One of the most difficult and controversial subjects to find accurate information on is cholesterol, the diet's effect on blood cholesterol levels, and whether (and how) higher levels of cholesterol lead to Coronary Heart Disease (CHD).
What makes this topic so difficult is that there's an overwhelming amount of information and it's incredibly polarizing and contradictory.
Additionally, you can find the answer you're looking for, so cognitive bias is a real danger here.
Before I begin I have to admit I'm incredibly reticent to write about this topic, as people's decisions regarding cholesterol are deeply personal and important, and I know from the outset that I have reached different conclusions than many of the people around me. My goal here isn't to irritate or offend anyone, it's more an attempt to make the best informed decisions I can for my own health.
I find reading these studies and trying to analyze/understand the numbers involved to be a bit confusing, as there are five numbers to be considered:
(The terms "good", "bad", and "very bad" seem a bit arbitrary to me)
(You'll have to commit these to memory to make sense of any of this)
Some summary notes on these numbers:
The fact that there's "good", "bad", and "very bad" cholesterol is odd to me (that there are different variants). The fact that the ratio of "bad:good" is somehow germane is also odd.
The guidance on what a safe level of LDL is keeps changing, and a moving target just means you have to re-think those 5 numbers above every few years (which isn't helping, nor does it inspire confidence).
And the reality of this maddeningly confusing topic is that, you can find whatever answer you'd like when doing research, which makes it very difficult to avoid your own cognitive bias.
I set out to learn what we know about cholesterol, how diet impacts it, and what the treatments are (and how effective they are).
I began at the very beginning, which was: "Why do we care about this at all? (as in, who told us to care?)"
I'd like to begin with some of the high-level conclusions I reached after my research, and then attempt to back-fill how I reached them.
I understand these things to be true at the end of my journey:
So the answer is different depending on your age and the condition of your vascular system. If you're young and have a 0 Calcium Score, well you're best bet is to exercise and eat a "whole foods" diet (read: keep your vascular system healthy).
If you're 80 years old and your vascular system is profoundly compromised due to decades of poor diet, you may have to take a statin to avoid a heart attack (and understand that this may not change your ultimate mortality).
Either way, CHD is a symptom of an underlying problem, and cholesterol itself is not the problem, diet is the problem.
For the rest of this article, I'll endeavor to fill in how I reached those conclusions.
We Talk About The Wrong Things
I think nearly all of the discussion about food and nutrition ignore the elephant in the room, which is that our diets have changed substantially over the past 40 years, and as a result, it's helpful to look for correlative (and/or causal) deleterious downstream health effects as a result of these changes.
(Think of it's a Occam's Razor as applied to the question "Why are we, as a society, so sick?")
Less important, but still germane, is the engineer in me that, when faced with a complex system that was failing for unknown reasons, nearly always applied the following strategy: "Fix what you know is broken and hope that the unknown [broken] stuff resolves itself".
So What's Broken? (And Is Known To Be Broken?)
(I apply the exact same logic to diabetes, which is also an epidemic / diabetes and cardiovascular outcomes are closely linked).
(Same for the obesity epidemic)
Why Do We Never Talk About Sugar and Highly-Processed Foods?
This is why I think the focus on cholesterol is a focus on a symptom and not an underlying problem. There are simply too many other [largely unexplained] problems that are not accounted for via an examination of cholesterol alone.
Incidentally, the WHO recommends a daily limit of 25g of "free sugars", which are both "added sugars" (like granulated sugar) and those naturally present in fruit juice.
It's always been deeply suspect to me that the American RDA for sugar is 50g, which is 2x the WHO guidance.
From the US FDA guidance on sugar:
One has to wonder why this is. Shouldn't there be an RDA for total sugars like there is for everything else? It is suspicious indeed, this lack of guidance.
I have to admit that I stumbled upon this theory during my research. I was incredibly dissatisfied with the research on statins, and also on the lack of discussion on the effects of a high-glycemic/processed-food diet on the body.
There have been several studies on prolonged/elevated insulin levels in your blood to various systems in your body, and it's been shown that two things are true:
There are an awful lot of references now on this idea/research. Some quick excerpts:
Your Arteries May Be Suffering Insulin Resistance Too:
Insulin Resistance and Coronary Heart Disease in Non-diabetic Individuals:
And every once in awhile, a huge hole is poked through the classical assumptions about cholesterol, lipid ratios, and CHD, as occurred with surprising results from a clinical trial:
Hmmmm... why is that? Haven't we read for that past 20 years that the ratio of LDL:HDL is the best predictor of CHD? Haven't we read that lowering LDL and raising HDL is the key to heart health?
This is a tricky one to explain away. And even more difficult to defend the whole "lipid ratio" number as being germane.
(Incidentally, you'll also have to explain why we have an epidemic of obese 6-month olds / Kim et al, Obesity 15:1107, 2006). Perhaps it's too much fried chicken?)
People who are looking for more satisfying explanations are noticing the insulin resistance problem:
This was one fundamental assumption that's nearly universal, despite it not being true: that diet has a significant impact on serum cholesterol.
