Since the days of Ancel Keys, the man who first introduced the theory that a high-fat, high-cholesterol diet causes heart disease, many individuals have been concerned about their cholesterol levels. While the more LDL (low-density lipoprotein) cholesterol running around in the bloodstream, the higher the potential for heart attack and coronary artery disease, the problem of plaque build-up and the resulting inflammation is more complex.
Heart Disease Begins When LDL Cholesterol Invades Damaged Arteries
Heart disease begins with repeated injury to arterial walls. This injury allows small, dense LDL cholesterol to make its way into the inner lining of the arteries, setting the stage for heart disease. Without injury to the arteries, plaque cannot form, since its presence is an attempt to heal the body of the damage. Arterial injury is thought to occur in a variety of ways:
- high blood pressure
- tobacco smoke
- diabetes
- inflammatory stresses involving the immune system
- a virus or bacterial infection
- chemical abnormalities in the blood
The more LDL cholesterol circulating in the blood, the greater the chance that small, dense LDL particles will get trapped in the arterial lining once it’s been injured. While high circulating insulin and the resulting insulin resistance are linked to high cholesterol synthesis and decreased cholesterol absorption, the path that actually leads to heart disease requires an immune system response. As long as the LDL particles are not chemically altered or damaged, the body won’t consider them a threat.
Coronary Artery Disease Risks: How LDL Particles Get Damaged
There are two ways that LDL particles become chemically altered or damaged. One way is through oxidation by free radicals, and the other is by being irrevocably bound to sugar in a process called glycolation. Both processes result in damaged LDL cholesterol and are, therefore, risk factors for coronary artery disease. Damaged LDL particles cause the immune system to begin an attack against them.
White blood cells called macrophages attach themselves to the artery wall and burrow into the lining. Their job is to eat and digest the damaged LDL particles. During this process, the white blood cells transform into foam cells, and begin collecting cholesterol, fatty material, and cell debris as a way to plug up the damage.
Although the plug makes the blood vessel lining bulge slightly into the artery, it is not large enough yet to restrict blood flow. However, once the first stage of plaque build up begins and the mass firmly attaches itself, smooth muscle cells from deeper within the artery lining migrate upwards.
Insulin Resistance Speeds Plaque Build Up
If an individual is insulin-resistant, high fasting insulin levels cause these muscle cells to migrate rapidly. Once at the area of plaque build up, with the help of insulin’s ability to stimulate increased synthesis of collagen and other connective tissue, the muscle cells grow or merge with the macrophages.
When enough foam cells accumulate, they form patchy deposits large enough to restrict blood flow. If plaque build-up continues, it can attract calcium crystals which attach themselves to the plaque mass resulting in hard, brittle arteries. Calcium is the last stage in the process of heart disease; after which the plaque can crack, ulcerate, and release debris into the bloodstream, further narrowing the passageway.
Reduce Insulin Levels to Reverse Heart Disease
Reversing the damage before plaque reaches the stage of calcification is possible, but only if insulin levels are reduced; artery recovery is not possible in the presence of hyperinsulinemia. This is because elevated insulin levels encourage glycolation and excess LDL cholesterol formation, speed up the migration of smooth muscle cells from the artery interior, and increase synthesis of collagen and connective tissue.
Heart disease is when plaque builds up in an artery leading to the heart. However, any artery can be injured, laying the initial groundwork for damaged LDL particles to invade and begin the process of coronary artery disease. To reverse the process of plaque build up and thereby regain cardiovascular health, a diet that lowers basal insulin levels needs to be considered and implemented.
For more information on the effect of small, dense LDL particles being more detrimental than the large, fluffy variety, see Does the Atkins Diet Raise LDL Cholesterol Levels.
References:
Merck Manuals, online medical library, merck.com, “Atherosclerosis” (accessed July 26, 2010)
Journal of Lipid Research, Pihlajamakl, Jussi, Gylling, Helena, Miettiner, Tatu A. and Laakso, Markku, “Insulin resistance is associated with increased cholesterol synthesis and decreased cholesterol absorption in normoglycemic men,” 45:1, 507-412, 2004; doi:10.1194/jlr.M300368-JLR200
Eades, Michael R., M.D. and Eades, Mary Dann, M.D., Protein Power: The High-protein/Low-carbohydrate Way to Lose Weight, Lower Cholesterol and Blood Pressure, and Restore Your Health – in Just Weeks!, Bantam Books, 1996
Vickie Ewell - Vickie has worked with autistic individuals for 9 years. She has celiac disease and specializes in gfcf living.
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