This is a transcript of the Gastropod episode, Omega 1-2-3, first released on August 13. It is provided as a courtesy and may contain errors.

PAUL GREENBERG: It was a little bit of a grueling thing. It’s funny. I was—I never went out on a Jet Ski as a younger person, and I was, I think, 47 when I started on this on this book. So you know it turns out riding a Jet Ski is not a lot of fun, if you’re 47.

NICOLA TWILLEY: The Jet Ski mounted hero of today’s episode is… 47-year-old Paul Greenberg.

CYNTHIA GRABER: Well, he’s not 47 anymore. That was when he started the book, so he’s a few years past that now.

TWILLEY: Like us all, he’s getting older. And that, actually, is what led him to the topic of his book.
GREENBERG: I did start this book in, you know, in the throes of kind of a panic about middle age. And when you Google all the things that are going wrong with you in middle age—your joints hurt, your blood pressure is going up, losing your memory—and you Google solutions for this, you know, what comes up again and again are Omega-3 supplements. So it struck me as a way, a lens for looking at the Omega-3 was to look at it through the lens of the sort of panic that you that you get in middle age around all these things.

TWILLEY: This episode is not about the panic.

GRABER: It’s about the Omega-3s. In fact Paul’s book is called The Omega Principle. Omega-3s have come up in our reporting this year, you might remember we talked about how important these fats are in our Alzheimer’s episode. But what are Omega-3s?

TWILLEY: And why is everyone from Dr. Oz to the American Heart Association telling us to eat more of them? Is there any science behind the idea that Omega-3s are miracle molecules?

GRABER: You’ve probably heard that there are Omega-3s in oily fish like salmon, but what about the pills you can buy at the drug store? Where does the Omega-3s in those come from?

TWILLEY: And what is this Omega-3 boom doing to our oceans, not just our bodies?

GRABER: All that, plus some adorable and mischievous sea lions. But first, we have some really exciting news: we are turning five! Next month!

TWILLEY: I know, we don’t look it. Or even act it sometimes. But it’s true. And five in podcast years is like… I don’t even know. It’s impressive. And we want to celebrate!

GRABER: But we need your help to do it! We’re planning a special birthday episode for September—yes, there will be birthday cake, at least the story of birthday cake—but the episode will be built on your votes.

TWILLEY: That’s right, we need your help to plan the perfect birthday party episode. We want you to vote for your favorite episodes from our first five years, so we can revisit the top ten in our birthday show! We have a link to our voting form on our website.

GRABER: We can’t make this special episode without you, so go vote! You have until August 23 to vote!

TWILLEY: Okay, we’re about to get back to this episode—which was made possible thanks to generous support from the Alfred P. Sloan Foundation for the Public Understanding of Science, Technology, and Economics, as well as the Burroughs Wellcome Fund for our coverage of biomedical research.

PRE-ROLL

TWILLEY: So 47-year-old Paul is on a Jet Ski with his guide, Jet Ski Brian.

GREENBERG: And so I told him I didn’t really want to go fishing. I wanted to actually watch this company called Omega Protein fish for menhaden.

TWILLEY: Paul was on his Jet Ski, in the Chesapeake Bay, watching this big blue ship scoop up these tiny silvery fish called menhaden. The company that owns the ship— Omega Protein—it’s actually the largest processor of menhaden in the U.S..

GRABER: Paul watched the mother ship lower little aluminum baby ships into the water. The boats circled the school of thousands of menhaden, and they scooped them together with a net.

TWILLEY: The ocean went frothy as the little fish thrashed around in the net, and Paul said suddenly the air smelled like watermelon—apparently that’s what menhaden smell like, although I wouldn’t know because I’ve never eaten one.

GRABER: Me neither, and probably none of you listeners have either. Because none of these oily menhaden get eaten—they’re being converted into things like fish meal and fish oil—fish meal to feed animals. And fish oil for Omega-3 supplements.

TWILLEY: So what are these magical Omega-3 things?

GREENBERG: Omega-3 fatty acids are polyunsaturated fat fatty acids. You know you can go wheels within wheels to get more and more deeply exactly what that means, but basically what it means is that they have a double bond at the tail end of their structure between two carbon atoms. And that makes them much more sort of dynamic and flexible.

GRABER: And that flexibility of these Omega-3 fatty acids is awesome for fish that swim fast in cold waters. But these types of fats first evolved not to help with swimming but to turn sunlight into energy. They played a key role in photosynthesis in the very earliest and simplest microscopic creatures that swam in the oceans.

TWILLEY: These little phytoplankton guys, they’re like tiny, super-basic algae. They only did one thing, which was photosynthesize. And they were making Omega-3s to grease the wheels of their sunlight harvesting machinery. And they got really good at it. They harvested so much sunlight and breathed in so much carbon dioxide that they completely changed Earth’s climate.

GREENBERG: But not the climate change we are all obsessed with. But climate change going in the other direction. So back in the days of the early Earth, we had a atmosphere that was very soaked in carbon dioxide.

