B Complex and Vitamin D: Best Time to Take

Quick answer

NIH describes no effect of a B complex on vitamin D. Vitamin D is fat-soluble and best taken with a meal that has some fat. Adults need 15 to 20 mcg (600 to 800 IU) a day, with a limit of 100 mcg (4,000 IU). Biotin in a B complex can distort a vitamin D blood test.^1,2,3

Key facts

Vitamin D is best absorbed with a meal or snack that includes some fat. In a trial of 50 older adults, a breakfast with fat gave a 32% higher peak than a fat-free one.^1,4
B vitamins dissolve in water and the body passes the excess in urine, whereas vitamin D is held in body fat.^2,5
Blood 25-hydroxyvitamin D has a half-life of about 15 days, so levels change over weeks.²
One laboratory review lists vitamin D and vitamin B12 among the blood tests that biotin can affect.³
The adult upper limit for vitamin D is 100 mcg (4,000 IU) a day. Limits for the B vitamins are 35 mg for niacin, 100 mg for B6 and 1,000 mcg for folic acid.^1,6

A water-soluble group and a fat-soluble vitamin

The eight B vitamins all dissolve in water. The body keeps small stores of most of them, takes up a limited share of each dose and passes the rest in urine. Vitamin D is the opposite kind. It dissolves in fat, needs fat in the gut to be absorbed well, and is held in body fat, which is one reason people with a higher body weight tend to have lower blood levels.^2,5

That difference shapes the practical questions. The two are handled differently in the gut, and the NIH fact sheets for both describe no effect of one on the other. We found no trial of the two together.^2,7

What each is graded for

Provides folate and vitamin B12, which the body needs to make DNA and normal red blood cells*^7,8,9,10,11

Moderate evidence

A long-established role of both vitamins rather than a finding from supplement trials. NIH describes vitamin B12 as required for healthy red blood cell formation and DNA synthesis, and folate as needed to make DNA and for cells to divide; when either runs short, red blood cells form abnormally. The Institute of Medicine found no observable health benefit from B vitamin intakes beyond those that avoid the signs of running short.

Amount studied: Recommended amounts for adults: 400 mcg DFE of folate and 2.4 mcg of vitamin B12 a day

Contributes to normal immune function*^2,12,13

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 a B complex and vitamin D

The B complex has no clock time in our sources, so vitamin D sets the terms. It wants a meal with some fat in it, at whatever hour that is. A study of 17 people whose blood levels had stayed low on supplements found that moving the same dose to their largest meal raised levels by about 57% over 2 to 3 months, although it had no comparison group, so it is a hint rather than a rule.^1,14

Taking a B complex at that same meal fits what we know. Niacin as nicotinic acid flushes less with food, and folic acid is absorbed well with or without it.^9,15

A detail that matters if you test your vitamin D

People who take vitamin D often have a blood test to see where they stand. B complex products can contain biotin, and biotin can interfere with tests built on it. One laboratory review lists vitamin D and vitamin B12 tests among those at risk, with thyroid and some hormone tests.^3,16

Biotin leaves the blood relatively quickly, so a laboratory that suspects interference can test a fresh sample after a pause. Tell the lab and your doctor that you take biotin before the draw.¹⁷

Blood tests measure 25-hydroxyvitamin D. Levels of 20 ng/mL (50 nmol/L) or more are adequate for most people, levels below 12 ng/mL (30 nmol/L) are too low, and levels above 50 ng/mL (125 nmol/L) are too high and might cause health problems.^1,2

Amounts and our products

Vitamin D and the B vitamins with limits, for adults per day^1,6,18,19
	Recommended	Upper limit
Vitamin D	15 mcg (600 IU); 20 mcg (800 IU) from age 71	100 mcg (4,000 IU) from all sources
Niacin	14 mg NE (women), 16 mg NE (men)	35 mg from supplements and fortified foods
Vitamin B6	1.3 mg at ages 19 to 50	100 mg
Folate	400 mcg DFE	1,000 mcg of folic acid

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

What’s in ours

Men's Multi: Vitamin B1, 7 mg per serving, from the label

Vitamin D appears in several of our products, and its limit counts the sum. If you take more than one of them, our overlap check adds up the label amounts.

Too much, medicines and who should ask first

Too much vitamin D raises blood calcium. Signs include nausea, vomiting, muscle weakness, confusion, great thirst and kidney stones, and they are linked to blood levels far above normal. Extremely high levels can cause kidney failure, and such cases almost always come from far too much vitamin D in supplements.^1,2

Ask your pharmacist how far apart to take them

Orlistat, a weight-loss medicine, reduces the absorption of fat-soluble vitamins, including vitamin D. Its label advises a daily multivitamin with vitamins A, D, E and K taken at a separate time from orlistat, and in its trials low vitamin D levels were more common on orlistat than on placebo.^1,20,21

On the medicine's label

Ask your pharmacist or doctor first

B complex supplements can contain biotin. The levothyroxine label says biotin interferes with thyroid hormone tests built on biotin and streptavidin, which may give wrong results, and tells patients to stop biotin and any biotin-containing supplement for a time before thyroid function testing.^16,22

On the medicine's label

Ask first if you have high blood calcium, kidney disease, kidney stones or an overactive parathyroid gland.¹
Ask first if you take a thiazide water pill, a statin, steroid tablets, orlistat or a bile acid sequestrant, which vitamin D can interact with.^1,2
Ask first if you take levothyroxine or have blood tests coming up, because biotin in a B complex can distort results.^22,23
Ask first if you take methotrexate, an anti-seizure medicine, metformin or an acid reducer, which have cautions with B vitamins.^7,9
Ask first if you are pregnant or nursing, or giving vitamin D to a baby or child.¹

Questions people ask

Can you take B complex with vitamin D?

The NIH sheets describe no effect of one on the other, and many multivitamins contain both. Keep each limit in mind, and take the vitamin D with a meal that has some fat.^1,2,7

What is the best time to take a B complex and vitamin D?

Our sources name no hour for either. Vitamin D is best absorbed with a meal or snack containing some fat, so take both at a meal you eat regularly.^1,7

Can biotin in a B complex change my vitamin D test?

It can in principle. One laboratory review lists vitamin D tests among those biotin can affect, and FDA says intakes above the recommended amount can make tests built with biotin read falsely high or low. Tell your doctor and the lab you take it.^3,23

Does a B complex contain vitamin D?

Not as a rule. A B complex combines B vitamins, and products differ in which ones, so the Supplement Facts panel is the only way to know.⁸

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line Men's Multi Ashwagandha Complex Immune Support

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.