Parikh 1 Nishi Parikh Lifespan Nutrition Dr. Michael Zemel March

Parikh 1 Nishi Parikh Lifespan Nutrition Dr. Michael Zemel March 5, 2009 Cardiovascular Disease Prevention by a Vegetarian Diet “According to the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC), 16.7 million deaths were reported around the globe due to different types of cardiovascular diseases (CVD).” Many studies have shown that diet plays a major role in the development or prevention of cardiovascular diseases (1). One of the health properties of foods is their chemical composition. All foods are not created equal. While some have high concentrations of saturated fatty acids, others might have high concentrations of unsaturated fatty acids. For example, although many foods contain fatty acids, the type of fatty acids makes a difference in how they will be metabolized. Saturated fat has been linked to enhanced platelet aggregation whereas, unsaturated fat has been linked with decreased platelet aggregation. Platelet aggregation is a factor for atherosclerosis, leading to cardiovascular disease (2). As we see, the foods that one consumes have a direct link with the nutrients consumed and also the overall health of the consumer. Two major classifications of diets, vegetarian diet and omnivorous diet, have a significant difference in the foods and nutrients consumed. Foods involved in vegetarian diets have many healthy properties. Specifically, vegetarian diets prevent cardiovascular disease. A vegetarian diet mainly consists of consumption of fruits, vegetables, whole grains, and legumes and nuts (3). Three main types of vegetarian diets play a role in

Parikh 2 enhancing cardiovascular health: lacto-ovo-vegetarian, lacto-vegetarian, and vegan. All of these diets exclude meat, poultry, fish and seafood consumption. Lacto-vegetarian diets excludes eggs from a lacto-ovo-vegetarian diets which includes dairy and eggs. A vegan diet excludes eggs and dairy products (4). In order to understand the effects of nutrients on health and the prevention of cardiovascular disease, one must understand the causes of cardiovascular diseases esp. atherosclerosis, one of the diseases where arteries are clogged by fatty acid tissues which block the flow of blood (5,6). Some of the diet-related risk factors of cardiovascular disease or coronary heart disease are abnormal blood lipids, diabetes mellitus, systemic hypertension, high homocysteine levels, inflammation and abnormal blood coagulation (1,7). A vegetarian diet can alleviate these risk factors. One specific mechanism for fat blockage of the artery involves low-density lipoprotein (LDL) cholesterol. LDL particles are atherogenic when both the phospholipids and protein particles of the particles are altered. One example is oxidation. When the particles are oxidized, they are taken up by macrophages. These macrophages lose motility after being laden with cholesterol. Therefore they remain in the artery wall and become a part of the foam cell component of the atherosclerotic plaque. Dietary components called antioxidants can prevent this oxidation process (2). Of course, the major source of antioxidants are plant foods, abundant in vegetarian diets (1). Other compounds, homocysteine and high-sensitivity C-reactive protein, are associated with risk of heart disease. Clinical studies show that elevated levels of homocysteine are associated with an increased risk of cardiovascular disease. Homocysteine is involved in stimulation of vascular smooth cell proliferation and

Parikh 3 collagen synthesis. “It also affects endothelial cell function and adversely affects the anticoagulant sytem, which may in part explain its atherogenicity.” Also, high-sensitivity C-reactive protein (hs-CRP) stimulates inflammation. This is important because atherosclerosis can be advanced by inflammation in the artery along with the accumulation and oxidation of cholesterol and LDL-C. Hence, controlled levels of hsCRP are encouraged to avoid cardiovascular risk (3). Fruits, vegetables, whole grains, legumes and nuts contain numerous chemicals, including antioxidants, that are involved in the prevention of cardiovascular disease. Vegetarian diets contain cardioprotective compounds: fiber, antioxidants (Vitamin A, Vitamin E, and Vitamin C), and phytochemicals of which non-vegetarian diets generally lack. Plant-based diets also contain the cardioprotective minerals selenium and folate (1). Some other beneficial nutrients and non-nutrients consumed by vegetarians include “polyunsaturated fatty acids, especially long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid, docosahexaenoic acid, monounsaturated fatty acids, milk and phytochemicals, such as allicin( in garlic), polyphenols (in cocoa), isoflavones (in soy) and anthocyanins ( in red wines and grape juice) .” All of these nutrients and nonnutrients have cardioprotective properties (3). These compounds and some others are all involved with the prevention of cardiovascular disease. Phytochemicals often have an antioxidant affect. Another set of compounds, polyphenols, prevent agains LDL cholesterol oxidation and improve endothelial dysfunction, whereas soluble and insoluble fiber and sterols help reduce serum cholesterol levels. Also, antioxidants reduce oxidative stress and improve endothelial function, folate protects against coronary heart disease by its ability to reduce

