Vegetarian & Vegan Diets Explained
Article by: Consultant Dietitian Charity Chin
Vegetarian diets focus on plants-derived foods that include fruits, vegetables, legumes (dried beans, peas, lentils), whole grains, seeds, and nuts and excludes some or all foods derived from animals [1]. There are many reasons that people choose to follow a vegetarian or vegan diet, for some people it may be due to environmental concerns, humanitarian and ethical values, religious practices, avoiding hormones used in animal foods/products, or may be due to overall health considerations [1, 2].
When people think about vegetarian diets, they usually think about a diet that doesn’t include meat, poultry, or fish. But vegetarian diets vary in what foods they include and exclude. Within the broad category of vegetarian diets, there are several common subcategories, for example:
- Vegan diets: exclude meat, poultry, fish, eggs, and dairy products and foods that contain these products [1]
- Lacto-vegetarian diets: exclude meat, fish, poultry, and eggs, as well as foods that contain them, but include dairy products, such as milk, cheese, yogurt, and butter [1]
- Lacto-ovo vegetarian diets: exclude meat, fish, and poultry, but include dairy and egg products [1]
- Ovo-vegetarian diets: exclude meat, poultry, seafood, and dairy products, but include eggs and egg products [1]
Benefits of Vegetarian Diet
The purpose of following a vegetarian diet varies for each individual but one of the reasons is health benefits. The health benefits include reducing the risk of heart disease, obesity, hypertension, diabetes, and some cancers. According to the Academy of Nutrition and Dietetics, vegetarian and vegan diets are “healthful, nutritionally adequate, and may provide health benefits for the prevention and treatment of certain diseases” when patients and clients meet their daily nutritional needs [1].
Generally, vegetarians exhibit healthier dietary intake and lower body fat compared to non-vegetarians. Evidence indicates that the low intake of saturated fat and high consumption of dietary fiber and phytonutrient-rich foods, characteristic of vegetarian diets, result in lower total cholesterol and low-density lipoprotein cholesterol levels. This dietary pattern also improves glucose control, contributing to the prevention, reduction, and treatment of chronic diseases such as heart disease, stroke, weight management issues, type 2 diabetes, and metabolic syndrome. [4, 6, 7].
Vegetarian Diet Considerations
Vegetarian or vegan diets often feature processed foods, which may contain high levels of calories, sugar, fat, and sodium. Because of dietary restrictions, obtaining all necessary nutrients can be challenging. Here are some nutrients to be mindful of:
Vegetarian Diet’s Ideal Target Population
People of all ages, from young to old, can adopt vegetarian or vegan diets successfully by planning accordingly to ensure they receive essential nutrients for health and strength. Assessing acceptable foods helps individuals meet nutritional needs, achieve energy balance, ensure nutritional adequacy, and promote the use of a variety of plant-derived foods. Therefore, those opting for vegetarian or vegan diets must include a wide variety of foods and focus on protein, iron, calcium, vitamin D, omega-3, zinc, iodine, and vitamin B12 to meet their nutritional requirements.
References:
- Nutrition Care Manual. Academy of Nutrition and Dietetics. 2018
- Becoming A Vegetarian. Harvard Health Publishing Harvard Medical School. 2020.
- Omega-3 fatty acids. Nih.gov.
- Krajcovicová-Kudlácková M, Bucková K, Klimes I, Seboková E. Iodine deficiency in vegetarians and vegans. Ann Nutr Metab. 2003;47(5):183–5.
- Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian diets. J Acad Nutr Diet [Internet]. 2016;116(12):1970–80.
- Walczyk T, Muthayya S, Wegmüller R, Thankachan P, Sierksma A, Frenken LGJ, et al. Inhibition of iron absorption by calcium is modest in an iron-fortified, casein- and whey-based drink in Indian children and is easily compensated for by addition of ascorbic acid. J Nutr. 2014;144(11):1703–9.
- Kahleova H, Levin S, Barnard ND. Vegetarian dietary patterns and cardiovascular disease. Prog Cardiovasc Dis. 2018;61(1):54–61.
- Leitzmann C. Vegetarian diets: What are the advantages? In: Forum of Nutrition. S. Karger AG; 2005. p. 147–56.
- Greupner T, Kutzner L, Nolte F, Strangmann A, Kohrs H, Hahn A, et al. Effects of a 12-week high-α-linolenic acid intervention on EPA and DHA concentrations in red blood cells and plasma oxylipin pattern in subjects with a low EPA and DHA status. Food Funct. 2018;9(3):1587–600.
- Iodine. The Nutrition Source. Harvard School of Public Health. 2021.
- Maares M, Haase H. A guide to human zinc absorption: General overview and recent advances of in vitro intestinal models. Nutrients. 2020;12(3):762.