Can You Take Vitamin D3 With Vitamin B12?

Quick answer

NIH describes no effect of vitamin B12 on vitamin D or the reverse. Vitamin D is fat-soluble and best taken with a meal that has some fat. Adults need 2.4 mcg of B12 and 15 to 20 mcg (600 to 800 IU) of vitamin D a day. Plant foods supply neither unless fortified.^1,2,3

Key facts

Adults need 2.4 mcg of vitamin B12 a day and 15 mcg (600 IU) of vitamin D, or 20 mcg (800 IU) from age 71.^1,2
The body stores 1 to 5 mg of B12, enough to last years. Blood 25-hydroxyvitamin D has a half-life of about 15 days, so vitamin D levels change over weeks.^1,3
Plant foods have no vitamin B12 unless it is added, and ordinary fruit, vegetables, grains, nuts, seeds and beans have essentially no vitamin D.^1,3
Depending on the definition used, 3% to 43% of older adults living at home have low B12, and older adults are among the groups more likely to run low on vitamin D.^2,4
No upper limit is set for B12. The adult upper limit for vitamin D is 100 mcg (4,000 IU) a day from all sources.^1,2

A water-soluble vitamin and a fat-soluble one

Vitamin B12 dissolves in water and needs a carrier protein called intrinsic factor, made in the stomach, to be absorbed. Vitamin D dissolves in fat, is absorbed with the help of fat in the gut, and is held in body fat. They travel different routes into the body, and the NIH fact sheets for both describe no effect of one on the other. We found no trial that tested the two together.^1,3

The two also differ in how fast their stores change. B12 stores last for years, so a shortfall builds slowly and can go unnoticed. Vitamin D levels in the blood have a half-life of about two weeks and respond to sun, food and supplements within weeks.^1,3

Groups that tend to run low on both

A different reason to ask about the pair is that the same people appear on both lists. Many older adults make too little stomach acid to release B12 from food, and older age also reduces how much vitamin D the skin makes. People who eat no animal foods get no natural B12, and fruit, vegetables, grains and beans supply essentially no vitamin D.^3,4

Ordinary fruit, vegetables, grains, nuts, seeds and beans have essentially no vitamin D. NIH lists apples, bananas, broccoli, carrots, almonds, brown rice, whole wheat bread and lentils at zero.³

Plant foods have no vitamin B12 unless it is added. Many breakfast cereals and nutritional yeasts are fortified with it, and the B12 they contain is well absorbed.^1,4

The overlap explains why fortified foods matter in both cases. In the US, almost all milk is fortified with vitamin D, and many plant milks and breakfast cereals have it added too. For B12, NIH points to fortified breakfast cereals and nutritional yeasts.^1,3

What each is graded for

The statements below are the ones our ingredient files grade most firmly for each vitamin. Both are about what getting enough does for people who would otherwise fall short.^3,4

Supplies vitamin B12 in a free form that most adults over 50 absorb well*^1,4

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

Supplies vitamin B12 for people who eat little or no animal food*^1,4,5

Moderate evidence

B12 occurs naturally only in animal foods, and NIH lists vegans and vegetarians among the groups more likely to run low, adding that fortified foods and B12 supplements help close the gap. In a 90-day trial in 40 vegans and vegetarians with marginal B12 status, 50 mcg a day under the tongue brought blood B12 back to adequate levels and lowered methylmalonic acid, a marker of shortage; 2,000 mcg once a week did too.

Amount studied: Recommended intake: 2.4 mcg a day; the trial used 50 mcg a day or 2,000 mcg once a week

Contributes to normal immune function*^3,6,7

Moderate evidence

NIH lists immune function among vitamin D's roles, and 'contributes to the normal function of the immune system' is a permitted nutrient-function statement in the EU. Whether supplements help people get through the year with fewer respiratory illnesses is unsettled: the latest pooled analysis, covering 40 trials and 61,589 people, found a small effect that was not statistically significant.

Amount studied: The recommended daily intake from food, sun and supplements

Best time to take vitamin D3 with B12

There is one timing instruction among the two vitamins: vitamin D is best absorbed with a meal or snack that includes some fat. B12 has no hour and no food requirement in the NIH sheets. B12 delivered under the tongue appears to work the same as B12 that is swallowed.^2,4

About 50% of a B12 dose is absorbed at 1 to 2 mcg or less, but only about 2% of a 500 mcg dose and 1.3% of a 1,000 mcg dose.⁴

For B12 the size of the dose matters more than the hour: about 50% of a dose of 1 to 2 mcg or less is absorbed, but only about 2% of 500 mcg. Taking both at a meal with some fat is consistent with the sources.^2,4

Amounts and our products

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

What’s in ours

Vitamin D3: Vitamin D-3, 50 mcg (2,000 IU) per serving, from the label
Men's Multi: Vitamin D, 10 mcg per serving, from the label
Ashwagandha Complex: Vitamin D3, 20 mcg per serving, from the label
Immune Support: Vitamin D3, 40 mcg per serving, from the label

Vitamin D appears in several of our products and its limit counts the sum. Our Ashwagandha Complex and Men's Multi each contain both vitamins at amounts shown on their cards. If you take them with Vitamin D3, our overlap check adds up the vitamin D.

Too much, medicines and who should ask first

Too much vitamin D raises blood calcium, with nausea, muscle weakness, confusion, great thirst and kidney stones among the signs, usually at blood levels far above normal. Extremely high levels can injure the kidneys. B12 has a different profile: NIH says it is generally considered safe even at large doses, though acne-like skin eruptions have been reported with high-dose supplements.^2,3,4,8

Your doctor may want to check on you

H2 blockers such as cimetidine also reduce stomach acid and can interfere with absorbing B12 from food, which NIH says can lead to low B12.^1,4

Reported in studies

Your doctor may want to check on you

Corticosteroid tablets such as prednisone can reduce calcium absorption and interfere with how the body uses vitamin D. In a US survey, very low vitamin D levels were twice as common among people taking oral steroids (11%) as among those who were not (5%).^2,3

Reported in studies

Ask first if you take metformin, a proton pump inhibitor or an H2 blocker, which can lower B12.¹
Ask first if you take a thiazide water pill, a statin, steroid tablets, orlistat or a bile acid sequestrant, which can interact with vitamin D.^2,3
Ask first if you have high blood calcium, kidney disease, kidney stones or an overactive parathyroid gland.²
Ask first if you have numbness or tingling in your hands or feet, balance problems or memory changes. These need testing rather than self-treatment.⁴
Ask first if you are pregnant or breastfeeding, or giving vitamin D to a baby or child.^2,4

Questions people ask

Can you take vitamin D3 with vitamin B12?

The NIH sheets describe no effect of one on the other, and many multivitamins contain both. Take the vitamin D with a meal that has some fat, and watch the vitamin D total across products.^2,3,4

Can you take vitamin B12 with vitamin D3 and K2?

Our sources describe no interaction between B12 and vitamin D or K. The one to ask about is vitamin K: it works against warfarin, and NIH advises people taking warfarin to keep their vitamin K intake the same from day to day.^9,10

Do B12 and vitamin D need to be taken at different times?

No source we read says so. Vitamin D wants fat in the meal, while B12 is absorbed best in smaller amounts.^2,4

Which is more likely to be low?

The NIH figures are not directly comparable. About 3.6% of US adults have blood B12 below 200 pg/mL, and 18% had vitamin D in the inadequate range while 5% had very low levels. Older adults are on the list of groups more likely to run low on both.^2,3,4

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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.