GRABER: As you might have heard, carbon dioxide in the atmosphere keeps things pretty hot. So then when those phytoplankton used a lot of carbon dioxide, the atmosphere got colder. Pretty dramatically colder.

TWILLEY: Which fortunately the little phytoplankton could adapt thanks to … our heroes, the Omega-3s.

GREENBERG: It turns out that having Omega-3 fatty acids in your membranes makes your membranes more pliable and more dynamic at colder temperatures.

GRABER: One important thing about Omega-3s is that they come in different flavors. There’s the one used in photosynthesis called ALA, and it’s still around in leafy green plants today. And then there’s one called DHA. The early sea creatures turned their ALA into DHA to make them cold-water powerhouses.

GREENBERG: And that’s basically it was used for. But you know as evolution goes of course whatever things were originally designed for gets repurposed and reconfigured for other purposes further down the line.

TWILLEY: The first phytoplankton were photosynthetic, but if you have a system for gathering light, it’s just a few short evolutionary steps to having a system for sensing light. Aka the eye. And these plankton with eyes became hunters—they started eating the eyeless photosynthetic plankton to get their energy.

GRABER: And then at some point in evolutionary history, those hunter plankton didn’t bother making Omega-3 fatty acids themselves anymore. They just ate them.

TWILLEY: Those Omega-3s—specifically the DHA variety—they still play an essential role in the parts of the eye that pick up light. For all animals with eyes, including us. We couldn’t see without Omega-3s.

GREENBERG: What I found throughout looking at Omega-3s was it’s kind of the Forrest Gump molecule.

GRABER: First of all, Omega-3s are everywhere in the plant world, because they’re critical for photosynthesis. Omega-3s are literally the most abundant fat on earth. And then, as we just said, they’re critical in all animal’s eyes for the same light sensing reason.

TWILLEY: Basically, they’re so bendy and flexible that they’re super useful anywhere you want to be dynamic and mobile—anything that has to move fast or transmit signals fast.

GRABER: Moving fast—so remember those tiny watermelon-scented menhaden? They have to swim super fast in cold water. And so they are super oily and packed with Omega-3s. And another tiny creature that has to swim really fast? Sperm. Also full of oily Omega-3s.

TWILLEY: Other places you might find this Forest Gump molecule are the heart—depending on your blood pressure, that’s moving pretty fast. Also, hummingbirds. Their wings have to beat 52 times per second and so those muscles are crammed with Omega-3s.

GRABER: Another weird place you can find Omega-3s: in the hooves of the caribou that roam the frozen tundra. The fact that Omega-3s stay flexible in the cold helps keep the caribou’s blood circulating even when their hooves are marching through the super cold permafrost of the Arctic.

TWILLEY: But the tissue with the largest amount of Omega-3s is your brain! Your brain isn’t moving, but all the cells in it are sending signals really fast, so they need to be bendy and flexible too.

GRABER: In fact, a few decades ago, a scientist named Michael Crawford got interested in the relationship between Omega-3s and our brains.

GREENBERG: Yes, so Michael Crawford, he was based in Africa and he did some initial look—sort of looking at comparative analysis of different brains. And I think he looked at 40 different mammalian brains and what he found was that the size of your brain was directly dependent on the amount of DHA Omega-3 fatty acid that was available. So that, you know, sort of leading to this conclusion later on that Omega-3s, DHA Omega-3 fatty acids were an essential part of the human brain.

GRABER: As I said before, those earliest hunters with the earliest eyes, they didn’t bother making Omega-3s, even though they needed them, because they could just eat them. And we’re the same way. We eat all the Omega-3s we need, either from green plants or really mostly from oily fish that eat those plankton to power their cold-water-tolerant bendy muscles.

TWILLEY: There are so many freaking phytoplankton making Omega-3s—I mean, literally, there’s one species of phytoplankton alone that is the most abundant species on earth. So although almost all animals need Omega-3s, pretty much none of them actually bother making them.

GRABER: Omega-3s are the fats everyone is obsessed with, and you can see why—we need them to think. And to see. But they aren’t the only Omega fats out there. Any plants that can photosynthesize can make Omegas—and not just Omega-3s.

GREENBERG: So there are Omega-6s, there are Omega-9s. Omega-12s. There’s all sorts of Omegas.

TWILLEY: You’ve probably heard of Omega-6s, they’re not as famous as Omega-3s, they’re like the less well-known, less desirable sibling.

GREENBERG: Organisms that use Omega-6s as their primary fatty acid tend to be more rigid. Because the Omega-6 itself is a much more rigid structure. So when we look at things like corn and soy, particularly corn oil and soy oil, they tend to have a nutritional profile that leans towards Omega-6. And in fact many things on land are going to tend towards Omega-6 because, well, they need to stand upright.

GRABER: Omega-6s are also actually a critical part of our diets. We’d die without them. They’re in seeds and seed oils—corn oil, sunflower and safflower and soy oil, sunflower seeds, pumpkin seeds.

