that drilled down on sodium consumption of Asian Americans, as we've noted before, soy sauce is really high in sodium. Those studies found that fewer Asian Americans were salting their rice water, which could be leading to a miscount of around 325 mg per day for folks who eat rice regularly but don't salt their rice water.

Michael: Because also, even salting your pasta or your rice can be a teaspoon or 3 tablespoons depending on the person. Even that is not completely accurate. I'm just nitpicking now. But it's just so hard to do these studies.

Aubrey: That's exactly right. That's the whole point, Mike, is it's so fucking hard to do these studies and it's so fucking hard to extrapolate anything that approaches like a level of certainty that a civilian person like you or I would expect to see. There are so many other factors with hypertension. Your baseline life stress is as much a factor. Your socioeconomic status, your educational attainment. It's not possible for us to isolate. When we're only looking at salt in someone's life, we can get closer to the mark, but we can't go, “Okay it's just specifically the salt. It's only the salt.

Michael: Right.

Aubrey: Because of this large boom of research in salt, there are some studies that are like, “Wait a minute. We're looking at normotensive people.” It's your people, Mike.

Michael: It's my community.

Aubrey: Those studies find that there may be an association with very, very low-sodium diets and increased mortality. But those studies are not very large. And in a place like the US, most of us are so far over the mark that being very low sodium is genuinely difficult to do, even for the moms, uncles and neighbors who are like, “I don't even have a salt shaker in my house.” Right?

Michael: Right.

Aubrey: But that drop in the bucket of, “Oop, there's some wrinkles here is enough to generate a bunch of media coverage that's actually, maybe salt is good for you.” We're now 30 or 40 years into guidance saying you should probably reduce your sodium. So, this lands as an edgelord man-bites-dog story. Hey, wait a minute. What if everything we knew on this topic was wrong? It's an enticing little hook.

Michael: Someone should make a podcast with that as a concept.

Aubrey: Interesting. What if we're wrong about everything we thought?

Michael: Preconceptions that we have had previously?

Aubrey: So, there's this article that comes out in Science that collapses it into this. See, we're being misled. The science doesn't bear out these conclusions that we've been told. And maybe it's time to question the sacred cow of sodium reduction advice.

Michael: Right.

Aubrey: Those stories are not really contextualized in a broader conversation like the one that we're having today that is like, okay, but let's look at who needs it the most. Let's look at the scale of the problem here.

Michael: Because it sounds like at this time, the consensus is that if you have hypertension, you should think about reducing your salt. But if you don't have hypertension, you don't really need to worry about it.

Aubrey: Right. And if you do have hypertension, even if you're super motivated, your adherence is going to be low because it's not really possible for you to hang in our current food environment with a lower salt diet. So, one group of people who are promoting the "Salt is actually good for you hypothesis” are journalists who are interested in a new story. The other is the actual salt industry.

Michael: The salt industry? Is that just like the packaged foods industry?

Aubrey: No. There's big salt.

Michael: Big salt exists.

Aubrey: There is. Their lobbying arm was called the Salt Institute, so they named it so that they billed themselves as "The world's foremost experts on sodium." So, they tried to make themselves seem kind of like they were academics, but they are straightforwardly an industry lobby group.

Michael: They should have called it the Sodium Podium [Aubrey laughs] because we're standing there and we're talking to you.

Aubrey: The Salt Institute was founded in 1914 in the US. Their highest profile president was someone named Lori Roman. Lori Roman was someone who had already been in the media because she had already been in a political leadership position. She was the executive director of the American Legislative Exchange Council, ALEC. They opposed divestment from apartheid in South Africa. They opposed "The homosexual movement" in the '80s and '90s. They provided the model policy for SB 1070, better known as Arizona's show me your papers law.

Michael: The only thing she loves more than salt is black people not voting.

Aubrey: And in some cases, not living, because they also fomented stand your ground laws, voter ID laws.

Michael: Okay, fuck it. Never eat salt again. I've heard enough. [Aubrey laughs]

Aubrey: So, this is the thing that absolutely jokerfied me is I was like, “Okay, so fuck these guys.”

Michael: Yeah, fuck salt.

Aubrey: Also, one of the Salt Institute's staffers, someone named Morton Satin, which I think is very funny.

Michael: Morton.

Aubrey: The salt guy was named Morton.

Michael: Even weirder that he has a yellow raincoat on and an umbrella wherever he goes.

Aubrey: Morton Satin also wrote extensively for the Weston A. Price Foundation.

