What is a vegetarian diet?
A vegetarian diet is defined as an eating pattern that excludes all meat products, including red meat, poultry, and seafood as well as any byproducts of slaughter, such as gelatin.[1] This definition can be confusing because of a lack of standardization. Variations on the vegetarian diet include the lacto-ovo vegetarian diet, which includes dairy products and eggs, and lacto-vegetarian and ovo-vegetarian, which include only dairy products or only eggs, respectively. Some people who eat fish and other seafood products — usually called a pescatarian diet — also refer to their diet as vegetarian, although this is not within the usual definition. Other types of diets that are sometimes grouped in with the vegetarian diet include the flexitarian diet — a diet that focuses on including mostly plant-based foods but allows animal products in moderation — and the semivegetarian diet that also focuses on plant-based foods and excludes red meat products but still includes fish, poultry, or both.[2][1][3][4]
Within research, vegetarian and vegan diets are often studied together or referred to interchangeably, which can introduce confusion. Vegan diets are different from vegetarian diets in that they do not include any animal products (no meat, eggs, seafood, poultry, dairy products, or honey), and people who follow a vegan lifestyle often avoid animal products outside of food, such as leather goods, wool, or fur.
What are the main benefits of a vegetarian diet?
A vegetarian diet has several potential benefits. People who eat a vegetarian diet tend to have lower total cholesterol levels, LDL cholesterol levels, triglyceride levels, and apolipoprotein B (ApoB).[5][6][7][8] There is also some evidence, although it is not consistent, that people who follow a vegetarian diet may have lower blood pressure.[9][5][10][11] These factors contribute to a lower risk for ischemic heart disease (IHD) and a lower risk for cerebrovascular disease, including stroke.[6]
There is some evidence showing that a vegetarian diet is associated with a lower risk of developing type 2 diabetes.[12][13][14] It can also be used as an adjunct to standard treatment to further improve glycemic control in people with type 2 diabetes, as it can lower fasting blood glucose and HbA1c levels.[15][16][17][18] However, the evidence for a vegetarian diet for the treatment of diabetes is inconclusive, and it should not be used in isolation to treat type 2 diabetes.[19]
What are the main drawbacks of a vegetarian diet?
As with any diet that excludes certain food groups, there is a concern that nutritional deficiencies could develop. In the case of vegetarianism, the micronutrients of concern are the ones that occur primarily in animal products, such as iron, zinc, and vitamin B12.[2]
Low iron levels are more common in vegetarians, especially in premenopausal women.[20][21] Meat contains heme iron, but plant foods contain non-heme iron, which is more difficult for the body to absorb. Eating plant sources of iron together with sources of vitamin C may improve absorption. While iron stores might be lower, the prevalence of iron deficiency anemia is not higher in vegetarians, suggesting that the low stores are not necessarily a problem.[22][21] It could be worth monitoring iron levels in some cases, such as children and during pregnancy.[22]
Another concern is zinc. In omnivorous diets, the majority of the zinc intake comes from meat, especially from beef. When eating a vegetarian diet, it is possible to get a similar zinc intake through legumes, whole grains, nuts, and seeds, but this requires careful planning.[22][23] However, so far there is no clear evidence that the lower zinc intake associated with a vegetarian diet causes any long term health concerns.[24]
Vitamin B12 is less of a concern for vegetarians than for vegans, because dairy products and eggs contain a substantial amount of vitamin B12, but vitamin B12 deficiency is still more common among vegetarians than people who eat an omnivorous diet.[25] Including foods fortified with vitamin B12, such as cereals and grains, can help increase the daily vitamin B12 intake. In some cases, a supplement might be necessary. Monitoring or supplementing vitamin B12 is especially important during pregnancy and for early childhood development.[26]
How does a vegetarian diet work?
