Are Saturated Fats Good or Bad For You?

In this Article (Index)

• The Saturated Fats Controversy
• What are Saturated Fats
• Saturated Fats
• The difference between "Saturated Fat" and "Saturated Fatty Acid"
• Unsaturated Fats
• Fat is also made by the body
• Saturated Fat and Health
• The Diet-Heart Hypothesis
• Reducing Saturated Fat Intake: hardly any effects!
• The Seven Countries Study
• It is the sugar not the fats
• Dietary saturated fats and circulating saturated fatty acids
• Natural oils and fats vs. "processed fats"
• Dairy based fats
• Dark chocolate fats
• Meat Fats

The Saturated Fats Controversy

The U.S. Dietary goals have focused on lowering the intake of saturated fats, also known as saturated fatty acid (SFA) since the late 1970s as a way to reduce the risk of cardiovascular disease.

However these guidelines are based on some studies conducted in the 1950s, 60s, and 70s, follow up randomized trials were relatively small, so these conclusions are outdated.

Recent studies however paint another picture: statistical meta-analysis of dozens of clinical and observational studies "find no evidence that reduction in saturated fat consumption may reduce CVD incidence or mortality." These opposed views require clarification and analysis as we will see in this article (1).

There is no robust evidence that current population-wide arbitrary upper limits on saturated fat consumption in the United States will prevent CVD or reduce mortality Astrup et al., 2020 (1)

What are Saturated Fats

A fatty acid is a special type of organic molecule composed of a backbone of carbon atoms linked to each other, with hydrogen atoms bonded to the carbon atoms and a carboxyl group attached to its tip.

A carboxyl group consists of an oxygen atom with a double link to the last carbon atom of the chain which is also linked to a hydroxyl group composed of one atom of oxygen and one atom of hydrogen. Its general formula is R—COOH where COOH is the carboxyl group and R is the remainder of the molecule.

They are called "acids" because they have a pH that is lower than 7. They are much weaker than inorganic acids like sulfuric acid oh hydrochloric acid, but nevertheless acidic.

The fats in your diet are known as triglycerides, meaning that they have a "head" formed by a glycerol molecule, a sweet-tasting type of alcohol, and three fatty acid tails linked to the head. That is why they are "tri" glycerides, "tri" = three.

These tails are what make a fat either liquid (like cooking oil) or solid (like lard). They come in different varieties depending on their tails.

Saturated Fats

Saturated fats have "straight" tails because the chemical bonds between the carbon atoms that make up the fatty acid chain are linked to each other by "single" bonds.

As they are straight, the tails can line up and pack closely together, and the electric attraction between close chains enhances this effect. The outcome is a dense substance known as solid fat.

Most animal fats are saturated fats, and some plant oils are also saturated, like coconut or palm oils.

They are called saturated because their carbon atoms have the maximum possible quantity of hydrogen atoms they can bind to, and are therefore "saturated".

The difference between "Saturated Fat" and "Saturated Fatty Acid"

A Saturated fat is a nutrient that is composed mainly of saturated fatty acid (SFA), and is solid at room temperature. Butter, butterfat, lard, tallow, cocoa butter found in chocolate, coconut, palm and palm kernel oils are all examples of saturated fats.

Other types of food which contain saturated fatty acids combined with other nutrients like protein and carbohydrates are not considered "fats" instead they are considered as foods that contain SFAs.

Unsaturated Fats

These fatty acids have "bent" tails due to the double bonds linking some of the carbon atoms along the chain. This does not allow them to pack neatly together so they occupy more space, and being less dense, they are liquid.

Depending on the number of double bonds they can be mono-unsaturated (only one double bond) or MUFAs, or poly-unsaturated (several double bonds) or PUFAs.

Most vegetable fats are of the unsaturated type.

The following image shows these different kinds of fats. Simple bonds are shown as C-C, double bonds as C=C.

Chain length: Types of Saturated Fats

The number of carbon atoms in the chain can range from 4 to more than 20, and saturated fatty acids (SFAs) can be classified as:

• Short-chain fatty acids (4 to 6 carbon atoms)
• Medium-chain fatty acids (8 to 12 carbon atoms)
• Long-chain fatty acids (14 to 20 carbon atoms)
• Very long-chain fatty acids (22 or more carbon atoms)

Food is composed of a mixture of different length saturated fatty acids (SFAs), in general, short-chain fats are found in dairy products while medium and long-chain fatty acids are found in red meat, dairy fats and also in certain plant oils.

Fat is also made by the body

The fatty acids found in your body, circulating in your blood, can have an external origin (exogenous source) or internal (endogenous).

