Dr. Michael Crawford: DHA and the Brain
OmegaMatters: Episode 11
Hosts: Drs. Bill Harris & Kristina Harris Jackson
Guest: Dr. Michael Crawford
Background and Key Takeaways: Dr. Michael Crawford has several decades of experience researching omega-3s, especially docosahexaenoic acid (DHA). In this episode, Dr. Crawford talks about how long DHA has been roaming the earth, why the placenta prefers DHA more than any other omega-3, how the brain recycles DHA, and how Dr. Crawford fortuitously met another great legend, Dr. Bang, in the 1960s, just prior to putting omega-3s on the map.
Dr. Kristina Harris Jackson: Hello. Welcome to Omega Matters. I’m Kristina. This is Bill. And today we are joined by one of the giants in omega-3 research Doctor Michael Crawford. He is a professor at the Imperial College London and the director of the Institute of Brain Chemistry and Human Nutrition. He’s had many major contributions to the field of nutrition and the brain over his long and productive career.
Dr. Kristina Harris Jackson: In 1972, he reported evidence that the brain required both arachidonic and docosahexaenoic acid, ARA and DHA, for growth, structure, and function, and now he focuses on why DHA specifically is required by the brain’s neuro-signaling to function and how to use this information to prevent and treat modern day neurodevelopmental disorders.
Dr. Kristina Harris Jackson: He has had an influential career as a scientist, author, and advocate for better nutrition for all through his work with the Mother and Child Foundation and the Little Foundation. He has received about every award possible in his field for good reason. And welcome Doctor Crawford to Omega Matters. Thank you so much for joining us.
Dr. Michael Crawford: Oh, thank you for all of that.
Dr. Kristina Harris Jackson: Is it about right?
Dr. Michael Crawford: Okay, let’s go! What do you want to know? (laughs)-
Dr. Kristina Harris Jackson: So let’s get into it. So we would like to know, we’re biologists, not quantum physicists, and we want know if you can explain exactly what DHA and arachidonic acid are doing in the brain in terms a biologist could understand. What are their main functions? Do they work together? Do they have separate roles? Can you paint a picture of that for us?
Dr. Michael Crawford: That a tall order. So let’s start at the beginning.
Dr. Bill Harris: Good.
Dr. Michael Crawford: So 600 million years ago sunlight was converted into carbohydrates and proteins and that’s about it by the anaerobic systems that lived on the planet. And when the oxygen tension rose as a result of the photolysis of water and, of course, the anaerobic photosynthesis been going on as well for a long time, and to make everything life possible, it all happened very quickly, it’s called the Cambrian Explosion, where all 32 phyla appeared on the planet almost instantly. Not quite instantly, but in this kind of time.
Dr. Michael Crawford: Anyway, one of the first things that happened was that instead of converting sunlight into carbohydrates and proteins, the early primitive lifeforms, like dinoflagellates as we have today, converted sunlight not into carbohydrates but into electricity. And we now know that they used docosahexaenoic acid (DHA) to do that.
Dr. Michael Crawford: If you’d analyze a dinoflagellate today, you’ll find there’s not only stuff full of DHA phosphoglycerides, but it also contains diDHA phosphoglycerides, the same material in your own eyeballs today.
Dr. Michael Crawford: So what happened was that it converted sunlight into electricity. And that, of course, sparked movement and it sparked the beginning of the nervous system, which eventually, of course, led to the brain. So DHA has been there since the very beginning of the signaling systems of the brain and it’s there today doing exactly the same thing. It’s also contributing to the flexibility of the membrane.
Dr. Michael Crawford: Arachidonic acid’s another story. I don’t think that we have the same kind of knowledge about arachidonic acid in the central nervous system as we have about DHA in terms of signaling, but arachidonic acid produces two things. First of all, it’s an important component of the inner cell membrane in particular. It’s responsible, to a large extent, for the fluidity of the membrane. It’s also quite important in things like the glial cells, which are looking after the maintenance of myelin and the neurons and so on and so forth, and so major contribution to the structure and function of the myelin of the glial cells.
Dr. Michael Crawford: And in so doing, it produces all these eicosanoids, these hormone-like substances that regulate cell function. So it has quite a different role to play in the brain compared to DHA, which is concerned with signaling of the phosphoglycerides in the photoreceptor, and it’s equally in high concentration, but not quite so much in the synapse and the neurons where it handles all the signaling systems. So that really, I think, sums it up.
