Anyone with even a passing interest in nutrition knows that any number of topics can stir up emotions. One of the worst offenders is cholesterol. Although pretty much every one knows of cholesterol, few actually know what cholesterol is and what role it plays in the body. It’s high time to set the record straight on cholesterol and show how diet and lifestyle can affect it.
The Building Block of… You
Cholesterol is an organic molecule composed of chole – the Greek word for bile, and stereos, another Greek word for solid. The latter designates a class of molecules known as sterol. This is the same class of molecule steroid hormones and vitamin D are a part of. Hence, all sterols are a type of lipid (fat) or derived from it. Of these, cholesterol is the main one produced in all animals, including humans.
Cholesterol serves many purposes in the human body. Most of it is found in the cell membranes, where it modulates membrane fluidity. A good portion of it serves to produce vitamin D and the various types of steroid hormones, such as testosterone and estrogen, but also cortisol, aldosterone, and many others. It is also an essential component of bile acids, compounds that enable the absorption of fat.
A typical 200 lbs male will have between 35-40 gr cholesterol in his body. He will also produce 1-2 gr per day, mostly in the liver. In fact, 75-80% of the cholesterol found in the body is produced by the liver and other tissues.
Do you have a liver? Then you will produce cholesterol. Simple as that.
Dietary cholesterol accounts for only 20-25% of total cholesterol. A typical daily intake is about 300-325 mg for a male in the United States.
It should be noted that there is a relationship between the endogenous production of cholesterol and exogenous (dietary) cholesterol. The more we eat, the less we produce. The less we eat cholesterol-rich foods, the more we produce.
This puts a serious damper on the cholesterol scare that would have you ban shrimp, eggs, and butter from the table.
The good, the bad, and the ugly lipoproteins
Cholesterol came to national attention in the late ‘60s-early ‘70s with the publication of the studies incriminating cholesterol in heart disease. Chief among the researchers touting a low-fat and low-cholesterol diet as heart-healthy was Ancel Keys.
Much has been said to disparage or discredit his research. A lot of the critics are valid, namely: using rabbits as test subjects being fed a fat-rich diet, choosing particular data sets (otherwise known as cherry-picking), and general fear-mongering. His studies were flawed indeed, but he was the first one to call our attention to the impact of diet and health, in the modern sense of the term, and to exponentially increase the field of study dedicated to lipids. A lot of his conclusions have been heavily nuanced or purely contradicted by modern scientists, in part thanks to research emerging from this very field.
One of the most common pieces of knowledge to come out of this is about HDL and LDL. The “good” and the “bad” cholesterol, respectively. This is a misnomer on all counts though. LDL is not the devil and HDL is no saint either. They both play a role in human health, and they are not cholesterol per se. They are protein drivers that chauffeur cholesterol from the liver to the cells, or vice-versa.
Driving Miss Cholesterol
Fat is not soluble in water. So to move around fat in the bloodstream, nature devised a clever trick. It would attach those fat molecules to proteins, forming lipoproteins. Think of it as a protein train hitched to several fat wagons.
HDL, or high-density lipoprotein, takes the cholesterol (and other fats) from the cells and brings it to the liver for disposal.
LDL, or low-density lipoprotein, does the opposite role of taking cholesterol and fats from the liver and delivering it to the cells.
The bad reputation that LDL enjoys comes from the fact that it is found in arterial plaque. This led many to believe it was the main culprit in plaque formation. However, many interactions lead to plaque deposit in the blood vessels. Oxidation and inflammation are key players. This is especially true since LDL is vulnerable to oxidation because of its weaker structure, compared to HDL.
Does high cholesterol matter?
For decades, people thought that high cholesterol levels were a marker of heart disease. Doctors use this value to predict incidence of death and coronary heart and blood vessel diseases.
The Framingham study researched the correlation between heart disease and cholesterol. The average value in developed countries is 210 mg/dl, which correspond to a 50% higher risk of premature death caused by atherosclerosis. Going from 200 mg/dl to 260 mg/dl increases that risk by 500%, while the Framingham study showed that no one died of cardiovascular disease with a cholesterol level of 150 mg/dl or below.
