January 8, 2013

Fat Tuesday: Gimme a 3! Gimme a 6!

As promised a few weeks ago, we’re finally going to get into the world of omega-3 and omega-6 fats. (I do tend to keep my promises, but I fully admit it takes me three or four times longer to follow through than it should. But the first step is acknowledging I have a problem, right?)

If you read popular magazines, watch television, or generally aren’t living under a rock, you’ve probably heard the terms omega-3 and omega-6 fats. And you probably have some vague idea that omega-3s are supposed to be good for us. Beyond that, if it’s all a big mystery, keep reading.

In the interest of not making this post a zillion words long (like I usually do…again, the first step is admitting to the problem, yes?), I’ll stick to some pretty basic ideas about these fats and next week I’ll get into why any of this matters for our health. Before we get into where we find 3s and 6s in our food and what they do inside us, I think it’s useful to figure out what the heck they are. And you know what that means…

Even though I described these fats in part 2 of this series, I think it’s worth reviewing since our main focus today is just these two and they might have gotten lost among all the others in previous posts. The first thing to know is that omega-3 and omega-6 fats are both polyunsaturated. All that means is they have more than one double bond between carbon atoms. No big deal. (Yikes! She’s talking chemistry again. Don’t worry…I’ll hold your hand.) They’re also both essential fatty acids.

Important point:  When we use the word “essential” in the dietary sense, it’s different from how we normally use it. It’s not essential that I have coffee every morning in the same sense that it’s essential I consume omega-3s and 6s. I might be able to survive without coffee—although it would be ugly, I assure you. REALLY UGLY. But I can not get omega 3s and 6s any other way than by eating them. And I need them. We, as a species, need them. Homo sapiens has a dietary requirement for them. 

If you value your life, don’t attempt morning conversation
with me until I’ve had some coffee.

When we say something is “essential” in our diet, we don’t just need them in our bodies. We “need” glucose, but we can make glucose from lots of other things, so we don’t actually have to eat any (contrary to what you might be used to hearing about “needing to eat carbs for energy”). On the other hand, omega-3s and 6s are essential in our diets because we can not make them from something else. To be specific, we need one kind of 3 and one kind of 6 – the “parent” essential fatty acids. I said in part 6 of this series that the human body is the ultimate reuse and recycle machine:  it’s great at converting stuff into other stuff. Two of the things it’s good at converting are these “parent” omega-3 and 6 fats into other types of 3s and 6s, each of which has different functions inside our bodies. So there are some kinds of 3s and 6s we don’t need to consume directly, but only if we get enough of the parent ones. And even though we usually hear about 3s being good for us and 6s being bad, the truth is they’re both essential. (More on all this next week.)

Whew. It’s getting a little stuffy in here, eh? Time for some pictures.

This is what an omega-3 looks like:

This is alpha-linolenic acid, or ALA – the parent omega-3.
It’s called omega-3 because the first double bond (the red thing) happens on the 3rd carbon from the methyl end of the molecule (the green thing). Seriously, don’t get skeered. You don’t have to master the science (or even understand it all that well) to learn some important things here.

This is what an omega-6 looks like:

This is linoleic acid, the parent omega-6.

Not surprisingly, this one is called omega-6 because the first double bond (still the red thing) happens on the 6th carbon from the methyl end (still the green thing). There are also omega-7 and omega-9 fats, but let’s tackle one huge thing at a time, shall we? (Nifty factoid before we table 7s and 9s for some other time: oleic acid, the main monounsaturated fat in olive oil, is an omega-9.)

Okay. So what?

Well, like I said, omega-3 and omega-6 fats are both essential fatty acids, and there are lots of different kinds of 3s and 6s. We can eat some of these different kinds pre-formed in foods (like in eggs and fish), or we can eat those “parent” fats (like in walnuts or soy oil) and hope that our bodies will convert them into all the other ones down the line. Our bodies can make certain 3s and 6s inside us, but only if we give them these parent fats (and it’s these—the starting materials—that are “essential”). It’s like making a home library with a really nice desk and bookshelves made of wood. You can only make the desk and shelves if you’ve got the wood to make them from, right? So step one is getting the right wood (fats). Step two is crafting the wood into furniture, but the thing is, some of us are better carpenters than others. That is, some people’s bodies are better than others’ at converting the parent fats into the other 3s and 6s.

Head spinning yet? Don’t worry. It’s actually not that complicated.

Let’s start with ALA—alpha -linolenic acid—the parent omega-3. Have you ever heard of fish oil? Fish oil is very rich in two kinds of omega-3 fat:  EPA and DHA. (Since I don’t want to scare you off, I’ll just say that if you want to know what those letters stand for, check them out on Wikipedia, or here.)  Obviously, we can get EPA and DHA by taking fish oil supplements or by my preferred method—just eating fish. But we can also make EPA and DHA from ALA. It’s a pretty long, complex process, though—like making that beautiful desk out of a plain ol’ pile of wood. Lots of steps along the way and lots of places for things to go wrong if you failed carpentry 101.

In the same way, we can get certain kinds of omega-6 fats by eating foods they’re found in, or our bodies can make them if we eat some LA—linoleic acid, the parent omega-6. But just like with the 3s, the conversion process is full of places for things to get screwy, and even a master carpenter is gonna face some pitfalls.

Check out this graphic, ripped off lovingly from this article, which gives some pretty awesome info about the whys and wherefores of 3s and 6s for those of you who want some hard-hitting nutritional info and can’t wait until next week.

I wasn't kidding about the conversions having lots of steps!!