TWILLEY: And even though they’re essential, they get a bad rap these days. Which we’ll come back to.

GRABER: Yes, we are going to come back to the relationship between these fatty acids and our health—but overall, it’s clear that these fatty acids are found in so many parts of our bodies and that they’re essential to our existence. But how did we figure that out?

TWILLEY: The answer involves rats with dandruff, Spam, and a Baptist scientist.

GRABER: This story starts back in the 1800s. That’s when scientists first really started to figure out what it was in food that was good for us.

GREENBERG: So you had the 19th century, which was all about the discovery of vitamins and minerals, right? And we kind of went through that whole thing.

TWILLEY: We talked about that whole thing in our vitamin episode—this complete shift in our understanding of what food was doing for us and our health.

GREENBERG: And into the 20th century, you know, medical research was always looking for new angles and people started to wonder did fat have any kind of nutritional quality to it.

TWILLEY: Back then, everyone knew fat was a great source of energy, in the form of calories. But no one realized fat was essential—like, you’d die without fat.

GRABER: Until George and Mildred Burr came along in the 1920s.

GREENBERG: These two scientists, the Burrs, a husband and wife team that did these deprivation experiments with rats where they deprived them of fat and then saw that when they didn’t have fat they actually wasted away and had all these other physiological problems.

GRABER: The rats looked pretty bad without any fat in their diet. They had dandruff and scaly skin. Their tails swelled and got ridges. They had no fur around their faces. And then they died.

TWILLEY: But if the Burrs gave them just three drops of lard before it was too late, they recovered! Pigs eat everything, some of those things have Omegas in them, and so lard has some Omega-3s and 6s in it. Not that anyone knew an Omega from Adam at the time. Omegas hadn’t yet been discovered. No one knew which of the chemicals in fats was saving the rats’ lives.

GREENBERG: So it was established that fats were important. But then what kinds of fats? And then a lot of sort of deepening research happened in the 50s, 60s, and 70s.

GRABER: Ralph Holman is the guy who discovered the Omegas. George Burr was his thesis advisor.

TWILLEY: George and Mildred Burr did their rat fat deprivation study and then they quit and moved to Hawaii to study pineapples. And Ralph Holman picked up the fat torch.

GREENBERG: He used to work for the Hormel company that was, you know, worked on Spam and so forth.

GRABER: All the different fatty foods and oils you might find in your kitchen have a combination of different fatty acids in them. Like lard, which is mostly an animal fat you’ve heard of called saturated fat, but it also has these Omega unsaturated fats. And some of those different types of fatty acids go rancid more quickly than others. Hormel wanted Ralph Holman to figure out which fats went bad, so the company’s Spam wouldn’t go bad.

TWILLEY: So Ralph did experiments to figure out what all these different fatty acids are. Which meant he was the one who discovered Omegas. And got to name them.

GREENBERG: But he was a Baptist growing up and he knew his Bible really well and he came up with the nomenclature and decided to call it Omega-3. Because there’s a line, I think, in Revelations. I am the Alpha and the Omega, the first and the last, et cetera, et cetera.

TWILLEY: In the Greek alphabet, Alpha is the first letter, and Omega is the last. It’s at the end. And that’s also where the distinguishing feature of these special fats is—the chemical structure that makes them so bendy and pliable.

GREENBERG: So if you count three carbon atoms in from the end, that’s where you’ll find your first double bond. So that’s why it’s called the Omega-3.

TWILLEY: And if the first double bond is six carbon atoms in—well, you’re looking at an Omega-6. And so on. Omega-3s just have more double bonds all along their length.

GRABER: These double bonds are what make them so flexible. But these bonds also react really easily with oxygen, and that makes them turn rancid super quickly. Ralph’s discovery was useful to Hormel—eventually scientists figured out how to get rid of those Omega-3s in processed foods to make them more shelf-stable.

TWILLEY: So at this point in history, thanks to George, Mildred, and Ralph—

GRABER: And Spam

TWILLEY: —all thanks to spam—so at this point, we’ve identified Omega-3s, we know that rats will develop dandruff and die without fat, but we don’t know what those fats are doing that is so essential. Meanwhile, scientists have started connecting animal fat and cholesterol to heart disease.

GREENBERG: And so there were these two doctors named Bang and Dyerberg who went to Greenland in the early 1970s

GRABER: Olaf Bang and Jorn Dyerberg went to Greenland because the Inuit there seemed like a paradox. They ate a lot of meat, mostly from seals, and a lot of fat. At the time, meat and saturated animal fat were thought to be the main cause of heart disease—but the Inuit had really low levels of heart disease. So Bang and Dyerberg tested their blood.

GREENBERG: And they were the ones who discovered that Inuit populations there had very, very high levels of Omega-3 fatty acids in their blood. They also had a diet that consisted primarily of marine mammals and fish.

TWILLEY: While Bang and Dyerberg were doing their Greenland thing, Michael Crawford was doing his brain measuring thing. And suddenly Omega-3s were the hot new molecule on the block.

