The problem with the way most people eat in today’s fast-paced modern world is that most of our life is spent in what is known as a “post-prandial” state. In other words, because we are fortunate enough to be able to eat three “square” meals every day we exist always in an “after-meal” condition. This doesn’t have to be a negative situation, however our food choices dictate what is happening in our arteries after we eat and our meal preferences are not always healthy ones.
Excess fat travelling through the cardiovascular system is a well-recognized cause of reduced artery function and atherosclerosis (the build-up of plaque within the lining of arteries that is made up of cholesterol and other fats, calcium, cell waste products and fibrin (a clotting material) ) (1,2). Our affluent lifestyle means that high fat levels in our blood vessels are often the norm during our waking hours. Over-consumption of unhealthy fat from animal-based foods, isolated plant oils or processed foods triggers inflammation inside arteries, damaging the inner lining of these vessels and decreasing their production of nitric oxide. Nitric oxide is responsible for proper functioning of the blood vessels including the prevention of inflammation and plaque build-up. (3). (See my blog entitled “What Does Eating Plants Do For Your Blood Vessels” for more information about this.)
How does the modern diet actually cause inflammation? Eating excessive amounts of calorie-dense high-fat and high-sugar foods causes abnormal increases in fat and sugar levels in the blood. High levels of nutrients such as these that have the potential to supply energy to the body can overwhelm the mitochondria (small organelles within cells whose job it is to take in nutrients and metabolize them (break them down) in order to extract their energy). With normal metabolism impossible, the system is flooded with free fatty acids and glucose molecules that end up being oxidized through the process of oxidation. Oxidation involves the splitting of oxygen molecules (O2) into single atoms with unpaired electrons. These unstable and hyper-reactive entities are called free radicals. They scavenge the body seeking another electron and in the process cause damage to cells, proteins and DNA. Oxidative stress results from excessive cellular damage caused by too many free radicals and is linked with aging and the development of many conditions including cardiovascular disease, some cancers, Alzheimer’s Disease, Parkinson’s Disease, macular degeneration, arthritis and lupus. Antioxidants fill the very important role for health by keeping free radicals in check through donating their electrons to the free radicals without becoming unstable themselves. Though the human body can produce some antioxidants, it is not capable of producing enough to extinguish all the free radicals produced by life processes. Fortunately antioxidants are easily acquired through diet. (4,5).
Luckily we have a way to fight this onslaught. Whole foods are capable of supplying the antioxidants needed to protect our arteries (as well as many other structures of our body) from oxidation and inflammation. Because the fats in whole foods are contained within a matrix of fiber and phytochemicals (including antioxidants) they do not lead to inflamed tissues. A wealth of scientific investigation supports this effect. For example, a 2017 study reviewed eighteen prior studies and found that people eating a diet of fruits, vegetables, whole grains and legumes lowered their levels of C-reactive protein (a marker of inflammation in the body) compared to non-vegetarians. Researchers credited the high amount of antioxidants such as phytosterols and dietary fiber in this type of diet with its positive effects (6). A 2015 review of recent studies concluded that a shift toward a plant-based diet will confer protective effects against atherosclerosis by increasing the function of the endothelial cells that line the arteries (7). A population-based prospective Swedish study of 32,561 women suggested that dietary total antioxidant capacity, based on intake of fruits, vegetables, whole grains, and coffee is of importance in the prevention of myocardial infarction. (8). A study on pecan ingestion demonstrated increased blood concentrations of antioxidants such as γ-tocopherol and a 26% reduction in the oxidation of LDL-cholesterol eight hours after their consumption (9). Let’s take a look at more evidence for the benefit to artery health by the addition of whole foods to our diet, even those that are high in fat and calories.
Walnuts can reverse negative food effects on artery function. In a randomized, controlled, crossover study, participants were asked to eat a high-fat meal consisting of salami, cheese and yogurt on white bread along with all the water they wanted to drink. In addition to this base meal, participants consumed either 25ml of olive oil soaked into the bread or 40 gm of shelled walnuts added to the sandwich. Both test meals contained 80 g fat and 35% saturated fatty acids. The same subjects returned one week later and consumed the other test meal. The functioning of their arteries was measured through ultrasound of the brachial artery immediately before ingestion of each meal and again four hours after eating. Results showed that the addition of olive oil lessened the drop in artery function caused by the high-fat meal. The addition of walnuts however actually abolished the impairment of artery function triggered by the high-fat meal. (10)
Peanuts show a similar effect. A randomized, controlled crossover trial randomly assigned participants to drink a standardized milkshake or a similar milkshake that also contained peanuts. The shakes were matched for macronutrient content in calories, fiber, protein, carbohydrates and fats (including levels of saturated, monounsaturated and polyunsaturated fats). Results showed that the regular milkshake decreased the ability of arteries to relax and dilate normally by about 20%. However, the milkshake with peanuts, in spite of containing exactly the same amount of saturated fat and sugar, resulted in no drop in artery function. The researchers credit this effect to bioactive compounds in peanuts and their skins such as L-arginine (an amino acid that is converted into nitric oxide by the endothelium that lines arteries) and phenolic antioxidants that inhibit damaging oxidative reactions. (11)
In a 2014 study, the inflammation-producing capability of calorie-dense, high-fat and phytonutrient-rich avocados was compared to that of high-calorie, high-fat, high-sugar, phytonutrient-poor ice cream. Using a randomized, crossover design, eleven healthy participants ingested four test foods of similar calorie level. The foods used were ice cream, avocado, the fat/protein component of ice cream, and the sugar component of ice cream. Four avocados were required to equal the number of calories in the ice cream. Results of the study showed that eating the ice cream or just the sugar components of the ice cream or just the fat/protein components of the ice cream all caused significant increases in oxidative stress. Ingestion of a calorie-equivalent amount of phytonutrient-rich avocado did not. Researchers state that “these data indicate that the ingestion of a phytonutrient-poor food and its individual fat/protein or sugar components increase plasma oxidation. No rise in oxidative stress occurs after a calorie-equivalent phytonutrient-rich food.” (12).
