A vegetarian diet involves the practice of only eating foods that do not come from animal sources. Instead, vegetarians typically consume plant-based sources of foods such as fruits, grains, legumes, nuts and vegetables. Some vegetarians eat eggs and dairy products while others do not.
People choose vegetarianism for many different reasons, including ethical concerns about eating animal products, religious beliefs or preference for the flavor of plant-based foods. These diets may provide many health benefits because plant-based foods are rich in nutrients, fiber and phytonutrients and low in various substances that may cause harm (e.g., cholesterol and saturated fat).
Most vegetarians can get all the nutrients they require simply by following a well-balanced diet that includes low-fat dairy products, whole grains, vegetables and fruits. However, strict vegetarians – or vegans – who do not consume any animal products face nutritional challenges that can only be addressed by careful dietary planning.
Nutrients that may not be present in adequate amounts in some vegetarian diets include calcium, iron, protein, vitamin B12, vitamin D and zinc.
Special populations must be especially careful about maintaining adequate nutrient content within a vegetarian diet. Women who are pregnant or breastfeeding generally are urged to wait until a later time to switch to a vegetarian diet. Women who are already vegetarians may not have to alter their diet much to ensure that their baby develops normally. However, it may be a good idea to consult with a registered dietitian.
Young children can eat a healthy vegetarian diet. However, it is crucial that parents closely supervise all meals to ensure that their children are receiving the variety of foods necessary to obtain nutrients crucial to growth and health. These include iron, calcium, vitamin B12, protein, zinc and vitamin D. Older adults face the same nutritional challenges as other adults. However, many older vegetarians also are at higher risk for deficiencies of vitamin D and vitamin B12.
About vegetarian diet
A vegetarian diet involves restricting one’s eating habits to foods from plant-based sources.
People choose vegetarianism for many different reasons, including simple preference for the flavor, ethical concerns about eating animal products or religious beliefs on plant-based foods. The British Medical Journal recently reported findings that children who score higher on IQ tests are more likely to become vegetarian.
All vegetarians may reap health benefits from their diet, regardless of the reason for it. Plant-based foods are rich in nutrients and phytonutrients essential to good health. These foods also are low in various substances that may cause harm (e.g., animal protein, cholesterol and saturated fat) and rich in substances thought to be beneficial to health (carotenoids, complex carbohydrates, fiber, folate).
Studies show that people who eat a vegetarian diet have lower rates of many diseases when compared to people who have a non-vegetarian diet. Such illnesses include heart disease, high blood pressure, type 2 diabetes and some forms of cancer. Vegetarian diets may lower the risk of these diseases in many ways. Consumption of higher intakes of fruits and vegetables may be responsible for the lower rates of cancer in vegetarians.
In addition, vegetarians tend to have a lower incidence of overweight and obesity. Levels of low-density lipoprotein (LDL) cholesterol – the so-called “bad” cholesterol – also appear to be lower in vegetarians. This may be due a diet low in saturated and total fat, and to a higher consumption of soy products. Soy products, such as tofu, contain phytochemicals thought to lower cholesterol levels.
Many other claims have been made on behalf of vegetarian diets. For example, University of Chicago researchers recently issued a report touting the environmental benefits of vegetarianism.
It should be emphasized that a well-balanced non-vegetarian diet also can provide similar health benefits. In the end, experts cannot conclusively state that a vegetarian diet is better for a person’s health than a non-vegetarian diet. Surveys show that vegetarians are more likely than non-vegetarians to make lifestyle choices that promote health, including not smoking, exercising regularly and avoiding excessive consumption of alcohol. These lifestyle choices may have as great or greater an influence on a vegetarian’s good health as dietary choices themselves.
In addition, all the potential benefits of a vegetarian diet can be undone if meals are not carefully planned to include nutrients that may be more difficult to obtain in a vegetarian diet than in a non-vegetarian diet. Iron is more easily absorbed from animal food (heme iron) sources. Non heme iron is found in certain plant foods, but it tends to require larger amounts of these foods to meet recommended iron levels. In addition, eating plant-based foods prepared in unhealthy ways – such as deep-fried vegetables or healthy foods topped with generous amounts of cheese, sour cream or butter – can be just as unhealthy as eating fatty animal-based products.
