December 11, 2012

Fat Tuesday Part 6 - What does it all MEAN?

Woohoo! It’s that time again—time for our weekly dose of the truth about dietary fats. As promised last time, this week I’ll finally start taking what we’ve learned so far and connect it to what matters most: what it all means when it comes time to EAT…and shop for food, cook, and all the other things that have to get done before we sit down at the table. (Wouldn’t it be nice if life was like it was on The Jetsons, and we could just pop a pill for breakfast, lunch, and dinner, and call it good? No dishes to wash, no time spent peeling and chopping? That would free up a lot of time, but then again, I like cooking, and heaven knows I love the taste of food. So all things considered, I guess I’ll stick with foraging at the grocery store and filling my house with awesome aromas.)

We’ve come a long way since the first post in this series, haven’t we? We’ve learned the differences between saturated and unsaturated fats; we’ve broken down lots of different kinds of fats and oils; we’ve talked about trans fats; and even learned about one type of trans fat that seems to be good for us. Believe it or not, though, we’ve barely even scratched the surface. We have lots more to get to, and we will. But for now, let’s buckle up for a little physiology lesson (uh-oh…) that will give us some idea of what fats and oils actually do inside us.

You know what that means…

Hopefully the science I’ve shared so far in this series hasn’t scared anyone away. Call me crazy, but I like explaining how and why things work the way they do. Seems like that’s a better way to help us all make sense of this than just telling you what’s good to eat and what’s not “because I said so.” I’m perfectly happy to pontificate endlessly about this stuff (ask anyone who knows me), but I think it’s only fair to show you that what I say is not my opinion, and it’s not what I heard on daytime TV or saw in a magazine at the supermarket checkout. (Although it would be nice it some of that stuff were true, huh? I’d like to have 6-pack abs by Christmas by doing nothing more than drinking green tea and walking around the block a few times, but somehow I don’t think that’s gonna cut it.) What I’m putting on this blog is backed up by cold, hard physiological facts. (Or, in the case of the textbooks on my shelf, room-temperature facts, hehheh.) In the interest of legitimacy and scientific rigor, moving forward I will try to cite sources a little more reputable and varied than just Wikipedia. I won’t stop using Wikipedia, but I recognize the importance of finding information in other places, especially because a lot of what I say regarding real health foods is controversial. (Okay, let’s not beat around the bush. It’s not just controversial; it straight-up goes completely against the low-fat, high-carb, whole grains “thing” that’s been going on for over half a century. Funny, isn’t it, that we’ve followed that advice but somehow ended up sicker and more overweight than ever? Just something to think about…)

There is so much to talk about when it comes to the role of fats in our bodies. Looking jiggly on our butts and thighs is only one of the things they do—and despite how much attention all that body fat gets, it’s probably the thing I’m least concerned with here. In fact, since we’re on the subject, can we all agree—just for now—to mentally disconnect the fat in foods with the fat on our bodies? Let’s call the dietary fats “fat,” and refer to our love handles, big booties, and thunder thighs as “adipose tissue.” ‘Cuz that’s what it is. Adipose tissue. And it doesn’t only come from the fat we eat. (More on that in a series to come on metabolism. I know, I know. Please, hold your applause.) 

The fat we eat does not automatically lodge itself in our bellies, hips, and thighs.

Since there is a ton to cover about fat (no pun intended), for today let’s keep it simple. We’re going to talk about one thing and one thing only. The cell membrane. (Yikes! Having flashbacks to high school biology?  Don’t get skeered; I’ll try to make this interesting. And if you could see me in person, I’m probably nicer to look at than your high school biology teacher was, regardless of your sexual orientation.)

Do we all remember what cells are? They’re the teeny-tiny, itty-bitty things that make us…well, us. Every part of us, from our eyeballs to our pinkie toes, is made of cells. We have erythrocytes (red blood cells), hepatocytes (liver cells), enterocytes (small intestinal cells), brain cells, pancreatic cells, muscle cells, and cells in every other type of tissue and organ. We are made up of trillions of these things. Basically, we’re just walking, talking sacks of cells. (Or, if you’re a Carl Sagan fan, we’re actually recycled stardust, but for the purpose of this post, we’ll call ourselves big sacks of cells. [And also if you’re a Carl Sagan fan, think of our bodies as “TRILLIONS AND TRILLIONS” of cells, instead of “billions and billions,” heehee. Loved that guy...and others.])

