This is the first of a two part series on atherosclerosis and will explain:

• What atherosclerosis actually is (and what it is not)
• Why it’s important, and
• What causes it

We will lay down a basic framework that will help you form a mental model so that next week we can cover what you need to know in order to prevent or reverse atherosclerosis.

What is atherosclerosis?
Atherosclerosis - commonly known as “ hardening of the arteries” refers to a disease process that causes damage to the arteries resulting in narrowing, blockage, occlusion and even rupture.
Atherosclerosis is the underlying cause of most cardiovascular disease (CVD) - including heart disease and stroke.

• Every 7 minutes a Canadian dies from heart disease or stroke
• Heart disease and stroke is the number one cause of death in Canada - accounting for 46% of all deaths; and also represent the single biggest cause of disability adjusted life years lost (DALY’s) - a measure of “lost healthy years”.
• 80% of premature heart disease and stroke can be prevented through healthy lifestyle choices
• Only 1 in 10 Canadians are in ideal heart health
• Over 90% of Canadians have at least one risk factor  

Atherosclerosis is both very common and very preventable.
Our view is that the key to prevention comes from really understanding how atherosclerosis develops.  This involves getting past some common misconceptions that have resulted from an oversimplification of the disease through the two dominant conceptual models used to explain atherosclerosis:

1. Clogged pipes (arteries) are the problem; and
2. Fat Clogs Arteries

The issue with each of these models is that they overlook some key facts and observations:

• Most cardiac events occur where there is minimal or moderate narrowing
• The cholesterol (fat) found in atherosclerotic lesions is not from the diet but produced by the liver.
• Most cardiac events occur in people with normal cholesterol levels

Before we go further here - let's back up and better understand the disease process:

• Low Density Lipoproteins (LDL) particles (the dominant transport vehicle for liver-produced cholesterol) enter the lining of the arteries - the subendothelial space.  
• Here LDL particles attach to proteoglycans molecules expressed in the lining of the artery.
• Once attached, the LDL particles, specifically, the phospholipds within, are prone to oxidation by reactive oxygen species.

At this stage - 3 things have happened:

1. LDL particles get in the lining of the arteries,
2. They get stuck and
3. They get oxidized.  

Oxidized LDL is toxic to the endothelial cells lining the arteries and this is the key step in the development of atherosclerosis.

• Endothelial cells, injured by oxidized LDL, now express molecules on their surface to mark their injury and trigger an immune response
• These molecules, vascular cell adhesion molecules, VCAM’s, attract monocytes, a type of white blood cell
• The now dysfunctional endothelial cells, also send out molecular messenger signals such as IL-6 and TNF-alpha which trigger liver cells to increase production of the inflammatory molecule C-reactive protein.
• The monocytes that attach to the endothelium, enter the subendothelial space, the intima and differentiate in macrophages - a specialized immune cell designed to inges toxic substances
• In this case the macrophages essentially eat up the oxidized LDL particles, and as these cells become full, stuffed with cholesterol, they are aptly named “foam cells”
• Multiple foam cells coalesce together to form a “fatty streak” in the artery wall - this is the hallmark of early atherosclerosis

Fatty streaks are almost ubiquitous and have even been found in utero!  This is the very earliest stage of atherosclerosis and almost all of us have disease at this stage.

• High Density Lipoprotein (HDL) - another lipid transport molecule - can enter the subendothelial space and take cholesterol from the foam cells, and subsequently distribute the cholesterol to other tissues in the body.
• Foam cells that do not get relieved of the cholesterol burden - produce a variety of molecules including angiotensin II, metalloproteinases, collagenases, elastases, and other proteins - all of which can further undermine the integrity and function of the endothelium
• At this point, the damage really begins.  The endothelial damage signals smooth muscle cells to the damaged area where they secrete a matrix to heal the arterial wall.  This matrix forms a fibrous cap that now can intrude into the lumen of the artery.

The atherosclerotic plaque, so formed, can become very large and can impede arterial blood flow to the extent in the heart that the muscle the artery serves can become starved of oxygen.  This narrowing and decreased blood flow, results in the the exertional chest discomfort known as angina.

• The metalloproteinases and collagenases produced by foam cells can also weaken the fibrous cap resulting in rupture of the plaque
• Rupture triggers a coagulation response - initially platelets accumulate, then fibrin forms, and clot can form.
• This process can occur rapidly and result in complete occlusion of the artery - even when the initial lesion did not produce significant narrowing - this occlusion occurring in a coronary artery is known as a myocardial infarction (MI) or more commonly referred to as a heart attack.

To summarize, atherosclerosis is caused by an inflammatory response to oxidized lipoproteins within the artery wall.  There are three main ingredients that trigger a lesion:

1. ApoB containing lipoprotein (mostly LDL) particles accumulating under the endothelial lining of arteries
2. Oxidation of the sub-endothelial LDL-particles, causes inflammation resulting in
3. Dysfunctional endothelial cells that trigger further immune response.