This idea is to ubiquitous that people actually get angry if you suggest it's not true.
(These next few points are all [apparently] incredibly controversial)
For most people, what you eat doesn't affect your body's cholesterol level very much at all.
The thing is, your body makes cholesterol, via your liver, and needs it to function. Your body consumes cholesterol via several processes in the body (e.g.: building human tissues, bile production in the liver, aiding in the production of sex hormones, etc). When you're taking a statin, you're actually battling your own body's internal systems.
The cholesterol from your diet is only approx 15% of your total cholesterol:
Your body is pretty good at regulating cholesterol. The levels go down in a few hours after eating a fatty meal (between 6 and 12 hours for most people).
It takes many months of a diet change to show results in the amount of cholesterol in your body (normally, cholesterol is only measured every 3-6 months when being monitored). If diet has such a huge impact on my blood cholesterol (such that I am encouraged to change my diet to lower my blood cholesterol levels), then why isn't the change quicker? It seems like "a week or two" would be more reasonable, but it even some measurable changes in 48-72 hours would seem possible if my diet really made that much of a difference.
(More Controversy Ensues)
Perhaps the most controversial advice is around whether to consume healthy fats... some advise "YES" (eat olive oil, avocado, and certain nuts), others advise "NO" (none of those).
(This is another incredibly controversial topic, for which you can find whatever answer you're looking for)
On the Yes Side:
On the No Side:
Overall, what I see from looking at a massive number of articles on this topic is that:
There have been studies on this subject, which is good. Anecdotal evidence or conclusions drawn without a study are not helpful:
My conclusions on this stuff are that it's fine to consume olive oil, nuts, and avocados as part of a whole-foods diet. If you also drink soda, eat processed cereal for breakfast, and consume fast food, well, eating these healthy foods is not going to magically un-do the damage of your poor diet.
(On the editorial side: it's a bit offensive to think that eating avocados could be bad for you. Given all of the horrible things people put into their bodies these days, does anyone truly believe that avocados are what's causing people to have heart attacks? To me, this kind of thinking verges on the insane).
One popular recommendation for people with high cholesterol is to switch to a vegan diet. This idea was popularized by a 2011 documentary called Forks Over Knives.
There are an awful lot of critiques of this documentary (a documentary I both watched and enjoyed).
I'm not exactly sure what the motivation is on the part of the producers was. If it was "Advance a Plant-Based Diet", that seems reasonable to me. If it was "Advance a Whole-Foods Diet", that also seems reasonable. What's odd to me is that they seem to violate two fundamental rules in their presentation:
Much has been made of this documentary and the critiques are exhaustive, so I won't include my own thoughts. Suffice it to say while there are parts of this documentary I really liked, however it's dogmatic drive to push veganism as the only viable diet option takes what is at it's core several reasonable ideas and overextends them.
Here are two critiques .. the 2nd one is incredibly exhaustive:
Forks Over Knives: The Latest Vegan Nonsense Dissected, Debunked and Destroyed
Oct 4th, 2011, Anthony Colpo
Forks Over Knives: Is the Science Legit? (A Review and Critique)
Sep 22nd, 2011, Denise Minger
This book was an incredibly fascinating read. It does an incredibly deep dive into the origin of the idea that high cholesterol leads to CHD. It also does a similar analysis of the effect of statins and low-fat diets on health and mortality.
Here are several excerpts from this book. They should be reasonably self-explanatory, but I'll try to group them logically:
On the lack fo a connection between diet and blood cholesterol:
On the flaws in the original study that yielded the great cholesterol myth:
On the fact that we're looking in the wrong place:
On the negative health outcomes for people on the lowest end of the cholesterol spectrum:
On the links between sugar and insulin resistance to adverse health outcomes:
Other countries have already dismissed cholesterol entirely:
On margarine (one of my personal axes, which I truly enjoy grinding):
On the negative health effects and/or lack of effectiveness of statins:
On the negative health effects of stress:
This book is a cornucopia of interesting studies and insights. They take the considerable trouble to fill in the missing pieces from the statin studies (e.g.: no net change in mortality, only a 1.5% reduction in heart attacks an strokes, and the associated negative health effects).
This diet is often recommended for people with high cholesterol.
It's arguably the most controversial diet I found. There are a lot of reasons for why this is so, and I'll list many of them below, but what makes it particularly controversial to me is that you can't consume fish, nuts, or any oils when on this diet.
This seems contrary to many data points, among them:
However, additionally, this diet is incredibly controversial due to the lack of underlying scientific rigor of any kind. Here are a handful of the problems with the original "study":
If Esselstyn was so confident that the diet works, he should design a study for the FDA to carry out; a study that actually controls some of the major variables involved.
As well, there are some contradictory studies (which were randomized with a control group and are able to be replicated):
This diet boils down to a "whole foods" diet in the end, in that, it's nearly impossible to eat processed foods while adhering to it, and so you're avoiding HFCS and other added sugars without explicitly intending to. I think that part of it is very good, even if it was incidental.
