Is Your Body Craving B12?

An essential vitamin goes lacking among vegans.

By Kevin RR Williams

NUTRITION If you plan or prepare meals for vegetarians, have them as patients, are thinking about becoming a vegan, have been one for more than a year, desire to eat healthy, have a compromised immune system, take antacids regularly, have had gastric bypass surgery, are pregnant or trying to conceive a child, have numbness or tingling in extremities, or are near 50 years of age, continue reading this compreshensive article to prevent serious illness and expensive medical bills.

Regardless of food choices, our goal is to stay healthy, right? Vitamin B12, also known as methylcobalamin or cyanocobalamin, is an indispensable nutrient commonly found in a variety of non-plant based foods, such as fish, shellfish, meat, eggs, and dairy products. Because animal products provide optimum food sources for vitamin B12, vegans have the greatest risk for deficiency. Vegetarians who eat eggs and milk products are also at risk because, on average, they consume less than half of the adult Recommended Dietary Allowance (RDA) of vitamin B12. [1,2]

Symptoms of Vitamin B12 Malnutrition

Our bodies send out unpleasant signals when they crave essential nutrients. Early vitamin B12 cravings include decreased energy: weakness, fatigue, light-headedness, rapid heartbeat (tachycardia), panting; dermatological and dental indictions: pallor, easy bruising, sore tongue, bleeding gums; gastric disturbance: upset stomach, weight loss, diarrhea or constipation. Vitamin B12 deficiency can ultimately lead to several neurological and cardiovascular problems, including paresthesia, depression and dementia [2] cardiac distress.

A normally functioning liver stores an adequate reserve of vitamin B12 for several years. Vegans are advised to have their B12 level checked every two years via methylmalonic acid (MAA) urine testing due to the unreliability of blood tests. Algae and other plant foods contain B12-analogues (false B12) that can imitate true B12 in blood tests while actually interfering with B12 metabolism. Values below approximately 170–250 pg/mL (120–180 picomol/L) for adults indicate a vitamin B12 deficiency. [3,4]

Not Just Vegans At Risk

Vitamin B12 is required for proper red blood cell formation, neurological function, and DNA synthesis. Vitamin B12 deficiency can have a number of possible causes. Typically it occurs in people whose digestive systems do not adequately absorb the vitamin from the foods they eat. [2,3] This can result from:

  • Pernicious anemia, a condition in which there is a lack of a protein called intrinsic factor. The protein, which is made in the stomach, is necessary for vitamin B12 absorption.
  • Atrophic gastritis, a thinning of the stomach lining that affects up to 30% of people aged 50 and older.
  • Surgery in which part of the stomach and/or small intestine is removed.
  • Small intestine conditions, such as Crohn's disease, celiac disease, bacterial growth, or a parasite.
  • Excessive alcohol excess consumption.
  • Immune disorders, such as Graves' disease, systemic lupus erythematosus or HIV.
  • Antacid abuse.

Our bodies don't produce vitamin B12. A developing infant depletes its mother's supply. So the RDA for pregnant women is 2.6 mcg per day, compared to 2.4 mcg per day for most adults. (Some nutritionists recommend more.) Most women take folic acid in a prenatal vitamin during pregnancy. While folic acid is important for preventing birth defects, it can also "mask" some of the signs of a vitamin B12 malnutrition, making a deficiency much more difficult to detect. For proper care, expectant mothers should inform their Ob/Gyn if they are vegans.

UPDATE: Optimum recommended B12 amount is now 4 to 7 mcg per day. However, more is advised to actually absorb this amount. —

Optimum Food Sources For B12

The easiest way for the average person to maintain adequate levels of vitamin B12 is to ingest it within foods. A full day's supply of vitamin B12 can be obtained by eating 1 egg, 1 chicken breast (6 oz) and 1 cup of plain yogurt. As the following table reveals, people restricted to plant-based diets are primarily limited to fortified foods (and perhaps tempeh and raw seaweeds with a caveat). **

Food [3]

Serving Size
per serving

Percent DV*
Clams, cooked 3 ounces 84.1 1,402
Liver, beef, cooked 3 ounces 70.7 1,178
Nori Seaweed, raw ** [4] 3 ounces 46.8 780
Kombu Seaweed, raw ** [4] 3 ounces 23.0 383
Breakfast cereals, fortified with 100% of the DV for vitamin B12 1 serving 6.0 100
Trout, rainbow, wild, cooked 3 ounces 5.4 90
Salmon, sockeye, cooked 3 ounces 4.8 80
Temepeh ** [4] 3 ounces 4.3 71
Trout, rainbow, farmed, cooked 3 ounces 3.5 58
Tuna fish, light, canned in water 3 ounces 2.5 42
Cheeseburger, double patty and bun 1 sandwich 2.1 35
Haddock, cooked 3 ounces 1.8 30
Breakfast cereals, fortified with 25% of the DV for vitamin B12 1 serving 1.5 25
Beef, top sirloin, broiled 3 ounces 1.4 23
Milk, low-fat 1 cup 1.2 18
Yogurt, fruit, low-fat 8 ounces 1.1 18
Cheese, Swiss 1 ounce 0.9 15
Beef taco 1 soft taco 0.9 15
Ham, cured, roasted 3 ounces 0.6 10
Egg, whole, hard boiled 1 large 0.6 10
Chicken, breast meat, roasted 3 ounces 0.3 5
*DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers determine the level of various nutrients in a standard serving of food in relation to their approximate requirement for it. The DV for vitamin B12 is 6.0 mcg. However, the FDA does not require food labels to list vitamin B12 content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet. To find the best sources of vitamin B12, the U.S. Department of Agriculture's Nutrient Database website [5] lists the nutrient content of many foods and provides a comprehensive list of foods [PDF] containing vitamin B12.

