Saturated Fats: Are They Good or Bad for Your Health? by Terrence Riley
This is a very complicated subject. For many years, organizations such as the Academy of Nutrition and Dietetics and the National Institute of Health have suggested individuals limit their saturated fat intake to less than 10% of total Calories in a day. However, in recent times, members of the fitness and healthcare community have been challenging these governmental recommendations claiming the negative stigma ascribed to saturated fats has been exaggerated or misleading. The movement generated strong pulls towards diets that emphasize fats and protein as the primary components such as the Paleolithic (Paleo) or the Ketogenic (Keto) diet. This topic is especially relevant in fitness communities where groups are sharing the experience of these specialty eating habits.
Eating one of these fat-centric diets is much different than the traditional recommended dietary constituents. A typical day in the life of a paleo dieter, for example, might consist of something closer to 30% total saturated fat intake, well exceeding the less than 10% governmental recommendation. So, what is the effect of a higher saturated fat intake? Are Paleo and Keto diets safe dieting options though they might increase saturated fat intake? Despite widespread encouragement of these higher fat diets, contemporary groups supporting these diets do not have conclusive data to back their claim, at least not until experimental science can grow with the difficulties inherent in the field of nutrition.
First, let’s quickly establish where you might find saturated fats in your diet and what they do in your body. As a general rule, saturated fats are found in a solid state seen mostly in animal fat, butter, unprocessed coconut oil, or egg yolks. Some of the exceptions to this rule include foods like whole milk or coconut milk which also contain saturated fats but in liquid form. After eating fat rich foods, the digestion and absorption occur in the small intestines. Longer chain fats (12+ Carbons) get broken down in your gut, absorbed into small intestine cells, and are reconstructed into fat globules containing proteins, cholesterol and a few other components. Smaller chains go right into the blood to be metabolized by the liver. The fat globules first get dumped into your lymph (“immune”) system where they make their way into your blood after some additional modifications. Eating a diet higher in saturated fat can cause more of these fat globules to enter the blood at one time thus increasing cholesterol levels. The nature of saturated fats in these fat globules can cause the structure to become more rigid making extra cholesterol necessary to maintain fluidity and stability. This can ultimately be another contributor to higher cholesterol levels which can mean an increased risk in cardiovascular diseases. These bodily mechanisms are purely based on hypothesis, meaning it has not been conclusively proven to be true. When well established hypotheses such as the one above is challenged by newer research, years of previous studies are always a major hurdle to surpass. This is exactly what is happening in the world of nutrition today.
A perfect example of this push and pull between the existing body of evidence and current research is apparent in an editorial written by Dr. Jeremiah Stamler in the American Journal of Clinical Nutrition.2 The article critiqued by Dr. Stamler was a meta-analysis that suggested no associations between saturated fats and an increase in risk factors (cholesterol, blood pressure, etc.) of cardiovascular diseases (CVDs).3 Dr. Stamler listed twelve points challenging the conclusions proposed by the authors of the recent study.2 Each point addressed a variety of issues including statistical methods, research analysis, and previous evidence. The
important takeaway from this editorial is the number and scope of studies connecting saturated fats to cardiovascular risks. A few of note referenced by Dr. Stamler include the National Diet Heart Study and the Multiple Risk Factor Intervention Trial.2 These trials correlate lower intakes of saturated fat with reduced health risks. Many other publications dating back to the 1970s (and possibly before) also find that reducing saturated fat intake can in fact reduce CVD risks. The reason old research is being challenged is because “correlation does not mean causation.” In other words, just because two things might happen at the same time does not
mean one thing caused the other. Contemporary studies are applying the adage of causation in hopes of asking the right questions that might lead to some clarification on the topic of saturated fats.
A recent article by de Souza et al. set out to refine the statistical causal relationship through a meta-analysis of observational research (similar to the previously mentioned trials).4 The study revealed a few interesting points of data.4 When a person replaced saturated fats with high glycemic carbohydrates (mostly refined carbs) their risk of CVD actually increased – though the amount was not listed in the discussion.4 On the other hand, there was a net reduction of CVD risk when consuming foods lower on the glycemic index (fiber containing foods). When discussing the results, the authors suggest the causal relationship between saturated fats and CVD risk isn’t as strong as previously assumed.4 Instead, the significance of reducing saturated fat may only be relevant when deciding what will take its place in the diet. More research will undoubtedly be necessary to clarify the importance of such distinctions.
The true answer to the complex question of whether saturated fats are “good” or “bad” for you, is that there isn’t enough evidence to provide a general recommendation. Previous research might suggest there is a connection but the methods were performed without considering the significance of what the individual was eating in place of saturated fats. This is not the same as saying saturated fats are “good” either. The physiological effects of eating more saturated fats are nuanced and have an effect at the individual level and should be generalized to everyone. So, before you commit to a new diet like Keto or Paleo, you should get your bloodwork examined by your doctor or a medical professional. Just like caffeine, some people may be sensitive to higher fat intakes and others may not be affected at all. The only way to know whether a diet or food is good or bad for you is to see how your body responds to the dietary changes.
2. Stamler, Jeremiah (2010). Diet-heart: a problematic revisit. Am J CLin Nutr 2010;91:497-9. 2010. American Society for Nutrition.
3. Siri-Tirano PW, Sun Q, et al. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated with cardiovascular disease. Am J Clin Nutr 2010;91:535-46.
4. De Souza, R. Mente, A. et al. (2015). Intake of saturated and trans usaturated fatty acids and risk of all-cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ 2015;351:h3978. Doi: 10.1136/bmj.h3978