What Causes Heart Disease?
If it's not saturated fat, what is it?
The data implicating saturated fat as causing heart disease, as I explain in this post, have come crashing down.
The most accurate way to talk about heart disease is in terms of risk factors instead of direct causes.
Evidence is mounting to show that some of the old risk factors were inaccurate.
Previous risk factors were thought to be:
High saturated fat intake
High cholesterol (LDL)
High red meat consumption
Risk factors based on newer research:
High insulin levels
High blood sugar levels (HbA1C, or average 3-month glucose levels)
High levels of chronic inflammation (C-reactive protein is one common marker)
High consumption of sugar and ultra-processed food
Risk factors both paradigms agree on:
Family history
Smoking
Stress
High waist-to-height ratio
High blood pressure
One reason why Keys’ theory that saturated fat causes heart disease stuck around for so long was that science needed to advance before evidence could show other pathways. That said, many voices, even during Keys’ time, believed sugar and carbs to be the culprit but had difficulty proving it.
The latest theories about why heart disease develops are complicated and not easily made into a bumper sticker or a slogan. These theories admit the multifactorial nature of heart disease and require some sophisticated knowledge of how the body works. Let’s take a stab at examining some of the newer theories.
High Blood Sugar as a Major Contributor to Heart Disease
The scientist and physician Joseph Kraft devoted his life to understanding heart disease, insulin resistance, and diabetes. He wrote:
Those with cardiovascular disease not identified with diabetes are simply undiagnosed.
This is a bold statement, and whether or not it can be proven that heart disease never develops without diabetes, this statement at least shows that Dr. Kraft’s decades of research found the terrible destruction that high blood sugar has on the heart.
A review study from the journal Circulation Research titled “Basic Mechanisms of Diabetic Heart Disease” confirms that diabetes causes damage to the heart:
Diabetes mellitus predisposes affected individuals to a significant spectrum of cardiovascular complications, one of the most debilitating in terms of prognosis is heart failure.
The irony here is that when saturated fat was demonized for causing heart disease, the processed food industry capitalized on this bad science by producing the fat-free food rage which peaked in the nineties. These ultra-processed food products, such as the SnackWell brand, replaced fat with sugar. And these Frankenfoods were deemed heart-healthy since they were fat-free. In reality, all that sugar was fueling heart disease.
This old heart disease paradigm is presumably why something as highly processed as Cheerios still claims to be heart-healthy today.
Aw, just look at how adorable that heart-shaped bowl is:
Moms who truly love their kids give them Cheerios. It helps lower the kids’ cholesterol. This is somehow good even though kids desperately need cholesterol for their brains to develop properly since the white matter of the brain is made up entirely of cholesterol. And the highly-processed oats have one of the highest levels of glyphosate (aka Round Up) of any industrial product and will produce inflammation that isn’t heart-healthy. But what do I know?
Below is a helpful diagram from the above-cited study showing how diabetes and prediabetes damage the heart. Keep in mind that diabetes researcher Dr. Jason Fung estimates that at least half the US population has either prediabetes or diabetes, and heart damage begins in the prediabetes stage.
Below could be our answer to why heart disease rates have sky-rocketed since the 1900s, at the same rate as processed food consumption has risen.
One thing you’ll notice in this diagram is the complexity of the problems to the heart caused by high blood sugar.
Inflammation’s Effect on Atherosclerosis
The pathway I want to deal with today is one of only ten listed above: inflammation’s effect on atherosclerosis (the deposit of plaque inside the artery wall.)
Let’s examine this quote from Basic Mechanisms of Diabetic Heart Disease:
In addition to the pro-inflammatory state evident in diabetes, how the body attempts to recover from this continuous insult may also be impaired.
My translation: Diabetes does two things: it causes chronic inflammation in the body, and it impairs the body’s ability to fight this inflammation.
We talk about inflammation on this Substack quite often, and I frequently implicate chronic inflammation as both the major driver and consequence of most modern diseases.
But let’s pause for a moment and define what it actually is. Acute inflammation happens when you bang your head and immediately develop a goose egg. This swelling is a result of the body sending reparative fluids including immune cells such as white blood cells, to the site of the injury. Acute inflammation is necessary for healing damaged tissues.
Chronic inflammation occurs when the body remains in a state of elevated stress. In the case of diabetes, this stress is the result of high levels of insulin and glucose which damage delicate tissues. This causes the insides of veins (epithelial cells) to become inflamed.
Infiltrating macrophages [white blood cells] exhibit defective phagocytosis [absorbing of harmful particles] of apoptotic neutrophils at the site of vascular inflammatory injury (efferocytosis)182.
My translation: When blood sugar is high, we’ve got a problem in the veins. Incidentally, this problem has nothing to do with the amount of saturated fat or cholesterol in the blood.
Instead, macrophages, a kind of white blood cell whose job is to remove dead cells and debris, are not properly absorbing apoptotic neutrophils (dead cell debris) in the injured and inflamed veins. Because the macrophages are not clearing away the debris, dead cells accumulate inside the veins. This contributes to further inflammation and delayed healing of tissue.
It is thus possible that defective resolution of inflammation may hence represent an additional mechanism of diabetes-induced cardiac damage secondary to macrophage infiltration, as is evident in other tissues192–194.
My translation: There are at least two pathways at work in how diabetic inflammation damages the heart (and keep in mind that inflammation is only one of ten ways diabetes damages the heart). The first is the infiltration of macrophages (aka pus). These cells have a very short lifespan, so they die, and dead cell debris accumulates. The second is the known fact that diabetics have an impaired ability to heal any tissue, aka diabetic ulcers. So it makes sense that the tissue lining the veins and arteries would not be able to heal either. This inflamed mess gets lined with puss and cholesterol in an attempt to mitigate the damage.