Parikh 4 homocysteine levels; some spices, herbs and condiments used in food preparations inhibit platelet aggregation and prevent thrombosis. Additionally, garlic has hypocholesterolemic, hypolipidemic, antihypertensive, antithrombotic, antihyperhomocysteinemic properties, and an ability to inhibit platelet aggregation. All of these properties are cardioprotective (1). Also, according to Venket Rao and Amir Al-Weshahy, fruits and vegetables have low levels of sodium. Consumption of fruits and vegetables displaces the consumption of salty foods. A controlled consumption of sodium controls blood pressure, reducing coronary heart disease risk (1). Cereal, another significant component of vegetarian diets, has many heart benefits. It contains fiber, linoleic acid, vitamin E, folate, and selenium. It also contains phytochemicals such as phytoestrogens of the lignan family and several phenolic acids with antioxidant properties. Legumes, vegetarian protein foods, contain fiber, phytoestrogens, isoflavones and folate, all of which are cardioprotective properties of legumes. Additionally, nuts contain much of the healthy fats omega-3 fatty acid alphalinoleic acid (1). Some polyphenols are known to prevent some oxidative damage and endothelial dysfunction. Red wine contains a type of polyphenol called resveratrol, green tea contains catechins, and pomegranate juice contains catechins and quercetin. Grape seeds contain proanthocyanidins . And tomatoes have been sufficiently studied and an inverse relationship shows the incidence of coronary heart disease and the consumption of lycopene, a carotenoid antioxidant phytochemical (1). As a reminder, all of these plant compounds control serum cholesterol, blood pressure, oxidative stress, homocysteine

Parikh 5 levels and improve endothelial dysfunction. All of these factors decrease risk of cardiovascular disease (1). Several studies have shown occurrences of favorable low density lipoprotein cholesterol levels, total cholesterol levels, antioxidant levels, blood pressure levels, and high-sensitivity C-reactive protein (hs-CRP) levels in vegetarians compared to omnivores. While low-density lipoprotein, total cholesterol, and antioxidant levels are associated with accumulation and oxidation of cholesterol and LDL-C, hs-CRP levels affect inflammation status. Exclusively, hs-CRP is considered a single independent cardiovascular risk factors (3). A study found in European Journal of Clinical Nutrition measured the fasting blood levels for glucose, cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein, white blood cell count, high-sensitivity C-reactive protein, and homocysteine in Taiwanese vegetarians compared to omnivores. The vegetarians had to have been on an ovo-lactovegetarian diet for at least one year to be studied as vegetarians. The study shows no significant differences in age, body mass index, blood glucose, white blood cell count, triglyceride and HDL-C levels in the vegetarians and omnivores studied. However, there were statistically significant differences in gender ratio, smoking rate, body weight, body height, total cholesterol, LDL-C and uric acid. Also, vegetarians had significantly lower levels of hs-CRP and higher levels of homocysteine compared to omnivores. This study and others have shown that vegetarians have a better lipid profile and a better controlled blood pressure (3). Although homocysteine levels are high in vegetarians, the cause is vitamin B12 deficiency caused by the exclusion of vitamin B12 foods. Furthermore, “no significant

Parikh 6 difference in carotid atherosclerosis, as measured by ultrasound, was found between these two groups. This implies that even with the higher homocysteine levels found in vegetarians, the carotid artery intima-media thickness and extra cranial carotid artery plaque score of vegetarians were, at least, not worse than in omnivores.” Additionally, “it appears that homocysteine is only one of the risk factors predisposing to atherosclerosis, whereas, the hs-CRP level represents the overall vascular inflammation status, which implies the presence of vascular damage, and is thus a direct sign of cardiovascular disease. (3)” Therefore, a vegetarian diet’s effect on maintaining low hs-CRP levels is much more significant than its possible occurrence of high homocysteine levels (3). Another study, studied the effects of long-term vegetarian diets on cardiovascular autonomic functions in healthy postmenopausal women. This study discovered “that women who had been vegetarians for at least two years had more optimal blood pressure and favorable lipid concentrations compared with omnivores, and that vegetarian diets may facilitate vagal regulation of the heart and increase baroreflex sensitivity…(8)” Finally, a case-control study suggests the benefits of foods directly with the risk of myocardial infarction. Norwegian men and postmenopausal women were studied. Subjects had to have no history of myocardial infarction or other serious illness. Upon a myocardial infarction occurrence in a study subject, dietary intake was analyzed for the previous year using a FFQ, Food Frequency Questionairre. Food consumption was compared between the cases and the controls. Study mediators created an “a priori diet score” by having a high score for diets that are hypthosized as healthy diets. These included low meat intake and high whole grain, vegetable, fruit, nut and legume intake. The foods in the healthy ranking were considered as protective against and those in the

