Timing is Everything

Knowing when to take your supplements is as important as knowing what to take. Make sure you get all of the benefits by taking your supplements at exactly the right time
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Knowing when to take your supplements is as important as knowing what to take. Make sure you get all of the benefits by taking your supplements at exactly the right time
When and how you take your vitamins, fish oil, and probiotics may be as important as what you’re taking.

When and how you take your vitamins, fish oil, and probiotics may be as important as what you’re taking.

You may have a near-perfect battery of supplements to strengthen bones, build blood, protect your heart, and prevent cancer. But when and how you take your vitamins, fish oil, and probiotics may be as important as what you’re taking. Get the most out of these seven common supplements, with this comprehensive guide to times, combos, and amounts.


In doses higher than 250 mg, calcium and magnesium tend to compete for absorption. But both are critical for bone health, and the extra convenience of taking them in a combined supplement may outweigh the relatively small percentage of each that may not get absorbed. Studies suggest that too much calcium with too little magnesium may contribute to calcification of the arteries, increasing the risk of heart disease. A 1:1 to 1:2 ratio of calcium and magnesium is best.

Best way to take calcium: Take calcium with food to boost absorption and reduce the risk of kidney stones, and in split doses—the body absorbs smaller doses better than large ones. Avoid calcium carbonate, the hardest-to-absorb form of the mineral. And if you can, take calcium at a different time of day than zinc and iron.


Because it can inhibit the absorption of other minerals, don’t take iron with magnesium, calcium, or zinc. Vitamin E and iron also block each other’s absorption, so don’t take iron with vitamin E or a multi that contains E. As for food, it’s best to take iron on an empty stomach for maximum absorption; unless you have a sensitive stomach, take it first thing in the morning. Wash it down with orange juice, not coffee or milk: caffeine and the calcium in dairy can interfere with the body’s ability to take in iron, while vitamin C can enhance iron absorption from supplements. To prevent constipation, avoid ferrous
sulfate, the form that’s most likely to cause constipation; look for a nonconstipating formula, and be sure to drink plenty of water and eat ample fiber.

Best way to take iron: 60 to 120 mg before breakfast, with orange juice, two hours before taking vitamin E or a multivitamin.

Vitamin D

Like other fat-soluble vitamins (A, E, and K), D is better absorbed if taken with a meal that contains fat; one study found taking vitamin D with dinner—usually the heaviest meal—increased blood levels of vitamin D by 50 percent. But don’t take it at dinner if you eat late, since vitamin D also interrupts the body’s production of melatonin and can disrupt sleep. If you’re a late diner, lunch may be the best option; add healthy fats like avocado, olives, salmon, or nut butter to your midday meal to improve absorption.

Best way to take vitamin D: up to 4,000 IU with lunch or early dinner that contain healthy fats.

B complex

B complex vitamins are water-soluble, so the body can only absorb so much at a given time (unlike excess fat-soluble vitamins, which are stored until they’re needed). Splitting the dose can ensure steady blood levels. Taking a B complex that combines all the Bs is more convenient; just be sure not to overdo it on the B6, since high doses over a long period of time can cause nerve damage. B vitamins tend to boost energy, so take them in the morning; at night, they can lead to restlessness and insomnia. They’re best absorbed on an empty stomach, but if you have a sensitive tummy, take them with a little food.

Best way to take Bs: in the morning and afternoon, before breakfast and lunch, on an empty stomach if possible, and in a combination formula that contains well under 100 mg of B6, the recommended upper limit.

Vitamin C

Like B vitamins, vitamin C is water-soluble and doesn’t require dietary fat to be effective. Splitting the dosage improves absorption, keeps blood levels elevated all day, and prevents the gastrointestinal distress some people experience with large doses (1,000 mg or more). Vitamin C enhances calcium absorption, but may interfere with the absorption of B12, so take them separately if possible. Buffered forms of vitamin C are best if you have a sensitive stomach.

Best way to take C: 250 mg twice a day, with breakfast and lunch.

Fish oil

Fish oil can cause significant gastric distress (like nausea and indigestion) so it should always be taken with food; the fat in a meal will also help its absorption. Because it can be hard to digest, take fish oil in divided doses, and never right before physical exercise or right before bed; the increased activity or prone position can interfere with digestion and cause heartburn or reflux. If you really struggle with digesting fish oil supplements, try an emulsified version, which may be easier to digest and absorb. And while fish oil mixes well with most other supplements, don’t take it with ginkgo biloba or other blood-thinning herbs; it can cause excessive bleeding.

Best way to take fish oil: 500 to 600 mg, twice a day, with breakfast and lunch, or with lunch and an early dinner.


Harsh stomach acids may destroy probiotics, so they’re best taken when digestive enzymes, bile salts, and stomach acids are low—in other words, on an empty stomach. Some studies suggest probiotics survive in the largest numbers when taken 30 minutes before a meal that contains some fat (which buffers stomach acids and helps probiotics survive to reach the intestines). However, some evidence also exists that food buffers stomach acid, so taking probiotics with a meal may offer increased protection for the microorganisms—and it’s hard to argue with the fact that probiotics were traditionally taken via cultured foods like yogurt or sauerkraut, which were eaten with meals. Additionally, different strains may have various tolerances to stomach acids. The jury’s still out, so you could experiment: try taking some of your daily probiotics before meals, and some with meals, and see what works best for you. But don’t take them post-meal: several studies show probiotic survival tends to be lowest when taken 30 minutes after eating. And choose a probiotic with a variety of strains for maximum effectiveness; be sure yours contains L. acidophilus, B. Longum, B. bifidum, L. rhamnosus, and L. fermentum at a minimum.

Best way to take probiotics:
5 to 25 billion CFUs of a broad-spectrum formula, half an hour before or with breakfast, lunch, or dinner. 

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