Everything that happens inside our bodies happens because of actions at the cellular level. When you touch a hot pan and pull your hand away as fast as you can, that movement happens because sensory cells in your hand felt something hot, transmitted that to your brain, and your brain told the motor cells to move—in this case, to move away from the pan. I’m not kidding when I say that everything that happens happens because of activity in some of these trillions of cells. You can digest food because cells lining your stomach secrete hydrochloric acid and digestive enzymes. You can breathe because cells in your lungs exchange oxygen and carbon dioxide with your blood.

Regardless of what kind of cell we’re talking about, all cells have membranes. To be specific, I’m talking about plasma membranes, and this is what surrounds the cell. It separates the inside of the cell from whatever’s outside. This is a much bigger deal than it might seem. See, the cell membrane is like a bouncer at a club. He decides who gets to come in and who has to be kicked out. If the bouncer’s going to do his job well, he’s got to look a certain way, right? You wouldn’t want a scrawny, timid boy-man at the entrance, would you? Of course not. You’d want someone tough and brawny. Think “Chuck Norris,” and not “Sheldon Cooper.”  The same is true of our cell membranes: they have to be built a certain way in order to function properly. When cell membranes don’t function properly, it is—to use the official scientific term—bad news. If the membrane is like a bouncer, then when it doesn’t work correctly, what happens? Good things (like vitamins, minerals, amino acids, glucose) can’t get into the cell, and bad things (toxins, waste products, excess sodium) can’t get out. Recipe for disaster? Yes.

Okay, that makes sense. So what does any of that have to do with the fats we eat? Good question! I can see you’ve got your thinking caps on. See, cell membranes are made of fatty acids. (Well, technically, they’re made from phospholipids, glucoproteins, cholesterol, and other stuff, but the main thing in cell membranes is fatty acids.) And they’re made from all three kinds of fatty acids: saturated, monounsaturated, and polyunsaturated. They need all three kinds of fatty acids. The membranes for different types of cells have different requirements for the particular proportion of saturated vs. unsaturated, so I can’t give you exact numbers on what cell membranes are made of. For our purposes here, it’s enough to know that we need all three to some extent.

For this to make sense, we’ll need to see what a cell membrane actually looks like. (Plus, we’ve gone a few paragraphs without a graphic, so we’re due.) Here are a couple of different representations of cell membranes. Let’s look at the first one:

The cell membrane is actually called a phospholipid bilayer. (Don’t worry. It sounds much more technical than it is. All it means is that it’s like a double door; it’s got two layers.) The “phospho” is for the phosphate group, which is shown as the little red balls on either edge of the membrane in this graphic. (That’s all you need to know about it now.) The lipid portion—the black and blue “tails”—is the one we’re interested in. Remember what we learned about the difference between saturated and unsaturated fats? Saturated fats have no double bonds, so they look straight. (I know the saturated fat in this graphic looks squiggly, but that’s just how they’re drawn in biochemical shorthand. When you compare it to the unsaturated fat below it, you can see that where the double bond is, the fatty acid bends

Our cell membranes look more like the lower picture – the one that has saturated and unsaturated fatty acids in it (the black and blue). When the membrane has the right “ingredients,” it can do its job, just like a bouncer that has the right build.

But membranes aren’t just fatty acids. There’s lots of “stuff” embedded in the membrane that also helps it do its job. Think of it like a huge estate—the home of someone with way more money than you could hope to make in a lifetime. (You know, the kind of residence that has a name, not an address. Like “Chateau de la Mar, instead of 319 Old Hill Road. [But not a van down by the river.”]) There are a lot of different ways to get into and out of an estate like that, right? There’s a front door, a back door, windows, the servants’ entrance, balcony doors, the ballroom entrance, the underground driveway for deliveries. And in order for these entrances to let people in and out, the house itself has to be built correctly, yes? If the house was made poorly, maybe the doorways and windows aren’t the right shape or size. If it starts sinking into its foundation, maybe that underground entrance becomes inaccessible.

