Vitamin B12 requires extra attention on a plant-based diet. This post covers how it’s made, where it’s found, and how to get enough vitamin B12 for kids. Plus vegan B12 supplement recommendations.
What is Vitamin B12?
B12, also called cobalamin, is one of the eight water-soluble B vitamins.
It’s needed for:
- DNA synthesis
- Cell metabolism
- Red blood cell formation
- Keeping nerves and blood vessels healthy, and
- Supporting growth and development.
It’s essential to get enough vitamin B12 for all of these processes to occur as they’re supposed to – and it does need some extra attention when following a plant-based diet.
Where Does B12 Come From?
Vitamin B12 is made by bacteria that live in the soil. It’s the only essential micronutrient for humans that is exclusively made by bacteria.
The predominant dietary sources of B12 are animal products, like beef, fish, and dairy. But there are also B12-fortified brands of nutritional yeast and non-dairy milks.
The reason animal products contain B12 is that most of them are eating plants that grow in B12-rich soil. Farmed animals also get it from eating B12-fortified feed, as well as being exposed to bacteria-rich manure and unsanitized water.
Humans produce some B12 in our intestine, but this occurs below the ileum where it’s not available for absorption.
The same is true for animals. There’s further evidence of this when you watch mostly or totally vegetarian animals in nature. Many of these eat their own poop – as this is an important way to obtain B12 on their plant-based diet.
Because humans (thankfully) don’t practice this same behavior, this is why supplementation is essential when there are not enough B12-rich sources of food consistently meeting needs in the diet.
Plants neither use nor store B12 and therefore aren’t a reliable source of the nutrient. You may have heard claims that plants like seaweed, algae, and fermented foods naturally contain B12 but those are inactive analogs that won’t contribute to B12 needs. The same is true of unwashed produce (but who is eating their produce straight from the ground and unrinsed, anyway?).
While fortified foods can provide some B12, the amounts can be inconsistent and possibly unreliable as B12 is light and heat-sensitive, and therefore broken down during storage of cooking. It’s why we believe that a supplement is the most reliable source for anyone who follows a plant-based diet: vegan, vegetarian or flexitarian.
So, supplements are best.
Vitamin B12 for Kids: Dosing Recommendations
Plant-based babies will get enough vitamin B12 from formula or breastmilk as long as mom is supplementing herself adequately. We recommend 250mcg a day of B12 during this time. Children should start receiving their own supplement at around 12 months. But how much do they need?
Understanding the RDA for vitamin B12 is a good start, but meeting your child’s needs requires looking beyond this number. This can be a little confusing, so let’s break down what influences B12 absorption and how to dose it accordingly for kids.
B12 Absorption
B12 absorption is a complex process that becomes less efficient with age.
Vitamin B12 requires a protein called intrinsic factor (IF), made by cells in the stomach lining, to be fully absorbed. After it binds to B12, this travels to the intestines where B12 is absorbed into the bloodstream.
But IF can only help absorb so much B12 at a time. And B12 absorption decreases significantly when the capacity of IF is exceeded.
In other words, the percentage of B12 our body can absorb in one sitting – like with a supplement – wanes as the dose increases. For example, about 50% is absorbed in a dose of 2 mcg but only 1-2% is absorbed in a dose of, say, 2000 mcg.
IF capacity becomes saturated at about a 1.5-2 mcg dose of B12. At doses of up to 2 mcg, about 40-50% of B12 is absorbed. After IF has reached saturation, the remaining B12 can be absorbed through a process called passive diffusion at a rate of about 1%.
The bottom line here is that while we only need a small amount of B12 daily if we’re going to get it all from one single supplement, we need to take a much larger amount than the RDA – or take it in multiple doses.
How to Dose
The B12 RDA for kids 1-3 years old is 0.9 mcg. But in order to absorb enough to meet daily needs given the factors above, kids should take a single 10 mcg supplement.
To complicate things further, if you’re giving B12 a couple of times a day, the amount that should be taken at once goes back down, since you absorb more when you take less.
So the same 1-3-year-old could either take a single 10 mcg supplement or two doses spread out ranging from about .5-1 mcg.
For more examples of B12 supplement dosing for kids, see this table, which outlines dosing guidelines ranging from once per week to up to three times daily.
Best Vitamin B12 for Kids Supplement
Unfortunately, most B12 supplements on the market don’t offer these low amounts as they’re usually created for adults. And while B12 is a water-soluble vitamin and there isn’t an upper limit, we’d prefer to stick to a level closer to kids’ needs than have to titrate doses ourselves.
That’s why we’re SO excited that after sharing these concerns with LiveWise Naturals (affiliate link), they developed a product with us in mind for the perfect dosing for toddlers! A single drop of their product provides 2.5 mcg or 5 mcg in 2 drops.