The developing process can be mitigated in its earliest phases by HDL-particles that take away the sub-endothelial cholesterol - even after it is taken up by the foam cells.

Evidence shows that the risk of atherosclerosis increases with increasing concentrations of LDL-particles in linear fashion - note this LDL-particle numbers, not LDL-cholesterol concentration. (while LDL-C and LDL-p are generally concordant, ie. they increase and decrease together, this is not always true - especially when insulin resistance is present).  LDL-cholesterol is what is commonly reported on the standard lipid panel.  A better test to understand your risk is the ApoB100 protein- which gives you the number of LDL-particles as each LDL-particle has one ApoB100

It must be stressed that LDL-P easily enter and exit the sub-endothelial space all the time - it is the oxidation of LDL-P that is key step in initiating atherosclerosis.  Only oxidized LDP-P is taken up by macrophages and foam cells.

What triggers the oxidation of the LDP-P?

Damaged, inflamed or dysfunctional endothelial cells create the conditions for LDL-P oxidation.
Common causes of endothelial dysfunction are:

• tobacco use,
• obesity,
• age,
• hypertension,
• hyperlipidemia,
• physical inactivity, and
• poor dietary habits or anything that results in low-grade chronic inflammation

Another key point is that the process that leads to an atherosclerotic lesion is systemic - so just identifying and treating lesions that cause blockage (ie. plumbing model) does not sufficiently decrease risk as there may be other non-obstructive lesions that can rupture and cause acute occlusion.

So in essence, with atherosclerosis we have a reinforcing cycle of:

• Endothelial dysfunction leading to the
• Oxidation and retention of lipoproteins in the subendothelial space leading to
• Inflammation that results in further
• Endothelial dysfunction

The take-home points to remember are:

• atherosclerosis is the number cause of death in Canada
• 80% of premature deaths from atherosclerosis are preventable
• the disease process is systemic and the conditions that lead to atherosclerosis affect all arteries
• because it is systemic - a systemic approach to prevention, treatment, and reversal of atherosclerosis is required
• atherosclerosis takes a long time to become symptomatic and most heart attacks occur in people who have had no prior symptoms
• atherosclerosis is caused by a combination of endothelial dysfunction that allows for the oxidation of LDL cholesterol in the lining of the artery, resulting in an inflammatory response that triggers further endothelial dysfunction.
• understanding an individual's
  • lipoprotein status
  • inflammation levels
  • endothelial function
• are essential in order to develop a coherent reduction strategy.

Next week - we will apply this framework to explain the Wellness Garage prevention and risk reduction strategy for atherosclerosis.

At Wellness Garage - we can help you understand and take control of your health.  Our comprehensive medical, fitness, nutritional and behavioral assessments give you baseline from which to measure your progress.  Our coaching helps you improve your behaviors, one habit at a time.

For more information - please book a free consultation.

50% of Americans have high blood pressure according to the new guidelines from American College of Cardiology and the American Heart Association.

Lost in the debate about whether this makes sense to label so many people with a disease was the recognition that normal blood pressure is now defined as 120/80 and the acknowledgement that the risks from blood pressure increase progressively, and linearly from levels as low as 115/75 in people from 40 to 89 years of age.  

For every increase of 20 mmHg systolic and 10 mmHg diastolic there is a doubling of mortality from both heart disease and stroke. 

Here is the Wellness Garage strategy for high blood pressure:

1. Know your blood pressure:

• be confidant that your blood pressure is normal. 
• If you get high readings in the doctor's office - get an automated BP cuff for home.
• If your doctor is not using an automated cuff - ask her why?  New guidelines are clear that physicians should be using automated cuffs.
• If your arm is large be sure to have a large cuff - make sure the doctor uses a large cuff.

2. Know whether you have insulin resistance:

• if your blood sugars are abnormal then you already have insulin resistance
• if your blood sugars are normal and you have abnormal lipids (high triglycerides and low HDL) and a waist size of >102 cm (40 in) in men or >88 cm (35 in) in women - you likely have a degree of insulin resistance
• insulin resistance disrupts one of the key hormonal systems regulating BP - the Renin-Angiotensin system (RAS)
• if you have insulin resistance - decreasing carbohydrates through a low carb, whole food approach makes the most sense - see #3
• if you are diabetic these changes should be medically supervised

3. Get moving - exercise is key

• aerobic exercise has been shown to lower BP 5-7 mmHg 
• resistance exercise lowers BP 2-3 mmHg
• these effects rival first line drug therapy and lower risk by themselves 20-30%
• recent evidence shows that exercise is superior to drug therapy in preventing death from stroke and is equal to drugs in prevention of heart disease mortality.