GREENBERG: It all kind of sort of smushed together. I think the very first dietary supplements that we started to see—Omega-3 dietary supplements—were really kind of like early 80s.

GRABER: These might have been the first supplements with the words ‘Omega-3’ on the label, but they certainly weren’t the first time we used fish oil as medicine. Which we are going to tell you all about.

MID-ROLL

GREENBERG: Yeah. So garum might just be the world’s first Omega-3 dietary supplement. It was an ancient fish sauce that seems to have come possibly from the Phoenicians, although we don’t know, I wasn’t there.

TWILLEY: The theory is that this fish sauce made its way from the Phoenicians through the Greeks and eventually to the Romans.

GREENBERG: What we do know for sure is that the Romans absolutely loved it. And, in fact, if you go to Pompei, if you were to try and reconstruct what Roman civilization was built around based upon what you found in Pompei, you would conclude that it was primarily a fish-sauce manufacturing country or empire. Because that there were so many vessels of this fish sauce called garum found everywhere.

GRABER: To make garum, ancient Romans took whole anchovies or mackerel, guts, heads and all. They mixed the fish with a lot of salt. And then they let the whole mess rot in the sun for months. They’d stir it occasionally, some people would add some wine. And, at the end, they’d funnel off the resulting liquid.

GREENBERG: Romans used it as a condiment. It was found in ancient recipes. It’s more common than salt in the recipes. So it was very salty so it provided that aspect to it. But it had a certain kind of stinky, umami-ish thing that it gave to food.

TWILLEY: Sounds delicious! But garum was more than just fish sauce. It was a supplement. Romans poured it down the noses of sick animals, they took it as a laxative, but also to cure chronic diarrhea, they believed it could restore a lost appetite, and treat everything from tuberculosis to migraine headaches.

GREENBERG: People used it as a curative as well for sciatica. Some people thought it could cure an upset stomach. People associated with with amorous qualities as well.

GRABER: It was a big deal. Romans brought their garum with them everywhere. Turns out, they might have been on to something.

GREENBERG: Recently some Spanish food scientists recreated, reconstructed how you would have made garum. They did that and then they sort of tested it for its nutritional qualities and it had a number of very useful nutrients including being very high in Omega-3 fatty acids.

GRABER: You might never have heard of garum, that’s kind of ancient history. But you might have heard of something that was used for a lot of the same health benefits, and that’s cod liver oil.

TWILLEY: Or maybe not, because, if you remember taking cod liver oil, you are pretty much an archaeological specimen yourself.

GREENBERG: Cod liver oil is sort of an interesting case because—so those who are a little bit older might remember a day when they didn’t know exactly what Omega-3 was but they did take cod liver oil. Cod liver oil is actually very high in Omega-3s. And the reason—so cod themselves, if you eat a fillet of cod, it’s actually not particularly Omega-3 rich or particularly oily. Cod tend to store their oil in their liver. And one of the reasons they do that is because it allows them to shuttle the Omega-3s over to their gonads when it’s time for reproduction.

TWILLEY: And just like human testicles, cod balls require plenty of Omega-3s to do their sexy thing.

GRABER: So we humans have been taking Omega-3 supplements in fish oil for thousands of years actually, if you consider the history of people swallowing some garum or cod liver oil to help with various ailments. They didn’t know those were Omega-3s. The people buying supplements today, though, they certainly do.

GREENBERG: Ralph Holman went to the store—this guy who had named them the Omega-3 fatty acids—went to a store and saw a jar of supplement—of fish oil—and it said “Omega-3s are here!” And he bought it. And he was so excited!

TWILLEY: Today, Paul says that Omega-3s supplements are a $15 billion industry—an industry that is still growing at seven percent each year. Omega-3s are also one of the world’s most profitable supplements. After all, they’re supposed to help with diseases of aging—heart disease, dementia, cancer, even—and the West is clogged up with all these boomers right now, who don’t want to go quietly into the night.

GRABER: But as a big a market as those aging boomers are for the supplement industry—and it’s a huge, huge market—it’s actually not the biggest market for these tiny fish. Today, oily fish, full of Omega-3s, are a super important ingredient in animal feed.

GREENBERG: And this is really the key, the killer app, so to speak, for little fish. First they started feeding all these little fish to chickens. Then they fed them to pigs.

TWILLEY: What happens is, in industrial hog production, piglets are not allowed to nurse for very long, so they don’t get enough Omega-3 fatty acids from their mothers milk. So the farmers have to add Omega-3s to pig infant formula.

GRABER: And this means that fish oil and fish powder have gone industrial. Chicken feed, pig feed. And actually it’s a major ingredient in cat food, too. And so a lot of the fish caught in the world are not eaten as fish.

GREENBERG: Yeah, a lot. It’s something like 20 to 25 million metric tons a year, which is, you know, around close to a quarter of all the fish that we catch is reduced. This completely invisible thing. And you know if you were to weigh that—you know, 25 million metric tons, what is that? That’s actually the equivalent of the human weight of the United States taken out of the sea every year.

