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There are quite a number of myths and quite a lot of controversy surrounding the issue of cholesterol. Some say it’s the cause of one of our deadliest conditions in the world–heart disease. While some say it doesn’t matter whatsoever. The truth probably lies somewhere in the middle.
The information I’m about to share will help provide some clearer answers to the whole cholesterol debate, particularly in regards to diabetes. And like all things we do here, we’ll explain it in easy to understand language and back everything we say with evidence.
Keep in mind that even much of the research shows contradictory results and may be distorted, in part, by research bias and interpretation of results – something that can occur quite frequently in science.
One thing to be aware of up front is that diabetes is highly correlated with heart disease – meaning, if you have type 2 diabetes, your risk of heart disease increases. Therefore, cholesterol is a key laboratory component doctors look at to assess your individual risk.
To understand cholesterol, heart disease, and diabetes and potential linkages, let’s first take a look at some of the physiology behind all this. Once you understand how your body works, it will help you understand cholesterol better.
Your Heart and Heart Disease
The main job of your heart is to pump oxygenated blood through the body, which provides cells and structures what they need to function correctly (nutrients, proteins, fats, carbs, enzymes, hormones etc, which are carried in the blood).
Your heart pumps blood to the body through arteries and receives it back through veins. If arteries are damaged (which is initiated by excess inflammation), plaque can build up at the damaged site. This plaque consists of many materials flowing through the bloodstream, one of which is cholesterol, a waxy substance produced by the liver.
As plaques become larger, they block more and more of the artery making it difficult for blood to flow through as it should. The need for blood to get to tissues causes the heart to pump more vigorously, increasing blood pressure. Excess sugar in the bloodstream complicates this process further, making the blood more viscous and difficult to pump.
Additionally, excess sugar in the bloodstream can be one of the key causes of that initial arterial damage (because excess sugar causes inflammation). If the plaque becomes increasingly blocked the blood vessel will have to be bypassed so the heart can use a different vessel (this requires major heart surgery).
If this is not caught in time and the plaque ruptures, the blood in the artery will clot and deprive the heart of oxygen. This is a heart attack. The heart muscle will die without emergency intervention to remove the plaque and restore blood flow. And if you’re not aware already, heart disease is the leading cause of death in the US and most other countries worldwide.
Based on the above explanation, it might be logical to conclude that cholesterol is “bad” and therefore we should avoid it at all costs ensuring that our diets are free from it. That’s what the public has been told for many years. However, we’ve learned that’s an overly simplistic line of thinking for many reasons.
Cholesterol is a essential for many body functions
While cholesterol is not considered an “essential nutrient,” that’s only because of the way in which cholesterol is defined as “it is required through the diet because the body cannot make it.”
This is incorrect.
The body CAN and DOES make cholesterol even if it’s not consumed in the diet because humans REQUIRE it to live. Cholesterol is a component of every cell necessary to maintaining its structure and is crucial for brain function. It is also required to make certain vitamins and hormones including estrogen, testosterone, cortisol, and vitamin D.
One of the reasons we know how crucial cholesterol is to life and health is by studying individuals deficient in it. Very low cholesterol has been linked with neurological conditions (poor memory, Parkinsons) and emotional problems (depression, anger/violence, suicide), as well as increased risk of death (ironically often from heart disease).
Cholesterol you eat does not equate to higher cholesterol in the bloodstream
This is perhaps one of the biggest misconceptions. We are always hearing things like “I can’t eat eggs because they are high in cholesterol” “your meal plans are so high in cholesterol” “I need a low cholesterol diet” – but here’s the truth of it: cholesterol in your diet has very little to do with cholesterol in your bloodstream.
Because cholesterol is a key nutrient, if we reduce our intake, our bodies will attempt to make more of it and if we eat more of it, the liver doesn’t make as much, and if there is an excess it will likely die off. This is the exact opposite of what we’ve all been led to believe all these years — the high cholesterol foods to not cause high cholesterol, your liver produces it internally.
While this has been evident in the research for quite some time, and the Dietary Guidelines committee made recommendations to the US government to remove the guidelines from public opinion (because there is no evidence), the latest 2015 Dietary Guidelines still include the same age old cholesterol recommendations – such a pity!
High cholesterol may not necessarily be a problem
Cholesterol in the bloodstream may not a problem if there isn’t arterial damage. Because the only way plaques can begin to form is if there is damage to the artery – cholesterol (at least in the way we think of it) does not cause that damage.
This artery damage can be caused by excess:
- LDL-p (low density lipoprotein particles – number and size)
- A diet high in processed foods
To confuse matters further, what is often referred to as “cholesterol” on a lab test is actually not cholesterol, but “lipoproteins,” which contain various amounts of cholesterol.
For instance, cholesterol is waxy and fat soluble. Since blood is water-based, cholesterol cannot travel through it freely (think of how oil and vinegar separate even when you shake them together–oil and water always repel). So to get around, cholesterol needs to be transported in lipoproteins.
Lipoproteins are structures that are water soluble on the outside, but contain fats on the inside. Cholesterol can then embed into these lipoprotein structures, which are produced by the liver and put out into the bloodstream to transport key materials, including cholesterol.
There are actually many types of lipoproteins, but the two you’ve probably heard of most are:
- HDL (high density lipoproteins)
- LDL (low density lipoproteins)
The density refers to the weight–fat is much lighter or less ‘dense’ than protein, so HDLs will have more protein, LDLs more fat/cholesterol.
The HDL is often referred to as “good” and the LDL as “bad.” But, it’s actually a bit more complicated than this.
