Saturated Fats; Bad, Good or Indifferent?
Since the 1960’s, dietary guidelines have recommended a reduction in dietary fat intake for the prevention and treatment of coronary artery disease (CAD). Numerous studies, as well as meta-analyses, have shown that dietary saturated fats have been associated with increases in low-density lipoprotein cholesterol (LDL-C), resulting in an increased risk of CAD.
In recent years, recommendations regarding dietary fats have been challenged. Those in favor of allowing more saturated fats in the diet point to studies showing that higher intakes of saturated fat are associated with increases in HDL-C and LDL-C, but there is a reduction in LDL particle number. Total LDL particle number is considered, by some, to be a stronger indicator of cardiovascular (CV) risk than lipoprotein measures.1 The studies also show that high saturated fat levels decrease triglyceride levels, making this analysis more complicated than simply looking at the LDL-C lipoprotein measure. The EPIC-InterAct case-cohort study followed 500,000 middle aged adults in 10 countries and found that while processed meats like ham, bacon, and sausages were associated with CV mortality, red meat was not.2
The Mediterranean Diet
The Mediterranean diet has been praised for focusing on food groups: fruit, vegetables, whole grains, fatty fish, lean meat, oils, nuts, legumes, a blend of fats, carbohydrates, and proteins. Some professionals believe the dietary guidelines should direct people in patterns of eating rather than specifying the percent of daily fat, carbohydrates or protein. The PREDIMED Trial supports this type of pattern for eating. The PREDIMED Trial included 7447 men and women without CV disease, but with a high risk of developing CVD. The participants were randomly assigned to a Mediterranean diet group or a low-fat control diet. Those in the Mediterranean group supplemented their diet with either olive oil or nuts while group two followed a low-fat control diet. The primary endpoint of myocardial infarction, stroke, or CV death was reduced by 30% compared with the control group.
The most recent lifestyle management guidelines from 2013, written by the American College of Cardiology and The American Heart Association, recommended a goal of 5% to 6% of total calories from saturated fats. Studies have shown that LDL-C is reduced maximally with a 5% to 6% reduction in saturated fats.3,4,5 One of the diets that was involved in this decision was the DASH diet. The DASH diet focused on diet patterns with whole grains, fruits, and vegetables, reduced refined carbohydrates and dairy with a reduction of saturated fat to 5% of calories.
The Lifestyle Heart Trial
Lastly, there is The Lifestyle Heart Trial by Dr. Dean Ornish. This is the first and only randomized control trial showing that a very low-fat vegan diet alongside with lifestyle changes of exercise and meditation can reverse the progression of coronary artery disease. The vegetarian diet consists of no more than 10% of calories from fat. There is no added fat to foods. The fat has to come naturally from whole grains, vegetables, fruits, legumes, soy foods and small amounts of nuts and seeds. The one-year data showed that the percent of atherosclerotic coronary artery plaque improved after one year. This was found using cardiac PET scans.6 A follow-up 5-year study was performed that showed a dose-response correlation both at 1 year and 5 years between the degree of adherence to both the lifestyle program as a whole and the diet.7 In addition to the reversal of plaque, there was a 300% improvement in blood flow to the heart. Dr. Ornish spoke at the American College of Cardiology in 2016 and noted his findings. He stated that “the burden of proof is on others to show that a higher fat diet can reverse the progression of heart disease.”
- Prado KB, Shugg S, Backstrand JR. Low-density lipoprotein particle number predicts coronary artery calcification in asymptomatic adults at intermediate risk of cardiovascular disease [abstract]. J Clin Lipidol. 2011;5:408-413.
- Rohrmann S, Overad K, Bueno-de-Mesquita HB, et al. Meat consumption and mortality-results from the European Prospective Investigation into Cancer and Nutrition. BMC Med. 2013;11:63
- Obarzanek E, Sacks FM, Vollmer WM et al: DASH Research Group. Effects on blood lipids on a blood pressure-lowering diet: the Dietary Approaches to Stop Hypertension (DASH) Trial. Am J Clin Nutr. 2001;74:80-89. Abstract
- Harsha DW, Sacks FM, Obarzanek E, et al. Effect of dietary sodium intake on blood lipids: results from the DASH-sodium trial. Hypertension. 2004;43:393-398.
- Appel LJ, Sacks FM, Carey VJ, et al; OmniHeart Collaborative Research Group. Effects of Protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial. JAMA. 2005;294:2455-2464.
- Ornish D, Brown SE, Scherwitz LW, et al. Can lifestyle changes reverse coronary heart disease? The Lifestyle Heat Trial. Lancet. 1990;336:12-133.
- Ornish D, Scherwitz LW, Billings JH, et al. Intensive lifestyle changes of reversal of coronary heart disease. JAMA. 1998:280: 2001-2007.