Vitamin B12: What Is It And What Does It Do?

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Vitamin B12 is needed for producing and maintaining new cells, including nerve cells and red blood cells. It is also needed to help make DNA.

Vitamin B12 is bound to the proteins in food. Once you consume B12, the hydrochloric acid in your stomach releases the B12 from the protein. B12 then combines with a substance called intrinsic factor to be absorbed by the intestines.


How Much Do I Need To Consume?

There is insufficient information to establish an RDA for vitamin B12 for infants. In this case, an Adequate Intake (AI) has been established:

AgeMales and Females
0 to 6 months0.4 mcg/day
7 to 12 months0.5 mcg/day


The Recommended Dietary Allowance (RDA) for vitamin B12 is:

AgeMales and FemalesPregnancyLactation
1 to 3 years0.9 mcgN/AN/A
4 to 8 years1.2 mcgN/AN/A
9 to 13 years1.8 mcgN/AN/A
14 to 19 years2.4 mcg2.6 mcg2.8 mcg
19+ years2.4 mcg/day2.6 mcg/day2.8 mcg/day


What Are Sources Of Vitamin B12?

Vitamin B12 is attached to the proteins in animal foods. Breakfast cereals are fortified with vitamin B12, which is very important for people who do not consume an adequate amount of animal foods.

FoodAmountVitamin B12
Beef, top sirloin, lean, choice, broiled3 oz2.4 mcg
Breakfast cereals, fortified¾ cup6 mcg
Chicken, breast, cooked½ breast0.3 mcg
Egg1 large0.6 mcg
Haddock, cooked3 oz1.2 mcg
Liver, beef1 slice47.9 mcg
Milk1 cup0.9 mcg
Mollusks, clam3 oz84.1 mcg
Salmon, sockeye, cooked3 oz4.9 mcg
Trout, rainbow, farmed, cooked3 oz4.2 mcg
Trout, rainbow, wild, cooked3 oz5.4 mcg
Tuna, white, canned in water3 oz1.0 mcg
Yogurt, plain, skim1 cup1.4 mcg


Do I Need To Take Vitamin B12 Supplement?

Studies reveal that the majority of Americans consume an adequate amount of vitamin B12. People who do not consume meat or who have a stomach or intestinal disorder that interferes with absorption may need to take a vitamin B12 supplement. Older adults may have atrophic gastritis and may need to consume additional food sources and/or supplements. There are also some medications that can influence vitamin B12 absorption, including H2 receptor antagonists used to treat peptic ulcers, metformin, and proton pump inhibitors. Your doctor can determine your vitamin B12 levels with a blood test.


What Happens If I Don’t Have Enough Vitamin B12?

An inadequate amount of vitamin B12 can cause pernicious anemia. Signs of vitamin B12 deficiency are fatigue, constipation, weakness, loss of appetite, weight loss, and numbness and tingling in the hands and feet. You may also experience a difficulty in maintaining balance, confusion, dementia, depression, and poor memory. An excess intake of folate can mask the symptoms of B12 deficiency, so it’s important to have your levels checked with blood tests if there is a concern, especially if you consume a vegetarian diet.

Is There Such A Thing As Too Much Vitamin B12?

Currently, there is no Tolerable Upper Limit set for vitamin B12. This does not mean that consuming excessive amounts will provide any additional health benefits. It means that there is a very low potential for toxicity at high levels. The RDA was set for optimal health, so it is best to stick with those recommendations.

Stacey Chillemi

Founder of Healthy Living Inc., Stacey Chillemi actively writes about alternative & holistic wellness. Her first published book, Epilepsy You’re Not Alone in 1998, helped millions of people understand and cope with their disorder enabling them to live a happy, healthy and productive life.

Stacey Chillemi

Founder of Healthy Living Inc., Stacey Chillemi actively writes about alternative & holistic wellness. Her first published book, Epilepsy You’re Not Alone in 1998, helped millions of people understand and cope with their disorder enabling them to live a happy, healthy and productive life.