The cell membrane works the same way. Check out the drawing below. Embedded on and within the membrane itself—like doors and windows—are ion channels, transporters, and other things that are designed to bring certain things into the cell and send other things out—things that can’t just slip through the membrane without help. There are also receptors for things like insulin, serotonin, HDL, and LDL – kind of like security guards who stand outside the mansion and only let in people they recognize.

So it should be pretty obvious now what could happen if the cell membrane isn’t built the right way. Things that are supposed to get in can’t, and things that are supposed to get out also can’t. And it doesn’t end there. If the membrane itself is shoddy, then some of those transporters, channels, and receptors aren’t going to work right, just like the house with the doors and windows that aren’t the right shape and size. To give us some idea of what this means in real life, if our LDL receptors aren’t working right, we’ll have lots more LDL floating around in our bloodstream because it can’t get into the cells. (If you’re thinking LDL is the “bad cholesterol,” you’re right, but it is WAY more complicated than that. We’ll table that discussion for another day.) If your insulin receptors aren’t doing their job because the cell membrane is messed up, your blood glucose levels will be higher than they should be because insulin can’t get glucose into the cells. Are we starting to see how something seemingly irrelevant—like cell membranes—can affect big, BIG things downstream, like heart disease and diabetes? Now you know why I ended up loving biochem even though I was super scared of it when I first started.

The right building blocks make the difference between this...

...and THIS.

Okay. So what do we mean when we talk about the cell membrane not being built right? Well, remember that what gives the membrane its basic structure are fatty acids. And we need all three kinds—saturated, monounsaturated, and polyunsaturated. But what have we been told when it comes to food? Avoid saturated fats, right? Limit intake of saturated fats and emphasize the unsaturates. Ix-nay on the butter, lard, beef tallow, egg yoks, and fatty cuts of meat, and use olive oil, soybean oil, corn, canola, and safflower oils instead.

It should be easy to see how dietary imbalances can mess with our cell membranes. Too many polyunsaturated fats in the diet would mean too many get incorporated into the membranes. And when there are too many polyunsaturates, the membrane becomes “floppy.” In order to improve the structural stability of these floppy membranes, the body sends in reinforcements—kind of like load-bearing walls or studs—something that keeps the rest of the house (or membrane) from collapsing. What are these reinforcements? Cholesterol! (Yes, kids! Cholesterol is not out to kill us. It’s a repair substance. More on that some other time.)

Here’s where it gets a little dicey, and I’m not above admitting I don’t have all the answers. If there’s one thing the human body is good at, it’s converting stuff. Taking things and changing them into other things. We do it all the time. Our bodies are the ultimate reuse and recycle machines. We can turn proteins (amino acids) into carbohydrate (glucose); carbohydrates into fat (WHAT?! Yes, more on that in the metabolism series debuting soon); testosterone to estrogen, and fatty acids to other fatty acids. The part I’m not sure about is why our bodies don’t take the excess polyunsaturated fats and convert them into saturates if it would mean correctly made cell membranes. Maybe they do to some extent, but if so, they still don’t do it enough to make stable, proper membranes.

And what have we just said about cell membranes that don’t work right? Good stuff can’t get in, bad stuff can’t get out. And surprise, surprise, high intakes of polyunsaturated fats—y’know, the ones they’ve been telling us to use because saturated fats are (supposedly) so bad for us—have been linked to certain types of cancer. No wonder, if toxins and waste products can’t get out of cells! And also no wonder, since we learned in part 3 of this series that polyunsaturated fats are the most susceptible to oxidation and rancidity. (Oxidized fatty acids create free radicals in the body—molecules that can wreak havoc in many ways and are associated with the development of cancer, and the negative effects of aging.) 

So, until next time, do your cell membranes a favor — go eat some butter!

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

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