Types and differences of vegetarian diets
Vegetarianism is the practice of avoiding foods from animal sources and instead consuming plant sources of foods such as fruits, grains, legumes, nuts and vegetables. However, there are several different types of vegetarian diets characterized by the types of food included in the diet. They include:
Lacto-ovo-vegetarian. Eggs and dairy products are included in the diet, but meat, poultry and fish are excluded. Most vegetarians in the United States fall into this category, according to the American Dietetic Association.
Lacto-vegetarian. Dairy products are included in the diet, but meat, poultry, fish and eggs (and egg-derived products) are excluded.
Strict vegetarian (also known as vegan) No animal-based products of any kind are included in the diet. Excluded items are meat, poultry, fish, eggs, milk, cheese and other dairy products. In some cases, vegans may also avoid foods with animal products as ingredients (e.g., lard, beef tallow, butter).
Semi-vegetarian. Someone who generally follows a vegetarian diet but occasionally eats poultry or fish. Typically, the diet excludes red meat.
Nutritional challenges of vegetarian diets
Most vegetarians can get all of the nutrients they require simply by following a well-balanced diet that includes low-fat dairy products, whole grains, vegetables and fruits. However, strict vegetarians – or vegans – who do not consume any animal products face nutritional challenges that can only be addressed by careful dietary planning.
Many people who switch to a vegetarian diet can benefit from consulting a registered dietitian who can help plan a diet that contains adequate levels of all nutrients. This is especially important for women who are pregnant or breastfeeding, others during ages of growth (infancy, childhood and adolescence) and people recovering from an illness.
Nutrients that may not be present in adequate amounts in some vegetarian diets include:
Calcium. This mineral keeps bones and teeth strong, helps muscles contract, transfers nerve impulses, helps blood to clot, and regulates heartbeat. Vegetarians who consume dairy products should not have to worry about obtaining adequate calcium stores. However, vegans need to plan their diets carefully to obtain this mineral. Many plant foods provide calcium, include broccoli, sunflower seeds, nuts, legumes, some green vegetables (collards, kale, mustard greens), okra, rutabaga, bok choy, dried figs and tortillas. Calcium-fortified foods are good choices as well. These include breakfast cereals, orange juice, and soy or rice beverages.
Iron. Obtaining adequate levels of this mineral can be difficult for both vegetarians and non-vegetarians, especially women and children. Iron deficiency can lead to fatigue and iron-deficiency anemia (lack of red blood cells). Plant-based foods contain a version of iron called non-heme iron. Unlike the heme iron found in animal products, non-heme iron is not absorbed as well by the body. To improve absorption of non-heme iron, vegetarians are urged to include a food or beverage rich in vitamin C with every meal. This aids in the absorption of nonheme iron. Cooking with iron pots or skillets also may increase the amount of iron in foods. Finally, semi-vegetarians can boost their iron absorption by eating a little meat, poultry or fish. Vegetarians are cautioned to avoid drinks with tannin such as tea, when having an iron-containing meal. The tannins can interfere with the absorption of non-heme iron.
Protein. Most vegetarians obtain enough protein from plant-based sources such as legumes, nuts and seeds. However, these foods are lower in protein content than animal-based products such as meat, poultry, fish and eggs. As a result, vegetarians often have diets that are slightly lower in overall protein content than non-vegetarian diets. Unlike animal-based “complete” proteins, protein from plant sources usually lacks one or more essential amino acids. These are the building blocks of protein that only come from dietary sources. To obtain all of the essential amino acids, vegetarians must eat a diversified diet of legumes, nuts, seeds, grains, vegetables and fruits.
Vitamin B12. Also known as cobalamin, this vitamin helps the body make red blood cells and use fats and amino acids. Vegetarians who consume eggs and dairy products typically obtain adequate levels of dietary vitamin B12. However, vegans need to look elsewhere for their intake of this vitamin. Typically, this involves either supplements or fortified foods such as breakfast cereals, soy milk or rice milk products, or vegetarian burgers. The vitamin B12 contained in sea-based plant foods such as spirulina, tempeh, sea vegetables and miso is inactive and cannot be absorbed. Deficiency of vitamin B12 typically causes no short-term health problems. However, over time it can result in megaloblastic anemia and severe, irreversible nerve damage.
Vitamin D. This vitamin helps the body absorb calcium and phosphorus, which is important for strong bones and teeth. The body can make its own vitamin D if the skin is exposed to sunlight for about five to 15 minutes a day (or 20 to 40 minutes three times weekly). People who do not receive this type of sunlight can still get enough vitamin D through drinking milk, which typically is fortified with vitamin D. Because vegans do not consume milk, they need to be especially careful to get adequate levels of sunlight (particularly in northern climates) or to consume foods fortified with vitamin D, including breakfast cereals, some soy beverages and some calcium-fortified juices.