Not only is the process pretty complicated, but most of the steps require the same tools whether our bodies are making omega-3s or omega-6s. Kind of like the desk and bookshelves:  we’re making two different things, but we’ll need saws, sanders, files, hammers, and nails to make both, right? That’s how making 3s and 6s work. In order to make different kinds of 3s and 6s from the parent fats, our bodies use the same tools. This is a very important point. (You can tell because I made it bold, hehheh.) See, if both paths need the same tools, there’s gonna be competition. (Like when you and your kid sister fight over the last Oreo. You both want it, but only one of you is gonna get it. Sharing? HA! Not an option when it comes to cookies.)

So if the parent 6 and the parent 3 are competing for the same tools (in our bodies, they’re called enzymes…remember high school biology?), who’s gonna win? Well, it’s mostly a numbers game. The more 6s you have coming in, the more those 6s will crowd out the 3s, and vice-versa. In the graphic, you can see where the fats compete for enzymes (circled in red). We'll come back to this next week. It's important stuff.

And remember—I said some of us are better carpenters than others. Some people will be pretty good at making desks and bookshelves, and some will end up sitting among the stacks of two-by-fours, crying and feeling useless. There are two main reasons for this. Better genetics, maybe? Were your parents good carpenters?  HA! Actually, this might have a fair bit to do with it, but let’s start with the more obvious hiccup in the system first.  See the yellow circles in the graphic above? Some of the enzymes used in the conversion of ALA and LA to other omega 3 and 6 fats require certain vitamins and minerals. To be specific, we need B6 and biotin.

Okay, so what’s the issue there? Well, we might not have enough B6 or biotin coming in. We could not be consuming enough foods that contain them, or we might have other processes going on in our bodies that also require B6 and biotin. (Our bodies are resourceful; they very rarely use a vitamin or mineral for just one thing. Kind of like Alton Brown’s philosophy on cooking gadgets in his kitchen:  no uni-taskers allowed! Everything ought to have more than one purpose to justify its presence, and when it comes to getting jobs done inside our bodies, nutrients are prime examples of multitasking.) And let’s not forget that sometimes prescription drugs interact with nutrient absorption:  for example, birth control pills are known to deplete B vitamins.

So dietary factors can affect how well we convert those parent 3s and 6s into all the other ones down the line. Health status can also play a role. People with diabetes, hypertension, and/or metabolic syndrome tend to be poor converters. And what about those genetic factors? Let’s think about it logically:  Say you have Pacific Islander ancestry. It stands to reason your genes “expect” you to consume a lot of fish, so you wouldn’t have had to produce a lot of the enzymes that convert ALA into EPA and DHA. But if you’re from genetic stock of people who lived far inland, or in a mountainous place, maybe you produce more of those enzymes because you weren’t getting as much of the finished product from your diet. (Your ancestors were more accustomed to getting ALA from walnuts, for example, instead of a lot of pre-formed EPA and DHA from marine foods. My reasoning here is similar to the theory behind the prevalence of lactose intolerance among Asian populations:  historically, Asians weren’t dairying people, so they lose the ability to digest lactose after weaning from mother’s milk. Our bodies are pretty efficient machines. They’re not gonna waste a lot of energy making things they don’t need…or don’t expect to need.)

The other factor here is that humans, in general, are just not all that good at converting the parent fats into the various intermediates and end products. Human nutritional evolution might have conditioned our bodies to “expect” to get the different fats along the way directly from our diets, regardless of where we were living, to the point that none of us is a rock star when it comes to turning fats from almonds and vegetables into fats we can more easily get from eggs, fish, and organ meats.

Let’s get back to the competition idea, ‘cuz if you ask me, this is where things really get interesting. The more omega-6 we eat (specifically, linoleic acid, the parent 6), the more it will crowd out the omega-3 alpha-linolenic acid for use of the same enzymes.  And remember:  fats aren’t just these “things” that make our food delicious. We need them to build things inside our bodies (like cell membranes), and we also need them to make what we call signaling molecules—kind of like hormones…they send our bodies messages.

What kind of messages do they send? And why is the competition between 3s and 6s for those handy-dandy enzymes such a big deal? And how is all of this related to the one thing most of us care about—our FOOD?  Tune in next week. This whole business of 3s and 6s is a long story, so I’ll spare you the eye-strain and break it up into a few more parts.

Off the record:  Okay, look. I know I’m pretty bad at keeping things short and sweet. All I really want to do is make clear what we should eat and what we shouldn’t eat. But I don’t want to just make lists of “good foods” and “bad foods,” or say that you can each as much x, y, and z as you want, but you should limit intake of a, b, and c. I think it’s important to explain why. WHY should we limit some things and not worry so much about others? So that’s what I’m trying to accomplish with this series on fats. I want to get to the good stuff just as much as you do (all three of you…I may have lost someone last week, hehheh). But I feel like it’s irresponsible of me to trash-talk cottonseed oil and praise butter if we don’t even know what those things are on a chemical level, or to say we should eat certain foods and avoid others without knowing what they do inside us because of their chemistry.  

So I’m sorry things have to get a little technical (and long-winded) now and then, but I think we need to lay the foundation before we put the house up, y’know? All I know is, designing a nutritious, health-promoting diet is actually pretty easy when you understand how the human body works, and that’s what I’m trying to share with you. When we stick to the facts, we can tune out the TV pundits, the supermarket tabloids, and our Aunt Gussie, who lost 30 pounds by drinking shakes for a month but will gain back 40 next month.

When we know what food is and what it does inside us, knowing what to eat and what to stay away from is…Not Rocket Science.      

*Amy Berger, M.S., is not a licensed physician and Tuit Nutrition, LLC, is not a medical service. The information contained herein is not intended to diagnose, treat, cure, or prevent any medical condition.

1 comment:

  1. Biochemistry makes everything more interesting! I feel like I wrote your list 'People and Sites I Love'. Great post!