People who follow a vegetarian diet tend to eat more fruits, vegetables, whole grains, and legumes or add them into their diets as an alternative to animal products. These foods all have a high amount of fiber, a range of vitamins and minerals, and are often low in saturated fats.[2]
A lower intake of saturated fat combined with an increased intake of unsaturated fat and fiber can significantly lower the levels of LDL cholesterol in the blood. An increased intake of fiber can also help moderate blood glucose levels, improving blood sugar levels for people with type 2 diabetes. Fiber can also help with weight loss, because it slows the rate at which the stomach empties, and the high volume and low energy density of certain high-fiber foods can help with appetite control by increasing satiety.[2][27]
The increased intake of fruit and vegetables leads to an increased intake of vitamin E and vitamin C, minerals like magnesium, and antioxidants including polyphenols and tannins. These factors contribute to the antioxidant and anti-inflammatory effects of the vegetarian diet that could improve cardiovascular health.[27][28][2]
What are other names for Vegetarian Diet
- lacto-ovo vegetarian (if it includes eggs and dairy products)
- ovo vegetarian (if it includes only eggs)
- lacto vegetarians (if it includes only dairy products)
- a vegan diet
- a whole-food, plant-based diet (This term could be used to describe a vegetarian diet, but it can also refer to other plant-based diets.)
Frequently asked questions
A vegetarian diet is defined as an eating pattern that excludes all meat products, including red meat, poultry, and seafood as well as any byproducts of slaughter, such as gelatin.[1] This definition can be confusing because of a lack of standardization. Variations on the vegetarian diet include the lacto-ovo vegetarian diet, which includes dairy products and eggs, and lacto-vegetarian and ovo-vegetarian, which include only dairy products or only eggs, respectively. Some people who eat fish and other seafood products — usually called a pescatarian diet — also refer to their diet as vegetarian, although this is not within the usual definition. Other types of diets that are sometimes grouped in with the vegetarian diet include the flexitarian diet — a diet that focuses on including mostly plant-based foods but allows animal products in moderation — and the semivegetarian diet that also focuses on plant-based foods and excludes red meat products but still includes fish, poultry, or both.[2][1][3][4]
Within research, vegetarian and vegan diets are often studied together or referred to interchangeably, which can introduce confusion. Vegan diets are different from vegetarian diets in that they do not include any animal products (no meat, eggs, seafood, poultry, dairy products, or honey), and people who follow a vegan lifestyle often avoid animal products outside of food, such as leather goods, wool, or fur.
A vegetarian diet has several potential benefits. People who eat a vegetarian diet tend to have lower total cholesterol levels, LDL cholesterol levels, triglyceride levels, and apolipoprotein B (ApoB).[5][6][7][8] There is also some evidence, although it is not consistent, that people who follow a vegetarian diet may have lower blood pressure.[9][5][10][11] These factors contribute to a lower risk for ischemic heart disease (IHD) and a lower risk for cerebrovascular disease, including stroke.[6]
There is some evidence showing that a vegetarian diet is associated with a lower risk of developing type 2 diabetes.[12][13][14] It can also be used as an adjunct to standard treatment to further improve glycemic control in people with type 2 diabetes, as it can lower fasting blood glucose and HbA1c levels.[15][16][17][18] However, the evidence for a vegetarian diet for the treatment of diabetes is inconclusive, and it should not be used in isolation to treat type 2 diabetes.[19]
A vegetarian diet can be used as a weight loss tool. On average, vegetarians have a lower BMI than people who eat an omnivorous diet.[29][30][13][31] A vegetarian diet could help some people achieve a calorie deficit. This may be partly attributed to an increase in satiety as a result of an increased fiber intake.[32] Long-term studies on the effect of vegetarian diets on weight loss are still needed, and it is important to remember that any diet could produce weight loss if it creates a caloric deficit.[2][32][33][11]
An association between a vegetarian diet and a lower risk of developing cancer has been found in several observational studies. Specifically, some studies report a decreased incidence of colorectal cancer,[34][35][36][37] gastric cancer,[38][39], and prostate cancer.[34][39] However, other studies have found that a vegetarian diet did not alter the prevalence of colorectal, breast, or prostate cancer.[40]
These findings are not definitive, and other factors that are not accounted for in the observational studies will significantly affect these results. For example, the lower cancer risk could be because people who choose to eat vegetarian diets tend to be more active and are less likely to smoke cigarettes.[41]
Athletes often look at nutritional strategies as a way to improve their performance. A vegetarian diet can be a successful strategy for athletes, but it requires a significant amount of planning.[2]
