Plant based diets, or vegetarian diets, have been associated with improved health, along with reducing the risk of many chronic diseases. A healthy vegetarian diet focuses on high fiber, low saturated fats, and low calorie foods, such as vegetables, fruits, grains, legumes, nuts, and plant based oils. The components of a properly planned vegetarian diet may help in reducing the risk factors for developing chronic diseases, and be of a benefit in treatment of these diseases such as obesity, diabetes, and cardiovascular disease. In this study, I aim to find evidences from previous studies, and conduct research on how a vegetarian diet is associated with prevention and management of chronic diseases.
I was born in a vegetarian family, a family that belongs to a culture where most of the population practices vegetarianism. After I moved to the United States, I realized that the food culture was extremely different than mine, meat was easily available, and was consumed by most of the population. I started to question different diets, including my own, and started reading about how diet affects our health, and how different diseases are prevalent in different populations around the world. I believe that our food choices and habits are highly influenced by our family, friends, environment, and society. I also believe that as the society understands the benefits and harm of different diets, we try to move towards a direction that benefits our overall health. We see that more and more people are turning towards a vegetarian diet these days, for various reasons. Many doctors and nutritionists recommend vegetarian diets to possibly reduce the prevalence of chronic diseases and to assist in the treatment of many. It becomes really important to find out if properly planned vegetarian diets could possibly lower the risk of, or be of a benefit in management of chronic diseases. If sufficient research supported that different diets directly influenced our health conditions, a higher percentage of our society may be willing to consume vegetarian diets to protect themselves from such chronic diseases.
Purpose of the study
The purpose of this study is to examine the effectiveness of a vegetarian diet in prevention and treatment of chronic diseases. Chronic diseases can result from poor diet choices, environmental and genetic factors, and affects millions of people around the world. As of 2012, among civilian, noninstitutionalized US adults, approximately half (49.8%, 117 million) had at least 1 type of multiple chronic conditions (Ward, Schiller, & Goodman, 2014). The data on chronic conditions is alarming, and so, increased focus and swift action on reducing the burden of these diseases on the society is urgently needed. Health experts and nutritionists are now leaning towards a plant based diet that is low on the glycemic index, saturated fats, rich in fiber, and have antioxidant properties to prevent and slow the progression of these diseases. As the population grows, and along with that the population of individuals with chronic diseases, it becomes important to advice and recommend diet therapies that are evidence based, and are effective in preventing and treating chronic diseases.
Significance of the study
Chronic diseases, such as diabetes, cardiovascular disease, and obesity, are a fast growing public health concern in the world. According to the Centers for Disease Control and Prevention, an estimated 30.3 million people of all ages, or 9.4% of the U.S. population, had diabetes in 2015 (CDC, 2017-a), more than one-third (36.5%) of U.S. adults have obesity (CDC, 2017-b), and 1 in every 4, about 630,000 Americans die from heart disease each year (CDC, 2017-c). The data on these health conditions is alarming, and diet is a major factor linked to the prevention and overall management of these diseases. Features of a healthy vegetarian diet, one that is composed of vegetables, fruits, whole grains, legumes, and nuts, may be associated with improving blood sugar, lowering the risk of diabetes related complications. Improvement in blood pressure, total cholesterol, and a healthier vascular system may also be achieved through the consumption of a vegetarian diet. Since planned vegetarians diets, that are low in glycemic index, tend to promote weight loss, vegetarians usually tend to have a lower BMI, which could also be a pertinent factor for protection against obesity, and other related complications. Avoidance of non-vegetarian foods, such as meat products with high saturated fat, could be of a benefit for weight control and optimum BMI. Interventions, such as dietary changes can be effective in prevention and progression of these diseases and overall health. As society progresses with new innovations, and scientific accomplishments, it becomes important that this scientific knowledge and evidence be used to protect ourselves from factors that create a risk of acquiring such chronic diseases. This study can hopefully be used to raise awareness on how a vegetarian diet can be of a benefit in improving health, and in prevention from chronic diseases.
Keywords and Operational definitions
Vegetarian diet/plant based diet ��� A diet mostly consisting of plant based foods
Chronic disease ��� A disease that lasts three months or more, and cannot be cured by medication. (Example, diabetes, cardiovascular disease, and obesity)
BMI ��� Body Mass Index, measure of body fat based on weight and height
Metabolic syndrome or abnormalities ��� a group of risk factors that raises the risk of developing diseases
Glycemic Index ��� A ranking of carbohydrate in foods according to how they affect blood glucose levels