Vitamin B12 Supplements

A macrobiotic diet typically consists of 50-60% whole cereal grains, 5% soups, 20-25% vegetables, and 5-10% beans and sea vegetables. Occasionally, small quantities of other foods, such as seafood, may be included. Meat is avoided and little or no dairy or eggs are eaten. Vitamin supplements generally are not taken. [6]

Trace amounts of vitamin B12 can be found within tempeh, seaweeds and organic plants in specific geographic regions.** But unless and until these foods are shown consistently to correct vitamin B12 deficiency, vegans should not rely on them as a vitamin B12 source. [6]

 Spirulina Tablets

Sadly, many raw vegans think they are ingesting plant-based vitamin B12 but in reality they aren't. Spirulina is not considered to be a reliable source of vitamin B12. Spirulina is a microalga supplement that predominantly contains pseudovitamin B12, which is biologically inactive in humans. Therefore, it is not possible to get sufficient amounts of vitamin B12 by eating unwashed organic produce, seaweeds or mushrooms grown in B12-rich soil. [7,8] Vitamin B12 can be produced industrially only through bacterial fermination-synthesis for supplements and fortification.

To prevent malnourishment, Dr. Andrew Weil recommends taking 50 mcg as part of a B-Complex that contains a full spectrum of B vitamins, including biotin, thiamine, B12, riboflavin and niacin. [9,14] If for any reason you choose to avoid fortified foods or supplements, recognize that you are carrying out a dangerous experiment that many have tried before with consistently low levels of success. [10]

To get the full benefit on a vegan diet, do one of the following:

  • Eat fortified foods 2 or 3 times a day to get at least 3 mcg B12 a day.
  • Take one B12 supplement daily providing at least 10 mcg.
  • Take a weekly B12 supplement providing at least 2000 mcg.

Take care that excess heating or pre-washing water-soluble vitamins, like B12, may destroy their potency. Most water-soluble vitamins breakdown quickly and are absorbed into the bloodstream. There are oral and sub-lingual tablets available. Generally, they cannot be amassed in our body and thus need to be consumed everyday. Instead of filtering and excreting the excess like other water-soluble vitamins, your body stores some B12 in your liver. Outside of darkened urine, which may mask other genitourinary problems, there are usually no other symptoms of overconsumption, though vitamin B12 is contraindicated with surgical stents, some medicines, and pre-existing medical conditions.

Vegetarian B12 Requirements

This is no treatise against veganism. Being informed may determine whether any of us decides to include animal products (like eggs, cheese or yogurt) in our diet or not. Consider the information presented as important guidelines to becoming a successful vegan, vegetarian, pescatarian or flexitarian, if you will. [11]

We should not assume that because we are eating only vegetables we must be healthy. Whether motivated by concern for animals, environmental impact, excessive antibiotics in the meat supply or a desire to minimize fats and lose weight, a vegetarian or vegan diet requires planing. [12] Along with a variety of the best fresh fruits and vegetables, we must include essential protein, omega-3, calcium, vitamin D and vitamin B12 as part of our regular nutrition.

Persons over 50 are advised to take a B12 supplement even if they consume animal products. Vitamin B12 deficiency symptoms intersect cardiovascular, endocrinological, dermatological, urology, gastroenterological, rheumatological, neurological, and obstetrics specialties. If you have health issues, it is wise to consult with a qualified physician before pursuing alternative health remedies.

Are you craving vitamin B12? You should be, whether you are symptomatic or not. It's an essential vitamin affecting our energy, skin, digestion, heart function, genetic reproduction and thought processes. Which source will you choose?

Nutritional guidelines are available for vegans/vegetarians from [13] Not as a replacement but as a reminder, the MyPlate Has Veggies poster summarizes daily meal portions of key food groups and clarifies misconceptions about the ChooseMyPlate graphic. For example, "dairy" represents calcium for vegans. You can order your poster online in a variety of sizes from

Check out the informative video at for a shocking commentary on the Safest Source of B12.

Tags: erectile dysfunction, macroalgae, registered dietitians, remedy, palpitations

  1. Vitamin B12 Background. ^
  2. Vitamin B12 Deficiency. ^
  3. Vitamin B12 Dietary Supplement Fact Sheet. ^
  4. USDA National Nutrient Database. ^
  5. Vitamin B12 absorption. ^
  6. B12 in Tempeh, Seaweeds, Organic Produce, and Other Plant Foods. ^
  7. Recommended Supplements for Vegans. ^
  8. Vitamin B12 sources and bioavailability. Watanabe F. Exp Biol Med (Maywood). 2007 Nov; 232(10):1266-74. ^
  9. Facts About Vitamin B12. ^
  10. What Every Vegan Should Know About Vitamin B12. ^
  11. Not All Vegetarians Are The Same. ^
  12. Vegetarian diet: How to get the best nutrition. ^
  13. Tips for Vegetarians. ^
  14. Vitamin B12 Overview. ^
  15. Are vitamin B12 injections helpful for weight loss? ^

** Due to insufficient data and geographic differences, USDA does not assign B12 values for these items. Food processing may affect results. Tempeh in Indonesia or Thailand, dulse, Chlorella, raw nori, Aphanizomenon flos-aquae, and coccolithophorid algae might warrant much further attention for providing B12. [6]