The popularity of vegetarian diets is on the rise. In fact, according to a 2018 Gallup poll, 5% of Americans consider themselves vegetarian. That translates to about 16 million people. (15) People choose to follow a vegetarian diet for various reasons. For some, it’s for ethical or environmental concerns. For others, it’s for the many health benefits that the diet has to offer. Keep reading to learn more about the benefits, limitations, and how to start a vegetarian diet.
What is a vegetarian diet?
A vegetarian diet is one that excludes meat and some animal products. There are several types of vegetarian diets, including:
- Lacto-ovo-vegetarian diet: excludes all meat, but includes eggs and dairy products
- Lacto-vegetarian diet: excludes all meat and eggs, but includes dairy products
- Ovo-vegetarian diet: excludes all meat and dairy products, but includes eggs
- Pescatarian diet: includes dairy and eggs and excludes all meat, except fish and seafood
- Vegan diet: excludes all animal products, including meat, poultry, fish, seafood, dairy, eggs, honey, and gelatin (18)
Benefits of a vegetarian diet
Many benefits are associated with vegetarian diets.
1. Higher diet quality
When compared to non-vegetarians, lacto-ovo-vegetarians and vegans report higher overall diet quality. Quality is determined by how closely one’s diet adheres to fruit, vegetables, whole grains, seafood, and plant-based protein, and sodium recommendations. (33) Vegetarians typically report greater daily intake of fruits and vegetables and lower intake of soft drinks and processed foods than the general population. (17)(32)
2. Healthier body weight
Obesity is a worldwide public health concern contributing to a significant rise in chronic diseases such as heart disease and type 2 diabetes. (5) The World Health Organization (WHO) reports that as of 2016, 1.9 billion adults worldwide were overweight, and 650 million were obese. (43)
A large body of research demonstrates that vegetarians are much more likely to have a normal body weight and body mass index (BMI) than non-vegetarians. According to one study, mean BMI was lowest in vegans and lacto-ovo-vegetarians (23.6 and 25.7 kg/m2, respectively) compared to non-vegetarians (28.8 kg/m2). (38) Furthermore, a meta-analysis demonstrated that vegetarian diets may have more significant effects on weight reduction than omnivorous diets. (20)
3. Reduced risk of type 2 diabetes
Type 2 diabetes is one of the fastest-growing chronic conditions, affecting 10.5% of the United States population and 8.8% of Canadians. (4)(23) However, despite its increasing prevalence among the general population, rates are significantly lower in those eating a vegetarian diet regardless of body weight. Of individuals with a BMI of >30 kg/m2, 9.4% of lacto-ovo-vegetarians compared to 13.8% of non-vegetarians have diabetes. In contrast, individuals with a BMI <30 kg/m2, 2.1% of lacto-ovo-vegetarians compared to 4.6% of non-vegetarians have diabetes. (38)
According to a 2017 meta-analysis, vegetarian diets are associated with a reduced risk of type 2 diabetes. Several factors are believed to play a role in this risk reduction. For example, vegetarians typically have lower BMIs and superior insulin sensitivity compared to those who eat meat. (24) Other studies demonstrate that diets rich in fiber from whole grains, (1) fruits, and vegetables, particularly root vegetables and leafy greens, may help prevent type 2 diabetes. (7)
4. Improved cardiovascular health
Research shows that a vegetarian diet may be protective against the incidence of and mortality from ischemic heart disease, a chronic condition characterized by narrowed heart arteries. A 2017 meta-analysis of observational studies reported that vegetarians and vegans had significantly reduced total cholesterol and low-density lipoprotein (LDL) levels than omnivores. (11) If you have high cholesterol, adopting a plant-based diet may effectively reduce your total cholesterol and LDL levels. (42)
The EPIC-Oxford study, which observed over 48,000 participants over 18 years of age, concluded that pescatarians and vegetarians had a 13% and 22% lower rate of ischemic heart disease than meat-eaters, respectively. These results are likely due to the lower BMI, blood pressure, and cholesterol levels often observed in vegetarians. Conversely, this study also demonstrated that vegetarians had a 20% higher risk of stroke than meat-eaters; however, more research is necessary to pinpoint the specific cause of this observed increase. (37)
