- Causes Atherosclerosis, Not Cholesterol
By Dr Harold Gunatillake Health writer
FRCS, FACS (US), FIACS (US),
AM (SING), MBBS (Cey)
How does inflammation linked with heart disease and stroke?
‘Inflammation’ is the process by which the body responds to any form of injury or infection, and its manifestations are redness (opening up minute blood vessels to bring in cellular and hormonal material for healing), swelling (increase body fluids to stack healing material), among other biochemical changes. It can happen anywhere on the skin, within the body, and even inside arteries. In fact the scientists are learning to understand that inflammation may play the initial part in all diseases, including atherosclerosis (hardening) of arteries with plaque formation.
These inflammatory changes are believed to occur in the inner lining and possibly in the muscle layers of the arteries, especially in areas where the impact of the blood turbulence is most affected. Such trauma causes tiny cracks on the inner lining which initiates the onset of inflammation. Brushing the inner lining of an artery with a tooth brush, will show the same inflammatory picture.
For many years we were given the description that the build up of plaque commences with fatty streaks within an artery leading to blockage and heart attack or stroke. This plaque become clogged by a blood clot and starves the heart with oxygen rich blood. It is observed that this theory is far from the truth as these types of blockages cause only about 3 out of 10 heart attacks.
In most heart attacks the coronary arteries are not severely narrowed by plaque. The researchers believe that vulnerable plaque may be buried inside the artery wall and may not always bulge out and block the blood flow through the coronary artery. This observation made the researchers to look at how inflammation affects the arteries, and whether inflammation could lead to a heart attack or stroke. What they found was that inflammation was the key factor in the initiation of the plaque and not LDL cholesterol, once believed to be. This vulnerable plaque was filled with different cell types that help with blood clotting, and the cholesterol found in them was just bystanders.
Pathogenesis of atherosclerosis (hardening of arteries with plaque formation) is associated with other chronic infections like rheumatoid arthritis, ankylosing spondylitis, polymyalgia, lupus and other inflammatory rheumatic diseases which includes psoriatic arthritis, and these latter inflammatory diseases also cause accelerated atherosclerosis associated with a high rate of death from heart disease. These diseases have a greater susceptibility to atherosclerosis. Atherosclerosis is also a normal aging factor in normal people, without any inflammatory condition as described above.
A team of researchers in Norway and the United States affiliated with Cleveland Clinic Foundation and Brigham and Women’s Hospital in Boston, focused on the aortas of recent recipients of coronary bypass graft surgery, and compared biopsy specimens from patients with inflammatory rheumatic disease with those from patients without such disease. Their study, presented in the June 2007 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis), affirms inflammatory rheumatic disease and smoking as independent predictors of vessel wall inflammation. The vascular inflammation might be a factor that promotes atherosclerosis and the formation of aneurysms.
At present and in the past it was believed that LDL cholesterol manufactured in the liver for the daily metabolic and endocrine requirements caused the atherosclerosis leading to heart disease and stroke. Can we believe that the very antioxidant cholesterol the liver manufactures for one’s wellbeing and survival is responsible for the inevitable atherosclerosis that occurs in arteries? The theory goes that LDL-cholesterol is good until it is made ‘bad’ by the free radicals in the blood stream. A far fledged theory to promote ‘statins’ to reduce beneficial cholesterol in the blood stream by the giant US companies through researchers and doctors to enrich themselves through such marketing.
What causes vulnerable plaque?
This would be the million dollar question. The fat droplets floating in the blood stream are absorbed by the arterial inner lining causing release of proteins (called cytokines) that lead to inflammation.
These cytokines make the artery wall sticky, which attracts immune-system cells, called monocytes present in the blood. The monocytes creep into the arterial wall and turn into larger cells called macrophages. These scavenging large cells begin to soak up fat droplets. It is these fat filled macrophages, it is believed, form plaque with a thin covering.
When this inflammation is combined with other stresses, such as high blood pressure, the thin covering over the plaque can rupture and bleed. The blood cells, mainly platelets get stuck to the sticky cytokines and clumping of these cellular material forms a clot large enough to block the artery.
Dr Dwight Lundell, past Chief of Staff and Chief Surgery at Banner Heart Hospital has this to say – “The only accepted therapy was prescribing statin medication to lower cholesterol and a diet that severely restricted fat intake. These recommendations are no longer scientifically or morally defensible. The discovery a few years ago that inflammation in the artery wall is the real cause of heart disease is slowly leading to a paradigm shift in how heart disease and other chronic ailments will be treated.
The long-established dietary recommendations have created epidemics of obesity and diabetes, the consequences of which dwarf any historical plague in terms of mortality, human suffering and dire economic consequences.
Despite the fact that 25% of the population takes expensive statin medications and despite the fact we have reduced the fat content of our diets, more Americans will die this year of heart disease than ever before.
Statistics from the ‘American Heart Association’ show that 75 million Americans currently suffer from heart disease, 20 million have diabetes and 57 million have pre-diabetes. These disorders are affecting younger and younger people in greater numbers every year.
Simply stated, without inflammation being present in the body, there is no way that cholesterol would accumulate in the wall of the blood vessel and cause heart disease and strokes. Without inflammation, cholesterol would move freely throughout the body as nature intended. It is inflammation that causes cholesterol to become trapped.”
It is bringing to light that diets low in fat is not what the doctors should recommend when the culprits are polyunsaturated fats and carbohydrates causing repeated injury to our blood vessels, resulting in heart disease, stroke, diabetes and obesity.
Overload of simple, highly processed carbohydrates (sugar, foods cooked with rice and wheat flour) and the excess consumption of omega-6 vegetable oils like corn, sunflower, and soybean found in many of our processed foods, are today considered as creating such chronic inflammatory changes in the inner lining of arteries.
Colombo is becoming a refuge for many food outlets for starchy processed foods cooked in Omega-6 type of polyunsaturated oils. Look around the main and side streets, what you see are small unclean food outlets feeding the people with foods such as hoppers, pittus, indiappams, thosais’, wadeis’, among others- all processed starchy foods prepared with oils like sun-flower, vegetable and corn. The more heart healthy oils – the omega-3 types like canola, monounsaturated oils like peanut, olive oil, and saturated coconut oils are far too expensive to be utilized in these cost cutting food outlets, and furthermore not available freely in our markets. The richer elite class patronizes cleaner food outlets for their pastries and cakes, and rice packets, all using similar oils. Most of these omega 6 types of oil are trans-fat sold in supermarkets to increase the shelf life of the oils. Overload of highly processed carbohydrates and excess consumption of omega-6 vegetable oils are the biggest culprits of chronic inflammation and not beneficial cholesterol manufactured in the liver (90%) and found in foods such as eggs, and sea foods, and dairy products.
Assessing the degree of chronic inflammation by C reactive protein (CRP)
Cardiologists can today measure the extent of chronic inflammation of blood vessels and the risk of heart attack or stroke, by performing a simple blood test to measure the level of a substance called C-reactive protein manufactured in the liver that increases with systemic inflammation. C reactive protein is a marker that doctors use to measure inflammatory activity in the body. Studies show that the higher the C-reactive protein levels in the blood, the greater the risk of a heart attack. There is a more sensitive test called highly selective (hs) C-reactive protein assay to determine the risk of heart disease, available in most countries, including Sri Lanka.
Medicines like ACE inhibitors (high blood pressure medication) and aspirin appear to reduce inflammation in the body, which may prevent heart attacks in people who already have high C-reactive protein levels. Cholesterol lowering drugs called statins also have been found to lower C-reactive protein levels.