Understanding Vegetarian Diets: Benefits, Risks, and Nutritional Considerations

Vegetarian Diet

Classification of Vegetarian Diets, Risks for Infants and Children

Definition

Vegetarianism is the practice of abstaining from the consumption of meat, including red meat, poultry, seafood, and the flesh of any other animal.

Motivations for Choosing a Vegetarian Diet

• Abstention from by-products of animal slaughter
• Respect for life
• Other: health-related, political, environmental, cultural, aesthetic, or economic

Classification

• Ovo-vegetarian: Includes eggs but not dairy products.
• Lacto-vegetarian: Includes dairy products but not eggs.
• Ovo-lacto vegetarian: Includes both eggs and dairy products.
• Vegan: Excludes all animal products, including eggs, dairy, beeswax, and honey.

Some vegans also avoid animal products such as leather (and possibly silk) for clothing and goose-fat for shoe polish.

• Raw veganism: Includes only fresh and uncooked fruit, nuts, seeds, and vegetables. Vegetables can only be cooked up to a certain temperature.
• Fruitarianism: Permits only fruit, nuts, seeds, and other plant matter that can be gathered without harming the plant.
• Sattvic diet: A plant-based diet that may include dairy (not eggs) and honey but excludes anything from the onion or leek family, red lentils, durian fruit, mushrooms, blue cheeses, fermented foods or sauces, alcoholic drinks, and often also excludes coffee, black or green tea, chocolate, nutmeg, or any other type of stimulant such as excess sharp spices.

Types of Vegetarianism

• Buddhist vegetarianism: Different Buddhist traditions have differing teachings on diet, which may also vary for ordained monks and nuns compared to others. Many interpret the precept “not to kill” to require abstinence from meat, but not all. In Taiwan, su vegetarianism excludes not only all animal products but also vegetables in the allium family (which have the characteristic aroma of onion and garlic): onion, garlic, scallions, leeks, chives, or shallots.
• Jain vegetarianism: Includes dairy but excludes eggs and honey, as well as root vegetables.
• Macrobiotic diets: Consist mostly of whole grains and beans.
• Semi-vegetarian diets: Consist largely of vegetarian foods but may include fish or poultry, or sometimes other meats, on an infrequent basis. Those with diets containing fish or poultry may define meat only as mammalian flesh and may identify with vegetarianism. A pescetarian diet has been described as “fish but no other meat.”

Nutrition

• Most vegetarian diets are low in or lack animal products.
• They are also usually lower in total fat, saturated fat, and cholesterol than non-vegetarian diets and therefore have a lower risk of obesity, coronary artery disease, high blood pressure, diabetes mellitus, and some forms of cancer.
• High levels of dietary fiber, folic acid, vitamins C and E, and magnesium, and low consumption of saturated fat are all considered to be beneficial aspects of a vegetarian diet.
• Western vegetarian diets are typically high in carotenoids but relatively low in omega-3 fatty acids and vitamin B12.
• Vegetarian diets can be healthy and nutritional if carefully planned to include essential nutrients. However, it can be unhealthy if it contains too many calories and/or saturated fat and not enough important nutrients.

Nutritional Considerations in a Vegetarian Diet

Proteins

• Plant proteins alone can provide enough essential and non-essential amino acids as long as sources of dietary protein are varied and caloric intake is high enough to meet energy needs.
• Whole grains, legumes, vegetables, seeds, and nuts all contain both essential and non-essential amino acids.
• Soy protein is nutritionally equal to protein of animal origin.

Iron

Vegetarian diets typically contain similar levels of iron to non-vegetarian diets, but this iron has lower bioavailability than iron from meat sources, and its absorption can sometimes be inhibited by other dietary constituents.

• Vegetarians may have a greater risk of developing iron deficiency than non-vegetarians.
• The richest sources of iron are red meat, liver, and egg yolk—all high in cholesterol.
• Other sources: dried beans, spinach, and dried fruits.
• Consuming food that contains vitamin C, such as citrus fruit or juices, tomatoes, can increase the amount of iron absorbed at a meal.

Vitamin B12

• It is only present in foods from animal sources.
• Vegans need a reliable source of vitamin B12.
• It can be found in some fortified breakfast cereals, some brands of yeast, and vitamin supplements.
• Vitamin B12 can also be obtained from fortified yeast extract products.

Vitamin D

Vegans who do not get much sunlight may need vitamin D supplements.

Zinc

• Needed for growth and development.
• Good plant sources include grains, nuts, and legumes.
• Shellfish are a very good source of zinc.
• Supplements should contain no more than 15-18mg zinc.

Fatty Acids

• Plant-based, or vegetarian, sources of Omega 3 fatty acids include soy, walnuts, pumpkin seeds, canola oil, kiwifruit, hempseed, algae, chia seed, flaxseed, echium seed, and leafy vegetables such as lettuce, spinach, and cabbage.
• Olives (and olive oil) are another important plant source of unsaturated fatty acids.
• Plant foods can provide alpha-linolenic acid, which the human body uses to synthesize the long-chain n-3 fatty acids, EPA and DHA.

Calcium

Intake in vegetarians and vegans can be similar to non-vegetarians, as long as the diet is properly planned.

Risks of an Inadequate Vegetarian Diet

Long-term deficiencies in an inadequate vegetarian diet may lead to the following complications:

• Osteoporosis as a result of lack of calcium causing bone demineralization
• Rickets in children due to lack of vitamin D
• Iron deficiency anemia due to low iron storage
• Macrocytic anemia due to vitamin B12 deficiency
• This has been observed in infants breast-fed by mothers who are strict vegetarians
• Emaciation or slow growth in vegetarian infants and children

Essentials of a Vegetarian Diet

• Balancing vegetarian food and nutrition is vital to maintaining a healthy vegetarian diet.
• Strict vegetarians may be at risk of several nutrition deficiencies, e.g., vitamin B12, riboflavin, zinc, calcium, iron, and essential amino acids (e.g., lysine and methionine).
• Vegans and vegetarians are also at risk of energy deficiency in the form of calories, particularly in children.
• Another issue in vegetarianism is low protein quality based on protein digestibility and amino acid composition. The risk associated with the protein quality of plant foods is based on a lack of certain essential amino acids that are found in natural combinations in animal protein. Combining different vegetarian nutrition sources of protein can ensure that all essential amino acids are found in a healthy vegetarian diet.