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In 2014, a prominent cardiologist shared his personal experience in using a nutritional approach to lower the creep of his LDL cholesterol. Dr. Kim Allan Williams is a talented mentor and colleague of mine and was then president of the American College of Cardiology. He revealed that while his diet was healthy overall, with plenty of fruits, vegetables, and fiber, his LDL cholesterol had climbed to 170.1 Dr. Williams then reviewed earlier studies by Drs. Ornish and Esselstyn and became a vegan. The result: his LDL cholesterol went down from 170 to 90 mg/dl.
As a practicing cardiologist trained in functional medicine, I seek to apply functional nutrition interventions in caring for my patients. Yet Dr. Williams’ journey highlights the confusion and controversy still surrounding the impact of various nutritional styles on cardiac disease, including cardiac events and mortality.
Recommended Dietary Pattern: Mediterranean Diet
For decades, cardiologists and many physicians have endorsed a Mediterranean-style diet pattern. The American College of Cardiology Guideline on Lifestyle Management to Reduce Cardiovascular Risk recommends a “dietary pattern that emphasizes intake of vegetables, fruits, and whole-grains; includes low-fat dairy products, poultry, fish, legumes, non-tropical vegetable oils, and nuts; and limits intake of sweets, sugar-sweetened beverages, and red meats.”2 This recommendation has the highest rating as Class I, Level of Evidence A. The same nutritional advice was subsequently reflected in the Guideline on the Management of Blood Cholesterol3 and further emphasized in the 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease, which is notable for a call to “minimize the intake of processed meats, refined carbohydrates and sweetened beverages” to reduce risk.4
The Mediterranean diet has been evaluated extensively, including large, randomized prospective studies such as PREDIMED5 (which reaffirmed many of the earlier findings from 2013 in the updated statistical analysis in 2018). To date, the Mediterranean diet is one of the only nutritional patterns with strong scientific support for impact on total, cardiovascular, and cancer mortality and a reduction in cardiovascular event rates.6
Looking at the Mediterranean, vegetarian, and vegan food pyramids, one can appreciate that there is a large plant-based component for each. In addition, animal products such as red meat are used in moderation in the Mediterranean diet. Thus, further research with a focus on the benefits and risks of plant-based contribution in various dietary styles is likely to produce more actionable data and refine our understanding regarding the role of various types of naturally occurring macronutrients.
Plant-Based Diet Research
However, many guidelines and recommendations mostly ignored earlier studies by Ornish and colleagues, who investigated small and observational cohorts of patients and documented benefits of plant-based, vegetarian, and vegan-like diets. Combined with a structured stress and exercise regimen, such diets had a profound effect on patients with advanced heart disease, including such findings as:7
- Reduction of inflammation
- Decrease in subsequent cardiac events
- Improved vitality
- Angiographic reduction in the size of coronary plaques
Observational data from the Seventh-day Adventists has shown favorable impact of plant-based diets on cardiac and cancer mortality.8 Most recently, metabolomic studies from the Cleveland Clinic identified the contribution of animal products through metabolism by the gut microbiome as detrimental to vascular endothelium and independently prognostic in acute coronary events.9
Based on these studies, there has been a renewed interest in a nutritional approach to heart patients that relies on the elimination of animal products. A plethora of recent studies, based on PURE data, produced contradictory results, highlighting the need for further research.10 The PURE study, conducted in 18 countries and 5 continents, showed lower mortality associated with saturated and unsaturated fat intake and higher mortality associated with high carbohydrate intake. The quality of macronutrients matters, and this study has drawn criticism as many of the consumed carbohydrates were processed, refined foods.11 The investigators concluded that a plant-based diet that was mostly based on highly refined carbohydrates, indicative of a “poverty diet,” which is also high in sodium and low in animal products, was detrimental; the plant-based diets that permit use of animal products and complex carbohydrates were associated with health benefits.
It is important to note that PURE included diverse populations, including the countries with poorer populations where access to plant-based refined carbohydrates was often more readily available than healthier alternatives, including meat. It is also possible that due to the proportion of refined carbohydrates in the diet, many participants were suffering from vitamin and mineral deficiency, readily addressed by animal products. The value of the PURE study is in presenting us with real-world data that highlights the need to address the social determinants of health, of which food insecurity is a major component.
We are far from settling these great nutritional debates. As a functional medicine–trained cardiologist, I often explain to my patients that there is a difference between foundational and interventional nutrition approaches and explain the concepts of hormesis and allostatic load as those relate to food-induced vascular responses. In clinical practice, I may start with an elimination diet and proceed to either a cardiometabolic (Mediterranean-like) food plan. I occasionally start with IFM’s Mito plan combined with intermittent fasting for patients with insulin resistance or diabetes.
Current advances in personalized testing have allowed for personalized risk stratification, including assessments like the following:
- LPLAC2, MPO, and Lp(a)
- Evaluation of the nuances of lipid metabolism through particle fractionation
- Expansion of cardiac imaging capabilities through cardiac CT and cardiac flow imaging
These data inform personalized treatment plans based on individualized risk, a cornerstone of any effective cardiovascular functional medicine program.
More importantly than the starting plan itself, I find that modifying the nutritional approaches by rotating them based on a patient’s clinical history, and proceeding to more interventional nutritional styles such as an elimination, ketogenic, or vegan diet based on advanced marker work up and genetic, metabolomic, and microbiome evaluations, is key to success. This allows for a dynamic approach that is far superior to the “one-size-fits-all” cardiology guideline recommendations
- O’Connor A. Advice from a vegan cardiologist. New York Times. Published August 6, 2014. Accessed August 18, 2020. https://well.blogs.nytimes.com/2014/08/06/advice-from-a-vegan-cardiologist/
- Eckel RH, Jakicic JM, Ard JD, et al. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014;63(25 Pt B):2960-2984. doi:1016/j.jacc.2013.11.003
- Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2019;73(24):e285-e350. doi:1016/j.jacc.2018.11.003
- Arnett DK, Blumenthal RS, Albert MA, et al. 2019 ACC/AHA guideline on the primary prevention of cardiovascular disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2019;74(10):1376-1414. doi:1016/j.jacc.2019.03.009
- Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts. N Engl J Med. 2018;387(25):e34. doi:1056/NEJMoa1800389
- de Lorgeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon Diet Heart Study. Circulation. 1999;99(6):779-785. doi:1161/01.cir.99.6.779
- Ornish D, Scherwitz LW, Billings JH, et al. Intensive lifestyle changes for reversal of coronary heart disease. JAMA. 1998;280(23):2001-2007. doi:1001/jama.280.23.2001
- Fraser GE. Vegetarian diets: what do we know of their effects on common chronic diseases? Am J Clin Nutr. 2009;89(5):1607S-1612S. doi:3945/ajcn.2009.26736K
- Li XS, Obeid S, Klingenberg R, et al. Gut microbiota-dependent trimethylamine N-oxide in acute coronary syndromes: a prognostic marker for incident cardiovascular events beyond traditional risk factors. Eur Heart J. 2017;38(11):814-824. doi:1093/eurheartj/ehw582
- Dehghan M, Mente A, Zhang X, et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Lancet. 2017;390(10107):2050-2062. doi:1016/S0140-6736(17)32252-3
- Harvard T.H. Chan School of Public Health. PURE study makes headlines, but the conclusions are misleading. The Nutrition Source. Published September 8, 2017. Accessed August 18, 2020. https://www.hsph.harvard.edu/nutritionsource/2017/09/08/pure-study-makes-headlines-but-the-conclusions-are-misleading/