March 28, 2018 | Christine Pacheco, MD
Education

My brother, an engineer, recently asked me what my thoughts were on several types of diets, including the ketogenic diet. After a more detailed discussion with him, I realized there are numerous dietary theories and regimes preached in fitness communities that I had not heard much about during my fellowship training, and I was curious to know if there were any underlying scientific merits to some of these trending nutrition regimes.

As cardiology FITs, we are at the forefront of some of the most modern pharmacological and interventional technologies, and we communicate the clinical benefits, potential risks and side effects of these therapies to our patients. Lifestyle modifications, including nutrition and exercise, are often mentioned as non-pharmacological targets with proven benefits. However, an in-depth discussion around precise details surrounding nutrients and current trends is often overlooked in busy clinics, leaving us potentially underexposed as trainees to this relevant aspect of patient counseling. In future everyday practice, we will be questioned by patients and peers concerning the benefits or disadvantages of different foods in terms of cardiovascular disease prevention as they attempt to reconcile food trends and fads with available evidence-based findings.

U.S. News & World Report, recently released their "Best Diet" report by panel of experts from various scientific backgrounds, and ranked the Mediterranean and DASH diets – dietary patterns currently recommended in the 2013 AHA/ACC Guideline on Lifestyle Management to Reduce Cardiovascular Risk – as the most effective and sustainable diets of 40 different types in promoting weight loss and overall health benefits. Following the publication of the PREDIMED trial in 2013, a randomized-controlled study of 7,447 patients at risk of cardiovascular disease demonstrated that those randomized to Mediterranean style eating, and using 1L of extra-virgin olive oil per week or consuming 30 g of mixed nuts per day, had 30 percent fewer adverse cardiovascular events than the control group. The Mediterranean diet has become one of the most common diet recommended by the clinical cardiovascular community.

Dean Ornish, MD, et al., demonstrated in a Journal of the American Medical Association study nearly 20 years ago that a 10 percent fat, plant-based diet, in conjunction with physical activity, smoking cessation and stress management, resulted in coronary artery plaque regression over five years, without the use of statins. Although adherence to this diet can be challenging, it was ranked ninth by panel experts due to overall health benefits.

Low carbohydrate diets have previously been advocated as they have been associated with greater short-term weight loss than low-fat diets. However, data on cardiovascular outcomes is lacking. Although conflicting data exists, when compared in a randomized controlled trial with a six-month follow-up, very-low-carbohydrate and high-fat-intake diets were associated with a similar amount of weight loss, improved triglyceride and HDL cholesterol levels than high-carbohydrate and low-fat diets, which were associated with lower LDL cholesterol levels. Ketone levels correlated with weight loss in the very-low-carbohydrate diet subjects but not in the low-fat diet, suggesting that higher levels of ketone may reflect dietary compliance and not necessarily promote satiation and sustained weight loss, as advocated by ketogenic diet regimes that were ranked last by the recent U.S. News & World Report on "Best Diets."

Cardiovascular prevention counseling should always be incorporated in patient discussions and advice pertaining to nutrition is no exception. The importance of nutrition and the scientific merit of different diet trends should be further incorporated into preventative cardiology lectures throughout cardiology fellowship training so that as future cardiologists and key players in cardiovascular prevention counselling, we have all the tools necessary to promote balanced and beneficial nutrition to our peers, patients and communities.

This article was authored by Christine Pacheco, MD, Fellow in Training (FIT) at Cedars-Sinai Medical Center in Los Angeles, CA.