Should You Limit Saturated Fat In Your Diet?
Today I want to examine a very long-held belief: that saturated fat is detrimental to our health. I specifically want to look at the relationship between saturated fats and cardiovascular disease. Let’s start by getting a better understanding of what saturated fats are.
Saturated fats (SFA) are found in many foods. In fact, every single food that contains fats also contains saturated fats. Below is a list of foods that contain higher amounts of saturated fats:
– Meats (beef, pork, lamb)
– Chicken (dark meat and skin)
– Eggs
– Dairy products (whole milk, butter, cheese, sour cream, ice cream)
– Oils (coconut oil, cocoa butter, palm oil)
– Lard
– Nuts
– Chocolate
Saturated fats are usually solid at room temperature. Saturated fats get their name because all of the carbon atoms are ‘saturated’ with bonds to hydrogen atoms. You may have heard of ‘unsaturated fats’, and these differ because some carbon atoms are missing bonds to hydrogen atoms. All foods that contain fat have both saturated and unsaturated fats. Interestingly, dairy products are the only food group that contains more saturated than unsaturated fats.
So, should we be limiting saturated fats? Well, according to the American Heart Association, no more than 6% of our calories should come from saturated fat. For the past 40 years we have been hearing advice to follow a diet that is low in fat, especially saturated fat. As it turns out, these recommendations were built on a foundation of no or very poor evidence. One study that played a key role in the vilification of saturated fat showed that cardiovascular disease risk was lower in countries where saturated fat intake was lower (1). This was a very poor quality study since many other factors can account for varying cardiovascular disease risk between countries. It’s well-known that higher saturated fat intake can increase one’s LDL cholesterol, which has led people to assume saturated fat will cause cardiovascular disease. However, saturated fats also raise HDL levels and lower triglyceride levels, which could conceivably offset any risk attributed to raised LDL levels.
Although elevated saturated fat intake can increase LDL levels, there is little evidence to demonstrate that saturated fat causes cardiovascular disease. A systemic review by Schwingshakl & Hoffman (2) found that reducing saturated fat intake resulted in no significant difference in all-cause mortality, cardiovascular mortality, cardiovascular events, and myocardial infarction (heart attacks). They found the same was true when saturated fats were substituted with other fats (i.e. polyunsaturated fats).
Some meta-analyses have found a significant reduction in cardiovascular events when saturated fats are replaced by polyunsaturated fats (PUFA). However, only one meta-analyses found a significant difference in CVD mortality and all-cause mortality. The majority of meta-analyses have found replacing SFA with PUFA results in no change in CVD mortality or all-cause mortality. In 2017, Hamley et al (3) conducted a meta-anlalysis whereby inadequately-controlled randomised controlled trials were removed. When analyzing only the adequately-controlled studies, they found no change in CVD events, CVD mortality, and all-cause mortality when SFA are replaced with PUFA.
In reality, since recommendations to reduce saturated fats were introduced, most of the population has replaced SFA with carbohydrates, especially refined (high-glycemic) carbohydrates. According to Siri Tarino et al (4), replacement of SFA with carbohydrates can increase triglycerides, increase small-dense LDL, and reduce HDL – all of which can increase cardiovascular disease risk. In a study by Jakobsen et al (5), they found that replacing 5% of calories from SFA with 5% of calories from high-glycemic carbohydrates increased heart attack risk by 33%.
The point of this article is not to say that saturated fats are very healthy or that you should increase your intake of saturated fats – I just want to demonstrate that saturated fats are not to be feared and avoided any longer. Depending on which studies you look at, you can make a case for or against reducing the intake of SFA in the diet; however, the majority of the data show that reducing saturated fats is not necessary and will not reduce your cardiovascular disease risk. According to Harcombe (6), no meta-analysis of randomized controlled trials or prospective cohort studies has found any significant link between saturated fat intake and all-cause mortality or cardiovascular mortality.
To further add complexity to this issue, it also matters what you replace saturated fats with. If you were to replace saturated fats with omega-3 fats, then this will likely reduce your cardiovascular disease risk. If you replace SFA with omega-6 PUFA or low-glycemic carbohydrates, there will be no difference in your cardiovascular risk. If you replace saturated fats with high-glycemic carbohydrates, you may actually increase your cardiovascular disease risk. It also matters which types of saturated fats you consume. If your saturated fats primarily come from cakes, cookies, pastries, pizzas, and other processed foods, then you’re cardiovascular risk will likely skyrocket. However, if your saturated fat intake is made up of cheese, meats, eggs, nuts, coconut oil, etc., then this will not affect your cardiovascular disease risk.
I realize this is a very controversial topic and there’s still room for debate on this issue. My opinion is based on the evidence that I have gathered and examined to date, and I am more than happy to hear if you have a different opinion and opposing research to show me. If you’re thinking about making any dietary changes or would like to improve your cardiovascular health naturally, contact our naturopathic clinic to schedule an appointment.
Yours in health,
Dr. Michael Morsillo, H.B.Sc., N.D.
Newmarket Naturopathic Doctor
16655 Yonge St., Newmarket, ON
905-898-1844 ext. 135
dr.morsillo@gmail.com
www.drmorsillo.com
References:
1) Keys A. Coronary heart disease in seven countries. I. The study program and objectives.Circulation 1970;41(4 Suppl):I1–8.
2) Schwingshackl L, Hoffmann G. Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression. BMJ Open 2014;4:e004487.
3) Hamley S. The effect of replacing saturated fat with mostly n-6 polyunsaturated fat on coronary heart disease: a meta-analysis of randomised controlled trials.
4) Siri-Tarino PW, Sun Q, Hu FB, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 2010;91:535–46.
5) Jakobsen MU, Dethlefsen C, Joensen AM, et al. Intake of carbohydrates compared with intake of saturated fatty acids and risk of myocardial infarction: importance of the glycemic index. Am J Clin Nutr. 2010;91:1764-8.
6) Harcombe, Z. US dietary guidelines: is saturated fat a nutrient of concern? Br J Sports Med. 2019; 53:1393-1396.