Vitamin B12 vs Folate: Key Differences

Quick answer

Folate and vitamin B12 are both B vitamins needed for DNA and red blood cells, yet they differ in source, amount and limits. Adults need 400 mcg DFE of folate but only 2.4 mcg of B12 a day. B12 occurs naturally only in animal foods, and only folic acid has an upper limit.^1,2

Key facts

Adults need 400 mcg DFE of folate a day but only 2.4 mcg of vitamin B12.^1,2
Folate comes from leafy vegetables, beans and liver, and folic acid is added to enriched grains. B12 occurs naturally only in animal foods.^1,2
At least 85% of folic acid taken with food is absorbed, against about 50% of food folate. B12 absorption falls from about 50% at 1 to 2 mcg to about 2% at 500 mcg.^3,4
Folic acid has an adult upper limit of 1,000 mcg a day from supplements and fortified foods. No upper limit is set for B12.^1,2
The body keeps 1 to 5 mg of B12, enough to last years, while blood folate falls quickly after supplements stop.^2,5

What each vitamin is

Folate is vitamin B9. Food contains it in forms with a chain of extra glutamate pieces that the gut trims off before absorbing it. Folic acid is the man-made form used in fortified foods and most supplements, and an enzyme in the body must convert it before it can be used.³

Vitamin B12 contains the mineral cobalt, which is why compounds with B12 activity are called cobalamins. In food it is bound to protein, and stomach acid frees it before it joins intrinsic factor, a protein made in the stomach, to be absorbed. The B12 in supplements and fortified foods is already free but still needs intrinsic factor.^2,4

What they share is the job description. Both are needed to make DNA and red blood cells, and both take part in handling homocysteine. That overlap is why they are sold together, yet it does not make one a substitute for the other.^3,4

Side by side

Folate and vitamin B12 compared^1,2,3,4
	Folate (vitamin B9)	Vitamin B12
Recommended adult amount, per day	400 mcg DFE	2.4 mcg
In pregnancy	600 mcg DFE	2.6 mcg
Natural food sources	Beef liver, leafy greens, asparagus, beans, oranges, nuts	Fish, meat, poultry, eggs and dairy; clams, oysters and beef liver are richest
Plant foods	Many are good sources	None, unless fortified
Added to foods	Folic acid in enriched flour, bread, pasta, rice and cereals	Some breakfast cereals and nutritional yeasts
Share absorbed	About 50% of food folate; at least 85% of folic acid with food	About 50% at 1 to 2 mcg or less; about 2% at 500 mcg
Common supplement forms	Folic acid, methylfolate	Cyanocobalamin, methylcobalamin
Upper limit	1,000 mcg of folic acid from supplements and fortified foods	None set
Body store	15 to 30 mg	1 to 5 mg

Where each one has its own evidence

The statements below are the ones our ingredient files grade for each vitamin separately. Folate has its own evidence for cell division and for pregnancy, while B12 has its own for the nervous system and for adults over 50.^3,4

Has a role in making DNA and in normal cell division*^1,3,6

Moderate evidence

A long-established role of the vitamin. NIH describes folate as needed to make DNA and other genetic material and for cells to divide, and the EU, after review by its food safety authority, permits the statement that folate has a role in the process of cell division. It describes what folate does at recommended intakes, not an added effect from larger amounts.

Amount studied: Recommended intake: 400 mcg DFE a day for adults, from all sources

Contributes to maternal tissue growth during pregnancy*^1,3,6,7

Moderate evidence

Pregnancy raises the need for folate because of its role in making DNA while tissues grow quickly, so the recommended amount rises from 400 to 600 mcg DFE a day. The EU permits this statement. Separately, US advice is that everyone who could become pregnant gets 400 mcg of folic acid a day from supplements, fortified foods or both, on top of food folate, and the US Preventive Services Task Force recommends a daily supplement with 400 to 800 mcg.

Amount studied: 600 mcg DFE a day in pregnancy from all sources; 400 to 800 mcg of folic acid a day as a supplement for anyone who could become pregnant

Contributes to normal functioning of the nervous system*^4,8

Moderate evidence

NIH describes B12 as required for the development, myelination and function of the central nervous system; myelin is the coating around nerve fibers. The EU permits this statement. In trials summarized by NIH, B12 supplements given alone or with other B vitamins for 1 to 5 years did not change measures of memory and thinking in older adults.