Research questions
1. Can vegetarian diets benefit in prevention or treatment of chronic diseases (data from scholarly articles)?
2. Do Americans consume the daily recommended amounts of fruits and vegetables in their diet? (testable)
3. Do vegetarians have a better metabolic profile than non-vegetarians (data from previous studies)?
4. Will non-vegetarians consider to consume mostly a vegetarian diet for health benefits? (testable)
5. Do vegetarians tend to have a lower BMI than non-vegetarian diets (data from previous studies)?
Null hypotheses
1. Plant based diets are not effective in the prevention and treatment of chronic diseases.
2. American diets meet the daily recommendation of fruits and vegetables.
3. Non-vegetarians tend to have a better metabolic profile than vegetarians.
4. Non-vegetarians are less likely to consider a vegetarian diet, even if it promotes better health.
5. People who consume a vegetarian diet ted to have a higher BMI than those who consume a non-vegetarian diet.
Literature review
Research suggests that the portfolio of a vegetarian diet may play an important role in the prevention and management of chronic diseases. Comprehensive and appropriately planned vegetarian diets can be nutritionally adequate and appropriate for all ages, and can have many health benefits. Craig and Mangels (2009, p. 1267) suggest that vegetarian diets tend to be lower in saturated fat and cholesterol, high in dietary fiber, high in vitamins and minerals, and are associated with many health advantages, such as, lower blood cholesterol, lower levels of blood pressure, lower risk of hypertension, lower BMI, and lower cancer rates. Appropriately planned plant based diets can be very nutrient-dense, low in calories, and high in fiber, vitamins, and minerals. Several studies show a positive relationship between metabolic profile and a vegetarian diet as compared to a non-vegetarian diet. Studies also suggest that a diet pattern that is plant based may also help prevent chronic degenerative diseases. A cross-sectional and longitudinal study was performed on all sub-types of vegetarians compared with non-vegetarians on all metabolic traits, including waist circumference, BMI, systolic blood pressure (SBP), diastolic blood pressure, fasting blood glucose, total cholesterol (TC), HDL, LDL, TAG and TC: HDL ratio, with data collected from 1994 to 2008 in Taiwan. The study included 4415 lacto-ovo-vegetarians, 1855 lacto-vegetarians and 1913 vegans, and each vegetarian was matched with five non-vegetarians based on age, sex and study site. The longitudinal follow-up showed that each additional year of a vegan diet lowered the risk of obesity by 7%, each additional year of ovo-lacto vegetarian diet increased abnormal HDL levels by7%, as compared to non-vegetarians. In the cross-sectional comparisons, all sub-types of vegetarians showed lower likelihoods of abnormalities on all metabolic traits, except HDL and TAG, as compared with non-vegetarians (Chiu et al., 2015, p. 1313).
Vegetarians have a lower mortality risk from ischemic heart disease, as well as lower LDL “bad” cholesterol, lower blood pressure, lower rates of hypertension and type 2 diabetes, lower body mass index and lower overall cancer rates. These benefits are attributed to lower intakes of saturated fat and cholesterol and to higher intakes of fruits, vegetables, whole grains, nuts, soy products, fiber, and phytochemicals in plant foods. (���Vegetarian diets may prevent���, 2010, p. 1)
Studies on diabetes prevention and management have shown many benefits of a vegetarian diet on prevalence of diabetes and glycemic control in patients. The prevalence of type 2 diabetes in people following different types of vegetarian diets was compared with that in non-vegetarians in the Adventist Health Study-2 from 2002 to 2006. Tonstad, Butler,Yan, and Fraser (2009, p. 791) illustrated that all variants of vegetarian diets (vegan, lacto-ovo, and pesco- and semi-vegetarian) were associated with substantially lower risk of type 2 diabetes and lower BMI than non-vegetarian diets. BMI was found to be lowest in vegans (26.3), and went incrementally higher in lacto-ovo vegetarians (25.7), pesco-vegetarians (26.3), semi-vegetarians (27.3), and non-vegetarians (28.8). Type 2 diabetes prevalence was found to be 2.9 per cent in vegans, and increased to 7.6 per cent in non-vegetarians. This study suggests that there might be a substantial benefit of a vegetarian diet in prevention of diabetes and obesity. Similarly, in a 74 week study on 99 patients with type 2 diabetes, who had been randomized to a low-fat vegan diet and an ADA diet, Barnard et al. (2009, p. 1588S) reported that the vegan diet had significantly favorable effects on glycemic, weight, and lipid control, almost similar to single-agent drug treatment. Hb A1c changes from baseline were -0.40 and 0.01 for vegan and ADA diets, total cholesterol decreased by 20.4 and 6.8 mg/dL in the vegan and ADA diet groups, LDL cholesterol decreased by 13.5 and 3.4 mg/dL in the vegan and ADA groups, and weight loss in kg decreased by 4.4 in vegans and 3.0 in ADA diets, respectively. The results from these studies show that a vegetarian diet not only helps prevent diabetes, it can also achieve optimum blood sugar levels in patients suffering from this disease.
