The role of various types of fat in the diet is controversial. Our knowledge continues to evolve.
Saturated fats have long been labelled bad, but the evidence isn’t as clear as you would think. Americans have been told over and over to pursue a low-fat diet, but has this done more harm than good? Some saturated fat is required for health. We have greatly decreased saturated fat, but what are we eating in its place? The answer in many cases is refined carbohydrates. Is this part of the puzzle in trying to understand the obesity, metabolic syndrome and type 2 diabetes epidemics.
The science literature seems to support replacing saturated fat with polyunsaturated fatty acids (PUFAs) and not poor quality refined carbohydrates and added sugars that increase levels of triglyceride and small LDL particles and reduce high-density lipoprotein cholesterol. A good general dietary recommendation is to substitute saturated fat with polyunsaturated fat and minimally processed grains.
A study published in the AJCN, concluded that replacing saturated fats with polyunsaturated fatty acids (PUFAs) could benefit the heart, but replacing them with refined carbs could increase risk factors for heart disease.
Even this advice is not all that simple. Different saturated fatty acids may have different cardiovascular effects, and not all PUFAs are equal. For example, Americans eat a lot of omega-6 fatty acids and the omega-6 to omega-3 ratio in the American diet has been a source of concern. The main omega-6 that has been implicated as a source of problems in the American diet is linoleic acid due to its prevalence in vegetable oils. Linoleic acid has been shown to be pro-inflammatory and appears to interupt the conversion of short chain omega-3s into longer chain EPA and DHA. One way to obtain more omega-3 is to eat more fish. An omega-3 DHA/EPA supplement can also be helpful.