In a new book, Scottish doctor Malcolm Kendrick outlines what he believes really underlies cardiovascular disease.
There’s a huge clue in the title. It’s called The Clot Thickens so it’s no surprise that he thinks the key is blood clotting.
Heart disease and stroke, he says, start with damage to the lining of arterial walls. A clot forms over the damaged area, like a scab. A new layer of lining then grows over the clot, which becomes encased in the arterial wall.
In most cases, what’s left of the clot might break down and be removed, but if the damaged area is large, if several clots occur in the same spot, or if the body’s repair systems aren’t working so well, the clotty build-up (or plaque) can restrict blood flow.
People who champion the cholesterol theory also see plaque as a major problem, but they believe it occurs because we eat saturated fat which increases LDL-cholesterol, and this LDL-C finds its way into the arterial wall.
Kendrick argues that anything which damages the arterial wall, hampers the repair process, or makes the blood clot more easily increases our risk of heart disease or stroke.
He came to this conclusion after decades of trying to understand why our risk of cardiovascular disease is increased by so many different things.
We commonly hear about diabetes, high blood pressure, cholesterol, visceral fat, smoking and so forth, but there are a host of other factors that also beef up our risk, often dramatically, but are talked about far less.
These include air pollution, drugs such as cocaine, some health conditions (e.g. rheumatoid arthritis, lupus, chronic kidney disease and mental illness) and certain medications such as proton pump inhibitors.
Let’s take a quick look at how clotting features in this broad spectrum of risk factors.
Diabetes and metabolic syndrome
You might remember I wrote last year about a major American study on what causes heart disease in women. First and second place went to the twin disorders of type 2 diabetes and metabolic syndrome.
Metabolic syndrome refers to a cluster of five conditions: high blood sugar, a big waist, high blood pressure, high triglycerides, and low HDL cholesterol.
High blood sugar is bad news for arteries. The lining of a healthy artery has a protective coating — like Teflon — which helps guard against clotting. High blood sugar strips it away.
Heart disease in women isn’t necessarily caused by the kind of plaque blockage I mentioned above. We, more than men, are susceptible to damage in much smaller blood vessels which, if they lose their protective coating, can stiffen, swell up, leak or burst.
If some small vessels are destroyed this way, blood pressure will increase because the blood has to work harder to get through the remaining ones.
Of course, blood pressure will also rise when plaque build-up limits the space the blood can travel through. So while we commonly think of raised blood pressure as leading to heart disease, in fact, it’s a sign that the process is already underway.
Smoking, air pollution and other smoky things
Smoke generally damages arteries, as does anything involving tiny toxic particles that can be inhaled into our lungs and enter the bloodstream.
It’s not good news for people who work around fine dust (e.g. from coal or crystalline silica) or fight fires.
In addition, COPD (chronic obstructive pulmonary disease) greatly increases the risk of heart disease. While COPD is serious in its own right, damaged lungs are a sign that nasty substances have been entering them, leaking into the blood and affecting the arterial lining for years.
In the same way that snorting it destroys the nose, cocaine destroys the cardiovascular system by attacking the arterial lining. How it became the drug of choice for the cool set is anyone’s guess.
Some health conditions e.g. rheumatoid arthritis, lupus, chronic kidney disease and mental illness
Rheumatoid arthritis and lupus are autoimmune diseases. While any autoimmune condition can increase our risk of heart disease and stroke, some do so more than others. The inflammation typical of these conditions damages the blood vessels. On top of that, the steroid medications used to treat them can spike blood sugar.
While kidney disease is often caused by diabetes, several drugs can be a problem too. These include painkillers codeine and morphine, and anti-inflammatories such as ibuprofen (Nurofen) or diclofenac (Voltaren). The latter make us clottier. They’re fine short-term but not for long periods.
In older people, dehydration also damages kidneys too, which is one important reason to drink enough water.
Kidney disease and blood pressure affect each other—high blood pressure is bad for the kidneys, and kidney disease raises blood pressure.
Mental illness increases our risk of cardiovascular disease through the production of the stress hormone cortisol.
Cortisol is a fight or flight hormone. When the body thinks it’s about to fight or flee, it releases glucose from places such as the liver to provide quick energy.
If we don’t end up doing either of these things, we’ll have extra sugar running around in our bloodstream. This has to go somewhere, and it’s stored as fat around our organs.
To join the dots, cortisol raises our blood sugar which can increase fat around our middle. This can lead to type 2 diabetes, which destroys the lining of the arteries and their protective coating.
Proton pump inhibitors
These are commonly prescribed drugs for treating reflux. They tend to end in -prazole, so for example, Omeprazole is sold as Prilosec, and Esomeprazole is Nexium or Guardium.
They’re only meant to be used in brief spurts, but they’re often taken for years, and they impair the lining of the arteries.
If you need a long-term way to reduce stomach acid, choose a product that works differently, e.g. Ranitidine, which is branded as Zantac.
The list of factors that amplify our risk of cardiovascular disease doesn’t end there, but hopefully the ones I’ve mentioned are enough to give you a sense that it’s diverse collection.
The bottom line is that they all harm or inflame the lining of our arteries, which encourages blood clotting.
In addition, menopause and ageing hamper our arteries’ ability to repair themselves, making us more vulnerable to this damage and clotting as we get older.
I think Kendrick is on the right track. For now his case won’t shift the medical world’s attachment to the cholesterol theory, but the idea that saturated fat increases LDL-cholesterol can’t explain how wood fires, cocaine or diseases such as lupus contribute to heart disease, as they very much do.
Clearly the picture is far bigger than that.
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