This is the sixth in our “Controversies” series and the second article regarding the subject of fats.
It is fair to say that there is no more hotly debated nutritional subject than that of the saturated fat.
Let’s clarify the confusion by closely examining the scientific evidence.
What Is a Saturated Fat Anyway?
All fats are made of a molecule of glycerol and three molecules of fatty acids, which, in turn, consist of chains of carbon atoms linked to each other by single or double bonds.
A saturated fat is made of fatty acids made up of carbon atoms linked by single bonds. That means these carbon atoms are also attached to (saturated with) hydrogen atoms.
Most animal fats are saturated fats.
Most plant fats are unsaturated fats.
How Do Saturated Fats Affect Your Health?
Saturated fat consumption is associated with a variety of chronic diseases including:
- Heart Disease: Eating saturated fats often leads to dyslipidemia, an abnormal amount of lipids in the blood, which in most cases equals to elevated total cholesterol, triglycerides, and LDL (the ‘bad’) cholesterol — known risk factors of cardiovascular disease.
- Cancer: A diet high in saturated fats has been linked to a variety of cancers including prostate, breast, stomach and esophageal cancer.
- Diabetes: Once we control for weight, alcohol consumption, smoking, exercise and family history, the incidence of diabetes is significantly associated with the proportion of saturated fat in our blood.
- Obesity: Fat begets fat. A high-fat diet has been shown to lead to leptin resistance in the brain and a consequent loss of the balance between food intake and energy expenditure, which ultimately results in body mass gain.
- Fatty Liver Disease: Saturated fat has been found to be particularly toxic to liver cells, promoting the formation of fatty liver disease.
Of these health associations, the most widely discussed is the link between saturated fats and heart disease.
The debate centers on the fact that while we know there is a clear, significant association between the consumption of saturated fats and blood cholesterol levels, some argue that it is less obvious that saturated fats actually causes heart disease.
Let’s examine what we do know.
Saturated Fat and Cholesterol: a Linear Relationship
There is no question that an intake of saturated fat elevates total cholesterol, specifically LDL (the ‘bad’ cholesterol).
In fact, the relationship between cholesterol and saturated fats is so consistent that you can predict how much blood cholesterol levels will go up based on the amount of saturated fat you eat.
For example, if you eat 30 percent of your calories from saturated fat, you can expect your LDL cholesterol to increase by 50 points.
Furthermore, an increase in saturated fat intake is always associated with significant increases in LDL ‘bad’ cholesterol, even when you keep your calorie intake stable.
But Does Saturated Fat Cause Cardiovascular Disease?
So we definitively know that saturated fats elevate blood cholesterol levels.
What is more difficult to prove is that elevated cholesterol actually causes cardiovascular disease.
This does not mean that there is no cause-effect relationship among saturated fats, blood cholesterol levels, and heart disease. It simply means it is harder to demonstrate the relationship depending on the type of study done.
For example, in a quasi-experimental community-based study in Finland, widespread reduction in saturated fat intake (and concurrent increase in the consumption of fruits and vegetables) in one community (North Karelia) over the course of 25 years (1972-1997) resulted in a significant decline in both the risk factors and the death rates from coronary heart disease.
At the same time, a recent meta-analysis found the exact opposite result, with the authors concluding that there was no association between eating more saturated fat and a higher risk of heart disease.
So what explains these research disparities?
Part of the problem in establishing a causal relationship is that, like any chronic disease, cardiovascular disease is complex.
Not only does cardiovascular disease take a long time to advance, but also many factors impact its development and progression.
A second issue when it comes to positively identifying saturated fats as a cause of heart disease stems from the limitations and flaws of the research itself.
1. In a classical way, to show an unequivocal link between saturated fat, blood cholesterol levels and elevated risk of heart disease, we would need to feed saturated fat to a group of people, in a controlled and randomized manner, while another group would forgo its consumption. We would then have to monitor both groups for a long period of time in order to identify the development of cardiovascular disease.
This type of experiment has been successfully done to show the first (and faster to detect) part of the equation, i.e. that the consumption of saturated fat will raise blood cholesterol levels. However, given that we cannot keep people in a controlled environment for a long enough period of time, we settle for ‘observational’ population studies which can only infer that high blood cholesterol is associated with (versus the cause of) a higher incidence of cardiovascular disease.
2. Furthermore, most studies have not tested dramatic enough reductions in saturated fat levels, making it impossible to evaluate the real impact of lowering saturated fat consumption below recommended levels.
3. Equally, many experiments have failed to take into account whether the saturated fat has been replaced by another food. For example, if saturated fat is swapped out for trans fat, white flour, white sugar or highly processed foods, this could ‘cancel out’ the benefits of the lowered saturated fat intake, giving us inconclusive findings.
4. And a final flaw with current research is that most studies analyze only one isolated factor (like saturated fat) rather than the entire diet or the summation effect of different elements in the diet.
Looking at the Whole Picture
“The whole is greater than the sum of its parts.”
Food (and food’s contribution to chronic disease) is a package deal.
Remember… you do not go to the store to buy a container of saturated fat!
You eat food.
When studying the link between diet and health, we need to think about the effect of food as a whole on our body system.
There is no single nutrient or food that is responsible for all cardiovascular disease, cancer, diabetes and obesity we see in this country. The whole diet matters.
All of the above begs an obvious question.
Is saturated fat a problem on its own?
Or do the health consequences ‘blamed’ on saturated fats actually stem from an overall unhealthful animal-based diet low in the nutrients found in a plant-based lifestyle?
The answer is both.
By itself, study after study shows us that saturated fat is bad for you because, among other things, it elevates blood cholesterol levels.
But saturated fat is also problematic because of the company it keeps.
If you eat a diet that is high in saturated fat, you are most probably eating an animal-based diet, which will also be high in total fat, trans fat, cholesterol, protein (and leucine-rich amino acids), heme iron, phosphatidylcholine, and its metabolite choline – all of which are independently associated with a higher incidence of cardiovascular disease, cancer, and/or diabetes.
Not to mention you will likely be missing out on the fiber, antioxidants and nutrients of a plant-based diet.
Equally, if you eat a minimally processed plant-based diet but then douse it with high-fat oils (especially tropical plant oils, which are high in saturated fat), you are once again at risk.
So saturated fat is bad for you in and of itself. But it is also a sign that you are eating an overall unhealthful animal-based diet that is jam-packed with other negative elements, all of which contribute to chronic diseases.
How Much Saturated Fat Is Too Much?
So is there an acceptable level of saturated fat?
Similar to trans fats, the National Academy of Sciences has set no upper limits for saturated fats, believing that any intake above zero increases ‘bad’ LDL cholesterol.
The global scientific consensus is that any saturated fat intake should be kept under 10 percent of your total calorie intake, but the latest American Heart Association guidelines recommend reducing saturated fat to 5-6 percent of total calories.
What does that translate to in practical terms?
You need to eliminate (or at least greatly minimize) your consumption of the leading saturated fat-containing food sources, which are cheese, pizza, pastries, ice cream, chicken, pork, and burgers.
Even two slides of cheese a day (as your only animal-based food source) would take you over the top.
In the end, the easiest and simplest solution is to eat a SOS-free, minimally processed plant-based diet – a diet which will be naturally free of trans fat and very low in saturated fat.