Michael: Every one of our episodes leads to the same URL. The same people saying the same shit.

Aubrey: Their advocacy efforts have generally been completely and totally unhinged.

Michael: Right.

Aubrey: Nearly every time a finding came out that suggested unlimited salt might not be a great choice for everyone, the Salt Institute would pop out of its trash can to advocate against it both in government and in media. In 1996, for instance, the Salt Institute asked the FDA to repeal regulations that allowed some manufacturers to label things as low sodium if they were low sodium.

Michael:  Okay.

Aubrey: They're like, “They shouldn't be able to advertise that.”

Michael: Yeah, just pushing the evil, yeah.

Aubrey: They made a stink every time the dietary guidelines came out because each one includes some mention of sodium reduction. The arguments why they opposed it changed as public opinion changed.

Michael: Right.

Aubrey: In 2016, for example, Lori Roman told The Hill, quote, "It's almost as preposterous as limiting water. People are naturally wired to get the salt they need. By lowering sodium levels in food, you run the risk of increasing obesity." 

Michael: What?

Aubrey: Her thinking is, people want a certain amount of salt, so they'll just eat the volume of food that gets them that amount of salt.

Michael: So, I'm holding the salt constant but just adjusting the amounts of food.

Aubrey: I'm going to eat three times as much if there's one third as much salt, which you're like, “Lady, absolutely not.”

Michael: I don't think so.

Aubrey: And they also start to get some salt-curious pieces out of centrist outlets. One of them comes from our friends at The Atlantic and is titled "The Great Salt Debate: So bad?”

Michael: Question mark, love those.

Aubrey: It seems like it's going to litigate the science of, wait a minute. What do we know now about salt consumption and how dangerous it is? It's not that. It is straightforwardly a profile of a guy who works for the Salt Institute.

Michael: Oh, wait, really?

Aubrey: Yeah.

Michael: Oh, that's so fucking funny.

Aubrey: He does seem a true believer. But, again, a bunch of his stuff is just going, the science isn't perfect. And actually, maybe it's good for you. And actually, we need to have more research before we make any recommendations. Absolutely ideally, and we could study this for another 50 years and still feel like the results were inconclusive.

Michael: The funny thing is I remember this. I didn't do a deep dive, you know, this is before we did the show. But I remember being like, “Oh, okay, salt is chill. I just don't need to think about my salt consumption.” And that's basically what I've done every day ever since.

Aubrey: Yeah. Yes.

Michael: So, I'm part of the problem.

Aubrey: So, while this debate is going on, while all of this research continues, so does policymaking. The FDA rolls out some voluntary sodium reduction programs which don't do nothing. They did more than I expected them to do. There are companies that reformulated their products. Hilariously, Campbell's did a big rollout being like, “We're cutting our sodium by 40%.

Michael: I remember that.

Aubrey: People had such a negative reaction to it that Campbell's sort of rolled it back.

Michael: Really? They actually reversed it.

Aubrey: They reversed big parts of it. They didn't go back to their original super high sodium levels, but they did increase sodium again. They dropped the labeling. And actually, that's part of what happens from here on out is that companies start reformulating their products to be lower in sodium, which is good, but none of them are talking about it.

Michael: It's also so funny to me that the population is pissed off there's less sodium in their food. [laughs]

Aubrey: People get so irrationally mad. It's like gluten levels of anger.

Michael: It's not like you can't just add salt. If Campbell's chicken soup tastes bad, you just add a half teaspoon of salt when you make it. It's not that big of a deal.

Aubrey: It's really not. And people lose their minds.

Michael: I add salt to my peanut butter and it's bomb as hell because you have to stir it anyway because it separates. Like almond butter is awful without salt. If you just add a fuck ton of salt, it's so much better. So, I don't complain there's not enough salt in the peanut butter, I just add fucking salt.

Aubrey: That's right. And also, again, we're not even talking about palatability for so much of this, right?

Michael: Right. I salted my peanut butter and my heart is small as hell. People are always telling me I have a small heart.

Aubrey: The FDA rolls out these voluntary sodium reduction programs. That again surprised me that they did as much as they did. The American Heart Association started advocating with companies directly to reformulate. Nestlé, General Mills, PepsiCo, Kraft Heinz, Subway, and Panera all took on voluntary initiatives to reduce sodium in their products in the 2000s and 2010s. And more Americans were self-reporting that they checked labels for sodium. That's them telling someone, I checked the label for sodium.

Michael: Right.

