Vegetarian diet
A vegetarian diet is characterized by the exclusion of meat from one’s meals, focusing instead on plant-based foods. This dietary choice has been linked to various health benefits, such as lower blood pressure, reduced cholesterol levels, and a decreased risk of certain diseases, including heart disease and some types of cancer. There are different types of vegetarian diets, including lacto-ovo vegetarianism, which includes dairy and eggs, and veganism, which excludes all animal products. Transitioning to a vegetarian diet can be achieved gradually, with recommendations to start by reducing red meat and incorporating plant-based alternatives that mimic the taste and texture of meat.
Research indicates that a well-planned vegetarian diet can be nutritionally adequate, although attention must be paid to certain nutrients that may be less abundant in plant foods, such as vitamin B12, iron, and omega-3 fatty acids. Combining various plant-based foods can help achieve the required nutrient intake, and many nutritionists advocate for a diverse diet rich in whole grains, legumes, fruits, and vegetables. As the popularity of vegetarianism grows globally, particularly in countries like India, the accessibility of vegetarian options has significantly increased, reflecting cultural shifts in dietary preferences.
Vegetarian diet
- DEFINITION: A diet that avoids the consumption of meats.
- PRINCIPAL PROPOSED USES: Blood pressure, heart disease prevention, high cholesterol, weight loss
- OTHER PROPOSED USES: Anxiety, allergies, arthritis, asthma, cancer, dementia, depression, diabetes, gout, hemorrhoids, kidney stones, osteoporosis, premenstrual syndrome
Overview
A vegetarian diet has many health benefits and may actually reduce the incidence of some diseases. The Academy of Nutrition and Dietetics has stated that properly managed vegetarian diets “are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases.” A 2023 poll conducted by Gallup found that 4 percent of Americans follow a vegetarian diet. Other countries have much higher rates. For example, an estimated 30–40 percent of the population in India identified as vegetarian in the 2020s.
The defining characteristic of a vegetarian diet is abstention from meat consumption. There are, however, a number of different types of vegetarian diets, ranging from the lacto-ovo vegetarian diet, which includes dairy products and eggs, to the vegan diet, which excludes all meats and animal products. The focus here is the lacto-ovo vegetarian diet.
Mechanism of Action
A vegetarian diet works through eliminating the consumption of meat products that are high in saturated fat and cholesterol, while increasing the intake of high-fiber, cholesterol-free, plant-based foods.
Uses and Applications
The transition to a healthy vegetarian diet can be simple with some education and planning. A healthy vegetarian diet centers on decreasing fat intake and increasing fiber intake. This can be accomplished through emphasizing fresh fruits and vegetables, beans and other legumes, and whole-grain foods that are high in fiber and low in cholesterol and saturated fat. The diet avoids processed foods and refined sugar. A healthy vegetarian diet fulfills all these criteria.
Many nutritionists, however, recommend that a person transition to a vegetarian diet in stages, allowing the body to adjust by substituting a few meat meals each week with vegetarian food. One should start by reducing and eliminating red meat, then gradually eliminating pork, poultry, and fish. A simple way to make the transition is to use readily available soy-based meat substitutes such as tofu, tempeh, and textured vegetable protein, which are high in protein and can have a meat-like texture and taste. During the twenty-first century, the numbers of options available to transition to a vegetarian diet increased significantly. At the same time, while meat alternatives such as plant-based burgers created to have a texture and taste more similar to those made of meat became more popular, some nutritionists cautioned that they might not be as healthy of an option for vegetarians due to high levels of and sodium and calories.
In 2003, what was then the American Dietetic Association (later the Academy of Nutrition and Dietetics) published a set of guidelines for North American vegetarian diets, recommending the following elements:
Whole grains. Six servings per day, including wheat, oatmeal, quinoa, couscous, and rice. Grains provide fiber, iron, and B vitamins. If possible, one should soak grains overnight to increase their digestibility.
Vegetables and fruits. Six servings per day, including carrots, leafy greens, collards, brassicas (broccoli, cabbage, brussels sprouts), apples, oranges, and bananas. Brassicas are rich in vitamin C, fiber, and carotenoids. Leafy greens and collards are sources of calcium, protein, and many vitamins, including C and A. Fruits are rich in vitamins B and C and calcium. Fresh vegetables and fruits have the highest vitamin content. One should steam or lightly cook vegetables to maintain higher nutrient value.
Legumes, nuts, and other protein-rich foods. Five servings per day, including beans, peas, soy, nuts, dairy foods, and eggs.
Fats. Two servings per day, including vegetable oils, walnuts, mayonnaise, butter, and margarine.
