Omega-3s and brain health: what the science really says | Dr. Bill Harris & Prof. Sarah Berry

Welcome to ZOE Science and Nutrition, where world leading scientists explain how their research can improve your health.
One in five people have a mental health condition. Millions are living with dementia. Brain health is rightly in the spotlight. These conditions are complex, and there's no single cause. But some scientists believe that one nutrient might play an important role. Omega-3s. For this episode, we're lucky to have the world's leading expert on omega-3s with us, right here in the studio, Dr. Bill Harris.
With over 300 papers published on the topic, he's professor in the Sanford School of Medicine at the University of South Dakota. And most recently, Bill has focused on the links between omega-3s and brain health. Bill is joined by Professor Sarah Berry, a world leader in large-scale human nutritional studies, a professor in nutrition at King's College London, and chief scientist here at ZOE. Today, we'll explore Bill's latest research on omega-3s and brain health, and provide simple tips to make sure you're consuming enough.
Bill, thanks for joining us today. Glad to be here. Thank you. And Sarah, it's great to have you as my co-host today. Pleasure. So Bill, we have this thing that we always do at the start of the show, which is a set of rapid-fire questions and answers that come in from our listeners. Now, we have one very strict rule, which is very hard for professors. You're allowed to say yes or no, or if you have to, a one-sentence answer. You're willing to give it a go? Let's try it. All right. Are the majority of people in the West deficient in omega-3? Yes. Are plant-based sources of omega-3 as good as animal sources? No. Is grass-fed beef high in omega-3? No. Are supplements the best way to get adequate amounts of omega-3?
They're an adequate way. I prefer food. Bill, could consuming adequate omega-3s reduce your dementia risk? Yes. And what's the biggest myth you've heard about omega-3s? That plant-based omega-3s are the same as fish-based omega-3. Love that one. I hear that all the time. And it's not true? That's a myth. Absolutely not true. I remember growing up that my parents always had fish oil supplements. And there was also a period that I was being told I should be eating lots of salmon. Then I feel I was told, well, that's not such a good idea. Now I'm just sort of confused about omega-3s. And I suspect there are a lot of listeners who are in the same situation that I'm in. And I understand that you just have some fascinating new research about how omega-3s might affect not just our heart health, but also our brain health, from mental health to dementia. But before we jump into how this affects our health, could we just start with what are these omega-3 fatty acids? Why are they essential? Why do we care? Why do we care? So omega-3 fatty acids are fatty acids typically found in fish oils. They're made primarily by these little single celled organisms in the ocean that convert sunlight and sugar into omega-3 fatty acids. And then the little fish eat the little cells. And then the big fish eat the little fish. And so salmon, for example, doesn't really make omega-3 any better than we do, but they eat it. So their levels are high because they eat a lot. Why are they essential? You know, sitting here with Sarah, I can't really say essential because EPA and DHA, which are the two omega-3s that are most important, that are in fish oils, fish and fish oils, are not actually essential in the diet, because strictly speaking, in a nutritionist's point of view, if you have an essential nutrient, if you don't eat it, you die. And there are plenty of people on this planet who are vegans, who eat no preformed EPA and DHA. They eat the precursor and that apparently gives them enough to survive, grow up, reproduce and live a life. So, I think of EPA and DHA Omega-3s as very bioactive, very important for health, but not essential for life. I've gone from Omega-3s and now you've already mentioned DHA and EPA. Could you just help me to understand that? Right, right. So Omega-3 is like a class, a family. If you look at the chemical structure of it, they all have a similar last name, so to speak, which is Omega-3. And then there are four or five fatty acids in that family. The three that we hear most about, one is called ALA, which is alpha-linolenic acid, which is a plant based Omega-3. And then it's grown up super cousins, are the two that we get in fish, which are called EPA and DHA. EPA and DHA are the two that are in fish. ALA is the one that's in plants. And those are the three major ones in the family. Why do they matter at all? You were saying they're not literally essential, so I can live without them, so they're not like vitamin C, I don't get scurvy. Correct, you don't get scurvy. But I get the sense that they are doing something of importance. They are important for many biological factors. They find their home and when we eat them, they end up getting into cell membranes. And all our cells have some, a little or a lot of omega-3, depending on really how much you eat. And I think the way I like to explain why they're useful, and it's a little difficult in some times because it's not like you can stay for vitamin C. If you don't have vitamin C, your teeth fall out. Okay, that's a problem. Omega-3 is more subtle, but as the omega-3s get into the cell membranes, they sort of act like grease on a hinge on a door. Because every cell has doors that let good things in, like nutrients, and the cell also has a door that opens up out to dump the trash. And if you've got enough omega-3 in your cell membranes, those doors swing smoothly. If you don't, they don't swing so smoothly, and some of the good stuff doesn't get in, some of the bad stuff doesn't get out as well, and the cell just gets older and unhealthy. So they sound quite important. They're important. They're important. And Bill, I'd love at this point to pick up on the myth that you said, which is about plant-based sources, because you've now talked about EPA, DHA, which are found in fish, and then ALA, the alpha-linolenic acid, which we know can come from plant sources. And lots of people say, well, you can get all the EPA and DHA you need from plant sources. But we know that actually how much you can convert is actually quite small. Quite small. And so I wonder if you could explain a little bit about that to listeners. Sure. There is a mechanism in the body, there are processes, that will take ALA, which is 18 carbons long. So fatty acids are simply a chain, a linear chain of carbon atoms. And this one's 18 carbons long. And it has three, what we call double bonds in chemistry. Many fatty acids have no double bonds. These have three double bonds. The EPA and DHA are 20 or 22 carbons long, and they have five and six double bonds. So in order to go from the ALA, which is 18 carbons and three, you gotta add two or four more carbons to the molecule, and you gotta add more double bonds. There's a lot of processing there, and it's difficult to do. The body is maybe 5% of the ALA you eat might get converted to EPA. And less than that goes on to DHA. So it's much more, if you really wanna increase your EPA and DHA levels, the important omega-3s, eating them preformed is the best way to do it. You don't have to make them. Yeah, and I think that's a really important point because lots of people, Jonathan, say, well, you can get all of your really good omega-3s, which is what Bill's been talking about, the EPA and DHA from plant sources, through this process in the body where it converts the ALA to these longer chain, more desaturated versions. But actually the conversion is really limited. And so it's interesting to hear, that it's estimated only around 5%. And so that's why as nutrition scientists, we always say, if you can get what we call preformed EPA and DHA, because our bodies are pretty rubbish at converting it. Can I just ask one clarification? Because you were describing the way that these omega-3s help my cells let things in and out better. And this is why it's like a more finely performing cell is how I was understanding. Sure. I think that's fair. It needs to be the EPA and DHA types of omega-3, not the ALA that was from plants. Is that what you're saying? That's correct. So if I eat all of this stuff from plants, it's got this ALA omega-3, but then my body, I'm thinking about some sort of refinement process, right? From crude oil to petrol. Like it's a lot of hard work to turn this then into these special forms of omega-3. Right. But if I were to eat them directly, then I don't need to do the refinement, and it goes straight to help bring me out. Yeah. A fair amount of the ALA we eat just gets burned like other fats. So it doesn't even get a chance to be converted into EPA and DHA in the liver, which is pretty much where that happens. So right away you're behind the eight ball because you're losing a lot of it just for energy. I like to do a little drum roll when announcing something exciting at ZOE. And that really exciting thing is that our plant-based gut supplement, Daily 30, is now available in the US. Daily 30 sold out in the UK when it launched, and now we're expecting it to sell out in the US too. 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