When to Take Vitamins: Morning, Night or With Food?

For most vitamins, the time of day does not change how well they work, so take them when you will remember, usually with a meal. The real timing rules involve spacing: iron is best taken in the morning away from meals and coffee, calcium can block iron, iron can block zinc, and all three interfere with some medicines.

A multivitamin, taken by about one-third of US adults¹, is the simplest case: we found no trial of when to take one, so take it when you will remember. For context, a 2022 review of 84 vitamin and mineral supplement studies (739,803 people) found little or no benefit for cardiovascular disease, cancer or death, apart from a small benefit for cancer incidence with multivitamins².

The best time is the one you will keep up, with a meal. We found no trial showing that a particular hour improves the effect of a standard multivitamin, and the research that exists concerns single nutrients.

The evidence on meals is mixed for fat-soluble vitamins such as vitamin D:

• Supports a meal: in a Cleveland Clinic cohort of 17 patients, taking their usual vitamin D with the largest meal raised serum 25(OH)D from 30.5 to 47.2 ng/mL over 2 to 3 months³. There was no control group.
• Does not: in a randomised crossover trial of 88 people, a 50,000 IU oily-solution dose showed no significant difference in blood levels fasting or with a high-fat breakfast⁴. A review found that the amount of fat does not seem to change vitamin D3 absorption much, though it noted that few data exist⁵.

Calcium and vitamin B12 behave differently. Calcium supplements absorb best in doses of 500 mg or less, and absorption is generally greater with food⁶. B12 from supplements is absorbed at about 50% at doses under 1-2 mcg but only about 2% at 500 mcg⁷. If you take vitamin D with vitamin K, see vitamin D3 and K2 supplements. The fat-soluble versus water-soluble vitamins guide explains why the two groups differ.

For most vitamins, neither is better, and taking them at night is fine. There are three exceptions:

• Iron: in 34 iron-depleted women, absorption was 37% lower in the afternoon than in the morning, though that gap did not reach statistical significance (p = 0.059)⁸. Morning is the safer choice.
• Vitamin B6: in a placebo-controlled trial of 100 adults, 240 mg of pyridoxine before bed for five days raised dream recall but did not change dream vividness or other sleep measures⁹. A B complex in the same trial lowered self-rated sleep quality and raised tiredness on waking⁹. That B6 dose is more than twice the 100 mg daily upper limit for adults¹⁰.
• Calcium or iron with thyroid medicine: keep them at least 4 hours from levothyroxine whatever the hour, so an evening dose is fine only if it is spaced (see below)^{6, 11}.

If you want to take magnesium at night, our guide on when to take magnesium covers it.

No vitamin is banned at night, but two are worth moving. High-dose B6 increased dream recall in a trial, and iron may absorb better in the morning, though that result was not statistically significant^{9, 8}.

Neither B6 nor a B complex improved sleep in the dreaming trial, so they are poor choices if sleep is the goal⁹. Our guide to sleep supplements and the insomnia page cover what has been tested.

Usually not. Taking supplements with food is easier on the stomach, and iron is the main example: food can help reduce nausea, constipation and stomach pain¹¹.

Iron is the exception for absorption, because an empty stomach helps. The trial behind most of the numbers below advises taking iron in the morning, away from meals and coffee⁸:

• Coffee: cut iron absorption by 54% in iron-depleted women, and a breakfast with coffee cut it by 66%⁸.
• Tea and herbal tea: beverages with 20-50 mg of polyphenols per serving cut iron absorption from a bread meal by 50-70%, and black tea cut it by 79-94%¹². Adding milk made little difference¹².
• Orange juice: taking 100 mg of iron with juice instead of coffee or breakfast gave about four times the absorption⁸.
• Vitamin C: 80 mg raised iron absorption by 30%, and 500 mg added nothing more⁸.

The vitamin C and iron absorption page has the wider evidence. If iron upsets your stomach, taking it with food can help¹¹, but keep coffee and tea away from it^{8, 12}.

No pair of vitamins is dangerous at normal doses, but several minerals compete or interfere with medicines. These are the pairs with data:

• Calcium and iron: in a trial of 54 women given a small 5 mg iron dose on an empty stomach, calcium (as calcium chloride) at 1,000 mg or more cut nonheme iron absorption by an average of 49.6%, and the authors saw no inhibition below 800 mg¹³. The NIH suggests taking individual calcium and iron supplements at different times of day¹¹.
• Iron and zinc: 25 mg or more of iron can reduce zinc absorption and plasma zinc¹⁴.
• Zinc and antibiotics: quinolone and tetracycline antibiotics bind zinc. Take the antibiotic at least 2 hours before or 4-6 hours after zinc¹⁴.
• Calcium and quinolone antibiotics: take the antibiotic 2 hours before or after calcium⁶.

So there is no single pair that must never be combined. The practical rule is to take iron at a different time of day from calcium and from zinc^{11, 14}. The iron, calcium and zinc pages have dosing and safety.

Yes: the trials favour alternate days, and one leans towards mornings (see above). In two trials in iron-depleted women, 60 mg of iron on alternate days gave 21.8% fractional absorption versus 16.3% on consecutive days, and splitting 120 mg into two doses did not absorb better than one morning dose (13.1% versus 11.8%, not significant)¹⁵.

A later double-blind trial in 150 women found the same ferritin with alternate-day and daily 100 mg doses at equal total iron, but 1.56 times more gastrointestinal side effects on days with iron in the daily group¹⁶. In that trial, iron deficiency was less common at 6 months with alternate-day dosing (3.0% versus 11.4%). To keep the total dose equal, the daily group took iron for the first 3 months only, so by then it had been off iron for 3 months¹⁶.

