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Vegan and vegetarian sources of essential nutrients

Article author photo Arpi Gasparyan by Arpi Gasparyan | Last updated on August 05, 2023
Medically reviewed by Victoria Mazmanyan Article author photo Victoria Mazmanyan

In short, vegans consume plants (vegetables, fruits, grains, and nuts) and plant-based foods. Vegetarians consume plants, plant-based foods, eggs, and dairy products.

Both vegans and vegetarians do not eat meat, fish, and seafood.

This article aims to understand what nutritional deficiencies may be caused by a vegan or vegetarian diet and how to restore their supply and maintain health.

In order to have a healthy balanced diet, it is important to know which foods can provide the essential nutrients that often lack in vegan and vegetarian diets.  

Vitamin B-12

Vitamin B12, or cobalamin, is a water-soluble vitamin required for red blood cell formation, brain development and function, and DNA synthesis.

Vitamin B-12's primary sources are meat, dairy products, eggs, and fish; therefore, vitamin B-12 deficiency is more common in vegans than in vegetarians and pescetarians.

The daily recommended vitamin B12 intake (for adults) is 2.4 micrograms (mcg) (1).

Vitamin B12 alternative sources include yeast and fortified soy products, other fortified food, and milk substitutes (2, 3, 4, 5, 6, 7, 8, 9):

  • Yeast extract spread or marmite: 0.03 mcg (1tsp or 6g)
  • Nutritional yeast: 24mcg (16g)
  • Tempeh: 0.08mcg (100g)
  • Nasoya Lite Firm Tofu: 1.86mcg (0.2 package, 79g)
  • Nasoya Tofu Plus Firm: 1.22mcg (3 oz, 85g)
  • Pacific Nori: 1.9mcg (1 sheet, 2.5g)
  • Soy milk: 1.33mcg (100g)
  • Almond milk: 0.45mcg (100g)
  • Rice milk: 0.63mcg (100g)
  • Fortified milk: 1.5 mcg (1 cup, 246g)
  • Fortified breakfast cereals
  • Fortified bread
  • Mushrooms 

Vitamin B12 deficiency can lead to tiredness, lack of energy and muscle weakness, sore tongue, mouth ulcers, a sensation of pins and needles, usually in limbs, impaired vision, and psychological and neurological disorders, such as depression, confusion, and cognitive impairment (1, 10).

Usually, vitamin B12 deficiency presents clinical symptoms years after a deficient diet, as the body stores 1 to 5mg of vitamin B12 (1000 to 2000 times more than the daily intake of this vitamin) (1). 

Vitamin D and Calcium

Vitamin D, or calciferol, is a fat-soluble vitamin that promotes calcium absorption in the small intestine and regulates calcium and phosphate concentrations for proper bone growth and mineralization. Vitamin D modulates cell growth, neuronal, muscular, immune functions, and glucose metabolism.

Primary food sources of vitamin D are fatty fish (salmon, tuna, sardines), red meat, egg yolks, cheese, and fortified foods. Ultraviolet rays from sunlight also trigger vitamin D synthesis.

The daily recommended vitamin D intake (for adults) is 15 micrograms (mcg) or 600IU (11).

Vitamin D alternative sources include fortified soy products and other fortified food, milk substitutes, cheese, and mushrooms (4, 5, 7, 8, 12, 13, 14):

  • Exposure to sunlight
  • Nasoya Lite Firm Tofu: 3.08mcg (0.2 package, 79g)
  • Nasoya Tofu Plus Firm: 2.12mcg (3 oz, 85g)
  • Fortified soy drinks; for example, soy milk: 4.63mcg (100g serving)
  • Almond milk: 63.6 mcg (100g)
  • Rice milk: 1mcg (100g)
  • Fortified milk: 2.61mcg (1 cup)
  • Fortified fat spreads; for example, margarine spread 35-39%: 0.84mcg (1tsp, 4.8g)
  • Egg yolk: 0.628mcg (1 tbsp, 4g)
  • Cheese; some kinds of cheese naturally contain vitamin D, and some are fortified; for example, brick cheese: 0.14mcg (1 slice, 1oz, or 28g)
  • Mushrooms; mushrooms contain variable amounts of vitamin D: maitake mushroom, king oyster, and shiitake mushrooms
  • Fortified juices; for example, fortified orange juice with added calcium and vitamin D
  • Fortified breakfast cereals 

Vitamin D deficiency in children manifests as rickets, leading to soft bones and skeletal deformities. Severe cases may include developmental delay, hypocalcemic seizures, tetanic spasms, heart disease, and teeth abnormalities.

Vitamin D deficiency in adults causes osteoporosis (low bone density) and osteomalacia (soft bones), leading to bone deformities, bone fractures, and pain. Vitamin D deficiency also may cause hypocalcemic seizures, tetanic spasms, and tooth abnormalities (11).