GRABER: It is impossible to picture that, but, obviously, it’s a lot.

TWILLEY: Today, the biggest market for all those ground up tiny fish? Is: Other fish. Farmed fish.

GREENBERG: Because there are a lot of fish out there that just simply need Omega-3s. They just will die if they don’t get Omega-3s—salmon being one of them. So probably the global salmon industry is probably the biggest market right now for all these little fish.

GRABER: It’s not just that some animals can’t live without Omega-3s—salmon, for instance, and baby pigs. It’s also that other farmed fish, they grow faster when their diets are supplemented with fish meal.

TWILLEY: The little fish that are feeding all these bigger fish—for the most part, we’ve never heard of them. Like the menhaden that Paul Jet Skied out to see in the Chesapeake. Or like the Peruvian anchoveta.

GREENBERG: Which is the largest fishery in the world. Sometimes it’s been as much as more than 10 percent of the world catch.

GRABER: Paul traveled to Peru to see what a fish catch at this scale looks like. He sailed with a fisherman out into the turbulent Pacific at 2 AM.

GREENBERG: And I thought we were immediately going to go to the fishing grounds, but instead we stopped about an hour or two in and just waited. And I said why, why are we waiting? He’s like, well, we have to wait for the other boats. I’m like, you know that just goes totally contrary to everything a fisherman always thinks. You know, I want to be the first one out to the grounds.I was like, why? He’s like, well, you’ll see.

GRABER: So they wait. And then suddenly there are dozens and dozens of boats all around, all sailing together towards the same point.

GREENBERG: And I realized why we were doing this and the reason we were doing this is because there were so many sea lions that immediately got on the fishing nets that if you didn’t have a number of boats they would all congregate around one boat and eat basically eat your net to shreds. And what was really interesting about it was that you know you always see these sort of Greenpeace moments of like, oh, the poor sea lion who got caught accidentally. He was just minding his own business and he got scooped up by the net. But what was kind of crazy about this Peruvian situation—the sea lions totally knew the game.

TWILLEY: These sea lions were just lounging around, waiting for the humans to gather all the anchoveta together into a nice oily anchoveta ball. And then they would jump in the net.

GREENBERG: And they would just you know sit there and they would just eat and eat and eat and eat. And people would be shouting at them and they’d be like, they’d stick up their noses. Oh no, it’s too delicious here. I don’t want to leave! And eventually they would kind of harass them enough so they would leap over the net and get out.

GRABER: So it looks to Paul like a pretty healthy ecosystem. There are clearly a lot of fish out there, and the fishermen are all pulling in quite a hefty haul.

TWILLEY: In both Peru and in the Chesapeake—there seem to be shedloads of tiny fish, even though these companies scoop out so much.

GREENBERG: Everybody will say that their industry is totally sustainable, that they’ve—you know, they used to be overfished but now they’ve really worked it out and da da da. And granted a lot of these countries and regions and companies have made adjustments. But I always go back to the fact of what if 25 million metric tons of fish were still in the sea? What would the ocean look like if we had 25 million extra tons of prey, of food for whales, for birds, for the fish that we like to eat. And nobody could ever give me a clear answer on that.

TWILLEY: Paul’s point is, these little oily fish, they would normally be eaten by other sea creatures, or by seabirds, or they’d die and their nutrients would cycle around in the marine ecosystem. But now that food source is gone.

GRABER: And, frankly, any time we humans think there’s an endless supply of something, well, there isn’t. Hundreds of years ago, sailors said there was so much cod in the Atlantic they could practically walk across it. Then we fished nearly all of it.

TWILLEY: We talked about this in our counting fish episode—there are plenty of fishermen today who will still say there’s loads of cod in the ocean, even though there’s nowhere near as much as there used to be. It’s called a shifting baseline.

GREENBERG: And shifting baseline basically says that each successive generation has a diminished view of what it perceives as abundant in nature. Like the example of codfish: if I go out nowadays out of Long Island and I catch five codfish, I’ll think that I would have had a fantastic day. My father, if he goes out, if he catches five codfish, will think it’s a miserable day. And my grandfather, if he’d gone out, would think like what the heck has gone wrong in the universe that you could only catch five codfish.

TWILLEY: In other words, we don’t really know the environmental impact of our hunger for Omega-3s. But it’s a safe bet that there is one, and it isn’t great.

GRABER: But doctors and scientist are telling us to eat seafood, salmon in particular, and a lot of them are also suggesting Omega-3 fish oil pills. And both of those things are exactly what the Peruvian anchovetas are getting turned into. So maybe it’s worth it?

TWILLEY: Only if Omega-3s are doing all the miraculous things people claim they’re doing. Which, it turns out, scientists do have something to say about.

MID-ROLL

JOANN MANSON: The interest in Omega-3s has waxed and waned over the decades.

TWILLEY: This is JoAnn Manson—she’s an epidemiologist at Harvard Medical School.

MANSON: Interestingly, about 30-40 years ago, there was tremendous interest in Omega-3s in having a role reducing cardiovascular disease.