One of the first concerns is protein intake. Athletes may need higher protein intakes than the general population, but this is easily achieved with a carefully planned diet.[42][43] Vegetarian diets tend to have higher carbohydrate intakes compared to omnivorous diets, and this can actually be of benefit to some athletes, especially in endurance sports.[2] For female athletes, it is important to plan ahead, because an insufficient intake of calories and fats in people who are highly active can interrupt the menstrual cycle.[2][44]
Overall, it seems that a vegetarian diet can support athletic performance, but is not superior to an omnivorous diet. To ensure that the athlete receives a nutritionally complete diet, careful planning of calorie intake, protein intake, and micronutrient intake is important.[45][46]
One of the most common concerns about eating a vegetarian diet is that it is difficult to eat enough protein without animal products. However, a well-planned vegetarian diet that includes a variety of protein sources can provide sufficient protein.[42]
Protein requirements vary according to weight and to calorie intake, with the RDA being only 0.8 grams per kilogram of body weight (g/kg). However, most people would benefit from more protein, with the recommended range of 1.2–1.6 g/kg. Some highly active people or athletes might extend that up to 2.4 g/kg.[47] According to the EPIC-Oxford study, meat eaters reported an average of 1.28 g/kg of protein per day, and lacto-ovo vegetarians reported an intake of 1.04 g/kg of protein per day, so only slightly less protein on a daily basis.[48] In most adult vegetarians, protein intake is likely to be sufficient if the diet is varied and includes legumes, nuts, seeds, and whole grains, and possibly eggs and dairy products. In older adults, protein needs may increase, and a low protein intake could result in sarcopenia in the elderly, but there is no evidence associating this with a vegetarian diet as of yet.[49]
In a lacto-ovo vegetarian diet, the major protein sources are eggs and dairy products like Greek yogurt and cottage cheese. Plant-based protein sources, such as tofu and tempeh, can also be included in a vegetarian diet. A varied vegetarian diet that includes legumes (e.g., beans, soy, lentils), nuts, whole grains, and seeds will provide plant proteins that can contribute to daily protein intake. Finally, supplements like whey protein, pea protein, and soy protein can be helpful to people who are not managing to meet their protein intake needs.
As with any diet that excludes certain food groups, there is a concern that nutritional deficiencies could develop. In the case of vegetarianism, the micronutrients of concern are the ones that occur primarily in animal products, such as iron, zinc, and vitamin B12.[2]
Low iron levels are more common in vegetarians, especially in premenopausal women.[20][21] Meat contains heme iron, but plant foods contain non-heme iron, which is more difficult for the body to absorb. Eating plant sources of iron together with sources of vitamin C may improve absorption. While iron stores might be lower, the prevalence of iron deficiency anemia is not higher in vegetarians, suggesting that the low stores are not necessarily a problem.[22][21] It could be worth monitoring iron levels in some cases, such as children and during pregnancy.[22]
Another concern is zinc. In omnivorous diets, the majority of the zinc intake comes from meat, especially from beef. When eating a vegetarian diet, it is possible to get a similar zinc intake through legumes, whole grains, nuts, and seeds, but this requires careful planning.[22][23] However, so far there is no clear evidence that the lower zinc intake associated with a vegetarian diet causes any long term health concerns.[24]
Vitamin B12 is less of a concern for vegetarians than for vegans, because dairy products and eggs contain a substantial amount of vitamin B12, but vitamin B12 deficiency is still more common among vegetarians than people who eat an omnivorous diet.[25] Including foods fortified with vitamin B12, such as cereals and grains, can help increase the daily vitamin B12 intake. In some cases, a supplement might be necessary. Monitoring or supplementing vitamin B12 is especially important during pregnancy and for early childhood development.[26]
People who follow a vegetarian diet tend to eat more fruits, vegetables, whole grains, and legumes or add them into their diets as an alternative to animal products. These foods all have a high amount of fiber, a range of vitamins and minerals, and are often low in saturated fats.[2]
A lower intake of saturated fat combined with an increased intake of unsaturated fat and fiber can significantly lower the levels of LDL cholesterol in the blood. An increased intake of fiber can also help moderate blood glucose levels, improving blood sugar levels for people with type 2 diabetes. Fiber can also help with weight loss, because it slows the rate at which the stomach empties, and the high volume and low energy density of certain high-fiber foods can help with appetite control by increasing satiety.[2][27]
The increased intake of fruit and vegetables leads to an increased intake of vitamin E and vitamin C, minerals like magnesium, and antioxidants including polyphenols and tannins. These factors contribute to the antioxidant and anti-inflammatory effects of the vegetarian diet that could improve cardiovascular health.[27][28][2]
Update History
New page created
Research written by
Edited by
Reviewed by
