It’s funny. When people find out you’re vegan or vegetarian, suddenly everyone and their mother becomes your nutritionist, wondering if you get enough protein, if you take supplements and get enough Vitamin B-12, and if you’re malnourished and falling over yet, etc.
No one bats at eye or comments at people who sustain themselves off pizza, burgers, fries, and chips, but so many feel entitled to scrutinize the nutrient-content of plant-based diets.
But I digress. This post is about the main nutrient of concern for vegetarians and vegans. No, it’s not protein (which in fact, most people over-consume). It’s Vitamin B-12. If you’re vegetarian, vegan, pescatarian, have chronic bowel issues, and/or are over the age of 50, you should assess and consider if you are getting enough vitamin B-12.
I don’t very often flex my MS in nutrition muscles on the blog. I always intend to, but I find my brain so exhausted of academic/science writing from school that much of the time the blog is filled with recipe and lifestyle posts because those are fun and relaxing to write.
But I really do want to make an effort to communicate more nutrition info here on kbaked.com. Let me know if you like this kind of content and/or what other topics you’d like to see covered! Without further adieu…here’s what you need to know about Vitamin B-12.
What is Vitamin B-12?
Vitamin B-12 (also known as cobalamin) is a water-soluble vitamin and was the last vitamin discovered. It’s found in various forms, including cyanocobalamin (often found in supplements and fortified food), as well as methylcoablamin (a methylated form) found in animal products.
Cyanocobalamin needs to me methylated for your body to make use of it. Both are well-absorbed, and it’s currently unknown if there’s a “better” or more bioavailable form to consume.
Why is Vitamin B-12 important?
Vitamin B-12 is an essential micronutrient (meaning you can’t make it, you have to get it from the diet) responsible for many vital functions in the human body.
Vitamin B-12 is necessary for proper DNA synthesis, formation of red blood cells, and neurological function.
Vitamin B-12 acts as a cofactor for methionine (an amino acid) synthase, which catalyzes the conversion of homocyestine to methionine. This is important for a few reasons.
First, high levels of homocysteine are associated with increased risks of cardiovascular disease, heart attack, and stroke. The exact reason for this association (notice the word association, not causal relationship) is unclear. But it is well observed.
Second, the formation of methionine is important, as it is required for the formation of S-adenosylmethione (or SAM), which is considered a universal methyl-donor for a multitude of substrates, including DNA, RNA, proteins, hormones, and lipids.
How is Vitamin B-12 absorbed?
Vitamin B-12 absorption, like many things in nutrition, is a highly complex, intricate process. Vitamin B-12 found in foods is bound to protein, and needs to be released by hydrochloric acid and gastric protease in the stomach. Vitamin B-12 in supplement form does not require this separation.
Next, free vitamin B-12 must combine with intrinsic factor, a glycoprotein secreted by the stomach’s parietal cells. The intrinsic factor-vitamin B-12 complex can then travel to the small intestine. Most absorption of B-12 occurs in the distal ileum (aka further part of your small intestine) via receptor mediated endocytosis. Some is also absorbed by passive diffusion.
There’s a limit to how much can be absorbed at once. Usually no more than 1.5 micrograms per 5-50 microgram absorption can be absorbed from a single dose. Disorders that limit the amount of intrinsic factor can also limit B-12 absorption.
What are symptoms of Vitamin B-12 Deficiency?
Symptoms of Vitamin B-12 can seem vague or non-descript. For example, many people with Vitamin B-12 deficiency may experience weakness, fatigue, lightheadness, pale skin, pale skin, diarrhea or constipation, tingling or numbness (especially in hands and feet), depression, memory loss, behavioral changes, depression, and vision loss.
Many of these symptoms are also symptoms of other conditions, so detecting Vitamin B-12 deficiency can be difficult without a test.
These symptoms may arise months or years after low B-12 consumption. It was formerly believed that vitamin B-12 could be stored in the liver for up to 20 years, but the scientific opinion on this is changing, and many believe it to be far less time. Some estimate 10 years, while others estimate 2.
For now, the exact amount of time between inadequate B-12 consumption and signs and symptoms of deficiency is unknown, but if you’d like my personal opinion I believe it is far less than 2-20 years and that it varies greatly between individuals.
The point is, you may go vegan and not notice symptoms right away. But do not ignore these symptoms if they begin to creep up, especially if you’ve been neglecting monitoring your B-12 intake!
Who is at Risk for Vitamin B-12 Deficiency?
Vegans, vegetarians, pescatarians, and people who don’t eat a lot of meat should all monitor their Vitamin B-12 intake.
But it’s not just vegetarians and vegans who are at risk. Because Vitamin B-12 relies on proper function of intestines and stomach for absorption, those with stomach and/or intestine distress may be at risk for Vitamin B-12 deficiency. Individuals with IBD, Chron’s disease, IBS-D, atrophic gastrtis, celiac’s disease, parasite infection, and/or intestinal bacterial overgrowth.