Studies have also shown that vegetarians often have a lower risk and incidence of obesity. The carbohydrate requirement can almost entirely be provided by plant based foods, and when the carbs are healthy, low-glycemic-index based, low in saturated fats, and full of phytochemicals, there may be favorable effects in maintaining appropriate BMI and weight. Kennedy, Bowman, Spence, Freedman, and King (2001, p. 411) examined the association between a range of health and nutrition indicators and popular diets related to obesity, where the prototype diets included vegetarian (no meat, poultry, or fish) and non-vegetarian. The subjects in this study included 10,014 adults, from ages 19 years and older, and the data was gathered from the CSFII, Continuing Survey of Food Intake by Individuals from the year 1994 to 1996. The results from this research suggests that the lowest energy intakes were observed for those on a vegetarian diet, and the BMI���s were lowest in the vegetarian group. The positive benefits of increasing the consumption of fruits and vegetables in diets, which is an example of low-energy density food, may be of an effective approach to weight loss and obesity management.
Plant based foods that are rich in dietary fiber – such as, fruits, vegetables, whole grains and beans, may also lower LDL and total cholesterol levels, and reduce the risk of and heart diseases. Findings from a study of Caucasian western vegetarians that relate diet to BMI, plasma cholesterol concentrations, and mortality suggest that western vegetarians have a lower BMI (by about 1 kg/m2), lower plasma cholesterol concentration (by about 0��5mmol/l), and a lower mortality from Ischemic Heart Disease (by about 25%), as compared with non-vegetarians (Key, Davey, & Appleby, 1999, p. 271). Beans and whole grains rich in beneficial plant compounds, such as lignans, have been shown to lower cholesterol levels and reduce risk of cardiovascular disease, and phytic acid has been shown to stop abnormal cell growth and shrink tumor size (Zanteson, 2014, p. 6). Consumption of a balanced vegetarian diet can provide the major requirements of one���s daily vitamins, minerals, and guard against many chronic illnesses due to their antioxidant properties. When immune system does not work properly, the cells of our body are prone to damage from free radicles, which can thereby contribute to development of many diseases. Antioxidants that protect from these diseases, such as vitamins, beta-carotene, lycopene, and others, are a component of many fruits, vegetables, grains, and nuts. Plants containing natural compounds such as polyphenols, found in foods like berries, tea, and dark chocolate, have the ability to support antioxidant defenses, and may trigger expression of genes that are responsible to support processes within cells for controlling blood sugar and protect the health of blood vessels (Collins, 2014, p. 6). Higher intakes of plant based foods maybe related to strengthening the body���s natural defenses that guard against many chronic illnesses related to the cardiovascular system.
To get the necessary nutrients and energy, most vegetarian diets and food guide pyramids recommend that children and adults should consume between 3 to 7 servings of fruits and vegetables every day in order to support health and lower the risk of diseases. In support for this recommendation, an analysis of 14 years of data from the Nurses��� Health Study, and 8 years of data from the Health Professionals��� Follow-Up Study disclosed that there is a protective relationship between consumption of fruits and vegetables and ischemic stroke risk (Joshipura et al., 1999). In this study, it was found that median intakes of total fruits and vegetables were 5.8 servings per day for women, and 5.1 servings per day for men.According to this analysis, consumption of recommended amount of fruits and vegetables, especially cruciferous and green leafy vegetables, and citrus fruits were inversely associated with risk of ischemic stroke in both cohorts. Many studies and surveys that focus on food consumption show that most of the American population does not consume the recommended quantities of fruits and vegetables. The results from a 2013 MMWR report indicates that less than 18% of adults in each state in the United States consumed the recommended amount of fruit and less than 14% consumed the recommended amount of vegetables (Moore and Thompson, 2013). The data also suggests that increased attention to food environments in settings like child care, schools, communities, and worksites, might help improve fruit and vegetable intake in these public settings, and could help in the overall prevention of chronic diseases.
Becoming a vegetarian by itself doesn���t necessarily benefit a person, following recommended guidelines of an appropriately planned vegetarian diet that includes a wide variety of fruits and vegetables, whole grains, nuts, seeds, and healthy fats is what brings the benefits. It is possible to be a vegetarian and eat very unhealthy. When non-vegetarian diet becomes a habit, switching to a plant based diet can be daunting, confusing, overwhelming, and can go in the wrong direction. Ansel (2014) states, ���When meat, poultry and fish move to the sidelines it’s easy to reach for child-friendly favorites like French fries, pizza and macaroni and cheese��� (Pump Up the Nutrition, para. 2). Foods of this kind can lack in the important elements of nutrition and can be high in saturated fat and calories. In order to make a switch to a vegetarian diet, it is important to have good reasons, read research, plan ahead, find out about substitutions, and have fun with different combinations. Practicing portion control, and selecting healthier options from a vegetarian diet is an important factor in maintaining weight and disease prevention. Many celebrities and athletes try to make-up a significant portion of their diet vegetarian these days. Restaurants are changing the way foods were served in the past, by offering vegetarian options. These changes must be due to the reason that vegetarian diets support good health and are an important factor in disease prevention and management.
There are a number of reasons why vegetarian diets, the ones with increased intake of whole grains, vegetables, and fruits have been endorsed as public health policy. When benefits of plant based diets are evidence based, and are supported by the medical community in prevention and management of chronic diseases, more people may be open minded and willing to adopt a vegetarian diet for better health