DietsNutritionPlant Based Diet

Are Whole Food Plant Based Diets Nutrient Deficient?

Key findings:

  • Per nationwide poll in 2016: ~3.3% of American adults are vegetarian or vegan
  • PROTEIN:
    • Vegetarian and vegan diets meet or exceed recommended protein intakes
    • Regular use of soy and legumes will ensure adequate protein intake.
  • N-3 FATTY ACIDS:
    • Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA)
    • Long chain n-3 fatty acids (EPA and DHA) important for development and maintenance of the brain, eyes, cell membranes, pregnancy and cardiovascular diseases.
    • α-linolenic acid (ALA) is converted to EPA and DHA in the body.  Men should get 1.6 grams/day and women should get 1.1 grams/day of ALA.
    • The best plant sources of ALA are: flax seeds, chia seeds, camelina seeds, canola seeds, hemp seeds, walnuts and their oils
    • Note: high intakes of linoleic acid (vegetable oils, safflower oils) may reduce the conversion of ALA to EPA and DHA.
  • IRON
    • Vegetarians generally consume as much or slightly more iron than omnivores.
    • Iron stores of vegetarians are less than nonvegetarians.
    • Elevated iron stores (high ferritin levels) independently associated with risk of metabolic syndrome.
    • Absorption of non-heme iron from plant foods depends on the body’s need and regulated partially by the body’s iron stores.
  • ZINC
    • Zinc levels of vegetarians are lower than nonvegetarians but they are still within the normal range.
    • Zinc sources: soy products, legumes, grains, cheese, seeds and nuts
    • Soaking and sprouting beans, grains, nuts and seeds reduces binding of zinc by phytic acid and increases zinc bioavailability.
    • Citric acid can also increase zinc absorption
  • IODINE:
    • Plant-based diets can be low in iodine especially when limiting iodized salt or sea vegetables
    • Vegan women of child-bearing age should supplement with 150ug/day of iodine
    • Foods such as soybeans, cruciferous vegetables, and sweet potatoes contain natural goitrogens but they are not associated with any thyroid issues if iodine intake is adequate.
  • CALCIUM:
    • Lacto-ovo vegetarians have adequate intakes of calcium
    • Absorption of calcium related to oxalate, phytate, and fiber
      • Calcium absorption from low-oxalate vegetables (kale, turnip greens, Chinese cabbage, bok choy) is ~50%.
      • Calcium absorption from high oxalate vegetables (spinach, beet greens, swiss chard) is ~5%.
    • Calcium absorption from calcium-set tofu and fortified plant milk is ~30%.
    • Calcium absorption from white beans, almonds, tahini, figs, oranges is ~20%.
    • Calcium-citrate-malate absorption is ~36%.
  • VITAMIN D:
    • Low Vitamin D levels can be seen in winter or spring and in those living at high latitudes.
    • Vitamin D fortified foods include cow’s milk, some nondairy milk, fruit juices, breakfast cereals, and margarine.
    •  Vitamin D3 (cholecalciferol) can be animal or plant origin
    • Vitamin D2 (ergocalciferol) is made from UV irradiation of ergosterol from yeast.
    • At high doses, Vitamin D2 is less effective than D3
  • VITAMIN B12:
    • Not found in most plant foods
    • Vegans should consume B12 either through fortified foods or supplements
    • For vegetarians, one cup of milk and one egg per day gives ~66% of Recommended Daily Allowance (RDA)
    • Signs of B12 deficiency:
      • Fatigue
      • Tingling in fingers and toes
      • Poor cognition
      • Poor digestion
      • Failure to thrive in small children
    • Long-term B12 deficiency:
      • Stroke
      • Dementia
      • Poor bone health
    • B12 absorption via intrinsic factor (IF)
      • Intrinsic factor becomes saturated at about half the RDA and requires 4-6 hours before further B12 absorption can occur
      • Thus, fortified foods should be eaten twice per day to improve absorption
    • Passive B12 absorption occurs via diffusion at only 1%.
    • 4 types of B-12
      • Cyanocobalamin: most commonly used in fortified foods
      • Methylcobalamin: used in body’s enzymatic reactions
      • Adenosylcobalamin: also sued in body’s enzymatic reactions
      • Hydroxocobalamin: used in injections

Reference:

Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116:1970-1980.

 

 

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Sean Hashmi, MD, MS, FASN

Sean Hashmi, MD, MS, FASN is a practicing Nephrologist and Obesity Medicine Specialist in Southern California. He is founding director of SELFPrinciple.org, a non-profit 501c(3), non-commercial site focused on evidence-based nutrition, health, and wellness. Dr. Hashmi graduated from the University of California, San Diego Medical School. He completed his residency in Internal Medicine at UCLA-Olive View Medical Center followed by a fellowship in Nephrology at the University of California, Los Angeles.

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