Dr. Kristina Harris Jackson: That’s fantastic — to take it back to the beginning, that’s a great overview. So nowadays, there’s a lot of focus on omega-3s and the brain. And we know that we use omega-3 status, usually look at red blood cell omega-3 status to kinda represent tissue status in the body, but we know the brain is kinda different from all the other tissues. So to what extent do red blood cell tissue membrane levels reflect brain levels or is there another marker that reflects brain levels better than that?
Dr. Michael Crawford: So I’m not quite sure of the question.
Dr. Kristina Harris Jackson: Do we know how much DHA is in the brain by looking at blood levels of DHA?
Dr. Michael Crawford:
Oh, no I don’t think we can and Bill knows all about that. It’s interesting, because Tom Brenna has shown quite clearly that different proportions of arachidonic acid and DHA in different regions of the brain.
Dr. Michael Crawford: This is quite significant, actually, because we found in one of our studies with magnetic resonance that the supplements rich in DHA actually enhanced the development of certain regions, very specific regions, that are rich in docosahexaenoic acid, but not others. So it’s a region-specific phenomenon, same with arachidonic acid. It occurs in greater concentrations in some regions and less in others. And we are yet to really understand all that’s going on there.
Dr. Bill Harris: Right.
Dr. Kristina Harris Jackson: Was that in infants or was that in adults where you saw the different changes in the brain?
Dr. Michael Crawford: Well, the adult brain is not really much different from the young child’s brain. Most of the brain cells divide before we are born — 70% of them. And in fact, when you look at the early development of the brain, it’s fascinating because by the time a woman comes to us at Chelsea Westminster Hospital to report for pregnancy care, usually about 12 weeks, 12 or 13 weeks after conception, the brain cells that are all going to form the cortex and all the important things are already migrating to do so. So it’s a very early phenomenon in pregnancy and this has important implications, because it means, actually, that the period between conception and when the mother reports to us during the first trimester that there is hell of a lot of stuff happening. Really important stuff. Going from a fertilized egg to something that is identifiable as a human with a big brain is rapid, very fast.
Dr. Bill Harris: Something that comes up a lot is the importance of DHA and arachidonic acid, particularly during the conception and in utero, maybe the first couple of years.
Dr. Michael Crawford: Right.
Dr. Bill Harris: But can an adult, if they increase their DHA intake, can they affect their brain DHA levels?
Dr. Michael Crawford: I think there’s a simple answer to that: The answer is yes. The way the brain works is that it recycles stuff. Here we have an interesting thing, especially during the night. Rebuilding a lot of networks and things like that, refreshing them], in a sense.
Dr. Michael Crawford: But no recycling process is 100% efficient. So that means you’re losing DHA all the time. You’re probably losing arachidonic as well, although arachidonic acid is easier to replace. So, yes, the answer is that it’s important to keep up the pressure from decent levels of DHA in your circulation, so that the brain can pick up what it needs during this recycling process.
Dr. Michael Crawford: A very important thing is that you should always take a supplement, if you’re using supplements, before you go to sleep, because that’s when the most recycling of long-term memories and things like that is taking place.
Dr. Bill Harris: That’s interesting.
Dr. Kristina Harris Jackson: Taking it with dinner would be close enough?
Dr. Michael Crawford: Well, it depends when you have your dinner and when you go to sleep. It’s most likely too early to take them with dinner.
Dr. Kristina Harris Jackson: Oh, that’s interesting. You kind of brought this up in that DHA might be harder to come by than arachidonic acid. We’re almost philosophically wondering why DHA is so much more dependent on diet than arachidonic appears to be. Arachidonic acid seems to have more regulation in the body to maintain levels. Do you have thoughts on that?
Dr. Michael Crawford: Yeah, I think the answer is relatively simple. It comes in two packages. The first package is the biosynthesis to DHA and arachidonic acid. The biosynthesis of arachidonic acid put very simply, is so much easier. It’s only a couple of steps from linoleic acid, although, for both the first desaturation of linoleic and after the linoleic acid, afterwards is rate-limiting for both of them.
Dr. Michael Crawford: Now, so far as DHA is concerned, it’s a much longer path and it meets a hiccup round about getting to the immediate precursor, which is the 22 carbon with five double bonds. And that has to go through a high-energy process that our friend Howard Sprecher described years ago before it gets to DHA.