Parikh 7 low rankings were considered as possibly causative of myocardial infarction. Some of the foods that were considered protective included cheese and yogur, low fat dairy, tea, wie beer, liquor, wholegrain breads, wholegrain breakfast cereals, fish, chicken, nonhydrogenated vegetable oil, dressings, mayonnaise, and sauces, cruciferous vegetables, tomatoes, salad, other vegetables, nuts, and soup. Eight foods were considered as contributing to myocardial infarction risk: liver, high-energy drinks, red and processed meats, chips and snacks, sweets, and pizza. Results of the study concludes certain foods as particularly protective: tomatoes, salad, whole-grain breakfast cereal, cruciferous vegetables. Butter and margarine were associated with risk of myocardial infarction. However, high-fat dairy intake was greater in controls. More importantly, a strong and inverse association was observed between the a priori healthy diet pattern score and risk of myocardial infarction. “The strength of the association between the healthy diet pattern score and risk of myocardial infarction underscores the important role of diet in the disease. (9)” This study provides further evidence of the inverse relationship of fruits, vegetables, and whole grains and heart disease. Also, a diet high in vegetarian foods and low in meat products is cardioprotective. Such results have been seen in other studies with other populations as well (9). As we now see, vegetarian diets are not only for the particularly religious. A vegetarian diet can contribute to numerous health benefits, specifically heart health, and the prevention of cardiovascular diseases. Not only do vegetarian foods have many compounds (i.e., fiber, sterols, antioxidants, folate, phytochemicals, linoleic acid, omega3 fatty acid alpha linoleic acid, vitamin E, selenium, and isoflavones) that prevent many risk factors for cardiovascular diseases: abnormal blood lipids, systemic hypertension,

Parikh 8 high homocysteine levels, and abnormal blood coagulation, vegetarian foods are limited in the compounds that contribute to these risk factors as well (3,1). By limiting LDL-C levels and its oxidation, increasing hs-CRP levels, and controlling blood pressure, a vegetarian diet is considered as a cardioprotective diet (3).

References 1. Rao V, Al-Weshahy A. Plant-based diets and control of lipids and coronary heart disease risk. Curr AtherosclerRep. 2008; 10: 478-85. 2. Fraser GE. Diet and coronary heart disease: beyond dietary fats and low-densitylipoprotein cholesterol. Am J Clin Nutr. 1994; 59: 1117S-23S. 3. Chen CW, Lin YL, Lin TK, Lin CT, Chen BC, Lin CL. Total cardiovascular risk profile of Taiwanese vegetarians. Eur J Clin Nutr. 2008; 62: 138-144. 4. Brown J. Adolescent nutrition. Nutrition through the lifecycle. 2008; 3:360. 5. Encyclopædia Britannica Inc.. Cardiovascular disease. Accessed March 5, 2009. 6. Encyclopædia Britannica Inc.. Atherosclerosis. Accessed March 5, 2009. 7. Roberts WC. The cause of atherosclerosis. Nutr Clin Pract. 2008; 23: 464-467. 8. Chin-Hua Fu, Yang CCH, Chin-Lon L, Kuo TBJ. Effects of long-term vegetarian diets on cardiovascular autonomic functions in healthy postmenopausal women. Am J Cardiol. 2006; 97: 380-3. 9. Lockheart MSK, Steffen LM, Rebnord HM, Fimreite RL, Ringstad J, Thelle DS, Pederson JI, Jacobs DR. Dietary patterns, food groups and myocardial infarction : a casecontrol study. Br J Nutr. 2007: 98: 380-387.