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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Dr. Sean

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, 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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