The Best Time of Day to Take Each Supplement

You do not need a complicated schedule. But a few simple timing rules can help your body absorb more and reduce stomach upset.

Rule 1: Fat-soluble vitamins go with a meal that has some fat

Vitamins A, D, E and K dissolve in fat, so they absorb better with food that contains fat. Take them with lunch or dinner, not on an empty stomach.

Rule 2: Water-soluble vitamins are flexible

B vitamins and vitamin C dissolve in water and can be taken with or without food. Some people find B vitamins slightly energising, so they may prefer the morning.

Rule 3: Iron is the fussy one

• Iron is absorbed best on an empty stomach, but it often upsets the stomach. Taking it with a small amount of food is a reasonable compromise.
• Vitamin C can help absorption.
• Calcium, coffee and tea reduce iron absorption. Leave 1 to 2 hours between them.
• Only take iron if you need it. Too much is harmful.

Rule 4: Calcium in smaller doses

The body absorbs calcium best in amounts of around 500 mg or less at a time, so split larger doses. Calcium carbonate needs food. Calcium citrate can be taken with or without.

Rule 5: Magnesium is often an evening supplement

Many people take magnesium in the evening, because it can be relaxing. It can be taken with food if it upsets your stomach.

Rule 6: Omega-3 with a meal

Fish oil and other omega-3 supplements are better absorbed with a meal that has fat, and taking them with food reduces fishy burps.

Rule 7: Zinc with food

Zinc can cause nausea on an empty stomach. Take it with food. At higher doses, long-term zinc can interfere with copper and iron, so don't go above the label dose without advice.

Rule 8: Probiotics, keep it consistent

Follow the instructions on your product. Some are best taken before a meal, others with food. The most important thing is to take them regularly.

Which supplements should be spaced apart?

• Iron and calcium, as above.
• Magnesium or calcium and certain antibiotics (tetracyclines, quinolones), bisphosphonates and thyroid medicine. Your pharmacist can tell you the right gap.
• Levothyroxine is usually taken on an empty stomach about 30 to 60 minutes before breakfast, and several hours apart from iron and calcium supplements.

A simple daily example

• Morning, with breakfast: B-vitamins or a multivitamin.
• Lunch or dinner (with fat): vitamin D, omega-3.
• Evening: magnesium.

Always follow the label of your own products and your pharmacist's advice. If you take prescription medicine, ask before choosing a time.

Check your own list

Use the free Interaction Checker on VitaGuide to see whether your medicines and supplements may interact, or email our pharmacist for a review.

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This article is general information and not medical advice. It does not replace advice from your own doctor or pharmacist.

Sources to verify before publishing: NIH Office of Dietary Supplements fact sheets on iron, calcium, zinc, magnesium and vitamin D; levothyroxine product information on timing.