Post a Comment
morgansps 5pts

A few of you have made comments about the writer of this article "pushing for meat consumtion" or asking if she was paid by a meat company to create this post. Seriously? Can any person say anything these days without some people taking offence to it or seeing it as a personal attack?? It's so pathetic, what the hell has happened to everybody? Is it her fault that meat happens to be higher in B12 than veggies? She didnt make that happen, i can assure you it had higher B12 levels prior to her post as well! Also, if you actually read the enire post and you are able to actually read, she didn't say that people need to go out and start eating more meat than they normally do, she said that people with deficiency may need to take supplements....you know, like vitamins.....those things you have been aware of existing for the vast majority of your lives! Friggin relax people! In the future, try either not taking everything you read so personally or even better, if you read something that offends you, possibly even this comment I am leaving, act like a friggin adult, get the hell over it and move the hell on with your life. Trust me, you're going to be much better off in the long run if you do. Effin A........

ladylalala 5pts

Have you been paid by the animal farming industry to write this Stacey Chillemi? The fact your promoting and pushing for meat consumption without giving any vegan and veggi alternatives makes it seem so...shame

CassieStone 5pts

I had severe and debilitating muscle spasms, all day every day in 2008. My then physician prescribed vitamin b 12 injections monthly. The spasms have all but disappeared. I don't see that symptom listed. Has anyone else experienced this? My stomach was reduced for weight-loss in 2000, and I'm thinking it has something to do with the intrinsic factor?

KhyatiAcharya 5pts

what are the things a vegetarian can consume in his/her regular meal 

Sol D Nisha
Sol D Nisha 5pts

SraaVya Talla : check out, hope this helps u

Martina Sorensen Lydon
Martina Sorensen Lydon 5pts

Just had 1 B12 shot the other day and already feel a difference..could that ve possible after one shot?

Bholesh Kakiya
Bholesh Kakiya 5pts

Bullshit. Ayurveda should be to encourage vegetarian diet. Not consume meat products.

PeterChandler 5pts

B12 is important, but there are vegetarian / vegan alternatives such as yeast extract, Marmite or branded equivalent

Nancy Rogeria
Nancy Rogeria 5pts

do blood tests every 6 months and when needed take B12.

KellyRose1 5pts

Once you are getting B12 shots you don't get an accurate blood test of your b12 reading so they are pointless. I've been getting them for 15 years I'm now on 4 weekly I don't get blood tests .

Chrissy Windley
Chrissy Windley 5pts

ty, I so needed to know about what b12 is for and different deficiencies.

Sam Scarr
Sam Scarr 5pts

Thanks for the info.....I have injections every 8 weeks but never been explained

Sushil Shiwakoti
Sushil Shiwakoti 5pts

I can see vitamin b12 written in Red bulls cans too ... Is it any good for our body ?

Denise Nauracy Kmiatek
Denise Nauracy Kmiatek 5pts

I dont have IF, the atrophic gastritis also puts at higher risk for stomach cancer. Need to be scoped yearly.

Vañdà Young
Vañdà Young 5pts

There is a jab you can have every 3 month's in stead of tabs ,and try calcium with vitamin D \U0001f49c

Jennifer Lynne
Jennifer Lynne 5pts

random, Christina Graham we were just talking about this

Vanessa Farrell
Vanessa Farrell 5pts

This article doesn't state Nutritional yeast as a means to getting ones B12.

Brendalee Hartland McGovern
Brendalee Hartland McGovern 5pts

Wow I learned something new - and wonder, if I have a 15 yr old child that has a nuetrophil issue if amping her B12 intake might aid her

Kelly Ann
Kelly Ann 5pts

Could a 6 year old take 1 mg liquid B Complex dailly?

Kelly Ann
Kelly Ann 5pts

When is the best time to take b12 at night or in the morning?

Anita Vaughan
Anita Vaughan 5pts

Those are NOT just thoughts, those are facts that Sima Gandhi are sharing.!!!!

Sima Gandhi
Sima Gandhi 5pts

What other details are you looking for?

Manoj Sharma
Manoj Sharma 5pts

Ur knowledge is extremely good. Can u give more details since I am also B12 defecient

Massimo Vaj
Massimo Vaj 5pts

I'm a grower and I live up on the mountain, and I eat only what I grow, so I'm sure about what I'm eating. I know that can be different the situation in many places of India and also in other places of the world. I've lived in India for two years.

Sandra Brown
Sandra Brown 5pts

Massimo....you should NEVER eat unwashed fruits and vegetables, even if there are organic. Botchloma , (spelling may be incorrect) is found in soil and can make you very ill, there therefore u must wAsh.

Massimo Vaj
Massimo Vaj 5pts

It is enough, for vegetarians, do not wash fruits and vegetables organically grown, because B 12 is in the air, in the powder and in the rain. You can find it in the meet because animals eat unwashed vegetables.

Ayurveda 5pts

Thanks for sharing your thoughts, this will definitely help the community :)