If you're still under the impression that fat is the great evil that lurks within the
diets of highly developed nations, you have got to liberate yourself. To the extent that
there is one great evil, it's probably simple carbohydrates, not fats, and any notion to
the contrary that you still have hanging out in your head is, in part, the result of a
deliberate disinformation campaign that was propagated by the American sugar industry
in the 1960s and 70s.
According to a 2016 analysis of historical documents published in the Journal of the
American Medical Association, sugar trade groups paid scientists to produce research
that shifted the blame for heart disease from sugar to fats. In the ensuing decades, U.S.
health authorities and other experts promoted a low-fat, high-carb diet, thus ushering in
what Dr. David Ludwig of Harvard Medical School calls "arguably the largest public health
experiment in history."
He also calls it a "massive public health failure," because, "Throughout the ensuing
40 years, the prevalence of obesity and diabetes increased several-fold, even as the proportion
of fat in the US diet decreased by 25%."
The low-fat, high-carb philosophy that was bought and paid for by sugar barons made us
sicker and fatter.
Now, among the people who have already liberated themselves from this industry propaganda,
I think a new mythology is taking hold.
"There's nothing bad about fats — saturated, unsaturated, they're all good for you and
you should eat as much as you want."
Yes, fats can be good for you, certain fats in particular. But as Barry White said, "Too
much of anything is not good for you, baby," and the science exonerating saturated fat
is not nearly as settled as some people believe. And there is at least one form of fat that
you probably shouldn't eat ever.
Want details? Field trip to the University of North Carolina in Chapel Hill, where Dr.
Raz Shaikh does research on dietary fats, particularly as they relate to obesity and
diabetes.
"Certainly I think we all agree on, in the field, that consuming more Omega-3 fat, which
comes from marine sources — fish oils, is beneficial, or has potential beneficial effects."
Benefits for brain development, for example. Dr. Shaikh says that much is essentially settled
science. Potential benefits would include lowering inflammation among obese people.
Inflammation can cause all kinds of problems, including diabetes. Dr. Shaikh, in fact, just
published a study on this subject, but like a lot of this research, it's "pre-clinical,"
which means he wasn't studying humans yet. He was looking at cells.
In contrast, there is "clinical research," on humans, indicating that Omega-3s may be
good for your heart.
"Certainly for things like atherosclerosis and coronary artery disease. And I want to
point out: preventative effects. A lot of people think that if I eat something, it's
going to treat it. And basically, what we're finding, particularly with Omega-3 fatty acids
is [if] you take it as a treatment modality, it may or may not work out for cardiovascular
disease. It's a very debated topic. But there are some clear-cut benefits, and the best-described
one is triglycerides."
That's free fat floating around in your blood. Bad for your heart, and Omega-3s lower it.
But not all Omega-3s are alike. The "long chain" ones that we're talking about right
now comes from oily fish, like salmon. The "short chain" ones that come from, say, walnuts,
are probably beneficial too, but not for circulating fat. Your body can make the long-chain ones
form the short-chains ones, but not very efficiently.
"So if you don't eat fish, consume it as a supplement, and you can purchase them as supplements.
Or if you have elevated triglycerides, your physician may prescribe them for you."
Then there's the case of Omega-6 fatty acids that come from things like vegetable oil.
These can be good for you too, but they also provide an example of why it's dangerous to
boil this stuff down to "good fats" vs "bad fats."
"Certain populations metabolize fat differently, so African Americans compared to Americans
of European ancestry. African Americans, for a variety of reasons, are more prone to a
lot of diseases. Not all, but I'm talking about metabolic, obesity kind of diseases."
And one reason for that may be that African Americans appear to metabolize Omega-6s differently
— they might not be able to derive the same benefits from this as, say, I can.
"So maybe those are the people that need to be eating more Omega-3s. And that verdict
isn't out yet. It's just a hypothesis right now. But it's plausible, and there are data
that are suggesting that that's true."
So far we've been talking about polyunsaturated fats. Let's talk about monounsaturated fats,
the big example in my cooking at least being olive oil.
"Clearly increasing your consumption of olive oil has potential benefits."
Yeah it does, chief among those benefits being deliciousness. But there's also evidence that
it may reduce blood pressure and LDL, or "bad," cholesterol. So, yay olive oil. Yay olive
oil!
Now we come to the big controversy du jour: saturated fats. These are the fats that are
solid at room temperature and generally come from animals sources, like meat and dairy.
"Saturated fat raises LDL, your 'bad cholesterol,' and so that contributes toward atherosclerosis.
There's controversy around that, because there are studies out there that have shown potential
requirements for saturated fats, and there may be benefits for some of these saturated
fats. And again, it boils down to what type of saturated fat."
There's some research indicating that saturated fats from coconuts may be better for you than
fats from dairy, like butter and cream, which in turn may be better for you than fats from
meat. But in Dr. Shaikh's opinion, the jury is still out on all of that that, and it depends
who you are.
"If you're somebody that's got heart disease, that has elevated triglycerides, that has
high what's known as HbA1c, glycosylated hemoglobin — you're a diabetic, maybe it's not good
for you. Or if you're a 12-year-old kid who's growing, your needs are different."
Take me, for example. I've got a certified case of dad-bod.
I'd love to be a little bit leaner, but my cholesterol and blood pressure are like perfect,
so I tend to try to avoid saturated fats, purely as a means of watching my total calories,
and also making room for better fats, like olive oil. For all the good and bad things
you can say about fats, they are the most calorie-dense macronutrient, by far, and you
have to take that into consideration.
That said, there is plenty of evidence that even though carbs have fewer calories, simple
carbs like sugar and white flour might make you fatter than fats, because they mess with
your blood sugar and the hormones that regulate your nutrient absorption and you're appetite.
I don't know if I take in too much fat, but I definitely take in too much sugar. And alcohol.
Alcohol has calories, too.
Last thing to say in defense of fats is to point out that they are essential nutrients.
Your body uses them for all kinds of functions necessary to keeping you alive, and they're
necessary for your body to absorb other essential nutrients, namely vitamins A, D, E and K,
the "fat soluble" vitamins. So does that mean you have to eat a bunch of fat with every
meal in order to absorb all of the vitamins you're eating in that particular sitting?
As I understand it, that's still in question, but there is plenty of evidence that it helps.
Research out of Iowa, for example, has been looking at the effects of oily salad dressing
on nutrient absorption, and they've found a very strong correlation. The more dressing,
the more vitamins people were able to absorb out of their salads.
There is one form of fat that you probably shouldn't ever eat, and that's artificial
trans fats. These are oils that have been modified to be solid at room temperature and
have a really long shelf-life, and until recently these were everywhere in processed foods.
"At a very molecular level, they have effects on membranes, an effect on, you know, structural
effects. But trans fats in general contribute toward heart disease, and that's become very
well-accepted. And so, you can see, with food policy, that trans fats have been cut down."
One place where you or I might still encounter artificial trans fats in the kitchen is in
shortening. Where that leaves shortening, and the intimately intertwined discipline
of Southern-style biscuit-making, is a topic that we'll take on next week.