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.
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.
Best way to take calcium: two 500 mg doses, one with breakfast and one with lunch.
Don’t take iron with magnesium, calcium, or zinc—it can inhibit the absorption of other minerals. 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 non-constipating formula, and be sure to drink plenty of water. Iron is best absorbed from animal protein.
Best way to take iron: 60–75 mg before breakfast, with orange juice, two hours before taking vitamin E or a multivitamin. A second dose can be taken at a later time in the day.
3. Vitamin D:
Like the other fat-soluble vitamins (A, E, and K), vitamin D is better absorbed if taken with a meal that contains some fat; one study found that taking it with dinner—usually the heaviest meal of the day—increased blood levels of vitamin D by 50 percent.
If you’re a late diner, lunch may be your best option. Just add healthy fats such as avocado, olives, salmon, or nut butter to your midday meal to improve vitamin D absorption.
Best way to take vitamin D: up to 4,000 IU with a meal that contains healthy fats.
4. B complex:
Because B vitamins are water-soluble, the body can only hold onto 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 B, 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 absorbed well on an empty stomach, but if you have a sensitive tummy, take them with food.
Best way to take Bs: in the morning and afternoon, with breakfast and lunch, or on an empty stomach if possible, and in a formula that contains no more than 100 mg of B, the recommended upper limit.
5. 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 that some people experience with large doses (1,000 mg or more).
Vitamin C enhances calcium absorption, but may interfere with the absorption of B, so take them separately. Buffered forms of vitamin C are best if you have a sensitive stomach.
Best way to take C: 250–500 mg twice a day, with breakfast and lunch.
Because harsh stomach acids may destroy probiotics they’re best taken when digestive enzymes, bile salts, and stomach acids are low—in other words, on an empty stomach. Some studies suggest that 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 increase protection for the microorganisms—and it’s hard to argue with the fact that probiotics were traditionally taken via cultured foods such as yogurt or sauerkraut, which were eaten with meals.
Additionally, different strains of bacteria may have different tolerances to stomach acids. The jury’s still out on this idea, so your best bet is to experiment—try taking some of your probiotics before meals, and some with meals, and see what works best for you. But don’t take them after a meal: several studies show that probiotic survival tends to be lowest when taken 30 minutes after eating.
Choose a probiotic with a variety of strains for maximum effectiveness, including L. acidophilus, B. Longum, B. bifidum, L. rhamnosus, and L. fermentum.
Best way to take probiotics: 5–25 billion CFUs of a broad-spectrum formula, half an hour before eating, or with breakfast, lunch, or dinner.
7. Fish oil:
Because they can cause gastric distress, fish oils should be taken with food; the fat in a meal will also help their absorption. Because they can be hard to digest, take them in divided doses, and never right before physical exercise or bedtime—the increased activity or prone position can interfere with digestion. If you struggle with digesting fish oil supplements, try an emulsified version.
Best way to take fish oil: 500–600 mg, twice a day, with breakfast and lunch, or with lunch and an early dinner.