Zinc. This mineral is crucial for growth, repairing body cells and production of energy. It is found chiefly in meat, poultry and seafood. Vegetarians can obtain zinc through milk, cheese, yogurt or eggs. Vegans may face an additional challenge in obtaining enough zinc. However, many plant-based foods provide zinc, including whole grains, wheat germ, legumes, tofu, seeds and nuts. Zinc supplements usually should not be taken unless recommended by a physician.
In general, vegetarians can use plant-based foods to substitute for animals products, including the following:
Baked goods: Egg replacers, whipped tofu, milled flaxseed mixed with water
Tofu
Special populations and vegetarian diets
While vegetarian diets can provide many health benefits, people who choose to eat this way must be careful to plan meals that provide all the nutrients necessary for good health. This is especially true of certain populations.
Women who are pregnant or breastfeeding generally are urged to wait until a later time to switch to a vegetarian diet. Women who are already vegetarians may not have to alter their diet much to ensure that their baby develops normally. However, it may be a good idea to consult with a registered dietitian. Some experts recommend that vegetarians consume up to 300 additional calories a day during pregnancy.
Young children can eat a healthy vegetarian diet. However, it is crucial that parents closely supervise all meals to ensure that their children are receiving the variety of foods necessary to obtain nutrients crucial to growth and health. Children require sufficient amount of several vitamins, minerals and nutrients to grow and develop normally.
The amount of energy (calories) in vegetarian diets needs to be monitored to ensure adequate daily energy for children. Protein is vital for growth and is generally readily obtained from plant foods like legumes. Iron in plant foods is the less easily absorbable non heme iron and children may require additional iron-containing foods in order to meet daily requirements. In addition, vitamin C-containing foods should be included in the daily diet to help with iron absorption. Tannin-containing beverages such as tea should be avoided, because tannins interfere with non heme iron absorption. Calcium and vitamin D are essential for bone development, and childhood is a vital period for the development of strong bones for the entire lifetime. If a child does not consume dairy products, then calcium- and vitamin D-fortified foods are needed. Vitamin B12 is another vital substance contained only in meat, fish and dairy products. Vegan children require foods fortified with vitamin B12, or supplements as recommended by a pediatrician.
Fruits and vegetables can be introduced around the ages of 6 months to 9 months. Parents who wish to raise their children as semi-vegetarians may begin to introduce poultry around 9 months of age. Infants can get their protein from several vegetarian foods, including pureed tofu, cottage cheese, and pureed and strained legumes.
By the time a child is 1 year old, it may be necessary to include fortified cereals and nutrient-dense foods in the diet. Older children and teens can follow much of the same dietary planning as adults in fashioning a vegetarian meal regimen that is rich in important nutrients.
Older adults face the same nutritional challenges as other adults. However, many older adults may have limited exposure to sunlight. This makes older vegetarians more vulnerable to vitamin D deficiency unless they drink milk. In addition, older adults may have trouble properly absorbing vitamin B12. Because many vegetarians do not obtain this vitamin regularly from their diets, supplementation may be recommended.
People with certain medical conditions are urged to consult with a physician or nutritionist to make sure they get adequate nutrients from a vegetarian diet. In many cases, a vegetarian diet is beneficial for people with certain health problems.
For example, people who are obese and have type 2 diabetes may lose significant amounts of weight after switching to a vegetarian diet. This can help improve their health substantially.
Questions for your doctor on vegetarian diets
Preparing questions in advance can help patients have more meaningful discussions with health professionals regarding their conditions. Patients may wish to ask their doctor or registered dietitian the following questions related to vegetarian diets:
Should I consult with a registered dietitian before beginning a vegetarian diet?
What are the health benefits of vegetarian diet?
Is a vegetarian diet a good option for lowering my cholesterol levels?
Which type of vegetarian diet do you recommend?
What are some good substitutes for animal-based products often used in cooking?
What are some good fortified foods that can help me gain the nutrients I need?
Should I take supplements of any kind to ensure I get the proper level of nutrients?
Are there health dangers associated with a vegan diet?
I’m pregnant – should I wait until later to begin a vegetarian diet?
How can I make sure my child gets enough nutrients despite a vegetarian diet?
