The EPIC-Norfolk Study
Dietary Fatty Acids, Macronutrient Substitutions, Food Sources and Incidence of Coronary Heart Disease: Findings From the EPIC-CVD Case-Cohort Study Across Nine European Countries.
Journal of the American Heart Association 2021
Steur M, Johnson L, Sharp SJ, Imamura F, Sluijs I, Key TJ, Wood A, Chowdhury R, Guevara M, Jakobsen MU, Johansson I, Koulman A, Overvad K, Sánchez MJ, van der Schouw YT, Trichopoulou A, Weiderpass E, Wennberg M, Zheng JS, Boeing H, Boer JMA, Boutron-Ruault MC, Ericson U, Heath AK, Huybrechts I, Imaz L, Kaaks R, Krogh V, Kühn T, Kyrø C, Masala G, Melander O, Moreno-Iribas C, Panico S, Quirós JR, Rodriguez-Barranco M, Sacerdote C, Santiuste C, Skeie G, Tjønneland A, Tumino R, Verschuren WMM, Zamora-Ros R, Dahm CC, Perez-Cornago A, Schulze MB, Tong TYN, Riboli E, Wareham NJ, Danesh J, Butterworth AS, and Forouhi NG
DOI : 10.1161/JAHA.120.019814
PubMed ID : 34796724
PMCID : PMC9075396
URL : https://www.ahajournals.org/doi/10.1161/JAHA.120.019814
Abstract
Background There is controversy about associations between total dietary fatty acids, their classes (saturated fatty acids [SFAs], monounsaturated fatty acids, and polyunsaturated fatty acids), and risk of coronary heart disease (CHD). Specifically, the relevance of food sources of SFAs to CHD associations is uncertain. Methods and Results We conducted a case-cohort study involving 10 529 incident CHD cases and a random subcohort of 16 730 adults selected from a cohort of 385 747 participants in 9 countries of the EPIC (European Prospective Investigation into Cancer and Nutrition) study. We estimated multivariable adjusted country-specific hazard ratios (HRs) and 95% CIs per 5% of energy intake from dietary fatty acids, with and without isocaloric macronutrient substitutions, using Prentice-weighted Cox regression models and pooled results using random-effects meta-analysis. We found no evidence for associations of the consumption of total or fatty acid classes with CHD, regardless of macronutrient substitutions. In analyses considering food sources, CHD incidence was lower per 1% higher energy intake of SFAs from yogurt (HR, 0.93 [95% CI, 0.88-0.99]), cheese (HR, 0.98 [95% CI, 0.96-1.00]), and fish (HR, 0.87 [95% CI, 0.75-1.00]), but higher for SFAs from red meat (HR, 1.07 [95% CI, 1.02-1.12]) and butter (HR, 1.02 [95% CI, 1.00-1.04]). Conclusions This observational study found no strong associations of total fatty acids, SFAs, monounsaturated fatty acids, and polyunsaturated fatty acids, with incident CHD. By contrast, we found associations of SFAs with CHD in opposite directions dependent on the food source. These findings should be further confirmed, but support public health recommendations to consider food sources alongside the macronutrients they contain, and suggest the importance of the overall food matrix.
Lay Summary
Once thought to be the best dietary advice for the prevention of heart attacks, reducing saturated fat in the diet is increasingly questioned as a strategy for improving heart health. This change, which is evident in the increasing popularity of low carbohydrate, not low fat diets, is happening for a variety of reasons. These include a re-appraisal of the existing older research evidence, inconsistency in findings between research studies, and the recognition that diet is incredibly complex and that singling out nutrients alone without considering the foods they come from could be misleading.
To help resolve the ongoing uncertainty, we conducted research across nine countries of Europe testing the link between different types of dietary fats and the future risk of developing heart disease. This study was large as it involved 10,529 people who developed heart disease over time and compared them with 16,730 people who did not develop heart disease, who were randomly selected from 385,747 European Prospective Investigation into Cancer (EPIC) study volunteers in the EPIC-CVD Study.
Specifically, we tested three things. First we tested how each of total fat, saturated fat, monounsaturated fat and polyunsaturated fat are related with future heart disease risk. Second, we tested what happens to future heart disease risk when eating less of one type of fat (such as saturated fat) and eating more of another type of fat (such as mono- or polyunsaturated fat) or other nutrients like carbohydrates or protein. Finally, we tested what happens when we look at the foods that the saturated fats are derived from – such as meat, types of dairy and fish.
This research found that there were no strong associations between dietary saturated fat and future heart disease, or between substituting polyunsaturated or monounsaturated fat for saturated fat and heart disease. In contrast, there were important differences when the food sources of saturated fat were considered. The consumption of saturated fat from fermented dairy products (yoghurt and cheese) and fish was associated with lower future risk of heart disease, while the consumption of saturated fat from red meat and butter was associated with a higher heart disease risk.
These findings highlight that the link with heart disease for saturated fat differs depending on what food sources it comes from, and that therefore intake of nutrients such as specific types of fat should not be considered in isolation. This supports the adoption of a food based translation of recommendations for saturated fat intake in dietary guidelines.
A caveat is that this current research is based on observing the associations between diet and health, and this cannot prove cause and effect as it is not based on a randomised clinical trial. That said, conducting such clinical trials is not easy as people would have to consume prescribed diets for years which is not practical. The current findings are based on a large multi-country European study but they should be further evaluated in different populations with different dietary patterns and types of foods consumed, and if consistent findings emerge then we can be even more certain.