Three studies on heart disease
Jacob Schor ND, FABNO
January 14, 2105
Three studies about heart disease caught my attention recently. The first published in November 2015 compared adherence to a Mediterranean style diet with risk of myocardial infarction, heart failure and stroke. The second study published a year earlier in September 2014 compared adherence to a low carbohydrate diet with survival statistics among myocardial infarction survivors. The third calculated cumulative benefits of three lifestyle interventions, diet, exercise and not smoking in people who had already suffered a first cardiac event.
This Mediterranean study stands out because the cohort was Swedish. Past studies that associated Mediterranean diet adherence with lower all cause cardiovascular disease incidence and mortality have not answered a basic question, does this work outside of the Mediterranean? We have wondered whether vitamin D or sun exposure might be essential and necessary components for the benefits associated with this diet.
In this study, the diets of 39,921 Swedish women were based on consumption of vegetables, fruits, legumes, nuts, whole grains, fermented dairy products, fish and monounsaturated fat, moderate intakes of alcohol and low consumption of red meat, on a 0-8 scale. During 10 years of follow-up a high adherence to the Mediterranean diet was associated with a 26% lower risk of MI, a 21% lower risk of heart failure, and a 22% drop in risk of ischemic stroke. This study does not answer whether these women might have experienced greater benefit if they lived in a warmer and sunnier clime. 
The earlier study on low carbohydrate diets is important for several reasons. First it looked at people who had survived their first myocardial infarction and it begins to answer a fundamental question as to whether secondary prevention may differ from primary prevention, that is do we tell patients who’ve already survived a heart attack to do the same thing as when they were trying to prevent a first heart attack? Second, it examined a dietary pattern that has become quite popular despite a paucity of data on its impact.
While the evidence is strong that a Mediterranean dietary pattern is useful in prevention of primary disease, the best pattern for survivors of myocardial infarction is unclear. This study included data from 2258 women in the Nurses' Health Study and 1840 men in the Health Professional Follow-Up Study who had survived a first MI. Adherence to an low carbohydrate diet (LCD) that was high in animal sources of protein and fat was associated with a 33% increase in all-cause mortality and a 51% increase for cardiovascular mortality comparing extreme quintiles. 
These are truly troubling results. Low carbohydrate diets have been popular in recent years. The South Beach Diet, the Paleo Diets, the Atikins Diet and others have tended to move people in this direction. The findings reported in this study should give us pause and suggest that we hesitate following or encouraging such a low carb/high animal protein dietary pattern moving forward, at least for prevention of secondary heart disease.
A third study, this one from June 2014, gives us a measure of the benefit of exercise, diet and not smoking in prevention of a second heart attack or death from heart disease in patients. 4174 patients who had already experienced a heart attack, or had underwent cardiac catherization or coronary bypass surgery were analyzed and favorable lifestyle behaviors were compared with risk of further disease or death. Comparing patients who had 1, 2, and 3 versus 0 lifestyle factors in their favor (non-smoking, physical activity more than 4 times per week and high adherence to a Mediterranean diet), risk for heart disease recurrence dropped by 40%, 51% and 62%. Risk of death dropped by 35%, 43% and 59% with increasing favorable lifestyle factors. 
People often get caught up with the small stuff, fussing with small health trivia. It’s important to stay focused on the big things that they can do that make a difference in their health.
Full text of studies:
1. Atherosclerosis. 2015 Nov;243(1):93-8. doi: 10.1016/j.atherosclerosis.2015.08.039. Epub 2015 Sep 3.
A Mediterranean diet and risk of myocardial infarction, heart failure and stroke: A population-based cohort study. Tektonidis TG1, Åkesson A2, Gigante B3, Wolk A4, Larsson SC5.
2. J Am Heart Assoc. 2014 Sep 22;3(5):e001169. doi: 10.1161/JAHA.114.001169.
Low carbohydrate diet from plant or animal sources and mortality among myocardial infarction survivors. Li S1, Flint A2, Pai JK3, Forman JP4, Hu FB5, Willett WC5, Rexrode KM6, Mukamal KJ7, Rimm EB5.
3. Am J Cardiol. 2014 Jun 15;113(12):1933-40. doi: 10.1016/j.amjcard.2014.03.033. Epub 2014 Apr 1. Effect of sustaining lifestyle modifications (nonsmoking, weight reduction, physical activity, and mediterranean diet) after healing of myocardial infarction, percutaneous intervention, or coronary bypass (from the REasons for Geographic and Racial Differences in Stroke Study).
Booth JN 3rd1, Levitan EB1, Brown TM1, Farkouh ME2, Safford MM1, Muntner P3.