The body manufactures saturated fatty acids from carbohydrates and protein.

Examples of exogenous saturated fatty acids are the long chain myristic, palmitic, stearic, pentadecanoic and heptadecanoic acids.

As we will see below, circulating SFAs increase CVD risk.

Saturated Fat and Health

The Diet-Heart Hypothesis

With changing diets and lifestyles, the 1950s saw a surge in coronary heart disease (CHD) in Western countries and researchers like Ancel Keys, a physiologist at the University of Minnesota, focused on nutrition to find out if it could cause heard disease.

Keys suggested that high blood cholesterol levels clogged the arteries and caused heart attacks. He based this notion on a few experiments conducted on human subjects and animals, and on his observations in Spain, and Italy where less affluent people that ate less meat and dairy products had lower heart attack rates.

Keys concluded that the saturated fats raised cholesterol and caused heart disease, known as the "diet-heart" hypothesis.

The American Heart Association (AHA) didn't endorse this idea, citing a lack of evidence, but when Keys was appointed to the AHA's nutrition committee in 1960, he lobbied for the "diet-heart" hypothesis to be endorsed by the AHA. Starting in 1961, yet the AHA recommended that all men (and later, women) reduce their intake of saturated fat and replacing it with polyunsaturated vegetable oils. (2)

The Seven Countries Study

To back his theory, Keys promoted and led large scale study launched in 1957 that followed 12,770 men in 16 locations in seven countries: Italy, Greece, Yugoslavia, Finland, the Netherlands, the United States and Japan.

Keys selected the countries himself, and it is likely that due to his global travel, he chose the countries that would back up his diet-heart hypothesis. For instance, he excluded Switzerland, France and Germany where despite a high intake fo saturated fats, heart disease rates were low. This cherry picking of countries introduced a bias in the results of the study. (2)

Being an observational study, it didn't show a cause-effect relationship, it only suggested an association.
Similar studies conducted over the years have failed to confirm its conclusions, and apparently the culprit isn't the fat, its the sugars.

Reducing Saturated Fat Intake: hardly any effects!

The effects of reducing saturated fats intake for at least two years based on an analysis of 15 randomized controlled trials involving approximately 59,000 participants (5):

• Positive: Caused a 21% reduction in the risk of combined cardiovascular (CVD) events.
• Positive: It reduced serum cholesterol.
• Positive: Lower intake of saturated fats result in greater reduction in the risk of CVD events.
• Minimal: Small reductions in weight, serum total cholesterol, LDL cholesterol and BMI.
• Nil: Little or no effect on all‐cause mortality or cardiovascular mortality.
• Nil: Little or no effect on non‐fatal myocardial infarction or Coronary Heart Disease mortality.
• Nil: Little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure.

However, many high-risk participants in these studies with increased level of blood lipids are under treatment with statins, a medication that lowers lipids. So it is possible that participants are also protected by the medication and not the fat reduction in their diets.

A lower intake of saturated fats means less energy for the body, what should they be replaced with? Polyunsaturated fats, monounsaturated fats, carbohydrate or protein?

It is the sugar not the fats

When the Seven Countries Study was reviewed in 1989, the new analysis found that "coronary mortality best correlated not with saturated fats, as originally reported, but with 'sweets,' defined as sugar products and pastries." (2)

Additional studies in the US and Europe (high-income countries) have confirmed the carbs-heart link and refute the fat-heart negative effects (1):

• Replacing fat with carbohydrates wasn't linked to a lower risk of coronary heart disease (CHD) and could be linked to an increase in total mortality.
• There is no significant association between the intake of saturated fat and coronary artery disease or mortality.
• Some studies have suggested a lower risk of stroke with higher consumption of saturated fat!

A study that followed up 195,658 participants in the UK for over ten and-a-half years found that:

• No evidence that consuming saturated fat was associated with cardiovascular disease (CVD).
• The "best" diet (the one with the lowest risk for all-cause mortality) was one that included:
  
  • High Fiber: 10-30 g⁄day of fiber
  • High Protein: 14-30% protein
  • High monounsaturated fat (MUFA): 10-25%
  • Moderate polyunsaturated fat (PUFA): 5-7%
  • Moderate carbohydrate intake: 20-30%
• A higher risk of CVD and mortality was associated to a higher consumption of starchy carbs and sugar.