Aubrey: Which I think just means they know that that's the right health-conscious answer if they want to seem like a health-conscious person. But even if they're just saying it, there is some sense of, “Okay, well, the writing's on the wall. We should probably pay attention to this.”

Michael: Right.

Aubrey: And it's borne out by sales data. So, a 2017 JAMA study looked at grocery and convenience store sales data and found that between 2000 and 2014, Americans food purchases reflected a 12% drop in dietary sodium.

Michael: Okay.

Aubrey: Buying food and eating food are different things, of course, but if those sales data translate into dietary changes, that would be a 400 mg drop in sodium intake, which is really significant. That's 40% of the way to the FDA goal. [Michael laughs] That's a really, really significant drop.

Michael: We're still way over it, but it's getting there.

Aubrey: In 2019, to everyone's surprise, the Salt Institute closed.

Michael: Vaccinated?

Aubrey: [laughs] They didn't really say why, but there are a few things that could have played a role. One is the National Restaurant Association, which was a one-time ally of the Salt Institute, starts proactively working with its members to start to bring down the sodium levels in some of their dishes so that we have fewer of those "there's 7,000 mg of salt in this one salad" kind of thing.

Michael: I'll bet those emails are wild. [laughs]

Aubrey: I bet they're-- [Michale laughs] [crosstalk]

Michael: It's like the psycho salt lobbyists and the psycho restaurant lobbyists fighting.

Aubrey: In terms of where we are today, there is some disagreement about the specific threshold. But most major health institutions in the US agree that Americans on average consume more salt than we probably should. At the population level, it looks as if, again, all these measures are imperfect, it looks as if the US per capita sodium intake is plateauing. Some measures show it reducing a tiny bit. But the good news is that even without those salt interventions which could accelerate this, deaths related to heart disease have been declining since the 1970s.

Michael: Right.

Aubrey: A lot has changed since the initial burst of publicity around salt consumption and heart health. During this time, from 1969, the first low-sodium recommendation from the US government, to today, we have dozens of treatments that have come onto the market that are way more effective.

Michael: That's the other thing.

Aubrey: Earlier detection, the rollout of those little blood pressure machines and people taking pressure at home.

Michael: Yeah.

Aubrey: New treatments have entered the market. The first ACE inhibitor was approved by the FDA in 1981. Those lower blood pressure about twice as much as salt reduction. The same goes for SGLT2 inhibitors like Jardiance and Farxiga. Those received FDA approval for the first time in the 2010s. Those medications work regardless of a patient's salt sensitivity. And they don't have the same absolutely brutal adherence rates. Like a lot of people can take a pill once a day. The biggest barrier there is how expensive they are.

Michael: Right. I think there's this tendency to link it has to be lifestyle to this thing like salt equals strokes. But it sounds like many, many things contribute to it, one of which appears to be salt. But there's just lots of other stuff going on.

Aubrey: We've just gotten better at talking about a bunch of facets of it. And salt is one of many facets.

Michael: I do think this is the most "It depends" episode we've ever done.

Aubrey: It's such an "It depends" episode. You're exactly right.

Michael: Because some people should reduce their salt.

Aubrey: Some people should increase it.

Michael: And also, I'm just processing this in real time. Even if it's the case that you really need to reduce your salt consumption, it's really hard to do that. And there's more effective treatments.

Aubrey: Yeah.

Michael: It's not like, stop using light salad dressing. It's like, “Take a statin.”

Aubrey: I think that's right. And also the "Take a statin" stuff is more effective than an intervention that is very difficult to do with a very low adherence rate because of how difficult it is to do. Two things can be true at once. It can be true that it doesn't make sense to instruct most patients to reduce their sodium intake because of adherence, because some people have the opposite effect. But it can also be true that our food system has a ton of sodium in it. And we should be able to control for that in ways that allow people to have the control that they need.

Michael: Right.

Aubrey: So, that if you are a person who needs to up your sodium, you know that you're upping your sodium. And if you're one of the many, many, many people who need to control their sodium intake or who might benefit from that, then you also have the ability to do that. Right now the food system cuts in favor of the presumably small number of people who need more sodium in their diet. I think this is a really interesting case of, there is a lot of really nuanced research. There are folks who are inclined to pull that into definitive conclusions in any number of directions. And the truth is, this is a really complex issue that on a public health level is going to take a lot of interventions from a lot of directions. And one of those is sodium in our food system.

Michael: Although after the show comes out, everyone is swapping soy sauce for Baconators. [Aubrey laughs] Everyone's doing it.

Aubrey: For your health. [Michael laughs]

[music]