​
4. Eat better - lose weight

• optimizing your nutrition to lose weight makes a big difference - real whole foods with adequate protein, healthy fats and low glycemic carbodyrates. 
• studies show that in overweight or obese people a weight loss of 8kg will lower BP by 8.5 mmHg systolic and 6.5 mmHg
• these effects rival drug therapy and are though to be independent of exercise

5. Salt - stop eating packaged food and decrease how much you eat out - see #3

• for years the linkage between salt (sodium) intake and elevated BP has been clear and part of the established recommendations for preventing and treating hypertension
• more recently this has been challenged on at least two fronts
  • there is great variability between people on the basis of race, gender, age and dietary factors - resulting in the observation that some people at some times are salt sensitive - meaning that their BP increases with salt intake.
  • there is little convincing evidence to link decreased salt intake over time with better health outcomes.
• our advice is to start by eliminating the real culprits in the high salt world we live in - restaurants (especially fast food) and packaged food.  Eating real whole foods that you prepare yourself will result in a significant reduction of salt intake and will help with #3. 

6. Reduce Stress - meditate

• there is growing empirical evidence that the exposure to chronic psychological stress leads to the development of high blood pressure
• while many relaxation therapies are recommended and are effective in reducing stress, so far only meditation has been shown to reduce stress and lower blood pressures
• learning to meditate has never been easier with the introduction of apps like Headspace and Calm - finding 10-15 min per day to meditate will reduce stress and help you improve your blood pressure

7. Sleep - develop a great sleep routine

• depriving people of sleep in the short-term clearly increases blood pressure
• chronic sleep deprivation of < 5hrs per night doubles the risk of hypertension, while 
  • insomnia and restless leg syndrome have also been shown to increase incidence of high blood pressure
• if you snore regularly or stop breathing during the night -see you physician and get assessed for Obstructive Sleep Apnea
• develop a great sleep routine - get 7-8 hrs of high quality sleep

This 7 step strategy will allow you to take control of your blood pressure and do everything you can to either avoid medication or take as little as possible.

​For over 40 years, conventional wisdom has been that saturated fat causes heart disease and should be avoided or reduced.

The targets for reduction have gone progressively down over that time from < 10% to the American Heart Association’s current 5-7% recommendations.

During this time, the cardiovascular disease rate (CVD) has decreased to approximately 1/3 of their 1960's levels.  While there are many factors (decline in smoking, better control of hypertension, use of statin drugs, and the timely use of blood thinners in acute myocardial infarctions), some cardiologists point to this decline as proof that the nutritional recommendations made in the late 1970s to reduce fat intake and specifically target saturated fat are a big part of this success.

More recently, prominent experts have begun to challenge this.  

"Is saturated fat bad for you?" remains one of the most contentious and confusing questions in medicine today.

To answer this question we need to understand the background of what has become known as "The Diet-Heart Hypothesis".

In the 1960s, several observations were combined to form the diet-heart hypothesis, which stated:
Lowering cholesterol by replacing saturated fat with polyunsaturated fat (PUFA) from vegetable oil would:

• diminish the deposition of cholesterol in the arterial wall, 
• slow progression of atherosclerosis, 
• reduce cardiovascular disease and 
• improve survival

This hypothesis, which has been the dominant paradigm for cardiology over the past 40 years, was based on:

• evidence from randomized controlled studies that showed replacement of saturated fat in the diet with PUFA from vegetable oil lowers total cholesterol and LDL cholesterol
• observational evidence linking serum cholesterol to coronary artery disease and mortality

The logic of the diet:heart hypothesis:

• decreasing saturated fat reduces total cholesterol and LDL (A) and lowering cholesterol and LDL (B) lowers coronary artery disease and mortality (C) (A+B ---> C)

Then:

• decreasing saturated fat (A) reduces coronary artery disease and mortality (C) (A ---> C)

 
The problem with the Diet:Heart hypothesis is that there has been no solid evidence to support the logical leap (A--->C)