GRABER: This is the time that people were concerned about animal fats and heart health, and Bang and Dyerberg saw that the Inuit were doing well with their Omega-3 rich diet of seals and fish, so maybe Omega-3 pills would help the rest of us.

MANSON: And some of the randomized trials of Omega-3s that were done in the 1980s, 1990s looked promising. But then more recent trials were actually disappointing.

GRABER: There was a big study last year that looked at other studies—it’s called a meta analysis. And it showed that there was actually no heart benefit from taking Omega-3 fatty acid supplements.

MANSON: And that led to a lot of discouragement about Omega-3s.

TWILLEY: But JoAnn says the problem was that there were problems with a lot of these earlier studies.

MANSON: So the randomized trials of Omega-3s have included some trials with lower doses that may not be adequate dosing. Some trials that were short duration, even less than a year, or only one to two years. It’s been a mixed bag.

GRABER: Those earlier studies were also done on patients who already had heart disease, or had suffered from a stroke, or they had diabetes—they basically already had health issues. Which meant they weren’t necessarily a great test of whether Omega-3 supplements would help the general public.

TWILLEY: So JoAnn set up a trial of her own.

MANSON: Well, very surprisingly, the Vitamin D and Omega-3 trial, VITAL, was the first large scale randomized clinical trial of Omega-3s in a true usual risk population.

GRABER: JoAnn’s trial was called VITAL, and it was a fully randomized, double blinded trial. That meant some of the participants took a supplement, and some took a placebo, and none of the doctors knew which was which.

TWILLEY: There were more than 25,000 participants, all over fifty years old.

MANSON: But they were just all comers. Some of them did have hypertension or diabetes as you would have in the usual population but they were generally healthy.

TWILLEY: The folks in the trial who were getting the fish oil supplement got a gram of Omega-3s a day, the others took their placebo, and then JoAnn sat back and waited—for more than five years—to see what happened to everyone.

GRABER: JoAnn told us that if you look at how many people in the trial ended up having a heart attack or a stroke, well, the Omega-3s didn’t make a difference. But that changed if you took strokes out of the equation.

MANSON: We saw a reduction in fatal heart attack, about a 50% reduction there. So we did see significant reductions in coronary heart disease related events. We saw no reduction in stroke.

GRABER: Okay, no reduction in strokes, but the reduction in fatal heart attacks is intriguing.

TWILLEY: Where it gets really intriguing is in the differences between different participants. People who ate less than one and half servings of fish a week—so they weren’t getting a lot of Omega-3s in their normal diet—those people, if they got the Omega-3 supplement, a statistically significant percentage of them had a reduction in heart disease overall, even including stroke.

GRABER: In comparison, people who did eat fish did not see a reduction in heart disease from taking the supplement. But here’s an important thing to know: the percentage difference might look dramatic, but the numbers are really, really small. For instance, of the more than 13,000 people who didn’t eat a lot of fish, the difference in who ended up with heart disease and who didn’t was only about 40 people.

TWILLEY: Obviously if you’re one of those 40 people who didn’t get heart disease, that’s great, but 40 people out of 13,000 is not nearly the huge impact it might sound like if you just hear the percentage reduction. But it is statistically significant evidence for the benefit of Omega-3s.

GRABER: And there was another subgroup that seemed to benefit more than others from the supplement.

MANSON: We had very dramatic reductions in the risk of heart attack among the African-Americans with the Omega-3s. They actually had a 77 percent reduction in the risk of having a first heart attack. Now this could be a chance finding. This needs to be replicated. Because if African-Americans are benefiting this much from Omega-3 supplementation, it’s really important to know that. And it could play a role in reducing health disparities.

GRABER: Once again, the actual numbers are super super small, so the results are promising, but, as JoAnn says, it could be chance. Plus, we also want to point out that even if there is a benefit from the supplements for African-Americans, it might have nothing at all to do with skin color.

TWILLEY: In general, African-Americans have lower incomes than white Americans, they have poorer access to health care, they tend to live in more polluted areas, and of course, not unrelated to all of those other factors, they’re subject to discrimination and racism.

MANSON: So our findings in African-Americans could be due to a number of factors. One possible explanation is increased stress and even increased exposure to air pollution and some environmental risk factors where the Omega-3s have been implicated in having benefits.

TWILLEY: Right now, the only results JoAnn has from her VITAL trial are to do with heart health. But taking Omega-3s is supposed to have lots of other wonderful benefits, and the trial is looking at them too

MANSON: We’re looking at cognitive function, mood depression, risk of Type 2 diabetes, autoimmune conditions, and a number of other health outcomes. We’re still in the process of doing the data analysis. But stay tuned. We will have results from many of these other studies within the next three to six months.

GRABER: There’s plenty more research ahead, both for JoAnn and for other scientists who are looking at Omega-3s and health. These findings have to be confirmed by other scientists. And there are a lot of questions: how much Omega-3 do we need? Is more better?