Much of the research has shown that there are different types of LDL:
- “small dense” – which are harmful
- “large fluffy” – which are not problematic and may be protective
Total cholesterol alone does not provide an accurate picture of where this cholesterol is located and whether it might be harmful. Having a high HDL value, which is inarguably beneficial, also contributes to higher total cholesterol. This in itself has been used as grounds to administer cholesterol lowering medication, which is a bit contradictory!
An additional helpful marker is the number of LDL and HDL particles (this is another simple lab test that can be ordered known as LDL-p and HDL-p). Triglycerides are the food-form of these fatty acids and will be mostly impacted based on what you’d eaten prior to the test.
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Diabetic Cholesterol Numbers Explained
Total cholesterol: 180–240 mg/dL or 4.66–6.21 mmol/l
Total HDL cholesterol: 40–90 mg/dL or 1.0–2.33 mmol/l for women; 35–90 mg/dL 0.90–2.33 mmol/l for men (Note: Very high HDL over 90 mg/dl or 2.33 mmol/l can be dysfunctional)
HDL cholesterol subtypes: Greater than 25 mg/dL or 0.64 mmol/l for HDL2; greater than 15 mg/dL or 0.38 mmol/l for HDL3
Total LDL cholesterol: 80–130 mg/dL or 2.07–3.36 mmol/l. NOTE: For people with type 2 diabetes, the American Diabetes Association sets the primary target for LDL at less than 100 mg/dL or less than 2.6 mmol/l.
LDL cholesterol subtype Lp(a): less than 30 mg/dL or less than 0.77 mmol/l
Total triglycerides: 50–100 mg/dL or less than 0.56–1.12 mmol/l
Triglycerides subtype VLDL3: less than 10 mg/dL or less than 0.11 mmol/l
Note: these levels include measurements from an expanded lipid test, which you can ask for from your doctor (see below for more details).
Type 2 Diabetes and Cholesterol Levels
Those with diabetes may produce more cholesterol than those without diabetes, a condition frequently called diabetic dyslipidemia. There are many theories to the proposed mechanisms, but it is likely related to the many metabolic changes that have occur in the body, which includes altered hormonal balance.
Excess insulin and high blood sugar levels increase fatty acid synthesis in the liver, which means your body produces more cholesterol, triglycerides and fatty acids. This does not occur from foods that contain cholesterol, it occurs due to high blood sugar, high insulin and hormonal changes.
This is just one more reason to maintain tight blood sugar control, production of cholesterol normalizes.
Refined Carbohydrates and Sugar
Fructose, especially high fructose corn syrup (found in many processed foods), has been shown to increase triglycerides, LDL (the “bad” stuff), and apo-B/LDL-p (higher number of the worst type of lipoprotein).
Why? Because fructose is metabolized by the liver and contributes to fatty liver. Since the liver also manufactures cholesterol, well, it goes about dealing with this sugar by creating more cholesterol.
Sugar is sucrose – 50% fructose, 50% glucose, which means sugar also produces higher cholesterol.
Like studies surrounding fructose, similar results have shown both sugar and refined starches also contribute to higher cholesterol production. So you see, it’s the carbs NOT the cholesterol or fats you eat that lead to higher cholesterol.
A lower carbohydrate diet (such as the one we encourage here) has been shown to improve metabolic syndrome, including better glucose control, improved insulin sensitivity, weight loss, lower triglycerides, better HDL and lower LDL particle number/apo-B compared with a low fat diet.
And in fact, restricting carbs while consuming plenty of cholesterol-rich foods such as eggs has been shown to reduce inflammation and risk for cardiovascular disease.
So what’s the take-home message?
Cholesterol recommendations are complicated and controversial, but many facets to them are not.
People with type 2 diabetes ARE at higher risk for heart disease and there are many lifestyle habits that can help you reduce risk.
For example, focusing on a diet rich in non-starchy vegetables high in fiber is not controversial. Including a variety of healthfully sourced protein (chicken, fish, eggs, meat) is not controversial. Including moderate amounts of healthy fats (olive or coconut oil, nuts/seeds, avocado) is not controversial.
Starches should be kept minimal but if you do choose them, higher fiber options are best.
Moderate daily exercise also helps reduce risk for heart disease – aim for 30 minutes at least 5 days of the week.
While the American Diabetes Association and other organizations recommend specific targets for LDL, HDL and triglycerides, the best way to get a good idea of your risk for heart disease is to get an extended panel of your lipids (not just HDL, LDL and TG, but also Apo-B, LDL-p) and consider your family history, your blood pressure, and blood glucose levels.
The tests to ask your doctor for are either:
NMR (Nuclear Magnetic Resonance) – a lipoprofile test that includes measurements for total cholesterol, LDL, HDL, triglycerides, insulin markers, lipoprotein particle number and size, and lipoprotein subfractions.
VAP – an advanced lipid panel that also includes the normal cholesterol numbers plus lipoprotein subfractions, particle number and size.
Also, be aware, cholesterol lowering medications can cause side effects (one of which CAN include elevated glucose levels), so be sure to discuss concerns with your physician. Some research has also shown they are not as effective as made out to be, but we’ll save that for another controversial discussion. Additionally, if you are taking a statin, it is recommended to take a CoQ10 supplement since statins reduce the body’s ability to synthesize this key enzyme.
NOTE: There are clearly exceptions including those with genetic conditions such as familial hypercholesterolemia in which the body is unable to clear LDL the way it normally does, and other situations. Each person is unique, which is why individualized care is absolutely necessary. Please discuss your health with your physician and other healthcare providers to come up with a plan that works best for you.
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