The classic dissolve test: drop a multivitamin in warm water and stir for 30 minutes…  

What does that really say about that pill’s ability to be digested anyway? Since your stomach is basically a warm pouch for food to churn around a while, the home test is a decent illustration of how that pill will breakdown in your stomach. But it’s not the full picture since digestion goes beyond the stomach and it doesn’t work for time-released, enteric coated or chewable tablets and capsules. 

Here we give expert advice on when and how (with food vs. on an empty stomach) to take the most popular daily supplements so you can reap the benefits of optimal absorption. 

Vitamins and Minerals 

A traditional multivitamin/mineral containing only 100% the RDAs (except >250 mg calcium or magnesium) should not present any digestion or absorption issues for adults with healthy guts.

Most individual micronutrients are better absorbed when taken in small doses at mealtimes, though B vitamins should be taken on an empty stomach. Fat-soluble vitamins (A, D, E and K), magnesium and iron are best taken with food to maximize absorption and minimize gastrointestinal upset. 

Note that calcium, zinc and iron compete for absorption, so it’s best to take them at least two hours apart from one another. Consider pairing these individual supplements or getting them in combination: vitamin C helps iron absorption (particularly plant-based non-heme iron); and vitamin D aids calcium absorption. Unpaired calcium citrate is okay on an empty stomach. 

Most people take their multivitamin/mineral supplement in the morning instead of at night. Digestion slows down during sleep, so taking your nutrient supplement late at night would not be associated with an efficient absorption,” as told to The Washington Post by Jeffrey Blumberg, PhD, a professor of nutrition at Tufts University. Taking your supplement when you start your day with a routine also helps increase consistency.

Essential Fatty Acids and Fiber 

Fish oils (contains omega-3 EPA and DHA fatty acids) are generally better absorbed when taken with meals containing fat as that prompts the secretion of enzymes and bile salts needed for fat digestion. Plus, they can cause digestive upset on an empty stomach and produce “fish burps,” so taking them with food helps relieve or mask these effects. 

Fiber supplements by their chemical nature aren’t ‘digested;they’re fermented in the large intestine. As with most supplements, they should be taken with a glass of water.

If the intent is to promote fullness, lower cholesterol or moderate blood sugar levels, a powder form of soluble fiber consumed with food will slow initial digestion.

To relieve constipation as a stool softener or bulk-forming laxative, taking fiber at night is ideal because of its longer time to work while sleeping. So, taking fiber with your evening meal works for whichever form of fiber supplement you’ve got. 

Non-nutrient supplements

While most of the three-quarters of Americans that took dietary supplements in 2018 turned to vitamin & mineral supplements, 41% took herbals or botanicals according to The Council for Responsible Nutrition.

For items like coenzyme Q10, turmeric, collagen, probiotics and other non-sport supplements, recommendations on when and how to take them are across the board, depending on their form, dose and intended effect.

It’s said that black pepper helps turmeric become more bioavailable, so perhaps take that one with a peppery dish. Depending on your medications, you may need to take the supplement with your meals or between meals. 

Supplement Do’s 

Remember that supplementation can fill a gap if certain sources are eliminated in the diet (such as B12 for vegans) but it doesn’t make up for poor eating habits. You still need to eat a balanced diet rich in vegetables, legumes, whole grains, fruit, healthy plant fats and lean protein.

To better ensure your supplement contains what is on the label look for a USP verified mark, NSF certification or designation from an independent third party laboratory. Also, store supplements away from heat and light where they may degrade. 


  1. C Brissette. Morning or Night? With Food or Without? Answers to Your Questions About Taking Supplements.  February 5, 2019. Accessed 9.24.2019 
  2. J Donovan. Make the Best Use of Fiber Supplements. July 24, 2015. Accessed 9.24.2019 
  3. J Fletcher. When is the Best Time to Take Vitamins? September 28, 2017. Accessed 9.24.2019 
  4. T Frueman. How To Choose a Fiber Supplement. June 6, 2017. Accessed 9.24.2019 
  5. E Ward. Making the Most Out of Multivitamins. December 26, 2010. Accessed 9.24.2019 
  6. “2018 CRN Consumer Survey on Dietary Supplements.” Council for Responsible Nutrition, 2018,
  7. “How To Take Vitamins Properly.”,