Amount studied: Recommended intake: 2.4 mcg a day for adults, from all sources

Supplies vitamin B12 in a free form that most adults over 50 absorb well*^2,4

Moderate evidence

Many older adults make too little stomach acid to release the B12 bound to protein in food. B12 in supplements and fortified foods is not bound to protein, so it does not need that step, and NIH advises people over 50 to get most of their B12 from these sources. Depending on the definition, 3% to 43% of older adults living at home have low B12.

Amount studied: Recommended intake: 2.4 mcg a day for adults over 50, mostly from fortified foods or supplements

Forms and the idea that one is better

Both vitamins are sold in an ordinary form and in a pre-converted one. For folate that is methylfolate, the main form in blood. For B12 it is methylcobalamin, one of the two active forms. The sources take a different view of each.^3,4

Methylfolate, also sold as L-methylfolate or 5-MTHF, is the main form of folate in the blood. As a supplement it is absorbed as well as folic acid or better, but no official factor converts it to DFE: the FDA lets makers use the folic acid factor of 1.7 or their own lower one.³

Research has not shown that any supplement form of B12 is better than the others, and no evidence shows that the share absorbed differs by form.^2,4

Who tends to look at which

Folate is the one NIH names for anyone who could become pregnant: 400 mcg of folic acid a day from supplements, fortified foods or both, on top of food folate.¹
Teenage girls and young women are among the groups most likely to fall short of folate. Even counting supplements, 19% of girls aged 14 to 18 and 17% of women aged 19 to 30 get less than the average requirement.³
B12 is the one NIH names for adults over 50, who are advised to get most of their B12 from fortified foods or supplements.²
B12 is also the one to watch for people who eat no animal foods, since plant foods have none unless it is added.²

What’s in ours

Men's Multi: Folate, 680 mcg DFE (400 mcg Folic Acid) per serving, from the label

What’s in ours

Men's Multi: Vitamin B12, 27 mcg per serving, from the label
Ashwagandha Complex: Vitamin B12, 25 mcg per serving, from the label

Safety differences

The two vitamins are very different when it comes to amounts. Folic acid has a limit and B12 does not, and the limit exists because of how the two vitamins interact.^2,3

Large amounts of folic acid can correct the anemia caused by low vitamin B12 without stopping the nerve damage it also causes, so the B12 problem can go unnoticed until the damage is permanent. Large doses might also make the effects of low B12 worse.^1,3,9

The upper limit for adults is 1,000 mcg a day of folate from supplements and fortified foods, which for folic acid equals about 1,667 mcg DFE. It is 800 mcg for teens aged 14 to 18. Folate naturally present in food has no limit, and the limits do not apply to higher doses taken under medical supervision.^1,3

No upper limit is set for vitamin B12 because it has a low potential for harm. NIH says it is generally considered safe even at large doses, such as 500 or 1,000 mcg, because the body does not store the excess.^2,4

Acne-like skin eruptions have been reported with high-dose B12 supplements, mostly in case reports, and they generally clear after the supplement is stopped. In one small study, 1 of 10 healthy people given extra B12 developed acne a week later.^10,11

The medicines to ask about also differ. Methotrexate, anti-seizure medicines and sulfasalazine are the ones NIH names for folate. Metformin and acid-reducing medicines are the ones it names for B12.^1,2

Questions people ask

Is folate the same as folic acid?

They are related but not identical. Folate is the natural form in food. Folic acid is the man-made form in fortified foods and most supplements, absorbed better than food folate but needing conversion in the body. That is why labels use mcg DFE.³

Can vitamin B12 replace folate, or the other way round?

No. They share some jobs but each has its own recommended amount and its own food sources, and large folic acid doses can hide a B12 shortfall rather than cover for it.^3,4

Which one has an upper limit?

Only folic acid. The adult limit is 1,000 mcg a day from supplements and fortified foods. No upper limit is set for B12, which NIH says has a low potential for harm.^1,2

How do the signs of running short of B12 and folate differ?

Running short of either vitamin can change the red blood cells, and symptoms alone cannot tell them apart. NIH lists sores on the tongue and inside the mouth among the effects of too little folate, while low B12 can also affect the nerves. A blood test is the way to tell, and numbness or tingling needs testing rather than self-treatment.^1,3,4

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.