Cholesterol: Fact from Fiction

In this day and age, nearly everyone knows that high cholesterol is bad for your heart. In fact, the vegan movement has embraced this one in stride because, they claim, all animal products are responsible for heart disease, and nothing else is. But did you know you can have a cholesterol count in excess of 300 and still be healthy? How about the fact that fish, low fat, and fat free dairy products actually help prevent heart disease? How about that not all cholesterol is bad? And did you know you can lower your cholesterol, or keep it from becoming a problem in the first place, without going vegan?

This blog post is a bit different, because I'm basing it on information I read in a book. I'm home from college for the summer, and so I have time to read more. The book I read is called The Harvard Medical School Guide to Lowering Your Cholesterol, by Mason W. Freeman, M.D., who was an associate professor of medicine at Harvard Medical School, and is the chief of the Lipid Metabolism Unit at Massachusetts General Hospital. He also served as a head of the Novartis Translational Medicine program for Cardiovascular & Metabolic Diseases, and played a key advisor role at Relypsa, which developed the first chronic oral therapy for hyperkalemia, a potentially fatal condition affecting patients with kidney and heart disease. So basically, if anybody knows anything about cholesterol, it's this guy.

This blog post will contain page number citations, and you can get it on Amazon Kindle for ten bucks. However, it's also important to note that this book was published in 2005, so not all of the information is up to date. For example, at that point in time, doctors thought saturated fat was nearly as bad as trans fat, and yet recent research has shown that the relationship between saturated fat and health problems is a lot more complicated than that. For example, studies have found that saturated fat undeniably raises LDL (bad) lipoproteins, but it also raises HDL (good) lipoproteins in the same amount, so that the ratios stay the same. I'll explain more about different types of cholesterol-carrying lipoproteins in a moment. The problem comes with increased sugar consumption as well, which keeps the HDL from rising with the LDL and creates a problem. Cardiologist Aseem Malhotra, M.D. explains, "I am not for one minute suggesting that people over-indulge in saturated fat, but certainly from the evidence I have seen, the demonization of saturated fat has resulted in increased consumption of refined carbohydrates, which has resulted in greater obesity, and, in my view, has a stronger implication in heart disease. Furthermore, there is increasing evidence to suggest that excess consumption of omega-6 in vegetable oils may be atherogenic (i.e., damaging to the coronary arteries) by oxidizing LDL cholesterol particles," (In an interview with Whole Foods Magazine, discussing his peer reviewed paper, Saturated Fat Is not the Major Issue, published in the British Medical Journal in 2013, and referencing a paper called, Meta-Analysis of Prospective Cohort Studies Evaluating the Association of Saturated Fat With Cardiovascular Disease, which was published in the American Journal of Clinical Nutrition in 2010). Instead, researchers are now shifting their focus to sugar, which Freeman discusses in his book as an additional cause of high cholesterol, and therefore heart disease.

In spite of this antiquated view of saturated fat, however, Freeman doesn't ever advocate for giving up animal products entirely. Instead, he advocates for consuming meat in moderation (only about once or twice a day), and to choose lean cuts that lower fat intake, to prevent cholesterol numbers from rising.

But what is cholesterol?

Cholesterol is both a fat (I'll refer to fat molecules as lipids from now on) and a sterol (the main components of steroid hormones). But because they're part of the lipid family, cholesterol by itself is hydrophobic, meaning it doesn't mix with water. As you can imagine, this is a problem when it's dumped into the blood, whose main component IS water. To get around this issue, the body adds a protein to a lipid package that makes digested lipids soluble in water. We call these protein/lipid packages lipoproteins.

There are two main types of lipoproteins: low-density lipoprotein (LDL), and high-density lipoproteins (HDL). They differ in that HDL particles have more protein and less lipid in them, and LDL particles have more lipid and less protein. According to Freeman, "In most people, 60 to 70 percent of cholesterol is carried in LDL particles. LDL particles act as ferries, taking cholesterol to the parts of the body that need it at any given time," (page 3). So SOME LDL cholesterol is good, because it serves a purpose, in ensuring all the body's cells get the cholesterol they need for healthy cell membranes, to build bile acids necessary for intestinal digestion, and to produce vitamin D, and hormones like estrogen and testosterone that are necessary for survival and reproduction. The problem comes when there is too much LDL cholesterol in the blood. When this occurs, the LDL deposits cholesterol into arteries, which causes blockages and leads to heart attacks. HDL, on the other hand, has the opposite effect. Because it has more protein, it acts as a sponge, soaking up excess cholesterol in the blood and carrying it back to the liver, which either uses it to make bile or recycles it, if there's need for more cholesterol. That's right. The liver regulates cholesterol levels in the blood, and makes more cholesterol if the body needs it, even if you don't consume much dietary cholesterol. Why is this important? I'll explain in a minute. But I can't tell you how many times someone on social media has told me, "I bet you think cholesterol is good for you, don't you?" or "There's no such thing as good cholesterol! And since I'm a vegan, I'll never have high cholesterol at all!" Both are dangerous attitudes to have since they're as scientifically wrong as wrong can be. In fact, on page 6, Freeman states, "Your body does need food to fuel the cholesterol production process, but it can be virtually any kind of food, even the cholesterol-free kind. As long as the food contains carbon-which carbohydrates, fats, and proteins all do-it provides the body with the building blocks to make its own cholesterol." Sorry, vegans. Unless you only eat rocks, your body can make cholesterol.

