When to take vitamins and supplements: with food, apart or on an empty stomach

For most vitamins the hour of the day hardly matters. For a few it does — some are absorbed far better with food, some get in each other’s way, and coffee can quietly undo an iron tablet. Here is what is worth knowing about timing, and an easy way to make it stick.

This article is general information, not medical advice. Your doctor or pharmacist decides what you should take and how much — especially if you are pregnant, take medicines, or the supplement is for a child.

Food first, supplements for a reason

A supplement fills a gap; it does not replace a varied plate. The common good reasons are specific: vitamin D in the darker months or when you are rarely outdoors, B12 on a vegan diet, folic acid before and early in pregnancy, iron when a blood test shows you are low. If you are not sure you need something, a blood test tells you more than a guess.

With a meal: vitamins that need fat

Vitamins A, D, E and K dissolve in fat, not water, so they travel into the body together with the fat in a meal. In one study, people who took vitamin D3 with a meal containing fat absorbed about a third more of it than people who took it with a fat-free meal.

• Vitamin D, A, E, K — with a meal that has some fat in it: eggs, yoghurt, cheese, nuts, olive oil on a salad.
• Omega-3 (fish oil) — with food, which helps absorption and makes the fishy aftertaste less likely.
• Multivitamins — with a meal; on an empty stomach they often cause nausea.
• Calcium carbonate — with food, because it needs stomach acid. Calcium citrate is absorbed either way. The body takes in calcium best in doses of about 500 mg or less at a time, so a bigger daily amount is better split.

Apart: iron, calcium and your coffee

Iron is the one where timing matters most. It is absorbed best on an empty stomach, and several things get in its way:

• Coffee and tea within about an hour — their polyphenols bind iron.
• Calcium — from a supplement or a big glass of milk. Keep iron and calcium at least two hours apart.
• Zinc — at supplement doses, zinc and iron compete for the same way in. Take them at different times.

Vitamin C does the opposite and helps iron in: a glass of orange juice or some fruit with the tablet is a simple trick. If iron on an empty stomach makes you feel sick, a little food is better than skipping it. Some doctors now prescribe iron every other day, since studies found it is absorbed better that way than when taken daily — ask yours before changing the schedule.

When it doesn’t matter much

• B12 and other B vitamins — any time. Many people take them in the morning simply to remember.
• Magnesium — any time; with food it is gentler on the gut. Taking it in the evening is a popular habit, but there is little evidence that the hour itself changes anything. High doses can loosen the stool.
• Probiotics — follow the label; for most of them consistency matters more than the hour.

Supplements and medicines

Some minerals bind medicines in the gut. The best known: levothyroxine (for the thyroid) should be taken several hours apart from calcium and iron, and some antibiotics should be kept away from calcium, iron, magnesium and zinc. If you take any regular medicine, ask your pharmacist how to space it from your supplements — it takes them a minute.

More is not better

Supplements add up — a multivitamin, a vitamin D and a calcium tablet with D3 in it all count — and food comes on top. For adults, the tolerable upper intake levels set by the US National Institutes of Health include:

• Vitamin D: 100 µg (4,000 IU) a day
• Iron: 45 mg a day
• Zinc: 40 mg a day
• Magnesium from supplements: 350 mg a day (magnesium in food does not count towards this one)
• Vitamin A (preformed, as retinol): 3,000 µg a day
• Folic acid: 1,000 µg a day

These are limits for everyday intake, not targets. A doctor may prescribe more for a while to treat a deficiency — that is a different situation.

If your day is not a nine-to-five

Night shifts, late starts, a breakfast at noon: advice written for the clock (“in the morning”, “in the evening”) fits badly. Tie the supplement to a meal instead. “With breakfast” means with your first meal after sleep, whenever that is; “before bed” means a while after your last meal. The point of the timing advice is the food, not the hour.

Making it a habit

• Hang it on a meal. A routine you already have — breakfast, dinner — is the strongest reminder there is.
• Keep the pack where the meal happens, not in a drawer in another room.
• Count what is left, so the pack does not run out on a Sunday.
• Write down what you take and how much — it is the first thing a doctor will ask.

foodoo does this for you. Add a supplement from the list, by hand or from a photo of its label, and say when you take it — on waking, with a meal, before bed or at a set time. Reminders follow your own meals: a dose “with breakfast” comes 15 minutes after you log breakfast, whenever that is. It points out iron next to calcium or coffee and a plan that goes past an upper level, adds what your supplements bring to the vitamins in your statistics, and puts them in the report for your doctor.