Calcium-rich foods. Eight servings per day, including milk, cheese, fortified soy and fruit juices, and leafy greens.
Over the ensuing years, as more research in the area was conducted, organizations such as the Academy of Nutrition and Dietetics, as well as nutritionists, reviewed these foundational elements and built upon them to maximize the potential benefits of the diet. At the same time, debates continued over details such as recommended servings.
Scientific Evidence
Research has shown that people who eat a healthy vegetarian diet weigh less and have lower cholesterol levels, lower blood pressure, and lower rates of many diseases. Research has also shown that this diet can reverse the effects of atherosclerosis. The risk of men contracting prostate cancer and women getting breast cancer are almost four times as high for meat eaters, compared with those on a largely vegetarian diet. In addition, a vegetarian diet has been used successfully to treat osteoporosis, arthritis, allergies, asthma, gout, hemorrhoids, kidney stones, premenstrual syndrome, anxiety, and depression. A 2000 study of members of the Seventh-day Adventist Church (many of whom practice a lacto-ovo vegetarian diet) indicated that these members live, on average, two years longer than persons on a meat-based diet.
In 2014, a study published in the Journal of the American Medical Association: Internal Medicine confirmed the connection between vegetarianism and lower blood pressure through a new meta-analysis of all previous studies conducted on the subject. The researchers reported that their analysis suggested that a vegetarian diet is about half as strong as taking medication in terms of keeping blood pressure down. Neal Barnard, one of the lead researchers of the study, also stated that he believes those who consume meat and subsequently animal fat have higher blood viscosity that leads to higher blood pressure. Another large study found that vegetarians were about 25 percent less likely to die of heart disease than non-vegetarians.
A 2021 study published in the International Journal of Environmental Research and Public Health examined vegetarianism for its effect on quality of life. The results were mixed, with positive effects in physical health and environmental impact seen as increasing a person’s quality of life, and social and cultural barriers and limited access to plant-based foods having a negative impact on quality of life. Meanwhile, a 2024 analysis of over two decades of research on the health impacts of vegetarian diets concluded that such diets are successful in reducing overall risks of developing heart disease and certain types of cancer, including liver, prostate, bladder, and kidney cancers.
Safety Issues
A well-planned vegetarian diet is a healthy and safe diet overall; however, vegetarians need to be aware of particular nutrients that may be lacking in diets without meat. These nutrients include protein, vitamin B12, vitamin A, vitamin D, calcium, iron, zinc, and N-3 fatty acids. It is possible to get these nutrients from plant-based foods, but they are not as abundant as in animal-based foods. To reap the benefits of a vegetarian diet, it is important to eat a diverse mix of whole grains, fresh vegetables, fruits, leafy greens, legumes, and nuts and to consciously reduce cholesterol and saturated fat intake by limiting dairy, eggs, and high-fat foods.
Animal-based proteins are complete proteins but are high in cholesterol. Research has shown that plant sources can meet the body’s need for protein as long as a variety of plant foods are consumed. Most plant proteins are incomplete, lacking one or more of the essential amino acids. However, vegetarians can easily overcome this lack by combining a variety of complementary plant sources. In general, combining legumes such as beans, soy, and peas with grains such as rice, wheat, and couscous (for example, in beans and rice, hummus and crackers, or peanut butter and bread) forms a complete protein.
Those vegetarians who regularly eat eggs and dairy foods get adequate amounts of vitamin B12, yet the ADA recommends regular B12 supplements or foods fortified with B12. Vitamin A requirements can be met through eating carrots, leafy greens, or fruits (such as apricots, mangos, and pumpkins) that are rich in beta-carotene or by taking supplements. Vegetarians can get adequate amounts of vitamin D through regular exposure to the sun, by eating fortified foods, and by taking supplements.
Calcium is readily obtained by eating enriched soy products, nuts, legumes, dairy, and dark green vegetables such as broccoli and kale. Iron is available in raisins, legumes, tofu, potatoes, and leafy greens. Iron is absorbed more efficiently in the body if iron-rich foods are combined with those containing vitamin C, such as oranges, apples, and tomatoes. Zinc is abundant in pumpkin seeds, legumes, peas, lentils, whole grains, and soy products.
Vegetarians need to get adequate amounts of N-3 or omega-3 fatty acids. Vegetarian diets tend to be high in N-6 fatty acids but low in N-3 fatty acids (found in abundance in seafood and in some plants and nut oils). The body needs a balance of both. Vegetarian sources of N-3 fats include soy, walnuts, pumpkin seeds, and hemp seeds. Flaxseed oil is particularly rich in these fats.
Bibliography
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