Featured article in the Summer 2016 Issue of Nutrition Close-Up; written by Elizabeth J. Reverri, PhD, RD, LDN
Cardiovascular disease currently affects approximately 86 million adults in the U.S. and has been the number one cause of mortality for almost 100 years. Because traditional risk factors fail to predict up to 50% of cardiovascular disease, other cardiovascular disease risk factors take on greater importance.1
One such cardiovascular disease risk factor is endothelial dysfunction, which refers to the inability of the arteries to sufficiently dilate in response to an endothelial stimulus.1 Endothelial dysfunction contributes to the progression of atherosclerosis and is associated with many cardiovascular disease risk factors.2
The gold standard for measuring endothelial dysfunction is coronary epicardial vasoreactivity involving direct measurement of the coronary vascular bed using pharmacological stimuli. Unfortunately, this method is invasive, expensive, and timeconsuming.2 Noninvasive measurements of endothelial dysfunction include endothelial activation, such as increased soluble adhesion molecules (E-selectin, P-selectin, sICAM-1, and sVCAM-1), and endothelialdependent vasodilation, such as flow mediated dilation of the brachial artery, among other functional measures.3
The majority of studies investigating the effects of diet on endothelial function have studied specific foods or nutrients, rather than overall diet. These types of studies contribute to the understanding of the physiological mechanisms.4 Because food groups and nutrients are consumed as part of an overall eating pattern, investigating the effects of dietary patterns takes into account likely synergistic effects of whole foods3 and analyzes the diet in a more relevant manner.5
A review by Schwingshackl et al.6 investigated endothelial function after adherence to the Mediterranean diet. In general, the Mediterranean diet emphasizes regular consumption of fruits, vegetables, mostly whole grains, olive oil, beans, nuts, legumes, seeds, herbs, spices, fish, and seafood and moderate consumption of poultry, eggs, cheese, and yogurt.7 The researchers included randomized controlled parallel-arm trials or crossover trials that were a minimum of 12 weeks long in adults. Of note, one of the reviewed studies randomized adults with metabolic syndrome to receive either a Mediterranean diet or a prudent diet of 50-60% carbohydrate, 15-20% protein, and <30% fat. They developed an endothelial function score that assigned points to the sum of the responses from blood pressure and platelet aggregation. After two years, the participants on the Mediterranean diet showed improved endothelial function scores, whereas the control diet simply maintained endothelial function scores. It was found that along with the other studies in this review, the Mediterranean diet increased flow mediated dilation of the brachial artery and decreased the soluble adhesion molecule, sICAM-1, thus improving endothelial function.6
Defago et al.5 reviewed dietary patterns and endothelial biomarkers from observational and cross-sectional studies. They found several studies used factor analysis to identify a healthy dietary pattern and had beneficial responses on circulating endothelial biomarkers. From the Nurses’ Health Study, two dietary patterns emerged: one was a prudent pattern characterized by higher dietary intake of fruits, vegetables, legumes, fish, poultry, and whole grains, whereas the other was a so-called Western pattern with higher dietary intakes of red and processed meats, sweets, desserts, French fries, and refined grains. The prudent pattern was inversely associated with E-selectin, whereas the Western pattern was positively associated with E-selectin, sICAM-1, and sVCAM-1. A similar study design was applied to the ethnically diverse Multi-Ethnic Study of Atherosclerosis, but four dietary patterns were revealed. The beans, tomatoes, refined grains, and high-fat dairy products dietary pattern was positively related to sICAM-1. In contrast, the whole grains and fruit dietary pattern was inversely associated with sICAM-1. Lastly, among Iranian women, their healthy dietary pattern consisted of high amounts of fruits, vegetables, poultry, legumes, tea, and whole grains and was inversely associated with the adhesion molecules, sVCAM-1 and E-selectin, whereas the Western dietary pattern was positively correlated with sICAM-1 and sVCAM-1.5
Since these reviews were published, Sauder et al.4 assessed adherence to the 2010 Dietary Guidelines for Americans on various measures of vascular health. The Dietary Guidelines for Americans promotes a healthy dietary pattern emphasizing consumption of fruits, vegetables, low-fat dairy, whole grains, and lean meats. The researchers applied an adherence index tool to a food frequency questionnaire filled out by participants from the Framingham Heart Study. They found that closer adherence to the Dietary Guidelines for Americans was linked to better vascular health in adults under the age of 50 years, based on the following measures of vascular health: lower mean arterial pressure, carotid-femoral pulse wave velocity, and augmentation index.4
In conclusion, several healthy dietary patterns improve endothelial dysfunction. Ultimately, there are a variety of eating patterns that may reduce the risk of this emerging cardiovascular disease risk factor.
Elizabeth (Beth) J. Reverri, PhD, RD, LDN is a registered dietitian and human nutrition researcher at The Ohio State University.