5. Improved digestive health
A plant-based diet that’s naturally rich in fiber may improve gut health by promoting a diverse gut microbiota, the collection of healthy bacteria and fungi living in the digestive tract. Diversity is important since different strains of bacteria provide different health benefits. The fiber found in plant-based foods also encourages the growth of short-chain fatty acids that improve immunity, reduce inflammation, and influence intestinal function. (36)
Consuming more fiber as part of a vegetarian diet may also reduce the risk of diverticular disease, a condition that occurs when small bulging pouches form in the colon wall. One study demonstrated that vegetarians had a 31% lower risk of diverticular disease as well as a lower risk of complications related to the condition than omnivores. (9)
6. More sustainable
Animal agriculture has profound effects on the health of our environment. Approximately 16.5% of total greenhouse gas emissions are due to mass deforestation, nitrous oxide emissions from fertilizers and irrigation practices, and methane production from ruminant animals (e.g., cattle, goats, sheep). (39)(40) Although some farms employ regenerative agriculture practices to counter the harmful effects of industrialized animal agriculture, the majority of North America’s meat, dairy foods, and poultry products are produced by industrial livestock operations. (41)
Vegetarian and vegan diets are proposed as environmentally-friendly alternatives to omnivorous diets. It’s estimated that vegetarian diets produce 35% lower greenhouse gas emissions than omnivorous diets. (14) Are you wondering how the greenhouse gas emissions of animal and plant-based protein sources compare? The chart below depicts the greenhouse gas emissions for common dietary sources expressed in kilograms of carbon dioxide equivalents (CO2e) per kilogram of consumed protein food.
Potential concerns of a vegetarian diet
Certain precautions should be taken when following a vegetarian diet. Outlined below are some of the concerns associated with the vegetarian diet.
1. Nutritional deficiencies
Since vegetarians avoid meat, poultry, and other animal-sourced foods, they may be at increased risk of certain nutrient deficiencies. Nutrients of concern for vegetarians include:
Protein is another nutrient of concern for vegetarians; however, it’s possible to consume adequate protein on a well-planned vegetarian diet. Most people consume enough protein per day, regardless of whether they follow a plant-based or omnivorous diet. (26) The average sedentary person should consume approximately 0.8 g of protein per kg of body weight; however, you may need to consume more than this recommendation depending on your activity levels and health goals. (6) Vegetarians may also need to exceed the 0.8 g/kg/day recommendation considering that the protein found in plant-based foods may be slightly less digestible than animal protein. (6)(26)
If you’re a vegetarian, your integrative healthcare provider may perform routine blood tests to check for nutrient deficiencies and suggest supplements to fill gaps in your diet. Learn more about the top nutrients of concern for vegans and vegetarians on the Fullscript blog.
A 2021 meta-analysis investigating the mental and cognitive outcomes of plant-based diets noted a relationship between vegan and vegetarian diets and a higher risk of depression. (21) Nutritional deficiencies, such as iron and vitamin B12, are believed to be a potential explanation for this increased risk. (19) However, exclusions of major food groups, regardless of the source, may also be a contributing factor to depressive symptoms. (19)(28)
3. Bone density
Vegetarians and vegans are at increased risk of lower bone density and fracture, potentially due to reduced consumption of calcium, vitamin D, and other nutrients. One meta-analysis concluded that vegetarians have a lower bone density at the femoral neck (region below the ball of the hip joint) and lumbar spine than omnivores. (22)
Consuming adequate amounts of calcium and vitamin D can help reduce the odds of developing osteoporosis (brittle bones). (31) Top plant-based sources of calcium include soy products (e.g., soy milk, tofu, edamame), spinach, kale, chia seeds. Cow’s milk and yogurt are also excellent sources of calcium for vegetarians who consume dairy products. (29) Vegetarian-suitable sources of vitamin D are limited to UV-treated mushrooms, dairy, and fortified non-dairy beverages and breakfast cereals.