Studies have shown that many patients with migraines have vitamin D deficiency, and vitamin administration may improve migraine characteristics such as attack durations and severity (15, 16).

Calcium is a mineral primarily stored in the bones. Calcium keeps the tissues rigid, flexible, and strong, allowing proper bodily movements. Calcium participates in blood vessel contraction and dilation, muscle function, blood clotting, sending and receiving nerve signals, keeping a normal heartbeat, and releasing hormones and chemicals.

Primary calcium sources are dairy products, sardines, and salmon with bones. As the primary calcium sources are dairy products, vegetarians are less likely to have a calcium deficiency.

The daily recommended calcium intake (for adults) is 1000mg (17, 18).

Calcium alternative sources include leafy green vegetables, milk substitutes, soy products, and fortified food (7, 8):

Calcium deficiency reduces bone strength and may lead to osteomalacia, osteoporosis, and bone fractures. Calcium deficiency may also cause perioral numbness, tingling in hands and feet, and muscle spasms; in severe cases, kidney and brain calcification, depression, bipolar disorder, cataracts, heart failure, and seizures (17).

Iron

Iron is a mineral essential for hemoglobin synthesis, a protein that transfers oxygen from the lungs to tissues, and myoglobin synthesis, supporting muscle metabolism. Iron is also needed for growth, neurological development and neurotransmission, DNA synthesis, cellular functioning, and hormone synthesis.

Iron comes in two forms: heme iron and non-heme iron. Heme iron primary sources are meat and seafood, whereas non-heme iron sources are nuts, legumes, seeds, leafy greens, and fortified food.

The daily recommended iron intake is 8mg for men and women over 50 and 18mg for women ages 19-50.

People who do not eat meat should consume 1.8 times more iron than recommended, as heme iron is more absorbable than non-heme iron (19).

Iron alternative sources include plants and plant-based foods, fortified cereals, and dark chocolate (20, 21, 22, 23, 24):

Iron deficiency causes iron deficiency anemia or microcytic anemia. Pregnant women, people with heavy menstrual bleeding, frequent blood donors, and people with gastrointestinal bleeding and chronic disease have a higher risk of developing iron deficiency anemia. Common symptoms of iron deficiency anemia are tiredness, lack of energy, headaches, shortness of breath, heart palpitations, pale skin, hair loss, ringing or hissing noises in the head, and itchiness (19, 25).

Zinc

Zinc is an essential mineral required for the activity of nearly 100 enzymes. It also participates in DNA and protein synthesis, cell growth, immune function, growth and development, and wound healing. Additionally, zinc is necessary for a proper sense of taste and smell.

Zinc's primary sources are meat, seafood, and dairy products.

The daily recommended zinc intake is 11mg for adult men and 8mg for women. Zinc from plant products is less absorbable than zinc from meat due to phytates in legumes and whole grains that bind to zinc and prevent its absorption. Those who do not consume meat need a higher zinc intake than the average recommended amount (26).

Zinc alternative sources include fortified food, bread, whole grains and their bread, legumes and beans, nuts, and soy products (20, 21, 27, 28):

Zinc deficiency leads to reduced growth, loss of appetite, impaired immune function, inflammation, hair loss, diarrhea, irritability, impotence, and eye and skin lesions (26, 29).

Iodine

Iodine is an essential mineral and component of thyroid hormones T3 and T4. The thyroid hormones play a vital role in metabolic activity or rate. They also play an important role in the development of bones and brains in fetuses and infants, as well as many biochemical reactions such as protein synthesis and enzyme activity.

Primary sources of iodine are seaweed (nori, kelp, wakame), fish and other seafood, eggs, and dairy products. Plant foods' iodine content depends on the soil's iodine content, fertilizer use, and irrigation practices, making plant foods poor sources of iodine.

The daily recommended iodine intake for adult men and women is 150mcg and 220mcg for pregnant people (30).

Iodine alternative sources are iodized bread and table salt (31):

  • Bread made with sodium iodate
  • Iodized table salt: 310mcg (1tsp, 6.1g)

Iodine deficiency causes hypothyroidism, leading to goiter (thyroid gland enlargement). Symptoms of hypothyroidism include fatigue, lack of energy, psychological disorders, cold intolerance, weight gain, constipation, and dry skin. Iodine deficiency in pregnant people may cause miscarriage and stillbirth; congenital iodine deficiency syndrome in newborns (intellectual disability, stunted growth, delayed sexual maturation) (30, 32).

Protein

Proteins are complex molecules that play crucial roles in tissue and organ function, structure, and regulation. For example, enzyme proteins act as a catalyst by accelerating reactions; structural proteins partake in cell and tissue formation, and motor proteins provide movement of tissues and organs. Some proteins are hormones, such as insulin and growth hormone.

Proteins from various meat and dairy products are complete proteins, providing all of the essential amino acids the organism needs. However, most plant proteins are incomplete, meaning they lack one or another amino acid (33, 34).

