About 3 years ago, after reading the book Real Food, I finally decided to buy one gallon of whole milk. It took a lot of will-power not to take it back out of the cart before I reached the check-out; and then at home, I was practically trembling with anxiety about actually ingesting the stuff. Mentally, I had become convinced that it was the better choice, but emotionally there was so much invested in the low-fat endeavor, and such a strong stigma associated with eating fat.
It didn't even occur to me until this daring shift, 3 years ago, that maybe the reports of fat's evil nature weren't entirely true. It was what everyone said, what every health article was full of, and if you looked around you, it certainly seemed like you could make the connection between people eating fatty junk and getting sicker and fatter themselves. But, I've begun to see that fat is not necessarily scary or even fattening. Here's why.
No fats are exclusively one 'type' or another, they're all a mix. Olive oil, which is probably the only fat never to have fallen out of favor, is touted for its monounsaturated bounties; it's roughly 75% monounsaturated oleic acid. But guess what other foods have more monounsaturated fats than they do saturated? Egg yolks and lard. Ground beef. Chicken thighs, both with skin and without. In fact, they have more oleic acid than they do any other specific kind of fatty acid. So we've really been oversimplifying and vilifying the fats in our foods. (And if you don't believe me, I just double-checked the breakdown of each of those on nutritiondata.self.com and skipthepie.org, you can go play with that too.)
Another oversimplification the powers-that-be have taught us is that metabolism is an engine that burns whatever you put into it, and keeps the extra as fat. Calories in, burn 'em or store 'em, right? It turns out that in reality, metabolism is a complex medical subject that has infinite individual variations. It depends on all sorts of biofeedback loops and hormonal messengers, and reacts to different types of food in organ-specific ways. It's been fascinating to read about. I'm now convinced that you can, indeed, eat high-quality fat without putting it straight into your spare tire -- even if you're not running marathons on the side!
Lastly, it turns out that some of our most important organs and systems specifically rely on fats and cholesterol. Our body must get or manufacture enough to keep making hormones, cell membranes, and the majority of our brain tissue; to correctly absorb vital nutrients and keep them in balance; and our hard-working heart muscle actually prefers fat for its fuel. Let's get into a few details here for a minute.
We cannot live well without estrogen, testosterone, vitamin D, bile, and natural steroids, for example; their lack hovers under the surface of a lot of the metabolic problems and inflammatory traps our bodies are falling into these days. Popular wisdom teaches us that sunshine is an ingredient in vitamin D; cholesterol is actually the other. It is the basic building block of that entire list of hormones, and also plays a role in repairing cellular damage and allowing our neurons to communicate.
Next, cell membranes. We each have trillions and trillions of them, and they are active little buggers, constantly shuttling molecules in and out and directing communications within and without the cell. And -- no surprise -- they rely on fat and cholesterol for structural integrity and flexibility. The mix of fats and cholesterol have a profound effect on the 'floppiness' or 'stiffness' of the membranes and their ability to do their job. I'm not clear yet on what exactly that implies in terms of our food intake, because the research is still in an early phase; but I'm watching it, and I'd put a pretty big bet on seeing studies eventually show up that demonstrate the benefits of a more traditionally fat-based diet.
One of the bigger surprises to me was the fact that heart muscle -- and skeletal muscle, as well -- prefers to burn shorter-chain fatty acids. (These are the types of fat typically found in butter, coconut oil, or even goat cheese.) Working muscle can essentially swipe those types of fat right out of your gut and use them at the cellular level without needing them to be digested first. I think that's incredible.
You know, hopefully, that oil and water don't mix; when you ingest fats, then, it first requires a process called emulsification to get them into a form your mostly water-based body can take in. In your digestive tract, the smallest fats (the kind your muscles crave) can diffuse straight into the bloodstream and be immediately burned as fuel. The larger ones are worked on by secretions from your liver and pancreas, then packaged into specialized droplets that are put into the lymph system to circulate. They're finally dumped back into the bloodstream to be broken down by enzymes in the blood vessels themselves and carried where they're needed. Or to the liver, if nowhere else claims them.
Does anyone but me think that sounds a little crazy? That all those long, floppy vegetable oil molecules you ingest end up in your lymph system, until they're unceremoniously emptied into your blood at your neck, by the way? I was completely surprised by that when I learned it, and wondered why on earth the lymph system would be involved in this at all, since as far as I knew it was a detoxifying system, not a food-nutrient-transporting one.
So I looked into it, and in a still-unfinished way, here's what I've found. Your intestines (and digestive tract in general) have a lot more jobs than I thought, and are connected in all sorts of overlapping ways to other body systems. There's the enteric nervous system, which according to Wikipedia is the only part of the peripheral nervous system that contains complete reflex circuits capable of local, autonomous function. So the phrase 'going by your gut' may reflect the fact that your gut really thinks, in its own way. There are more neurons concentrated in there than anywhere else outside your brain/spine. Also, your intestines have a special relationship to your immune system. Who knew? Yet, it makes sense -- germs are constantly coming in by that route. Your body is not just going to wait and try to detect them in your bloodstream, it's going to try to catch them before they even get there! Your immune system embeds special patches of lymph tissue into the lining of your small intestine to 'sample' what's going through you and mount an immediate response, before the offending germ or molecule is even quite all absorbed into your bloodstream. Simply amazing. Add into this picture the newly emerging research on our vast microbiome, and you've got quite a confluence of interesting, quirky factors in your tummy.
So, back to fat. Here's my big leap of no evidence (there's your scientific disclaimer). I have a theory that much of that really long, polyunsaturated oil that our Western diet is full of gets misdirected. Take, for example, highly chemically-processed and genetically-modified corn oil -- say some of it makes it to the bloodstream and is used for energy, but a lot of the extra overloads the liver; also, as it's getting packaged and picked up by lymph in the intestine, maybe some of it gets tagged by an immune patch as toxic (not a huge stretch of imagination), causing constant inflammatory responses.
I just don't think our bodies know how to handle it all, and a lot of proverbial wires get crossed at the very least. At worst, we may be putting it all into our 'muffin tops', padding our liver with it, and still depriving our body of some essential building blocks. Much of the highly polyunsaturated oil we consume is literally impossible to get in nature, it's only through intense chemical/technological manipulation that it's even a product we can use. I wonder what effect that massive dietary shift has had on that complex neural/bacterial/immune relationship in our gut, that we're just beginning to understand? Top our diets off with too little fiber and piles of sugar, and our poor bodies are suffering rather an onslaught.
(Or pick up a copy of Real Food by Nina Planck, I can't recommend it enough. But I'll warn you it makes you hungry to read!)
http://www.ncbi.nlm.nih.gov/pubmed/23674795
http://www.lewrockwell.com/2010/06/joseph-mercola/eat-more-saturated-fat/
http://www.cholesterol-and-health.com/
One thing that makes me sad is what an uphill fight it is to get saturated fat absolved in mainstream media. There are still so many magazines, websites, and well-intentioned professionals whose information is out of date but who are still happily parroting the 30-year campaign slogans. And trying to get funds to study the positive effects of saturated fat is still a career-killer, unfortunately, which means that the best and brightest are not the ones pushing for real answers, they've gone in other more promising directions. Does someone want to professionally research Peyer's patches for me??
I check in on your blog now and then, and this was just fascinating to me. Thanks for sharing your research!
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