II. Definitions

  1. Vegetarian Diet
    1. Plant based diet consisting of fruits, vegetables, dried beans, peas, grains, seeds and nuts
    2. Vegetarian Diets typically typically exclude meat, poultry, fish and animal fats
    3. Flexitarians may add certain meats, such as fish and seafood (pescatarians) or poultry
    4. Vegans exclude dairy, eggs, and honey, while Lacto-Ovo-Vegetarians eat milk and eggs
  2. Vegan diet
    1. Vegetarian Diet that excludes all animal products
    2. Avoids dairy, eggs, and honey in addition to meat, poultry, fish and animal fats
    3. Vegans also avoid any animal products in general (cosmetics, animal-based clothing)
  3. Lacto-Ovo-Vegetarian Diet
    1. Vegetarian Diet that includes dairy products and eggs
  4. Plant Forward Diet
    1. Diet in which the meat main course is replaced by Vegetarian entrees
    2. Diet may include meat as a smaller portion of the meal

III. Epidemiology

  1. Worldwide Prevalence
    1. Asia: 19% (esp. India, where 40% are Vegetarian, related to hinduism)
    2. Africa and Middle East: 16%
    3. Central America and South America: 8%
    4. North America: 6% overall (2-3% of teens)
    5. Europe: 5%

IV. Indications: Vegetarian Diet

  1. Religion (e.g. Hinduism)
  2. Healthy Diet
    1. High fiber diet
    2. Diverse gut microbiome
      1. Associated with antiinflammatory effects and improved gut health
      2. Singh (2017) J Transl Med 15:73 [PubMed]
    3. Increased Plant Sterol intake, lower saturated fat intake and lower Cholesterol intake
      1. Bradbury (2015) Eur J Clin Nutr 69:1180 [PubMed]
    4. Reduced cardiovascular disease risk (Ischemic Heart Disease, Cerebrovascular Disease)
      1. Matsumoto (2019) J Nutr Sci 8:e6 [PubMed]
      2. Ornish (1998) JAMA 280:2001-7 [PubMed]
      3. Tong (2019) BMJ 366:14897 [PubMed]
    5. Lower risk of Hypertension (e.g. DASH Diet)
      1. Yokoyama (2014) JAMA Intern Med 174:577-87 [PubMed]
    6. Decreased Caloric Intake and lower Obesity Risk (reduced BMI, reduced Waist Circumference)
      1. Barnard (2015) J Acad Nutr 954-69 [PubMed]
    7. Improved glycemic control and lower Diabetes Mellitus risk
      1. Toumpanakis (2018) BMJ Open Diabetes Res Care 6:e000534 [PubMed]
    8. Improved quality of life, physical and emotional well being and Major Depression
    9. Cancer Prevention and decreased cancer-associated mortality (phytochemical intake, avoidance of red meat, processed meats)
      1. Aune (2016) BMC Med 14:207 [PubMed]
  3. Ethical concerns
    1. Animal slaughter
    2. Environmental impact (e.g. greenhouse gas or GHG emissions related to meat industry, other polutants)
      1. Example: Tofu requires 74 fold less land and 8 fold less water than equivalent beef Protein (25 fold less GHG emissions)
      2. https://ourworldindata.org/environmental-impacts-of-food

