Putting saturated fat in context-replacement and total intake matter.

Abstract

The manuscript ‘Saturated Fat: Villain and Bogeyman in the Development of Cardiovascular Disease?’ was recently published in European Journal of Preventive Cardiology.1 Given the extraordinary importance of nutrition on health, we would like to contextualize this review and help avoid unnecessary public confusion. We agree with the authors that complexities exist in nutritional research. With regard to this specific review, it is important to consider what macronutrient may have replaced saturated fatty acids (SFA) in cited studies. Specifically, was SFA replaced with polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), or healthful carbohydrates such as whole grains? Or was SFA replaced with refined grains, sugar, or harmful trans unsaturated fats? Many of the SFA studies and reviews cited by the authors did not account for replacement or were in the context of replacement with refined carbohydrates or trans fat. When replacement is accounted for, the adverse effects of SFA on cardiovascular outcomes are much more consistent. The authors actually report several meta-analyses of observational studies and clinical trials showing that replacing SFA with PUFA is associated with reduced risk of cardiovascular disease, even though they conclude these beneficial effects ‘remain elusive’. This was also demonstrated in a 2015 study of over 120 000 individuals showing that replacement of SFA with PUFA as well as MUFA or whole-grain carbohydrates was associated with improved cardiovascular outcomes, while replacement with refined carbohydrates or smaller amounts of trans fat was associated with no difference.2 Though this particular study accounted for replacement macronutrients and met all inclusion criteria for the authors’ review, it was not cited. The authors also failed to mention that several older studies supposedly vindicating SFA, such as the Sydney Diet Heart Study from decades ago, included PUFA from vegetable oil products high in harmful trans fat. Fortunately, vegetable oils with artificial trans fat are now banned in most industrialized countries.