Seems pretty straightforward, right?
Not so fast. The same study showed that 35% of heart attacks happened to subjects whose cholesterol levels were between 151 mg/dl and 200 mg/dl. This is considered a healthy, “safe” range. Other studies have also shown that low cholesterol blood values are associated with mental health issues, such as depression, and increase the risk of cerebral hemorrhage. Yikes!! In addition, low cholesterol leads to low levels of sex hormones, which are a risk factor (and a bummer) all on their own.
Furthermore, there are outliers, as in any population. For example, the population of the Greek island of Crete has recorded no heart attack in a 10 year study period. This is despite the cholesterol of the average Cretan being above 200 mg/dl. This is thought to be caused by the consumption of unprocessed fats in the diet, such as in the typical Mediterranean diet.
So all in all, cholesterol is not as important as other risk factors, such as
- Stress levels
- Overall dietary patterns
- Insulin resistance
- High levels of HbA1c
The real cholesterol problem
Previously in this article, I mentioned that 75-80% of cholesterol was manufactured in the liver. The question is not how it is done, but why.
You see, cholesterol production is a complicated process, requiring 37 steps. The enzyme that starts this whole cascade is the HMG-Coenzyme A reductase enzyme. This liver enzyme is activated by… insulin levels in the blood. This means that the higher the blood sugar, the lower the insulin sensitivity, the more insulin will be produced, and the more the HMG CoA enzyme’s activity will be ramped up.
We already know that high levels of blood sugar and poor insulin sensitivity tend to create more oxidation and inflammation in the body. Add to that higher production of cholesterol, and over time you have a ticking time-bomb. Although there seems to be genetic factors at play in all this, dietary patterns should be considered. Consumption of high levels of sugar and fat lead to a whole slew of problems, and you can now add cardiovascular issues to that list.
The dietary issues and how to fix them
The top 3 macro-nutrients are well-know: proteins, fats, and carbohydrates. In nature however, we rarely if ever find them packaged neatly all by themselves. Proteins usually come with fats, while carbohydrates come with phyto and micro-nutrients and fibers. But there is virtually no source of high levels of fats and carbohydrates together. Unlike in our modern diet where those are the 2 main ingredients of a lot of treats. Whenever fatty foods (aka junk foods) are depicted, they are things such as fries, burgers, pizza, and all manners of desserts.
Although they are rich sources of (mostly oxidized) fats, they are also very high in carbohydrates. The very combination that has no place in nature. Hence, it makes sense to limit that combination of macros in a single food, especially if they come in forms that might be harmful, such as trans fats. It should also be noted that in order to properly process those macro-nutrients, the body needs a lot of micro-nutrients, such as vitamins and minerals. When eating a lot of foods that are poor in micro-nutrients, this increases the stress on the body, compounding the problem.
No, eggs won’t kill you… but maybe bacon will.
So, cholesterol-rich foods are not the issue, or at least a very specific part of a much broader picture. Consuming eggs, shrimp, and butter is not likely to kill you in the context of a healthy, low-inflammation diet and lifestyle. This is made even more true if you consume minimally-processed, antioxidants-rich and nutrient-dense sources.
Many diets have been shown to have heart-related benefits. Whether they are the low-fat diet à la Ornish, the Mediterranean diet, the infamous Atkins diet, the vegetarian diet, or even the current trend of low-carb, high fat or keto diet. All have in common an emphasis on green leafy vegetables, higher consumption of lean protein, healthy fats, and an avoidance of the junk food type foods. This should be no surprise by now. The aptly named S.A.D (standard American diet) is a likely suspect. While ancestral-type diets and low-processed approaches have all enjoyed a measure of success in reducing, and even reversing, cardiovascular diseases.
So, eat your eggs and shrimp. Just make sure the rest of your diet follows suit and includes vegetables, fruits (if you deserve your carbs), lean protein, and heart-healthy smart fats.
Yours in health,
The Strength Community