Saturated Fat – A closer look at a demonized macro nutrient

Fat for a long time has been a demonized macronutrient. Just the name itself creates perhaps a biased opinion of its properties and its potential effects. There have been many changes to this thinking over the last decade with the popular view being that not all fats are bad and that there are actually some goods fats.

Saturated fat, however, has never been included as a “good” fat. The current guidelines by The American Heart Association limit the consumption of saturated fats to 5%-6% of your total calories. That works out to around 13 grams based on a 2,00 kcal diet. This was last reviewed in 2015 [1]. Saturated fat can be found in a variety of food products such as meat, dairy, oils, and butter. Most food products that are high in fat will have a varied composition of saturated, monounsaturated and polyunsaturated fats. Nuts and seeds, two popular ingredients that I like to use in smoothies can contain moderate to high amounts of saturated fat. Almonds, for example, have 3.8 grams per 100-gram serving.

A brief history of saturated fat

The leading causes of death in America is currently heart disease. In the early part of the 20th-century heart disease was an uncommon cause of death, however, deaths due to the disease peaked in the mid-1960s. The total number of deaths has declined since then to the present day rate [2]. The center for disease control lists high blood pressure, high cholesterol, and smoking as key risk factors. It goes on to say that 47% of Americans have at least one of these risk factors [3].

Creating guidelines on incomplete or inaccurate data

Researchers during this time discovered that saturated fat seemed to increase levels of cholesterol in the blood. As you can now see they could make a very simple observational conclusion, eating saturated fat causes an increase in cholesterol which in turn leads to a greater chance of developing heart disease, therefore, saturated fat is bad. There was, however, a slight problem with their conclusions. The research was conducted on animals, not humans and human data was obtained through observational analysis and assumptions and not experimentation.

This lead to the formulation of the dominant health and nutrition advice which was to follow a low-fat high carbohydrate diet. Many health authorities still set guidelines based on this advice. Ironically this advice could be seen as the start of the current epidemic of obesity and type 2 diabetes [4].

Last year The New York Times published an article titled “How the Sugar Industry Shifted the Blame to Fat”. It provides a small insight into how the sugar industry paid a group of scientists to cherry pick data to support their goals. It is a shame that this work shaped much of public opinion and propagated misinformation.

If you are interested in reading more about topics such as this I can highly recommend “Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming“. For me, it opened a new window into how the truth can be obstructed and the importance of verifying facts through respected peer-reviewed sources.

Saturated fat and cholesterol

You may have heard of HDL and LDL or the “good” and “bad” cholesterols. This is not an accurate description. HDL stands for High-density lipoprotein and conversely, LDL stands for Low-density lipoprotein. They are not cholesterol. They are in fact complex particles that are made up of various proteins that transport all fat molecules around the body. Studies have shown that high levels of HDL are associated with a decreased risk of cardiovascular events and heart disease whereas high levels of LDL are associated with a greater risk. Therefore statistics of total cholesterol can be misleading (this was the case in the 1960s).

It was seen that saturated fat raised LDL levels. What most failed to mention was that it also raises HDL levels too leading us to somewhat of a net gain of zero. Saturated fat is a class of fat, the other being unsaturated fat. There are many different types of saturated fat (the difference being the length of the fatty acid chain). Below are four common types of saturated fat. Each one can have different impacts on cholesterol levels. (The numbers in the brackets are the number of carbon atoms to the number of double bonds as these are all saturated fats they contain zero double bonds).

Lauric Acid (12:0) – Raises total cholesterol but with a stronger rise in HDL [5]
Myristic (14:0) – Raises LDL more than other fatty acids
Palmitic Acid (16:0) – Raises LDL with no effect on HDL
Stearic Acid (18:0) – Neutral effects

After reading numerous studies I have come to the conclusion that it is very difficult to summarize the total effects of individual fatty acids concisely. When combined with other fatty acids and unsaturated fatty acids the effects can change. Indeed, many studies compare levels with respect to other diets and how levels can change when substituting saturated fats for trans fats or carbohydrates. The variability of criteria is very difficult to summarize.

LDL, the “bad” cholesterol can be further classified into 2 more categories: small dense LDL and large LDL. The difference between the two is significant. Small dense LDL are small enough to penetrate the walls of arteries, stays in the bloodstream longer and is more easily oxidized. These 3 properties contribute to the likelihood of cardiovascular events. In fact, people with high levels of small dense LDL have a 3 fold increase of heart attacks [6]. Furthermore reducing saturated fat and replacing it with carbohydrates exacerbated the increase of small dense LDL [7].

Large LDL, however, is associated with a reduced risk of heart disease. Saturated fat has an interesting effect on LDL. It has been seen that saturated fat changes LDL particles from small dense ones to large ones [8][7].

Conclusions

Throughout the writing of this article, I have read a variety of conflicting and inconclusive information. However, I can generalize some points that most studies agree on. The demonization of saturated fat is unjust. Saturated fat is a much better alternative to trans fats which should be avoided at all costs. Saturated fats can have some beneficial effects however there is an equal amount of negative effects. These positive and negative effects are related to the type of saturated fat being consumed. Each type of saturated fat can influence HDL and LDL cholesterol levels in positive and negative ways depending on a variety of factors.

When saturated fat is replaced with polyunsaturated fat there is a reduction in cardiovascular events. Polyunsaturated fats reduce levels of both HDL and LDL.

Incorrect associations were made that have since spread and become popular wisdom that is proving difficult to change. A meta-analysis of 347,747 subjects has shown that intake of saturated fats was not associated with an increased risk of heart disease [9].

The majority of this article has looked at the effect of saturated fat on cholesterol and heart disease. As with other nutrients, an excessive consumption can lead to other health problems. High saturated fat diets have links to other medical problems including colon cancer.

Remember it is important to consume a varied diet, eliminate processed foods and exercise regularly. You should consult with your doctor before making changes to your diet.

Sources and further reading:

[1] The American Heart Association. Saturated Fat. healthyforgood.heart.org/eat-smart/articles/saturated-fats

[2] The American Journal of Medicine. The Epidemic of the 20th Century: Coronary Heart Disease. amjmed.com/article/S0002-9343(14)00354-4/abstract

[3] Center for Disease Control and Prevention. Heart Disease Facts. cdc.gov/heartdisease/facts.htm

[4] Science Direct – Journal of the American College of Cardiology. The diet–heart hypothesis: a critiquesciencedirect.com/science/article/pii/S0735109703016310

[5] PubMed.gov. Comparison of the effects of diets enriched in lauric, palmitic, or oleic acids on serum lipids and lipoproteins in healthy women and men. ncbi.nlm.nih.gov/pubmed/8644684

[6] Low-Density Lipoprotein Subclass Patterns and Risk of Myocardial Infarction. jamanetwork.com/journals/jama/article-abstract/374290?redirect=true

[7] The American Journal of Clinical Nutrition. Saturated fat, carbohydrate, and cardiovascular disease. ajcn.nutrition.org/content/91/3/502.short

[8] The American Journal of Clinical Nutrition. Change in dietary saturated fat intake is correlated with change in mass of large low-density-lipoprotein particles in men. ajcn.nutrition.org/content/67/5/828.short

[9] The American Journal of Clinical Nutrition. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. ajcn.nutrition.org/content/early/2010/01/13/ajcn.2009.27725.abstract