Meat, Fish and Chicken -- Further Skinny on Fats
(June 2, 2015)
It’s still probably safe to say that if you REALLY want to rank fish, chicken/poultry and red meat in order of Best to Worst (which I don't recommend, because each contributes something beneficial to the diet), then the order I just listed them in is still valid. Although, oddly, the reason we originally rated them that way -- because of their relative cholesterol and saturated/unsaturated fat contents -- doesn't really hold true anymore.
I want to do just a little TINY bit of chemistry here. Fats are classified and discussed according to their structures, because their structure determines how they are used in the body. And that structure is fundamentally pretty simple. If you don't already know it, a little bit of info here will be of great use to you. Your Future in nutritional reading is worth a couple of minutes of misery. Trust me.
Google tells us that fat is “a natural oily or greasy substance occurring in animal bodies, especially when deposited as a layer under the skin or around certain organs”. We knew THAT, of course. Fat is made up of a group of different molecules that all have the same simple underlying structure. The differences between them can be very small, but very small differences in structure can make for big differences in how that fat works in the body.
At the most basic level, a fat starts with a short little chain of carbon, hydrogen and oxygen atoms, like so, called glycerin or glycerol. Over there to the right...
If you brutally rip off those OHs, you will have three places where you can add more atoms. So if you then replace each of those three OHs with a long similar-to-glycerol-looking chain of carbons, oxygens and hydrogens, you get a molecule that (on paper) looks sort of like an "E".
Each of those chains is called a "fatty acid". The resulting molecule, with a backbone that used to be glycerol and with three chains of atoms attached to it in place of the OH groups, is now a "triglyceride" or a "lipid". Both words are just fancier ways of saying "fat". Sort of like when you are telling someone a recipe you say "shallots" instead of "scallion" because it sounds smarter.
So there is your basic fat / lipid / triglyceride. I'd tell you which one it is, except it appears that none of the ten thousand websites using this image that I looked through has any clue either.
That picture up there is of a SATURATED fat, because none of the three fatty acids contain extra bonds between the carbons. When that happens, the fatty acid (and the triglyceride it's being used in) becomes UN-SATURATED. Thusly:
If a fatty acid has just one of those extra bonds, the way the bottom one does, it's "monounsaturated”. If there are two or more, it's "polyunsaturated". The more you have of those extra bonds, the more liquid the fat will be at room temperature.
(Here is a wonderful, easy-to-read article with a bit more information on this, if you want it:
In a normal state of nature, fat of all kinds is hard to get. Your body really prizes fat, because it doesn’t realize that there are vats of it in cheap restaurants all over town. So it hangs on for dear life to whatever fat you feed it, good or bad.
Your body also operates on the assumption that, because fat is so scarce, it may not be able to get the ones that it really wants -- so it often will use whatever fat is available in the best way that it can. This is one reason "trans" fats are bad.
Trans fats are polyunsaturated fats that have had some of those extra bonds broken up, and thus their fatty acids made more saturated, by processing. Unfortunately the process turns them into fats that are not normally found in nature -- so when your body uses them to make cell membranes etc., the resultant structures don't work QUITE right. Good enough for government work very often, but not enough for optimum health.
I went through the chemistry because you hear it all the time. But when all that breaking things down to a molecular level is said and done, what is in a FOOD, and what happens when you eat it, is far more important than the component parts that make it up. Things work differently together than they do separately, especially in biology. How your body handles a particular nutrient has everything to do with the other things found in nature with that nutrient.
Broccoli is loaded with carcinogenic compounds. At least, they are carcinogenic if you eat them apart from the broccoli. Which no one ever does, or would do. It’s the food that counts – not an isolated part of it.That is a lesson that has been forced on us time and time again, when a food is found to be beneficial but its “active ingredient” turns out to be null or even harmful in isolation. Beta carotene prevents cancer when you eat it in a carrot or sweet potato -- but not when you swallow it in a pill. Most likely that is also true of resveratrol and fish oil, two other nutrients that are the latest of a long list of nutrients that haven't lived up to the hopes we once had for them.
Red meat is defined as pretty much everything on four legs. Most of its fat is saturated, and you find the most cholesterol there as well. By the way, this is what a cholesterol molecule looks like:
Just looking at it tells you it was stupid to automatically lump it in with saturated fat in the first place. As far as I have been able to find out, no one has ever found a solid link between EATING cholesterol and the levels of cholesterol in the BLOOD. And also as far as I can tell, no one important besides the American Heart Association is still pretending that it does.
“Chicken” can be lumped in with pretty much everything that flies (or that would fly, if given half a chance). The fat in poultry tends to be only partly saturated, so it’s squishy at room temperature. And “fish” swims and usually the fish category includes everything that lives in the water. Its fat is mostly unsaturated, which means it is liquid at room temperature. (That makes it an oil. A fat that is liquid at room temperature is an oil. Thus "fish oil".)
Those are the classic differences between the categories of animal food -- saturated fat and cholesterol were the only things we really cared about. Consequently, meat was supposed to be the biggest promoter of heart disease, and fish the least. That is probably still technically true. But it's not as cut and dried as we thought.
When we finally looked closer at red meat, we found several things. First, that trans fats promote heart disease MORE than saturated fat, which didn't fit. Next, that stearic acid (a saturated fatty acid found in animal food, and in its highest quantities in red meat) does NOT raise blood cholesterol. Then a little later, we found that when you break down the very general category of ‘red meat” a little more, you see that it is really only processed red meat (sausage, hot dogs and the like) that raise the risk of heart disease. And finally, with a loud flourish of trumpets, some very good studies have recently found that people who reduced the amount of saturated fat in their diets started showing MORE heart disease than those who did not. Why? Because what they were eating instead apparently promotes heart disease MORE than saturated fat. What was that stuff? Flour and sugar. Wow -- who woulda thunk it.
That doesn't let red meat – and saturated fat -- completely off the hook. The carnitine in red meat is turned by our gut bacteria into carcinogenic compounds, for one. How we cook it often creates even more of pesky carcinogens. And there are a lot of calories in red meat.
Supplements of fish oil lately are showing much less benefit in heart disease than we were hoping for. But eating fish is still a very good thing.
Chicken is high in protein, low in calories, very palatable, and the fats in it are generally quite good for you. Don’t let the rumor that three out of four poultry inspectors refuse to allow chicken to be served in their homes because of the revolting, unhealthy, unsanitary conditions that they are processed in affect you too strongly :-) .
And in case you haven't heard yet, eggs are off the Bad list too. Because, one more time, eating cholesterol does NOT raise your blood cholesterol, and the demonizing of eggs was based entirely on their cholesterol content. If eating cholesterol DID promote heart disease, every shrimp would be a nasty little crawling, scavenging, heart attack in the making. And we've always known that THAT isn't true.
Does that mean you can eat as much red meat as you want? Yes! As long as FIRST you get 10-12 daily servings of vegetables and fruits, 2-4 servings of dairy (the fats in dairy products may be especially good for you) and 2-4 servings of whole grains. Ha! You knew there had to be a catch somewhere. And you were right.
--dr. diane holmes
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