It’s been ingrained in our minds for the last 30, maybe 40 years: “saturated fat causes heart disease.” How many times have you read the phrase “artery-clogging saturated fat?” Saturated fat and heart disease always seem to end up in the same sentence. However, in recent years, research is vindicating saturated fat.
In an article published in the journal Progress in Cardiovascular Diseases, Saint Luke’s Mid America Heart Institute cardiovascular research scientist and James J. DiNicolantonio, PharmD, and James H. O’Keefe, MD, examined the question of whether sugar has a greater impact on coronary heart disease than saturated fat.
Along with co-author, Sean C. Lucan, MD, MPH, MS, from the Albert Einstein College of Medicine, DiNicolantonio and O’Keefe evaluated the evidence to date linking saturated fats and sugars to coronary heart disease, considering basic science, epidemiology, and clinical trial data related to CHD risk, CHD events, and CHD mortality. The authors concluded that sugar consumption, particularly in the form of refined added sugars, are a greater contributor to CHD than saturated fats.
“While the original studies upon which the longstanding guidelines were based were largely observational,” said DiNicolantonio, “We now have more than a half century of data as well as increased understanding of how nutrition impacts the body and specifically coronary heart disease.”
The metabolic aspects of saturated fatty acids (SFAs) are complex but existing research suggests that certain SFAs may actually improve lipid profiles and heart disease riask. For instance, some SFAs increase high-density lipoprotein cholesterol (HDL), which is often referred to as the “good cholesterol” as this lipoprotein is associated with a reduced risk of heart disease.
Replacing saturated fats, or any other component, from one’s diet almost inevitably means replacing it with something else. When carbohydrates, particularly refined carbohydrates like sugar, replace saturated fats, which can have a negative impact on lipid profiles (HDL tends to fall and triglycerides tend to rise).
People don’t eat isolated fatty acids – they eat foods that are a mix of various fatty acids and other food constituents. While high intakes from processed meats may increase risk of CHD, higher intakes from dairy sources of saturated fat may not only pose no risk but actually decrease risk. It may be that the digestive by-products (in particular trimethylamine-N-oxide) cause the oxidative effects linked to red meat consumption. (Source)
Consuming a diet high in sugar for just a few weeks has been shown to cause high total cholesterol, triglycerides, LDL, oxidized LDL, uric acid, insulin resistance and abnormal glucose tolerance, low HDL, and altered platelet function. The overall effect of consuming a diet high in sugar on these numerous health markers is likely more detrimental to overall health compared to increased consumption of saturated fat, which can increase LDL but at the same time raise HDL.
Added fructose – generally in the form of sucrose (table sugar) or high fructose corn syrup in processed foods and beverages seems especially potent for producing harm. Consuming these sugars can lead to resistance in leptin, which is a key hormone in the maintenance of normal body weight. Excess fructose also markedly increases the risk for non-alcoholic fatty liver disease – the most common liver disease in the US and a strong independent risk factor for heart disease. The association between liver disease and heart disease is stronger than other heart disease risks, including smoking, hypertension, diabetes, male gender, high cholesterol or metabolic syndrome.
Sugars occurring naturally in fruits and vegetables pose no increased risk for heart disease, largely due to the fiber and antioxidants present in these foods. The problem is refined added sugars – with ultraprocessed foods being of greatest concern. Products with added sugars represent 75% of all packaged foods and beverages in the US and most commonly contain sucrose or high fructose corn syrup.
A diet high in sugar has also been found to promote prediabetes and type 2 diabetes. And patients with both of these conditions have a much greater risk for heart disease compared to normal healthy patients, particularly a severe narrowing of the left main coronary artery.
Ultra-processed foods also tend to be sources of saturated fats (think doughnuts and french fries) but the harms associated with eating these products may have nothing to do with the fat and everything to do with processed carbohydrates.
“After a thorough analysis of the evidence it seems appropriate to recommend dietary guidelines shift focus away from recommendations to reduce saturated fat and towards recommendations to avoid added sugars,” said Dr DiNicolantonio. “Most importantly recommendations should support the eating of whole foods whenever possible and the avoidance of ultra-processed food.”