The PURE (Prospective Urban Rural Epidemiological) study involving 135,000 subjects from 18 countries (mostly low and mid-income countries) on 5 continents does not support the link between saturated fat and heart disease:

• Consuming more, of all types of fat was linked to a lower death risk and was neutral regarding heart disease.
• However, a high-carbohydrate diet was associated with a higher mortality risk, but not with risk of cardiovascular disease.
• Participants in the highest quintile (the top 20%) of saturated fat eaters, where these fats represented about 14% of their total daily calorie intake, had a lower risk of stroke.

these observations would suggest there is little need to further limit the intakes of total or saturated fat for most populations. By contrast, restricting carbohydrate intake, particularly refined carbohydrates, may be more relevant today for decreasing the risk of mortality in some individuals (e.g., those with insulin resistance and type 2 diabetes) (1).

Dietary saturated fats and circulating saturated fatty acids

People with high levels of circulating saturated fatty acids (SFAs) have a higher risk of developing potentially mortal diseases such as: diabetes, metabolic syndrome, CVD, heart failure and a higher death rate. (1).

The main culprits are even-chain SFAs, especially palmitate with sixteen carbon atoms in its chain and palmitoleic acid.

Surprisingly, the circulating SFAs are not related to the ingestion of saturated fat, instead, they seem to be associated with the carbohydrate intake.

Low carbohydrate diets with a higher content of satuated fats, like the Keto Diet seem to decrease circulating SFAs. (1)

Clearly, the impact of dietary SFAs on health must consider the important role of carbohydrate intake and the underlying degree of insulin resistance, both of which significantly affect how the body processes saturated fat. This intertwining aspect of macronutrient physiology and metabolism has been consistently overlooked in previous dietary recommendations (1).

Additionally, research has suggested that there may be a genetic predisposition of increased CVD risk that is activated by dietary SFAs. This group of SFA sensitive people would benefit by reducing their saturated fatty acids intake.

Natural oils and fats vs. "processed fats"

In the past, before modern solvent-extraction or mechanical processes were invented, dietary fat was mainly unprocessed: oil-rich fruits such as nuts, avocado, olives, and dairy fats from cattle, sheep or gaots.

Nowadays, a large portion of fat is obtained from grains and seeds such as corn, sunflower, soybean, with processes that use petrochemical-derived solvents to extract the oil from the crushed seeds. The effects of these chemicals is often overlooked when evaluating oils.

There are certain foods like whole-fat diary, unprocessed meat, and dark chocolate that contain plenty of saturated fats but, are not linked to an increase in cardiovascular disease or diabetes risk, so "the totality of available evidence does not support further limiting the intake of such foods" (1)

Furthermore, the biologic effects of the different types saturated fats differ, and they are modified by the type of food and the carbohydrate content of our diets (1); so it isn't only a question of looking at SFAs only, the the diet and its variety also play a crucial role in health.

Dairy based fats

Dietary guidelines recommend consuming low-fat or fat-free dairy foods. This recommendation overlooks the fact that most low-fat yogurt is high in added sugars. Furhermore cheese and yogurt contain contain a complex mix of proteins, minerals, vitamins, probiotics and other fatty acids that have positive biological effects.
Studies have found that (1):

• Cheese and yogurt intakes are inversely associated with CVD risk
• Whole-fat dairy products may protect against type 2 diabetes.

Dark chocolate's fats

The source of chocolate, cocoa beans (Theobroma cacao) contain roughly 50-57% of fat known as cocoa butter. Its main components are oleic acid (33%), palmitic acid (25%) and stearic acid (33%). Dark chocolate is a much better option than milk chocolate not only because it has a higher content of antioxidants but because its added sugar content is much lower (4).

Stearic acid, with eighteen carbon atoms in its chain, has a neutral effect on CVD risk, and the health-promoting benefits of dark chocolate antioxidants may be more important for CVD and type 2 diabetes prevention than the potential negative effects of its SFA content (1).

Meat: the bad fats are in processed meats

Processed meats like bacon, cold cuts, hot dogs, chicken nuggets, sausages, peperoni, jerky, deviled ham, hamburgers, and corned beef, just to mention a few, aren ot the same as unprocessed red meat or poultry. Processed meat contains salt, nitrates, preservatives, additives, while unprocessed meat is just that, flesh without any additives.

The PURE study has shown that guideline limiting meat intake to reduce SFA intake and CVD risk is inconsistent:

We did not find significant associations between unprocessed red meat and poultry intake and mortality or major CVD.
Conversely, a higher intake of processed meat was associated with a higher risk of mortality and major CVD. Iqbal R et al., (2021) (3)

So quality and processing impacts on the risk of heart disease, not its SFA content. Meat is a great source of bioavailable iron, protein, minerals and vitamins so it is a key ingredient in a healthy diet.