Another study looked again at avocados and their effect on inflammation. The ingestion of meat causes inflammation through the production of free radicals during the oxidative degradation of its fats. Adding some avocado to a meat meal, in this case a meat burger, inhibits this process, lowering the inflammation that results from consuming the meat. The fat level in avocado is very high, providing about 80% of its available calories, but this fat, similar to that of other whole foods, is entangled within a structure that also includes fiber, vitamins and phytochemicals. The mechanism of the inflammation-lowering benefit of avocado is thought to occur through two attributes of avocado, its inherent fiber that has a cholesterol lowering effect and its antioxidants that decrease inflammation (13).
What is the take-home message here? We all want to have healthy arteries. No one wishes to experience atherosclerosis and its consequences of a heart attack or stroke. Investigations into whole foods have shown that foods in their natural state, vegetables, legumes, fruits, nuts, seeds and grains, are the food choices that promote healthy arteries and support proper functioning of the endothelial lining. Obviously the healthiest option is to simply eat a diet of exclusively whole plant foods. Such a decision however can be overwhelming. If this is where you’re at it is good to know that just adding some healthy, phytonutrient-containing whole foods such as nuts or avocados to an unhealthy meal can go a long way towards keeping your arteries well and happy.
3 Deanfield, J.E., Halcox, J.P., Rabelink, T.J. Endothelial Function and Dysfunction. Contemporary Reviews in Cardiovascular Medicine. Circulation. 2007; 115:1285-1295
4 O’Keefe, J.H., Gheewala, N.M. and O’Keefe, J.O. Dietary Strategies for Improving Post-Prandial Glucose, Lipids, Inflammation, and Cardiovascular Health. Journal of the American College of Cardiology, January, 2008; 51 (3): 249-255.
6 Haghighatdoost, F., Bellissimo, N., de Zepetnek, J.O.T., Rouhani, M.H. Association of vegetarian diet with inflammatory biomarkers: a systematic review and meta-analysis of observational studies. Public Health Nutr. 2017; 1-9.
7 Tuso, P., Stoll, S.R., Li, W. W. A Plant-Based Diet, Atherogenesis, and Coronary Artery Disease Prevention. Perm J. 2015 Winter; 19 (1): 62–67.
8 Rautiainen, S., Levitan, E.B., Orsini, N., Åkesson, A., Morgenstern, R., Mittleman, M.A., Wolk, A. Total antioxidant capacity from diet and risk of myocardial infarction: a prospective cohort of women. Am J Med. 2012 Oct; 125(10): 974-980.
9 Hudthagosol, C., Haddad, E.H., McCarthy, K., Wang, P., Oda, K., Sabate, J. Pecans acutely increase plasma postprandial antioxidant capacity and catechins and decrease LDL oxidation in humans. J Nutr 2011; 141:56–62.
10 Cortés, B., Núñez, I., Cofán, M. et al. Acute effects of high-fat meals enriched with walnuts or olive oil on postprandial endothelial function. J Am Coll Cardiol. 2006; 48(8):1666-71.
11 Liu, X., Hill, A.M., West, S.G. et al. Acute Peanut Consumption Alters Postprandial Lipids and Vascular Responses in Healthy Overweight or Obese Men. J Nutr. 2017; 147(5):835-840.
12 Khor A, Grant R, Tung C, et al. Postprandial oxidative stress is increased after a phytonutrient-poor food but not after a kilojoule-matched phytonutrient-rich food. Nutr Res. 2014;34(5):391-400.
13 Li, Z., Wong, A., Henning, S.M., et al. Hass avocado modulates postprandial vascular reactivity and postprandial inflammatory responses to a hamburger meal in healthy volunteers. Food Funct. 2013; 4 (3):384-91.
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