​The original evidence supporting the notion that decreasing saturated fat lowers coronary artery disease came from epidemiological studies in the 1960s that demonstrated a positive correlation between national levels of dietary fat consumption, specifically saturated fat, and heart disease mortality.  The most famous (or infamous) study was performed by the legendary Ancel Keyes and was called the "7 Country Study". 
 Keyes’ study was observational, based on low-quality data:  food diaries and public health records on the cause of death.  It also was not originally based on “7 countries” - Keyes actually reviewed 22 countries - and when one examines the data from all countries,  the correlation, while present, is far weaker.  Keyes has been accused of cherry-picking the data to make the correlative conclusion stronger.  
By today's standards, the “7 Country Study” would be considered deeply flawed, and recent observational studies have shown different results. 
In 2017,  the PURE study, a large 18 country epidemiological cohort study that followed 135,335 people for an average of 7.4 years, demonstrated that high carbohydrate intake was associated with a higher risk of total mortality, whereas total fat and saturated fat intake were related to lower total mortality.  Specifically, saturated fat intake was not associated with an increased risk of cardiovascular disease, heart attack, or cardiovascular disease mortality and was associated with a decreased risk of stroke.
Of course, the challenge with observational studies is that they can show correlation at best.
But correlation is not causation - my favourite example is the number of bathrooms in your home correlates with your net worth - the higher one's net worth, the more bathrooms.  If we confuse correlation with causation, we could erroneously conclude that having more bathrooms leads to higher net worth and could advocate that individuals should build themselves new bathrooms to increase their wealth!
The gold standard for proving causation is the randomized controlled study. 
No randomized controlled study has shown that replacement of saturated fat with vegetable oil significantly reduces coronary heart disease or mortality.
 One randomized controlled study that attempted to test the causal role of saturated fat in heart disease was the Minnesota Coronary Experiment (MCE).
 Conducted from 1968 - 1973, MCE was the largest (9570 people) and most rigorously executed trial of the diet-heart hypothesis and the only dietary study ever to include post-mortem assessment of coronary, aortic and cerebrovascular atherosclerosis grade and infarct status.
The MCE followed over 9000 institutionalized people living in state mental institutions and nursing homes, randomly assigning them to two groups.  One group maintained the standard diet high in saturated fat.  In contrast, the other group had half of the calories from saturated fat replaced with vegetable oil and corn oil margarine - high in the Omega 6 PUFA linoleic acid.  Unlike observational studies, the MCE had detailed records of every meal administered to these subjects over 56 months. 
This study probably could never be repeated as today's ethics boards would disapprove of experimenting on institutionalized patients without consent. 
So what were the findings?
In keeping with the first part of the diet-heart hypothesis - replacing saturated fat with linoleic acid did lower cholesterol by an average of 14%. Interestingly, this lowering of cholesterol DID NOT result in people living longer.
 In fact, the lower the cholesterol, the higher the rate of death (22% for every 0.75 mmol/L) and the vegetable oil group did not have fewer heart attacks or fewer atherosclerotic plaques.
So the MCE, the most rigorous trial ever done to test the diet-heart hypothesis, essentially disproved the notion that decreasing saturated fat improves cardiovascular outcomes – it even suggested that increasing vegetable oil was associated with greater mortality.
If this rigorous study was finished in 1973 and essentially disproved the diet-heart hypothesis, why did it not change the prevailing wisdom that saturated fat was bad?
It did not change minds because it was never published!
The investigators led by Ivan Frantz did not publish because the results were not what they expected, and they felt that something must have been wrong with their data.  When part of the study was published years later, in 1989, it only reported that the substitution of saturated fats with vegetable oils did not reduce the risk of heart disease or death. 

It was not until 2017 that the complete data was analyzed and the true results were presented.  Assisting the lead investigator Christopher Ramsden was Ivan Frantz’s son Robert (a prominent Mayo clinic physician himself), who had found old computer tapes and documents in his father’s basement.  Ivan Frantz died in 2009.  The account of this discovery was the subject of a brilliant Malcolm Gladwell podcast, “The Basement Tapes”
 Ramsden et al. showed that when the whole data set was thoroughly reviewed, the MCE study results counter the diet-heart hypothesis and show that the replacement of saturated fat with vegetable oil increases coronary events and death.
 While this was the first full reporting from the  MCE trial, a 2013 re-analysis of another 1960’s era landmark study – the Sydney Diet Heart Study (again by Ramsden) also showed that volunteers who replaced much of their saturated fat with polyunsaturated fats high in linoleic acid had a higher risk of death from heart disease.
In 2014, Chowdrury et al. reported a meta-analysis of 78 studies involving 650,000 people and concluded that there was no evidence that lowering saturated fat and increasing polyunsaturated fat intake decreases the risk of cardiovascular disease.
A landmark 2015 systematic review and meta-analysis of observational studies showed no association between saturated fat consumption and:

1. all-cause mortality
2. coronary heart disease (CHD)
3. CHD mortality
4. ischaemic stroke or
5. type 2 diabetes in healthy adults

These studies, in many ways, disprove the diet-heart hypothesis as overly simplistic.  
On the whole, this brings us to the answer to our question:

Is saturated fat bad for you?
The overall evidence from these studies says probably not – but the true answer lies in your own response to saturated fats.  

• What happens to your overall lipid profile, including LDL-cholesterol, LDL-particle number, triglycerides and HDl-cholesterol?
  
• How do these changes affect your overall risk for heart disease?

To learn more about heart disease:

• Atherosclerosis Part I
• Atherosclerosis Part II - Preventing, Treating, Reversing

To understand your own risk for heart disease, book a Comprehensive Lifestyle Medicine Assessment.