1. I think one of the must-watch lectures is Sugar: The Bitter Truth (2009). It's by Robert H. Lustig, professor of pediatrics at UCSF.
He does an excellent job quantifying just how much the typical western diet has changed over the past few decades, with a wonderful focus on added sugar.
2. The BBC just published a a fairly interesting look into the effects of eating a diet of highly processed foods called What Are We Feeding Our Kids? (2021).
It's a bit of a pain to view this outside of the UK (you need a BBC television license and a the specialized BBC video player), but it may be worth the effort.
If you watch it you'll learn about the shift from whole foods to highly processed foods, and how little we know about the effect of said foods on the human body.
3. I'd also check out Carb Loaded: A Culture Dying to Eat (2014), which examines the effects of our modern diet on health conditions such as diabetes, cancer, CHD, hypertension, and obesity.
(They also discuss insulin resistance, and how this leads the body to no longer be able to break down sugar in the blood)
4. I also liked the documentary Fed Up (2014), which examines the modern obesity epidemic and how the processed food industry, sugar lobby, and US government policy is fueling it.
(They cite 80% as the percentage of products in your supermarket with added sugar)
I came across a huge number of what I thought of as "distractions" while I was researching this topic. I'd like to mention a couple of them and give a quick overview of why I'm dismissing them summarily.
(It's funny how much internet debate there is on topics that are much more of an outlier than a data point. It's almost like the point of the "discussion" is to distract from the topic at hand)
To me, the Massai Tribe is a red herring in this discussion.
Allegedly, it's a group of people who eat mostly meat and dairy and yet do not develop CHD. One side says "This shows that meat and dairy do not cause CHD". The other side says "These people got CHD and died early as a result."
Everyone generally agrees that the Massai tribe eats a diet of several pounds of meat per day.
The controversy revolves around whether they develop CHD or not, and whether consuming meat & dairy contributes to this (and obviously the broader implications of this).
On the Pro-Meat & Dairy Side:
Masai and Inuit High-Protein Diets: A Closer Look: The authors favor the conclusion that diet fat is not responsible for coronary disease.
On the anti-Meat & Dairy Side:
Life expectancy for Maasai tribe is age 44 for women and 42 for men.
Why it's all a moot point?
Because ultimately it's an n=1 "study":
A lot has been made about the decline in CVD in Norway between 1939 and 1945, which was when Norway was occupied by Germany during the war.
The base claim is that once Germany invaded Norway, they confiscated all of the livestock, which means that meat and dairy consumption went way down. Interestingly enough, deaths due to CVD dropped significantly around the same time (at the very beginning of 1940).
Many people decided that this was causal (lower meat and dairy consumption meant lower CVD).
There are countless pages on the internet (and in print) dedicated to this debate, so I won't re-hash it here, but here are the high-level reasons I think it's a red herring:
So it's difficult to separate out the deaths from infectious diseases from the huge change in diet from the overall disruption of the war. To draw a straight line from lower animal product consumption to lower incidence of CHD seems a bit disingenuous.
"For many years, both the medical community and the general public have incorrectly associated eggs with high serum cholesterol and being deleterious to health, even though cholesterol is an essential component of cells and organisms. It is now acknowledged that the original studies purporting to show a linear relation between cholesterol intake and coronary heart disease (CHD) may have contained fundamental study design flaws, including conflated cholesterol and saturated fat consumption rates and inaccurately assessed actual dietary intake of fats by study subjects."
"The degree to which serum cholesterol is increased by dietary cholesterol depends upon whether the individual's cholesterol synthesis is stimulated or down-regulated by such increased intake, and the extent to which each of these phenomena occurs varies from person to person. Several recent studies have shed additional light on the specific interplay between dietary cholesterol and cardiovascular health risk. It is evident that the dynamics of cholesterol homeostasis, and of development of CHD, are extremely complex and multifactorial."
"In summary, the earlier purported adverse relationship between dietary cholesterol and heart disease risk was likely largely over-exaggerated."
Puleva Explores Heart Benefits of Olive Oil Extract
Recent research conducted at Puleva Biotech in Spain explored how the introduction of the antioxidant compound hydroxytyrosol found in olive oil extract lowers levels of LDL cholesterol. The hydroxytyrosol binds to LDL cholesterol in the blood stream and prevents oxidation and damage to the blood vessel walls. The protective powers of hydroxytyrosol against cell oxidation is a benefit to the heart, brain, and skin. The lipid profile of olive oil extract is similar to that of human skin. Olive oil extract contains a variety of antioxidants including vitamin E, carotenoids and pheno-lic compounds, such as hydroxytyrosol.
You have to fast for about 10 hours before the test because triglyceride levels can shoot up 20%–30% after a meal, which would throw off the equation. Alcohol also causes a triglyceride surge, so you shouldn't drink alcohol for 24 hours before a fasting cholesterol test. (Source)
Note: Of course this guidance is contentious (this is why we can't have nice things). There are several articles available that now tell you that fasting before a cholesterol test is completely unnecessary. It's par for the course when discussing this topic (literally nobody can agree on anything).