TWILLEY: But JoAnn’s study, which is just one study but is a really solid study, makes it seem as though Omega-3 supplements are beneficial for some folks. But assuming other scientists replicate these findings—does that mean people who would benefit from more Omega-3 should get those Omega-3s in pill form?

GRABER: In JoAnn’s study, she had to deliver those Omega-3s in capsules. Otherwise it’d be pretty obvious who was getting the Omega-3 and who had a placebo—some people would be eating a lot of mackerel and salmon and sardines, and some, well, they wouldn’t.

TWILLEY: But outside the constraints of a scientific study, is consuming your Omega-3s as a pill really the way to go?

MANSON: So, I’m glad you asked this question because I think the primary recommendation is to try to increase consumption of fish and not to jump to popping a pill.

GRABER: JoAnn says it’s not clear whether there’s really a difference between the two, but she says that one of the benefits of eating your Omega-3s in fish and not in a pill is that eating fish might be taking the place of eating something that’s not quite as good for you.

MANSON: So if you’re having fish more frequently you may end up having red meat, saturated fat, processed foods less frequently and you’re replacing them with a food that’s more healthful.

GREENBERG: The other issue is that the human body has evolved to incorporate nutrients based on food. And a lipid taken out of context of other lipids, and just sort of just a shot of lipid right there in the morning when people are most likely to probably take their supplement, seems to me maybe out of sync with what the body is able to deal with.

TWILLEY: What’s more, as regular Gastropod listeners know, all supplements are not created equal. Because there’s no real federal oversight of the supplement business, some are pure Omega-3 goodness. And some are not.

GREENBERG: The companies that are making supplements are making them from fish that weren’t necessarily refrigerated upon capture. Omega-3s are very dynamic compounds and they will oxidize very quickly and if they oxidize then they’re not really going to provide the health benefit that we’re looking for.

GRABER: The oils turn rancid, and when they’re rancid, they’re just not good for you any more.

MANSON: So it’s important to look on the label for some of the signs of quality control. The seals of U.S. Pharmacopeia, USP, and NSF. Various ways that you can tell that there’s some external audit going on for quality control.

TWILLEY: OK, but if you do find a good quality supplement— should you be taking it? Should we all be popping Omega-3s, just as back up?

MANSON: So our advice at this point would be not for the entire population to start taking a Omega-3 fish oil supplement because we really are not seeing overall widespread benefits.

TWILLEY: So fish is best. But do I have to eat those watermelon-smelling menhaden or what?

GRABER: Well, not necessarily menhaden—but yeah, different fish have different amounts of Omega-3s. As we said earlier, fish that swim really quickly in cold water have a lot of Omega-3s. You’ve heard of these fatty fish: herring and anchovies and sardines and mackerel and salmon and sablefish, otherwise known as Pacific black cod. Not the cod most people eat from the Atlantic.

TWILLEY: The problem with normal cod and other white fish—haddock, tilapia, flounder, grouper—is that they just don’t get enough exercise. Cod don’t swim for miles and miles and miles, like mackerel do.

GREENBERG: It’ll have a quick lunge but then most of the time it’s kind of a lazy kind of fish. So it’s not so essential to have these hard swimming oils in their bodies.

GRABER: If you’re only eating cod and haddock, you are probably not getting enough Omega-3s in your diet.

TWILLEY: But this question of enough—this is where it gets complicated.

GREENBERG: You know if you’re just talking to your family physician, a lot of physicians will say something like you know 500 milligrams a day. And you can kind of hit that amount if you have, I think it was like something like four anchovies a day. So like you know 8 little fillets of anchovies, which is really not a lot.

GRABER: But if your family physician does say this, well, it’s not actually based on settled science. We don’t know how much we need of these Omega-3s. And there’s another thing that makes this question even more complicated—

TWILLEY: So here’s the thing. We told you we outsource production of Omegas—we just eat them. And we also told you that the Omega-3s used in photosynthesis, the ALAs—that they are the most abundant fat in the world. And then we told you that our brains and our hearts need the other kind of Omega-3s, the marine kind.

GRABER: There’s some good news here—we can actually make that marine kind, in our bodies, from ALA from plants! We can convert the plant Omega-3 from flax seeds and chia seeds and leafy greens—we can convert it into the marine Omega-3 that our brains and our hearts need.

TWILLEY: But can we make enough? No one is sure. And part of the reason no one is sure is because it’s possible that the specific amount matters less than the ratio.

GRABER: Yes, the ratio. Specifically the ratio of Omega-6 to Omega-3. Remember, Omega-6s are in corn and soy, basically in seed oils. Omega-6s are critical, but some scientists think we shouldn’t have too much of them.

GREENBERG: Omega-6s interfere with the body’s ability to elongate short chain Omega-3 fatty acids that we’re getting from leafy greens and so forth. And they also seem to lead to the production of inflammatory compounds.

TWILLEY: And here’s why. Your body uses whichever Omega happens to be handy in order to build all the things it needs to be bendy and flexible, like cell membranes. Omega-3s are the bendiest and most supple of all, but, if Omega-6s are what’s most available, that’s what your body will use.