Additionally, individuals who take proton-pump inhibiting medications (often taken for acid reflux/heartburn) may be at risk, as these medications can decrease acid produced in the stomach, which is essential for B-12 absorption.
Exposure to nitric oxide (aka laughing gas) at the dentist can also halt B-12 absorption and multiple exposures can lead to deficiency.
Interestingly, high levels of serum folic acid can make B-12 deficiency. As folic acid fortification is mandatory in the United States, some scientists find this is an area of increasing concern. In fact, some are calling for a reassessment of the folate fortification level, and/or an addition of a B-12 fortification.
With age, the body is less and less able to absorb Vitamin B-12. According to national dietary surveys and blood level tests, 10-15% of the elderly population in the United States is B-12 deficient. As cognition also tends to decline around this time, this is a concern.
Those with prenicious anemia are also B-12 deficient, due to an autoimmune reaction that attacks the stomach cells that make intrinsic factor necessary for B-12 absorption.
How much Vitamin B-12 do I need?
The current recommendation dietary allowance (RDA) of Vitamin B-12 for healthy adults is 2.4 micrograms per day. That’s a teeny tiny amount.
Pregnant women are advised to consume 2.6 micrograms, while breastfeeding women should consume a recommended 2.8 micrograms each day.
What foods contain Vitamin B-12?
Vitamin B-12 is found mostly in animal products, including fish, meat, eggs, poultry, milk, milk products, algae products, nutritional yeast select fortified breakfast cereals, and other fortified foods.
Clams and beef liver, in particular, are very rich in Vitamin B-12, with 84.1 micrograms and 70.7 micrograms per 3 ounce portion, respectively.
Trout, salmon, and tuna can also be good sources of Vitamin B-12, each with over 100% of the RDA per 3 ounce serving.
A single egg contains 0.6 micrograms of Vitamin B-12, however, due to some of the proteins found in egg, much of the B-12 found in eggs isn’t well-absorbed.
Milk contains about 1.2 micrograms per cup, while chicken contains 0.3 micrograms per 3 ounce portion.
Some breakfast cereals, plant-based milks, and vegan condiments like nutritional yeast are also fortified with Vitamin B-12 (see section, below).
What are vegan sources of Vitamin B-12?
Vegan sources of naturally occurring Vitamin B-12 are few and far between. Certain types of algae are known to contain Vitamin B-12, and some studies have found these are well absorbed when taken in supplement form, but there is debate on whether or not algae foods alone can provide enough B-12 in one’s diet.
Outside of algae, vegans need to rely on fortified foods to reach their B-12 requirements. Below is a list of vegan Vitamin B-12 containing foods:
- Total Cereal: 100% RDA per 3/4 cup serving
- Silk Soymilk : 50% DV per 1 cup serving
- Marmite: 0.5 micgrograms / 15% DV per 35 gram serving
- Trader Joe’s Original Coconut Milk (the refrigerated one in the carton): 50% per 1 cup serving
- Bragg’s Nutritional Yeast: 40% per 1 tablespoon serving
- Trader Joe’s Nutritional Yeast: 130% per 1 tablespoon serving
- Malt-O-Meal High Fiber Bran Flakes:
- Kellogg’s All Bran Cereal: 100% per 1/2 cup serving
- Cheerios: 25% per 1 cup serving
- Kellogg’s Special K Cereal: 50% per 3/4 cup serving
- Nasoya Tofu Plus: 20% DV RDA per 3 ounce serving
- Corn Flakes: 15% per 1 cup serving
- Tempeh: amounts vary; the viability of tempeh-produced vitamin B-12 is, however, debated in literature and it is generally agreed that this should not be an individual’s primarily source
This list is by no means exhaustive. It’s simply meant to give you a few ideas next time you’re at the store, and/or inspire you to check products/compare brands of similar products. If you find any B-12 gems out there, let me know in the comments!
Also, none of these are affiliate links. I do not generally sponsor posts and am always 100% transparent when I do, as I want to instill trust in my readers.
Should I take a Vitamin B-12 supplement?
If you don’t eat fortified foods daily, I would suggest vegans, vegetarians, the elderly. those with malabsorption issues, adding a Vitamin B-12 supplement to your diet.
Importantly, many supplements come in mega-doses.According to the IOM, there is no known adverse outcomes associated with over-consumption of B-12.
Still, there’s no need to take a pill that gives you 50000% RDA Vitamin B-12 per day. You can easily halve or quarter supplements to not only meet your needs, and extend the life of your supplement bottle in the process.
Some supplements contain animal-derived sources of Vitamin B-12 and/or gelatin (usually the gummy varieties). Certain brands are vegan-friendly, and their packaging will usually let you know. If you’re concerned, I suggest searching on Amazon for vegan-specific vitamins.
Long Story Short:
You’re not invincible. Pay attention to your B-12 intact if you are plant-based or not a big meat eater or have digestive health issues! Supplementation can’t hurt.