Forms of Supplements
B12 supplements come in 4 different forms:
1. Cyanocobalamin: This is the manmade form of B12. It’s also the most common, well-studied, stable, and inexpensive form. It’s made up of a cobalamin molecule attached to a cyanide molecule. But as scary as this may sound, the amount of cyanide in a supplemental dose of B12 is actually less than most people consume on a daily basis.
2 and 3. Methylcobalamin and Adenosylcobalamin: These two are the “active” coenzyme forms of B12 that are used in chemical reactions.
4. Hydroxocobalamin: Both this form of B12 and cyanocobalamin are converted to the methyl- and adenosyl- forms in the body.
When it comes to the best form, cyanocobalamin and methylcobalamin are the most common ones used in supplements. And either one will do, as there’s not sufficient evidence to recommend one form over another for prevention or treatment of B12 deficiency.
For More Information:
For more guidance on supplements for predominantly plant-based kids, get your FREE copy of the Plant-Based Juniors’ Supplement Guide here!
Chime In: Do you have a favorite B12 supplement for your family?
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We eat a good amount of cheese and eggs. Should my daughter, therefore, take less of the supplement?
Hi Marsea; it really depends on the frequency. Because of the way B12 is absorbed, only a small amount is absorbed at one time. So, if you daughter is consuming eggs and cheese throughout the day most days then she’s likely OK (or, at the very least, likely OK with just a multivitamin with a smaller amount of B12). There are some studies showing that vegetarians have lower serum B12 levels, but again, it’s really variable on frequency of consumption. Some vegetarians consume dairy for most meals and some consume it 1-2x/week.
Just trying to understand your recommendations and dosing. I have a 1, 4 and 6 year old. Once a day I’ve been giving them a supplement with .6mcg included, the 1 year old more like .3mcg. What is your recommendation for once a day?
Hi Christina, is this the only source of b12 in their diet? If so, then we’d recommend an additional B12 supplement. We’d recommend 5mcg daily for 1-3 year old and 25mcg daily for 4-10
Hi lam a vegan at least one year since I ditched animal products I recently took B12 supplement but I got a lot of stomach upset does it mean it contains chemicals like artificial drugs or if not why then did it happen.
Is B12 in a multivitamin enough for a toddler or should I be giving my toddlers a B12 supplement?
Hello, The USDA recommends two 8 oz. cups of fortified, unsweetened soy milk for 2 year olds. Each cup provides 3 mcg. of B12, but it doesn’t specify if it’s methylcobalamin or cyanocobalamin. Would this be enough for vegan toddlers?
Thank you,
Arlynn Bottomley
Yes, but needs to be separated at different times throughout the day for best absorption.
Hi, Alex and Whitney. My serum b12 just came back high, so I came here to try and understand how to adjust dosing for myself and my family. I had been taking 1000 mcg sublingual methylcobalamin per day, plus there is some in my prenatal (but Dr. Greger recommends against relying on multivitamins for b12, since the b12 may not be absorbed — do you agree?). Based on what I’m reading here, it seems like I could be lowering my dosage to 250 mcg per day instead? And then for my 3-year-old, get the drops you recommend and do 5 or 10 mcg per day? And then for my 6-year-old and 11-year-old, the drops you recommend would be too costly to give them 25 mcg per day, so what would you recommend? I appreciate your help as I try to understand this! I’m concerned a about overdoing it (especially since there is b12 in our multivitamins that may or may not be absorbed), but I’m also concerned about not providing enough.
Hi Tammy- are you pregnant? The 250 mcg level is for pregnancy for a single dose. If you aren’t pregnant, then 25-50 mcg per day is fine. For your 3-year old, you could do the 10 mcg and then for your older kids, you can give them a biweekly dose of a higher level. and you could do the same for you if you aren’t pregnant– we just don’t have data on biweekly doses for pregnancy so don’t feel safe recommending it
Thanks so much for clarifying this for me! I’m not currently pregnant, but we are trying so I thought I’d just take that 250 mcg dose in case. We’re currently giving our 6-year-old and 10-year-old 250 mcg methylcobalamin 3 times per week. Does that seem reasonable to you? Thanks again! Really helps ease my mind.
yes– 3x a week is fine at that level. IOM has 100 mcg/3 times a week for those ages and EFSA has 500 mcg/3 times a week so between there should be a safe, adequate level.
Thank you again for all of your help. Really appreciate you taking the time to help me understand this fully. I have one last question — some reputable sources suggest taking higher amounts of B12 if you are taking it in methylcobalamin form, but it seems like your professional opinion is that whether we are taking cyano- or methyl- forms, we can follow the IOM or EFSA recommendations? Thanks so much!
The cyanocobalamin version is better studied, and that’s where most of the dosing recommendations come from. Not to say that methyl forms are bad, and we know that they are more popular, but we just don’t have the same data on dosing. However, with those higher levels it should be OK regardless of version.
Thanks so much for all of your guidance!