GRABER: Scientists think that if your cell membranes are made of Omega-6s rather than 3s, they’re not as flexible, and the communication between cells doesn’t work as well.

TWILLEY: And the movement of other chemicals around your body— it’s less fluid and more explosive because the cell membranes are a little stiffer. And some scientists think that more explosive movement is more stressful for your body and can cause inflammation. Which is bad.

GRABER: Right. And, one final point here, food technologists have gotten rid of as much Omega-3 as possible in processed food because it turns rancid quickly, as we told you. Omega-6 doesn’t go bad quite as fast. And corn and soy are so cheap. So our processed food world is full of Omega-6s, far, far more than we would have eaten in the past.

TWILLEY: So are our industrially produced animal products, because cows and pigs and chickens are fed corn and soy rather than grass and bugs and stuff.

GREENBERG: Terrestrial meats that are fed a feedlot diet will have an Omega-6 ratio far in excess of what we think probably Neolithic humans might have had in their own blood.

GRABER: This is all a hypothesis. Nobody has proven this ratio question—in fact, when we asked JoAnn about it, she didn’t even want to touch it.

TWILLEY: The basic mechanisms makes sense, biologically. The idea that the ratio of Omega-6 to Omega-3 in our diet has changed over time, and so has the incidence of all kinds of heart disease and other industrial world health problems—that’s based on observational evidence. But overall, it’s still an argument, not a fact. JoAnn agrees—there’s still huge gaps in our understanding when it comes to Omegas and health.

GRABER: But at the end of the day, whether or not the ratio matters, it’s not a bad idea to add more oily fish to your diet. Fish like mackerel, sardines, herring, salmon.

TWILLEY: Farmed salmon is actually often a little higher in Omega-3s than its wild counterpart. But it’s being fed anchoveta. And Paul says that’s not a good use of anchoveta.

GREENBERG: And you know the people who argue for the Peruvian anchoveta industry doing what it’s doing say, well, I mean, there’s nothing wrong with it. We’re still making human food. We’re just making these pellets that we’re sending to Norway so they can feed salmon. We’re just transforming it. I don’t know if I buy that argument. I think that, you know, a lot is lost in the process and we could probably do a lot better.

TWILLEY: What’s lost is that pound for pound, you are getting less food at the end by feeding the small fish to the big fish, than if you just ate the small fish. So it’s a waste. Not to mention the energy you use to reduce the small fish into pellets and ship them around the world.

GRABER: So it’s not really a great idea to feed the anchoveta to salmon instead of just eating those anchoveta directly—which Paul says taste exactly like anchovies.

TWILLEY: Or just leaving more in the oceans for all the other sea creatures.

GRABER: But Paul says maybe there is a better way to feed salmon and to make supplement oil—

TWILLEY: A way that is in fact how Omega-3s are created in the first place. By tiny microscopic phytoplankton, basically algae. I mean, why not cut out the middlemen?

GREENBERG: Why kill hundreds of millions of billions of fish every year to reduce into the supplement, when you could grow them using algae which would actually sequester carbon and do all these other kinds of things in the process.

GRABER: This is actually something that people are working on—they’re growing algae and harvesting Omega-3s. You can find algae-based Omega-3 fatty acids in supplements at the stores. But they’re really expensive right now. So they’re not being used as salmon feed.

TWILLEY: But hopefully that’ll change in the future. If farmed fish were being fed algae-based Omega-3—well, Paul says, that would be a game changer for the planet.

GREENBERG: So you know I think there are a lot of people out there who like never want to eat a farmed fish. And they think that they’ve heard all these bad things about about aquaculture. But what I realized was that we could conceivably produce fish and shellfish at a fraction of what—using the fraction amount of carbon and a fraction of the energy and just generally have this source of protein that was much greener.

GRABER: This is a change for a fish guy like Paul. He’s spent most of his life and career as a writer focusing on wild fish, but as he wrote this book, he came around to a new idea. Maybe it’s a better idea is to grow algae on land and use those algal Omega-3s to feed farmed fish. And leave more wild fish in the ocean.

TWILLEY: Maybe by growing marine Omega-3s on land, we can have our fish—farmed fish—and healthier oceans too.

GREENBERG: Interestingly, I started this book with this idea of trying to understand what the miracle supplement was. But I came away from it being like, huh, the sea and the products that we could get from the sea could completely reshape the way that we eat and make our footprint on the planet much much gentler.

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TWILLEY: But in the meantime, truly, my hot tip is to dissolve anchovies into all your sauces. It’s just salty umami deliciousness, no excess fishiness. Paul actually has even more recipes to help you love oily fish in his book, The Omega Principle, which we have a link to on our website.

GRABER: Thanks to Paul Greenberg this episode, and also to JoAnn Manson of Harvard University. And to the Sloan Foundation and the Burrows Wellcome Fund for supporting our science and health reporting.

TWILLEY: Do not forget to vote for your favorite episode for our birthday special. I cannot wait! I live for birthday cake.