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The Best Test for Arterial Disease

by Dr. Cate Shanahan
Home/Blog/Protect Your Mental Wellbeing During the COVID-19 Pandemic

Optimizing cardiovascaular health has been a controversial topic over the years. We hear lots about fats, cholesterol, what’s good, what’s bad. There are constantly new studies, and all that information can be confusing if we don’t know how to sift through it.

Let’s clear some things up. In my years of research, I’ve discovered that the factor that most directly impacts your arterial health is the process of circulating dietary fat and cholesterol through the arteries. Fat and cholesterol travel in your arteries in little blobs called lipoproteins, which have lipid (fat and cholesterol) in the center and protein coating the outside holding the lipid inside—sort of like a candy coating on an M&M.

Know Your Lipoproteins

There are two types of lipoproteins: Low Density Lipoprotein (LDL) and for High Density Lipoprotein (HDL). LDL is the so-called “bad” cholesterol, HDL is the so-called “good” cholesterol. In reality, these particles are not inherently “bad” or “good”, and calling them by these names has confused a lot of people.

Think of each lipoprotein particle as a delivery truck and the fat and lipid as the cargo.Those trucks need to deliver the cargo into your body tissues. That’s the destination—your brain, your muscles, your heart, your adipose, etc. If these cargo trucks are fully functional, that’s exactly what they’ll do. However, If the cargo trucks aren’t working properly, then some (or all) of the lipid they’re transporting doesn’t reach its destination.

What happens instead? Floating around aimlessly in your arteries, the damaged little trucks eventually crash. Instead of delivering fat to hungry tissues, or tucking it neatly into storage in fat deposits, the lipid instead ends up smashing into the inside lining of your arteries where it can accumulate to the point that it damages the artery and causes a heart attack or a stroke. The more of these small, faulty particles you have, the more urgently you need to identify the factor that is damaging the lipoprotein particles trying to deliver fats to your tissues.

Keep in mind that whether your LDL value is high or low, if your particles (trucks) are dysfunctional, this is something you want to change.

If your LDL number is high, say 160, that may or may not be a problem. Likewise, if your LDL is low, say 70, that may or may not indicate you’re in good shape. What matters more is their size, because that’s the best proxy we have to assess how well they function. Bigger lipoproteins = healthier lipoproteins.

What Foods Can Damage Your Lipoprotein Particles? 

The food you eat directly impacts the size of your lipoproteins.

If the foods you eat are full of polyunsaturated fatty acids (PUFAs) and do not contain antioxidants, then that’s a problem. Polyunsaturated fats are extremely susceptible to oxidation, which distorts them and makes them impossible for your body to process. Trans fat is one example of a distorted fat, and its so bad for us it’s been outlawed in several cities. But all PUFAs can distort during cooking or storage, even beneficial omega-3 fats like those in fish oils. One recent study concluded consuming these supplements exposes us to unacceptable levels of oxidized oil.

Because of what I know about lipid oxidation, whenever I find that a patient has small LDL particles, I take a complete diet history. And I start by assessing intake of these most commonly oxidized oils:

If you’re eating at restaurants (even high-end ones) or consuming store-bought salad dressings, condiments, dips, chips, granola, and other snack foods, even if they’re organic, you’re probably getting between 15-30% of your daily calories from these oils (or other less common, i.e. grape seed and rice bran oils) which are contaminated with toxic pro-inflammatory compounds in a concentration that ranges between 2-25%. Even if your Paleo plan is dialed in, there’s still a good chance you’re being exposed to these toxic oils if you’re not careful.

These pro-inlammatory fats act like tiny little explosives. They directly degrade you lipoprotein fat-delivery trucks to the point that they’re unable to function. Damaged lipoproteins lead to damaged arterial walls, leading to cardiovascular disease.

Bottom line, it’s not the kind of trucks carrying cargo around (LDL versus HDL, etc) it’s the kind of cargo they’re carrying. If the cargo is explosive, the trucks can’t drive to their destination and will end up overturned, spilling their contents inside your arteries.

Don’t want explosive cargo? The simple fix is to cut out industrial seed oils. Eat out less if you can, and when you do dig into restaurant fare, don’t be afraid to ask questions about the oils they use. Even the Olive Oil might be Canola in disguise.

Side-Note: your doctor probably won’t know this! We don’t learn about this in our regular training; I only know because I did graduate work in biochemistry at Cornell, and learned enough to understand the underlying chemistry of lipid oxidation, the molecular burning process that interferes with lipoprotein function.

The Best Test for Arterial Disease

So, you’ve cut out the industrial seed oils…but how can you truly ensure that lipoproteins are healthy and functioning?

There are quite a few tests out there that assess your risk of heart attack and stroke: coronary calcium beam tests, EKG, nuclear medicine scans, and angiograms—just to name a few. The tests I find most useful can tell me whether or not a your diet is optimal or if it may be contributing to plaque build up, thus increasing your chances of heart attack, stroke, blood clots, arterial claudication and more.

For a full assessment, I’ve created a panel of several relatively inexpensive fasting blood tests that I use to assess my patient’s risk: Insulin, Glycated Hemoglobin, CBC and and advanced lipid panel called CardioIQ. Each has a specific use, but the one that I want to focus on here is the CardioIQ, a test that helps to tell me whether or not your body is able to properly process the fats you eat and the fats your body makes. 

As we’ve established, dysfunctional lipoproteins carry less cholesterol and less fat than healthy lipoproteins because they’ve partially delivered some of their cargo. This makes them smaller. This is where the CardioIQ test comies in. Because a this test is one of the few currently available tests that can evaluate the size of the particles, it’s one of the best ways to answer the question about how well your particles function. A regular cholesterol test does not give you this information.

Now that you know what test you should get, here’s what the results mean:

If you have abnormally small LDL particles present in abnormally high numbers, that’s a problem. Remember, healthy LDL particles are big and fluffy and full of lipid cargo. Small LDL particles are partly emptied out. If you have small HDL present in abnormally low numbers that’s also a problem for essentially the same reason. If you’re interested in more detail on this, I explain why LDL particle counts go up and HDL go down in my bookDeep Nutrition.

The CardioIQ helps me assess the health of your lipoproteins, how well they’re working, which is more important than just knowing how much cholesterol and fat they’re carrying.

Before I let you go, there’s one very important thing you need to know if your LDL number is really high (over 190) and your particle size is good. LDL over 190 with large size particles can be a red flag indicating you have a genetic condition called familial hyperlipidemia, found in roughly 1 in 500 people. Roughly 50% of men with this condition have a heart attack by age 50, and women are also at extremely elevated risk. This possibility is something you need to suggest to your doctor, because many of us docs forget about this condition. If this sounds like you, I suggest you read up on it here. If your doctor is not familiar, ask for a referral to a lipidologist.

If you do have a genetic condition, this makes it all the more essential to keep your lipoprotein particles as healthy as possible. You can do that by eating plenty of antioxidant-rich fresh vegetables in salads (with home-made dressing), or gently steamed…good advice for all of us, genetic condition or not.

And remember, when it comes to knowing which fats are good and which are bad there’s really only one rule to keep in mind: Nature doesn’t make bad fats. Factories do.


The Paleo movement incorporates several different optimizing perspectives for helping you improve your health, all based on the latest science. Everyone is different. We want to support you in understanding your unique genetic makeup, symptoms and health goals so you can choose the path that is right for you.

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Dr. Cate Shanahan

Cate Shanahan MD specializes in weight loss, sports performance, and elimination of medication dependence using traditional foods.