Incidentally, this is why one can have a high cholesterol count and not be at risk for heart disease. For example, in the preface of the book, Freeman discusses a patient of his whose cholesterol count was over 300, which is extremely high and usually indicates a risk of heart attack. However, upon further testing, it was discovered that it was HDL which was high, and that LDL was low. This meant she was actually at low risk of heart attack, although she was advised to get a little more exercise.

But what of diet? It does have an impact. There's no debate about that. After eating a rich meal, the intestines package lipids called triglycerides and cholesterol into very low density lipoproteins called chylomicrons. For several hours after a meal, VLDL levels continue to peak. Eventually, enzymes take the triglycerides and place them into muscle or adipose (body fat) cells, until all that's left of the chylomicron is a chylomicron remnant, which is absorbed by the liver and recycled. However, there are other kinds of VLDL whose remnants remain in the blood, however, and are converted to LDL. And because there are usually more circulating LDL particles than your body can use, the liver is supposed to remove them and make them into bile or new lipoproteins. But if there are far too many and the liver can't keep up, they stick to blood vessels and become plaque. However, HDL helps the liver out so that it can trap chylomicron remnants and VLDL.

So how do I prevent heart disease?

Interestingly enough, Freeman doesn't say to cut animal products out of your diet entirely. In fact, he says on page 75, "Dietary calcium has no effect on atherosclerosis. In fact, a moderate amount of calcium from non- and low-fat dairy products helps lower blood pressure, reducing cardiac risk."

His major problem in this book seems to be fat, specifically trans and saturated fat. You'll get no argument from me that trans fat is bad, but Freeman didn't have the research we now have that proves our relationship with saturated fat is very complex, and a grey area of sometimes good and sometimes bad. In my opinion, though, you should still watch how much fat you're consuming because the body is very good at digesting fats, and fats are the most calorie-dense of all the macronutrients. Too many calories lead to lipids being deposited in the adipose instead of the muscle, and this causes obesity, which Freeman states is a definite cause of heart disease. However, Freeman is right when he says some fats are definitely good because they lower HDL. These two healthy fats are known as polyunsaturated fat (PUFA) and monounsaturated fat (MUFA). PUFAs consist of Omega 3s and Omega 6s, which are found in vegetable oils like corn oil, and in fish and seafood. In fact, Freeman is a big fan of fish (an animal product) for heart health. MUFAs, on the other hand, comes from oils like olive oil, avocados, and nuts.

But here's where it gets interesting. Freeman also emphasizes that carbohydrates (specifically refined carbohydrates like rice, sugary snacks, white bread, and pasta) have such a profound negative impact on heart health that he actually puts them in the "use sparingly" portion of his healthy eating pyramid on page 119, along with high glycemic foods like honey and potatoes. These foods contribute to insulin spikes, which significantly affect one's chances of obesity, diabetes, and, yes, heart disease. You can see how this becomes a problem if you're drinking rice milk instead of heart-healthy, low-fat dairy, because you hate farmers. Or if you're substituting potato-based starches for eggs when you bake. Or if you're using butter made out of coconut oil (which is pretty much pure saturated fat) because you think coconut oil is a cure-all, or vegan cheeses, again made out of coconut oil and potato starch. Not to mention that many vegan recipes that I've seen are rich in pasta and other refined carbs, because they fill you up in the absence of proteins. This is especially bad because Freeman states that the smaller the pieces of the carbohydrate, the worse the insulin spike, which increases your risk of mouth, stomach, colon, gallbladder, and ovarian cancers. And these insulin spikes also trick your liver into producing more cholesterol, which, as you'll recall, can be a problem that leads to heart disease. Not to mention that the current research I mentioned earlier also states that dietary sugar and refined carbs, as well as high-glycemic foods like potatoes, are a factor in raising LDL, since your body can make it.

And lastly, Freeman recommends daily exercise as part of a heart-healthy lifestyle. The importance of exercise cannot be overstated. Not only does it prevent obesity by ensuring that lipids go to the muscle instead of the adipose (this is why bodybuilders can eat a mountain of food and not put on fat), but it helps lower LDL by raising HDL.

The bottom line?

Animal products in and of themselves aren't to blame for the heart disease epidemic that plagues America. In fact, some animal products like low-fat dairy and fish may help decrease risk, and because animal products are excellent protein sources, they should not be substituted for high-glycemic dairy, meat, and egg substitutes like potatoes and rice, and for foods like coconut oil that are pretty much pure saturated fat. The focus on stopping heart disease should instead be on sugar, not meat, especially since our relationship with saturated fat has become more of a grey area of sometimes good and sometimes bad. It's not animal products that are the problem, and using them as a scapegoat just because you hate farmers isn't cool. All in all, the book I read was interesting and educational, and I would encourage you all to go to your local library (Fun fact! did you know there are more libraries in America than there are McDonald's, even omitting school libraries?) and pick up a book! You never know what you might learn!

MLA Citation for the book

Freeman, Mason W., and Christine Junge. The Harvard Medical School guide to lowering your cholesterol. New York: McGraw-Hill, 2005. Print.