Exposure to sunlight is an effective way to improve vitamin D status; however, UV exposure may increase your risk of developing skin cancer. A simple blood test can determine whether you have a vitamin D deficiency, which may prompt your practitioner to suggest a vitamin D supplement. Since vitamin D is a fat-soluble vitamin that can lead to toxicity in large amounts, it’s imperative that you receive proper testing before taking a vitamin D supplement. (30)
4. Dental decay
Consuming a plant-based diet may increase your risk of dental caries (cavities). A 2020 meta-analysis demonstrated that vegetarian diets may be associated with an increased risk of dental erosion, as well as decayed, missing, or filled teeth; however, results were inconclusive. (35) Consumption of acidic foods, such as fruits and vegetables, may lower the pH level in the mouth, contributing to dental erosion and the development of cavities. (25)
Prevent cavities by practicing good dental hygiene. Brushing twice per day, flossing, limiting between-meal snacks, and visiting your dentist for bi-annual visits can promote good dental health. (3) Consuming a healthy diet rich in nutrients, particularly B vitamins, vitamins A, C, and D, calcium, and protein can also promote healthy oral health. (34)
How to start a vegetarian diet
Use these tips as a guide for following a successful vegetarian diet.
1. Focus on whole foods
Ultra-processed foods, such as packaged chips, cookies, and frozen meals, contain preservatives, colorings, added sugar and sodium, fat, and other ingredients to preserve the shelf-life and palatability of the food. (12) Diets high in processed foods are associated with chronic conditions such as heart disease and type 2 diabetes; therefore, these foods should be avoided or limited. (27)
In contrast, whole foods are foods that undergo minimal processing and are closest to how they’re found in nature. Whole foods are naturally rich in micronutrients and antioxidants with health-promoting properties. Examples of whole foods include:
- Beans and legumes
- Dairy products (preferably fermented dairy without added sugar)
- Healthy oils (e.g., avocado oil, olive oil)
- Nuts and seeds
- Whole grains and pseudograins (e.g., barley, brown rice, whole wheat, quinoa) (2)
Did you know? Not all vegetarian-friendly foods are healthy. Chips, cookies, pizza, and refined grains are technically vegetarian but typically low in important nutrients and high in fat, sugar, and/or sodium.
2. Limit plant-based meat substitutes
Increased interest in vegan and vegetarian diets has driven the greater demand for plant-based meat alternatives, also known as meat analogs. Generally speaking, meat analogs are highly processed foods that may lack certain essential nutrients found in animal protein, such as vitamin B12, iron, and zinc. (10) These foods are best consumed sparingly. Instead, opt for whole food plant-based protein sources such as tempeh, tofu, beans, and legumes.
Did you know? One study reported that vegetarians following the diet for a short period of time and individuals who began a vegetarian diet at a young age are more likely to consume meat analogs regularly. (16)
3. Mix it up
Plant-based diets don’t have to be monotonous and flavorless! Explore different types of cuisines, try new recipes, and experiment with various foods and flavors. If you’re transitioning from an omnivorous diet, try creating plant-based versions of your favorite recipes. For example, consider using lentils instead of meat next time you make a spaghetti bolognese or substitute tofu or chickpeas in curries, stews, or chilis.
4. Make changes at your own pace
Starting a vegetarian diet may be challenging in the beginning. To ease your transition, begin by participating in “meatless Mondays” or slowly replacing a few meat-containing meals with plant-based options per week. Once you feel more comfortable and you’ve mastered some vegetarian recipes, you can fully adopt a plant-based diet.
5. Read labels
Reading nutrition facts labels is especially helpful if you’re trying to avoid dairy or eggs, as these ingredients are present in many foods. Look for these ingredients on ingredient lists or third-party certified products such as Certified Vegan.
The bottom line
Plant-based, vegetarian diets boast many health benefits such as a reduced risk of cardiovascular disease and type 2 diabetes, improved digestive health, and more. Vegetarian diets pose some risks; however, with some careful planning and guidance from your practitioner, you can successfully follow this popular dietary pattern. If you’re a patient, consult your integrative healthcare practitioner for recommendations on how to start a vegan diet before making significant dietary changes and to ensure the vegetarian diet is right for you.
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