These are small trials in young women^{15, 16}, and treating a deficiency is a clinician's decision. Our iron deficiency page covers the condition, and you can read our summaries of the absorption trial and the alternate-day trial.

People on levothyroxine, some antibiotics, dolutegravir or orlistat need to space supplements from their medicine. People on warfarin, thiazide diuretics, metformin or acid reducers should ask about the supplement and its dose, since spacing is not the documented fix. These are the documented cases:

• Levothyroxine: the label advises avoiding it within 4 hours of calcium carbonate⁶, and within 4 hours of iron¹¹. A review lists calcium citrate, calcium acetate and iron sulfate as clinically significant too¹⁷. See hypothyroidism for the condition.
• Dolutegravir (an HIV medicine): its label says to take it 2 hours before or 6 hours after calcium supplements⁶.
• Orlistat: with a reduced-fat diet, it can reduce vitamin D absorption¹⁸. Its label says to take a multivitamin at least 2 hours before or after orlistat, such as at bedtime¹⁹.
• Warfarin: vitamin K, which some multivitamins contain, decreases the effect of warfarin, so talk to your clinician before starting one¹. People on warfarin need a steady vitamin K intake from food and supplements²⁰.
• Thiazide diuretics: combined with vitamin D, they can lead to high blood calcium, especially in older adults and people with kidney problems or hyperparathyroidism¹⁸.
• Metformin and acid reducers: they can lower vitamin B12 absorption or status⁷.

The same sources set upper limits for adults: 4,000 IU (100 mcg) of vitamin D¹⁸, 45 mg of iron¹¹, 40 mg of zinc¹⁴ and 100 mg of vitamin B6¹⁰. Long-term B6 at 1-6 g a day can cause severe sensory neuropathy, and some reports describe it below 500 mg a day¹⁰. Europe's food safety agency set its adult limit for B6 at 12 mg a day¹⁰.

This schedule uses only the rules above. Adjust it with your pharmacist if you take medicine.

• Morning, away from meals and coffee: iron, with an orange juice or other source of about 80 mg of vitamin C⁸.
• With lunch: a multivitamin or vitamin D with your largest meal, and zinc separate from iron^{3, 14}.
• With dinner: calcium in a dose of 500 mg or less, with food⁶.
• Not at bedtime: high-dose B6, which increased dream recall in a trial, or a B complex, which lowered self-rated sleep quality⁹.

Use a pill organizer if the schedule is hard to remember, and keep it and any iron out of children's reach: accidental overdose of iron products is a leading cause of fatal poisoning in children under 6¹¹.

Supplements in this guide

• Multivitamin
• Iron
• Calcium
• Vitamin D
• Zinc
• Vitamin C

We searched PubMed for trials and reviews on vitamin timing, food effects, iron scheduling, mineral interactions and B6 and sleep, and read the NIH Office of Dietary Supplements fact sheets for multivitamins, iron, calcium, zinc, vitamin B12, vitamin B6, vitamin D and vitamin K, and the FDA label for orlistat. We cited 11 journal records, 8 fact sheets and 1 drug label, prioritising randomised trials and systematic reviews. We found no randomised trials comparing morning and night dosing for multivitamins, and the vitamin D food studies disagree. Researched October 2026, and corrected the same month after an independent review against the sources.

1. National Institutes of Health, Office of Dietary Supplements. Multivitamin/mineral Supplements: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/MVMS-HealthProfessional/
2. O'Connor EA, et al. Vitamin and Mineral Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2022;327(23):2334-2347. doi:10.1001/jama.2021.15650 Our study summary.
3. Mulligan GB, et al. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D. J Bone Miner Res. 2010;25(4):928-30. doi:10.1002/jbmr.67
4. Cavalier E, et al. A Randomised, Cross-Over Study to Estimate the Influence of Food on the 25-Hydroxyvitamin D₃ Serum Level after Vitamin D₃ Supplementation. Nutrients. 2016;8(5). doi:10.3390/nu8050309
5. Borel P, et al. Vitamin D bioavailability: state of the art. Crit Rev Food Sci Nutr. 2015;55(9):1193-205. doi:10.1080/10408398.2012.688897
6. National Institutes of Health, Office of Dietary Supplements. Calcium: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/
7. National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
8. von Siebenthal HK, et al. Effect of dietary factors and time of day on iron absorption from oral iron supplements in iron deficient women. Am J Hematol. 2023;98(9):1356-1363. doi:10.1002/ajh.26987
9. Adventure-Heart DJ, et al. Effects of Vitamin B6 (Pyridoxine) and a B Complex Preparation on Dreaming and Sleep. Percept Mot Skills. 2018;125(3):451-462. doi:10.1177/0031512518770326 Our study summary.
10. National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
11. National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
12. Hurrell RF, et al. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999;81(4):289-95. https://pubmed.ncbi.nlm.nih.gov/10999016/
13. Gaitán D, et al. Calcium does not inhibit the absorption of 5 milligrams of nonheme or heme iron at doses less than 800 milligrams in nonpregnant women. J Nutr. 2011;141(9):1652-6. doi:10.3945/jn.111.138651
14. National Institutes of Health, Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
15. Stoffel NU, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017;4(11):e524-e533. doi:10.1016/S2352-3026(17)30182-5 Our study summary.
16. von Siebenthal HK, et al. Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study. EClinicalMedicine. 2023;65:102286. doi:10.1016/j.eclinm.2023.102286 Our study summary.
17. Skelin M, et al. Factors Affecting Gastrointestinal Absorption of Levothyroxine: A Review. Clin Ther. 2017;39(2):378-403. doi:10.1016/j.clinthera.2017.01.005
18. National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
19. US Food and Drug Administration. XENICAL (orlistat) capsules, for oral use: prescribing information. Revised November 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/020766s038lbl.pdf
20. National Institutes of Health, Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/