Dr. Michael Crawford: And if you look at the vegetarian animals herbivorous animals, they actually can make reasonable amounts of arachidonic, but when it comes to DHA, it pulls up at the 22 five and you get lots of 22 five, but only a small, tiny amount of DHA. That’s why they have such small brains, you see, compared to their body size.
Dr. Michael Crawford: Now very small mammals, like rats and guinea pigs, things of that size, have very fast metabolic rates, so they can make as much as they want and as much as they need for their size. And that’s interesting, because animals like squirrels have a ratio of brain to body size bigger than we have.
Dr. Michael Crawford: And what happens is that as protein deposition is accelerated when the body growth’s going faster and faster, so the lipids lose out and you get this inability to synthesize DHA with DPA, docosapentaenoic acid, up there, and DHA down there. So their brain size just plummets.
Dr. Michael Crawford: So that is another very powerful evolutionary argument for the necessity of preformed DHA in the diet. Not quite so much the same argument for arachidonic acid.
Dr. Bill Harris: Is there a role for EPA or DPA in the brain?
Dr. Michael Crawford: DPA is present but EPA, no. In fact, funnily enough, if you look at placental function, what happens is that the placenta concentrates arachidonic acid across the placenta for the fetus. And it concentrates DHA for the fetus, but it sucks back, or alternatively the fetus rejects linoleic acid, and it rejects EPA and DPA.
Dr. Kristina Harris Jackson: Really?
Dr. Michael Crawford: So, really, the fetus only takes up DHA.
Dr. Kristina Harris Jackson: Interesting.
Dr. Michael Crawford: There’s a lot of people who talk about biosynthesis of DHA and before birth, but it’s really academic, because there’s so little precursor that gets into the fetus. It’s always highly selected for DHA.
Dr. Kristina Harris Jackson: That’s very interesting. That kind of answers the question of: Can ALA provide the needs of DHA? Really thinking about vegans and vegetarians and how the, when they’re pregnant, how they can make enough DHA.
Dr. Michael Crawford: Well, the vegetarians have one great advantage — they don’t eat a lot of crap that we eat.
Dr. Michael Crawford: Fatty acids all compete with each other. So if you eat a huge amount of non-essential fat, you’re going to depress the ability to use the essential fats. And that goes right through.
Dr. Bill Harris: So I had another question for you. So you were studying DHA and arachidonic, in the early ’70s. When did the work of Dyerberg and Bang cross your radar?
Dr. Michael Crawford: Ah, do you really want to know that?
Dr. Kristina Harris Jackson: Yes.
Dr. Bill Harris: Because, obviously, they were in the cardiovascular space and you were in the brain side of things.
Dr. Michael Crawford: It was 1966, I was at a uh- doing some work with Professor Ernst Baroni in Uppsala in Sweden. And I knew nothing about any of this kind of stuff, but having just been working in Africa, I had recognized that the sort of modern intensive agricultural system that we used in the UK was a load of rubbish by comparison with what we’d been eating in Africa.
Dr. Michael Crawford: Anyway, in Uppsala they had regular meetings where they invited people, and they invited Bang to come and give a talk about heart disease. Now, you may know that the Uppsala people are all into high powered physical methodologies and all sorts of things.
Dr. Michael Crawford: And here comes Bang talking about things like cholesterol and fatty acids and so on and so forth. It was something I knew nothing about at the time. This is 1966. And so it was really amusing because like most of the meetings at Uppsala, there was a lot of intensive questioning to speak out, but after Bang had finished his contribution, it was almost total silence. And I was amazed at this. I thought, you know, this revelation about cholesterol and hard fats and all this kind of thing and what unsaturated fats did to make it better kind of stuff was absolutely wonderful.
Dr. Michael Crawford: And I was very young at the time, so I didn’t want to make a song and dance about anything. But then one of the professors got up and said, “I wonder, Doctor Bang,” um, a professor, now I can’t remember his name, one of the prestigious professors at the at Uppsala had just died. And he said, “I wonder, Professor Bang, he had just died, and he drank a bottle of Schnapps nearly every day, and when we looked at his arteries, they were clean.” He said, “Did perhaps the alcohol dissolve the cholesterol?”.
Dr. Michael Crawford: So that was my first meeting with Bang. And after that when we got into the field, we had a lot of connection mostly with Dyerberg rather than Bang.
Dr. Bill Harris: Thank you, Michael.
Dr. Kristina Harris Jackson: Great. Thank you.
Dr. Michael Crawford: Keep well. Bye bye.