Primary protein sources are meat, fish, eggs, and dairy products.

The daily recommended protein intake is 56g for adult men and 46g for adult women (35).

Protein alternative sources include yeast and soy products, whole grains, legumes and beans, and nuts (2, 3, 7, 20, 21, 23, 28):

Protein deficiency may lead to metabolic problems, swelling, nervous system defects, wasting of muscle tissue, kwashiorkor, marasmus, impaired mental health, weakness of the immune system, and organ failure (36).

Omega-3 fatty acids 

Omega-3s help form cell membranes (DHA is high in the brain and eyes), provide energy for the body, and lower the risk of arrhythmias, heart failure, atherosclerosis, inflammation, cancer, dry eye disease, and neurological and psychological disorders. Additionally, omega-3 fatty acids play a significant role in fetal growth and visual and cognitive development (37).

Primary ALA sources are flaxseed, canola, soybean oils, chia seeds, and walnuts. EPA and DHA sources are fatty fish and other seafood.

The daily recommended intake for total fats is 65g, but not omega-3s. Omega-3 fatty acids are not listed separately in the USDA's daily recommended intakes (35, 37).

EPA and DHA alternative sources are algal oil, seaweed, and supplements (38, 39, 40):

  • Algal oil
  • Seaweed, such as nori, spirulina, chlorella, and wakame
  • Supplements 

Omega-3 deficiency may cause rough, scaly skin and dermatitis. Low levels of DHA and EPA are associated with ADHD, ASD, depression, cognitive decline, and Alzheimer’s disease (37, 41, 42).

References

  1. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
  2. https://fdc.nal.usda.gov/fdc-app.html#/food-details/167717/nutrients
  3. https://fdc.nal.usda.gov/fdc-app.html#/food-details/1991802/nutrients
  4. https://fdc.nal.usda.gov/fdc-app.html#/food-details/172468/nutrients
  5. https://fdc.nal.usda.gov/fdc-app.html#/food-details/175233/nutrients
  6. https://fdc.nal.usda.gov/fdc-app.html#/food-details/1862749/nutrients
  7. https://fdc.nal.usda.gov/fdc-app.html#/food-details/2257044/nutrients
  8. https://fdc.nal.usda.gov/fdc-app.html#/food-details/2257045/nutrients
  9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/
  10. Vitamin B12 or folate deficiency anemia - NHS
  11. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
  12. https://fdc.nal.usda.gov/fdc-app.html#/food-details/171415/nutrients
  13. https://fdc.nal.usda.gov/fdc-app.html#/food-details/329716/nutrients
  14. https://fdc.nal.usda.gov/fdc-app.html#/food-details/172176/nutrients
  15. https://pubmed.ncbi.nlm.nih.gov/31897949/
  16. https://pubmed.ncbi.nlm.nih.gov/31377873/
  17. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/
  18. https://medlineplus.gov/ency/article/002412.htm
  19. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
  20. https://fdc.nal.usda.gov/fdc-app.html#/food-details/173757/nutrients
  21. https://fdc.nal.usda.gov/fdc-app.html#/food-details/173740/nutrients
  22. https://fdc.nal.usda.gov/fdc-app.html#/food-details/169141/nutrients
  23. https://fdc.nal.usda.gov/fdc-app.html#/food-details/170093/nutrients
  24. https://fdc.nal.usda.gov/fdc-app.html#/food-details/170273/nutrients
  25. https://www.nhs.uk/conditions/iron-deficiency-anaemia/
  26. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
  27. https://fdc.nal.usda.gov/fdc-app.html#/food-details/335240/nutrients
  28. https://fdc.nal.usda.gov/fdc-app.html#/food-details/170686/nutrients
  29. https://www.ncbi.nlm.nih.gov/books/NBK493231/
  30. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
  31. https://fdc.nal.usda.gov/fdc-app.html#/food-details/746775/nutrients
  32. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6619426/
  33. https://www.ncbi.nlm.nih.gov/books/NBK555990/
  34. https://medlineplus.gov/genetics/understanding/howgeneswork/protein/
  35. Dietary Guidelines for Americans, 2020-2025
  36. Health complications caused by protein deficiency.
  37. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
  38. Docosahexaenoic Acid (DHA) Algal Oil
  39. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8124752/
  40. https://www.mdpi.com/1660-3397/18/6/301
  41. https://rnd.edpsciences.org/articles/rnd/abs/2005/01/r5101/r5101.html
  42. https://www.tandfonline.com/doi/abs/10.1080/09540260600583031
Article author photo Arpi Gasparyan
Education: General Medicine at YSMU
Last updated: August 05, 2023
Medically reviewed by Victoria Mazmanyan
Data provided by FoodStruct.com should be considered and used as information only. Please consult your physician before beginning any diet.