V. Management: Vegetarian Diet

  1. Examples of Plant Forward Diets common to medical studies
    1. Mediterranean Diet
    2. Dietary Approaches to Stop Hypertension (DASH Diet)
  2. Dietary Supplementation (esp. for Vegan diets)
    1. Dietary Iron (esp. in women of menstruating age)
    2. Dietary zinc (e.g. nuts, seeds, grains, legumes, tofu, dairy)
    3. Dietary Iodine (e.g. Iodized Salt, seafood, dairy products)
    4. Omega-3 Fatty Acid (e.g. flaxseed, chia seed, hemp seed, walnuts or Omega-3 Fatty Acid Supplements)
    5. Vitamin B12 (e.g. dairy, fortified cereals and other fortified foods, or daily Vitamin B12 supplement)
      1. Other plant based sources (e.g. fermented soy, seaweed, mushrooms, leafy vegetables) are inadequate for daily B12 needs
    6. Osteoporosis Prevention
      1. Ensure adequate Dietary Calcium intake
      2. Ensure adequate Vitamin D intake
    7. Vegetable Protein intake is typically adequate
      1. Protein-rich plant based foods include legumes, soy (e.g. tofu, tempeh), nuts and seeds
      2. Omnivores of North America and Europe ingest up to 2 times animal based Protein RDA (excessive, Obesity)
  3. Additional topics
    1. Eating Disorders
      1. Eating Disorder (e.g. Anorexia Nervosa) risk is not increased by prior Vegetarian or Vegan diet
      2. However, patients with disordered eating may select Vegetarian or Vegan diets as socially appropriate way to avoid food
      3. Be alert for underlying Eating Disorders
        1. However, avoid labelling typical Vegetarian Diets as restrictive when Caloric Intake is adequate
      4. Timko (2012) Appetite 58:982-90 [PubMed]
    2. Athletes
      1. Vegetarian Diets offer adequate Nutrition for Athletes
      2. Ensure adequate Caloric Intake
        1. See Female Athlete Triad
        2. Be alert for Relative Energy Deficiency in Sport
        3. Ensure adequate Calcium and Vitamin D in female endurance athletes with Amenorrhea
      3. Ensure adequate Protein (e.g. soy, legumes, nuts, seeds)
        1. Milk and eggs (if not vegan) may help supplement plant based intake in athletes
        2. Creatine supplementation may be considered in sprinters and Resistance Training
      4. As with all Vegetarians and vegans, ensure adequate dietary Vitamin intake
        1. Important Vitamins include iron, zinc, Iodine, Vitamin B12, Calcium, Vitamin D
        2. Encourage iron rich foods in female athletes
      5. Craddock (2016) Int J Sports Nutr Exerc Metab 26:212-20 [PubMed]
    3. Pregnancy and Lactation
      1. Vegetarian and Vegan diets offer adequate Nutrition in Pregnancy and Lactation
      2. Vegetarian and Vegan diets may be associated with Small for Gestational Age infants
      3. Vegetarians and vegans are less likely to experience pregnancy complications
        1. Gestational Diabetes
        2. Preterm birth
        3. Hypertensive Disorders of Pregnancy
      4. Supplement or increased dietary intake of the following
        1. Dietary Iron or Iron Supplement
        2. Vitamin B12 Supplementation
        3. Zinc
        4. Iodine
        5. Docosahexaeonoic Acid (DHA, omega 3 Fatty Acid supplementation)
      5. Sebastiani (2019) Nutrients 11:557 [PubMed]
      6. Raghavan (2019) Am J Clin Nutr 109:705s [PubMed]
    4. Children and Teens
      1. Vegetarian and Vegan diets offer adequate nutrition in childhood and teen years
      2. Ensure adequate Vegetarian Protein sources (beans, tofu)
      3. Ensure adequate dietary Vitamin intake (iron, zinc, Iodine, Vitamin B12, Calcium, Vitamin D)
      4. Amit (2010) Paediatr Child Health 15:303-14 [PubMed]
    5. Older patients
      1. Ingest Protein sources (e.g. tofu, soy, legumes, nuts, seeds) three times daily
      2. Encourage increased Vitamin B6 intake (e.g. potatoes, bananas, spinach, fotified breakfast cereal)
      3. Ensure adequate Vitamin B12 intake
      4. Omega-3 Fatty Acid Supplementation
      5. Vitamin D Supplementation (and Calcium)

VI. Complications: Vegetarian Diet Related Deficiencies (esp. Vegan)

  1. Macronutrient Deficiency
    1. Protein deficiency
      1. Most Vegetarians and vegans get adequate Protein intake (see above)
  2. Micronutrient Deficiency
    1. Vitamin B12 Deficiency
    2. Zinc Deficiency
    3. Omega 3 Fatty Acid deficiency
    4. Vitamin B2 Deficiency (Riboflavin Deficiency)
    5. Vitamin B3 Deficiency (Niacin Deficiency)
    6. Selenium Deficiency
    7. Iodine Deficiency
      1. Iodine is not found in sea salt or himalayan salt (only added to Iodized Salt)
      2. Other Iodine sources include seafood, seaweed and dairy products
    8. Calcium Deficiency and Vitamin D Deficiency
      1. Osteoporosis Risk

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