Dietary fat and fatty foods in the prevention of non-communicable diseases: A review of the evidence

Background: Reducing the intake of total fat, saturated fatty acids (SFA) and dietary cholesterol was a cornerstone of dietary guidance in past decades. This emphasis shifted recently from lowering the intake of total fat to focusing on the quality of dietary fat intake, the avoidance of industrial trans-fatty acids (TFA), and the sub-stitution of SFA with unsaturated fatty acids. There is also a trend towards investigating diet-disease associations of fatty foods rather than nutrients. Scope and approach: We aimed to summarize comprehensively the currently available evidence for total dietary fat, fat quality, and fatty foods such as butter, vegetable oils, nuts and seeds on risk of non-communicable dis-eases including cardiovascular disease (and its risk factors), cancer, type 2 diabetes, and neurodegenerative diseases. Key findings and conclusions: The findings from systematic reviews of prospective observational studies, which often compared extreme intake categories, found mainly no association of total fat, monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and SFA with risk of non-communicable diseases. Systematic re-views of randomized controlled trials indicate that SFA and/or TFA substitution with MUFA and/or PUFA im-proves blood lipids and markers of glycemic control (observed only for SFA replacement), with the effect of PUFA being more pronounced. A higher intake of total TFA was associated increased risk of cardiovascular disease. In line with current dietary guidelines, the available published evidence deems it reasonable to recommend replacement of SFA with MUFA and PUFA and avoidance of consumption of industrial TFA.