Draft report: Saturated fats and health Scientific consultation: 8 May to 3 July 2018 1 __________________________________________________________________________________________________________ This is a draft report and does not necessarily represent the final views of the Scientific Advisory Committee on Nutrition, or the advice/policy of Public Health England and UK Health Departments. Contents 1 Introduction ............................................................................................................ 15 Background .............................................................................................................................. 15 Terms of reference ................................................................................................................... 16 2 Methods .................................................................................................................. 17 Eligibility criteria and literature search .................................................................................... 17 Selection of studies .................................................................................................................. 19 Data extraction ......................................................................................................................... 20 AMSTAR assessment ................................................................................................................ 21 Methods for reviewing and grading evidence ......................................................................... 21 Grouping of evidence by research question ............................................................................ 22 Evaluation of the quality of identified evidence ...................................................................... 22 Approach to considering statistical models ............................................................................. 24 Grading of evidence ................................................................................................................. 25 Limitations of evidence ............................................................................................................ 28 3 Classification, biochemistry and metabolism ............................................................ 31 Chemical classification ............................................................................................................. 31 Nomenclature conventions of fatty acids ................................................................................ 33 Digestion and absorption ......................................................................................................... 35 Metabolism .............................................................................................................................. 37 Other roles of fats and lipids in the body ................................................................................. 40 4 UK and international recommendations ................................................................... 41 5 Dietary intakes and sources of saturated fats ........................................................... 44 Saturated fat intakes in the UK ................................................................................................ 45 Contributors to saturated fats intake ...................................................................................... 47 Socio-economic differences in saturated fat intakes ............................................................... 47 Polyunsaturated fats (n-3 and n-6) intakes in the UK .............................................................. 48 Monounsaturated fats intakes in the UK ................................................................................. 48 Summary .................................................................................................................................. 48 6 Temporal trends ...................................................................................................... 49 Average daily intake of saturated fats among adults .............................................................. 49 Percentage contribution of food groups to average daily saturated fats intake of adults ...... 49 2 __________________________________________________________________________________________________________ This is a draft report and does not necessarily represent the final views of the Scientific Advisory Committee on Nutrition, or the advice/policy of Public Health England and UK Health Departments. Long and short term trends in the percentage of energy derived from saturated fats from household food and drink purchases ....................................................................................... 49 Temporal trends in trans fats ................................................................................................... 50 Average daily intake of dietary cholesterol among adults ...................................................... 50 Blood lipids analysis among adults by sex and age .................................................................. 50 Summary .................................................................................................................................. 51 7 Background on health outcomes, intermediate markers and risk factors .................. 52 Background .............................................................................................................................. 52 Dietary fats and blood lipids .................................................................................................... 52 Cardiovascular diseases ........................................................................................................... 54 Blood pressure ......................................................................................................................... 54 Type 2 diabetes and markers of glycaemic control ................................................................. 55 Anthropometry ........................................................................................................................ 56 Cancers ..................................................................................................................................... 57 Cognitive impairment and dementias ...................................................................................... 57 8 Cardiovascular diseases ........................................................................................... 60 Total cardiovascular diseases (CVD)......................................................................................... 61 Saturated fat intake and CVD .............................................................................................. 61 Substitution of saturated fats with polyunsaturated fats (PUFA) (or unsaturated fats) and CVD ...................................................................................................................................... 64 Substitution of saturated fats with MUFA and CVD ........................................................... 67 Substitution of saturated fats with carbohydrate and CVD ................................................ 68 Substitution of saturated fats with protein and CVD ......................................................... 70 Coronary heart disease (CHD) .................................................................................................. 71 Saturated fat intake and CHD outcomes ............................................................................ 71 Substitution of saturated fats with PUFA and CHD outcomes ........................................... 77 Substitution of saturated fats with MUFA and CHD outcomes .......................................... 81 Substitution of saturated fats with carbohydrate and CHD outcomes .............................. 83 Substitution of saturated fats with protein and CHD outcomes ........................................ 85 Strokes ...................................................................................................................................... 86 Saturated fat intake and strokes ......................................................................................... 86 Substitution of saturated fats with PUFA and strokes ........................................................ 88 Substitution of saturated fats with MUFA and strokes ...................................................... 89 3 __________________________________________________________________________________________________________ This is a draft report and does not necessarily represent the final views of the Scientific Advisory Committee on Nutrition, or the advice/policy of Public Health England and UK Health Departments. Substitution of saturated fats with carbohydrate and strokes ........................................... 89 Substitution of saturated fats with protein and strokes ..................................................... 90 Summary .................................................................................................................................. 91 9 Blood lipids .............................................................................................................. 95 Serum total cholesterol ............................................................................................................ 95 Saturated fats intake