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Summary
On episode 529 of 40+ Fitness, Coach Allan sits down with Dr. Malcolm Kendrick, a general practitioner and author who has spent his career questioning the conventional understanding of heart disease. His book, The Clot Thickens: The Enduring Mystery of Heart Disease, lays out an alternative hypothesis for what actually causes heart attacks and strokes.
Malcolm argues the cholesterol hypothesis has never held up well under scrutiny. Things that clearly cause heart disease, like smoking and diabetes, do nothing to raise LDL cholesterol, which suggests something else is driving the damage.
His alternative is a thrombogenic (blood clotting) hypothesis: damage to the lining of the artery triggers small blood clots that get sealed over and built into the artery wall, repeating over and over until one clot finally blocks the artery. The conversation covers what actually damages that lining, including blood sugar, stress, and homocysteine, and what listeners can do to protect it.
Links
- https://drmalcolmkendrick.org
Key Takeaways
- The cholesterol hypothesis doesn't hold up under scrutiny. Things known to cause heart disease, like smoking, diabetes, and high blood pressure, don't raise LDL cholesterol at all, so there's no mechanism connecting them to the standard theory. Once an idea like this takes hold and gets reinforced by real drops in heart disease from statins, people stop looking for other explanations.
- Heart disease is a blood clotting disease, not a cholesterol deposit disease. Damage to the endothelium (the lining of the artery) exposes a substance called tissue factor, which triggers a clot. New endothelial cells grow over that clot, trapping it inside the artery wall rather than on top of it.
- Plaques grow the same way they start: damage, then clot, repeated. Repeated cycles of endothelial damage and clotting at the same spot narrow the artery over time, like potholes that keep reforming in the same place in a road, until a final clot big enough to fully block the artery causes a heart attack or stroke.
- The cholesterol found inside plaques doesn't come from LDL. LDL carries cholesterol as cholesterol esters, which cannot form crystals. The free cholesterol needed to form the crystals seen in plaques can only come from red blood cell membranes, not from circulating LDL.
- Lipoprotein(a), or LPA, may matter more than LDL. LPA is an LDL particle with an extra protein attached that blocks the enzyme responsible for breaking down blood clots. That makes clots at damaged arterial sites harder to clear, accelerating plaque growth wherever arterial damage already exists.
- High blood sugar directly damages blood vessels, large and small. Elevated glucose breaks down the glycocalyx, a protective coating on blood vessel walls, exposing them to injury and clotting. The same process in small vessels causes diabetic blindness, kidney failure, and amputations, all versions of the same underlying disease.
- Chronic stress drives blood sugar problems and heart disease. Cortisol works against insulin, and populations under sustained psychosocial stress show dramatically elevated heart disease rates. Malcolm points to young Aboriginal Australian women, whose heart disease rate runs roughly 30 times higher than the surrounding population.
- Elevated homocysteine damages arteries and may contribute to Alzheimer's. Homocysteine is a normal breakdown product that becomes damaging to the glycocalyx and endothelium at high levels. Certain B vitamins, folate, B6, and B12, help the body clear it.
- Dr. Kendrick's three strategies to get and stay well: protect your mental well-being through good social connection and getting out of stressful or unhappy situations; if your blood sugar runs high, cut carbohydrate intake; and get outside in the sunshine while you exercise.
“The first step is damage to the artery wall followed by a blood clot. The growth is damage to the artery wall followed by a blood clot. And the final event is damage to the artery wall followed by a big obstructive blood clot.”
Dr. Malcolm Kendrick
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