II. Definitions
- Vegetarian Diet
- Plant based diet consisting of fruits, vegetables, dried beans, peas, grains, seeds and nuts
- Vegetarian Diets typically typically exclude meat, poultry, fish and animal fats
- Flexitarians may add certain meats, such as fish and seafood (pescatarians) or poultry
- Vegans exclude dairy, eggs, and honey, while Lacto-Ovo-Vegetarians eat milk and eggs
- Vegan diet
- Vegetarian Diet that excludes all animal products
- Avoids dairy, eggs, and honey in addition to meat, poultry, fish and animal fats
- Vegans also avoid any animal products in general (cosmetics, animal-based clothing)
- Lacto-Ovo-Vegetarian Diet
- Vegetarian Diet that includes dairy products and eggs
- Plant Forward Diet
- Diet in which the meat main course is replaced by Vegetarian entrees
- Diet may include meat as a smaller portion of the meal
III. Epidemiology
- Worldwide Prevalence
- Asia: 19% (esp. India, where 40% are Vegetarian, related to hinduism)
- Africa and Middle East: 16%
- Central America and South America: 8%
- North America: 6% overall (2-3% of teens)
- Europe: 5%
IV. Indications: Vegetarian Diet
- Religion (e.g. Hinduism)
-
Healthy Diet
- High fiber diet
- Diverse gut microbiome
- Associated with antiinflammatory effects and improved gut health
- Singh (2017) J Transl Med 15:73 [PubMed]
- Increased Plant Sterol intake, lower saturated fat intake and lower Cholesterol intake
- Reduced cardiovascular disease risk (Ischemic Heart Disease, Cerebrovascular Disease)
- Lower risk of Hypertension (e.g. DASH Diet)
- Decreased Caloric Intake and lower Obesity Risk (reduced BMI, reduced Waist Circumference)
- Improved glycemic control and lower Diabetes Mellitus risk
- Improved quality of life, physical and emotional well being and Major Depression
- Cancer Prevention and decreased cancer-associated mortality (phytochemical intake, avoidance of red meat, processed meats)
- Ethical concerns
- Animal slaughter
- Environmental impact (e.g. greenhouse gas or GHG emissions related to meat industry, other polutants)
- Example: Tofu requires 74 fold less land and 8 fold less water than equivalent beef Protein (25 fold less GHG emissions)
- https://ourworldindata.org/environmental-impacts-of-food
V. Management: Vegetarian Diet
- Examples of Plant Forward Diets common to medical studies
-
Dietary Supplementation (esp. for Vegan diets)
- Dietary Iron (esp. in women of menstruating age)
- Dietary zinc (e.g. nuts, seeds, grains, legumes, tofu, dairy)
- Dietary Iodine (e.g. Iodized Salt, seafood, dairy products)
- Omega-3 Fatty Acid (e.g. flaxseed, chia seed, hemp seed, walnuts or Omega-3 Fatty Acid Supplements)
- Vitamin B12 (e.g. dairy, fortified cereals and other fortified foods, or daily Vitamin B12 supplement)
- Other plant based sources (e.g. fermented soy, seaweed, mushrooms, leafy vegetables) are inadequate for daily B12 needs
- Osteoporosis Prevention
- Ensure adequate Dietary Calcium intake
- Ensure adequate Vitamin D intake
- Vegetable Protein intake is typically adequate
- Additional topics
- Eating Disorders
- Eating Disorder (e.g. Anorexia Nervosa) risk is not increased by prior Vegetarian or Vegan diet
- However, patients with disordered eating may select Vegetarian or Vegan diets as socially appropriate way to avoid food
- Be alert for underlying Eating Disorders
- However, avoid labelling typical Vegetarian Diets as restrictive when Caloric Intake is adequate
- Timko (2012) Appetite 58:982-90 [PubMed]
- Athletes
- Vegetarian Diets offer adequate Nutrition for Athletes
- Ensure adequate Caloric Intake
- See Female Athlete Triad
- Be alert for Relative Energy Deficiency in Sport
- Ensure adequate Calcium and Vitamin D in female endurance athletes with Amenorrhea
- Ensure adequate Protein (e.g. soy, legumes, nuts, seeds)
- Milk and eggs (if not vegan) may help supplement plant based intake in athletes
- Creatine supplementation may be considered in sprinters and Resistance Training
- As with all Vegetarians and vegans, ensure adequate dietary Vitamin intake
- Important Vitamins include iron, zinc, Iodine, Vitamin B12, Calcium, Vitamin D
- Encourage iron rich foods in female athletes
- Craddock (2016) Int J Sports Nutr Exerc Metab 26:212-20 [PubMed]
- Pregnancy and Lactation
- Vegetarian and Vegan diets offer adequate Nutrition in Pregnancy and Lactation
- Vegetarian and Vegan diets may be associated with Small for Gestational Age infants
- Vegetarians and vegans are less likely to experience pregnancy complications
- Supplement or increased dietary intake of the following
- Dietary Iron or Iron Supplement
- Vitamin B12 Supplementation
- Zinc
- Iodine
- Docosahexaeonoic Acid (DHA, omega 3 Fatty Acid supplementation)
- Sebastiani (2019) Nutrients 11:557 [PubMed]
- Raghavan (2019) Am J Clin Nutr 109:705s [PubMed]
- Children and Teens
- Vegetarian and Vegan diets offer adequate nutrition in childhood and teen years
- Ensure adequate Vegetarian Protein sources (beans, tofu)
- Ensure adequate dietary Vitamin intake (iron, zinc, Iodine, Vitamin B12, Calcium, Vitamin D)
- Amit (2010) Paediatr Child Health 15:303-14 [PubMed]
- Older patients
- Ingest Protein sources (e.g. tofu, soy, legumes, nuts, seeds) three times daily
- Encourage increased Vitamin B6 intake (e.g. potatoes, bananas, spinach, fotified breakfast cereal)
- Ensure adequate Vitamin B12 intake
- Omega-3 Fatty Acid Supplementation
- Vitamin D Supplementation (and Calcium)
- Eating Disorders
VI. Complications: Vegetarian Diet Related Deficiencies (esp. Vegan)
- Macronutrient Deficiency
- Micronutrient Deficiency
- Vitamin B12 Deficiency
- Zinc Deficiency
- Omega 3 Fatty Acid deficiency
- Vitamin B2 Deficiency (Riboflavin Deficiency)
- Vitamin B3 Deficiency (Niacin Deficiency)
- Selenium Deficiency
- Iodine Deficiency
- Iodine is not found in sea salt or himalayan salt (only added to Iodized Salt)
- Other Iodine sources include seafood, seaweed and dairy products
- Calcium Deficiency and Vitamin D Deficiency
- Osteoporosis Risk