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Get the Most From Your Supplements

Learn how to maximize absorption


Absorption is key. Do the supplements you take work synergistically for optimal effectiveness?

Absorption is a complex bodily process that we don’t often consider when we take our daily supplements. How well our body absorbs supplements depends on many factors such as the delivery system used, stability of the product, and whether the supplements we take work synergistically for optimal effectiveness.


Multivitamins contain an array of nutrients including vitamins, minerals, and amino acids. Vitamins contained in our daily multivitamins can be fat soluble (such as vitamins D and E) or water soluble (such as the B-complex vitamins and vitamin C).

Fat-soluble vitamins are dissolved in fat, then delivered by the bloodstream. Excess vitamins are stored in the liver for future use.

Water-soluble vitamins dissolve in water and aren’t stored by the body. They have to be replenished every day.

How to take them:

  • Take a multivitamin within 30 minutes of a meal.
  • Take fat-soluble vitamins with meals to aid digestion and absorption.
  • Avoid taking vitamins B12 and C too close to bedtime as they can have stimulating, sleep-disrupting effects.

Vitamin D

Direct sun is the best source of vitamin D; however, it’s easier for those with paler skin to produce vitamin D. A fair-skinned person can produce an adequate amount of vitamin D in 15 minutes, whereas a dark-skinned person could take up to 2 hours—and that’s not wearing sunscreen.

Canadians are at risk of low vitamin D levels during the winter when fewer UV rays reach us. According to Environment Canada, UV rays are strongest from April to August when our skin easily synthesizes vitamin D3 from sunlight.

Studies have shown that supplementing with vitamin D3 may decrease mortality. According to a 2011 US study, vitamin D3 is approximately 87 percent more effective in raising and maintaining vitamin D concentrations and stores two to three times more vitamin D than vitamin D2. A 2013 study verified that vitamin D3 is more effective than vitamin D2 at maintaining healthy serum (blood) levels of 25-hydroxyvitamin D over the winter.

How to take it:

  • According to the Vitamin D Council, vitamin D can be taken with food or on an empty stomach.
  • Vitamin D is fat soluble, however, and one study found that taking it with dinner rather than breakfast increased its absorption and serum levels.
  • Take it in the form you prefer: capsule, tablet, drops, or liquid.
  • Certain medications can interact with vitamin D, so check with your health care practitioner for safety and/or dosage recommendations.


Calcium supplementation has long been synonymous with bone health. It’s also important for strong muscles and a healthy heart. An insufficient intake of calcium and vitamin D can lead to osteoporosis in women—and men. Another group that may be deficient in calcium is nine- to 18-year-old girls.

Vitamin D is vital to calcium absorption. Both work together to help prevent bone loss. In addition, vitamins C, E, and K; magnesium; and boron have also been shown to have a synergistic effect with calcium.

How to take it:

  • Spread out calcium intake since the body can’t absorb a large amount at one time.
  • Take no more than 500 mg at one time.
  • Don’t take calcium with any other mineral supplements or with a multivitamin/mineral.
  • Before taking calcium, consult your health care practitioner if you’re on medication, as many medications compete with calcium for absorption.


One of the most underrated minerals responsible for numerous cellular functions is magnesium. Magnesium is required for vitamin D absorption, heartbeat and blood sugar regulation, and healthy nerve and muscle functioning. Since intestinal absorption tends to decrease with age, magnesium is essential for older adults.

How to take it:

  • Transdermal delivery methods can be a preferred method of delivery, since for some people magnesium supplements can irritate the intestinal lining.
  • Leg cramps often experienced by pregnant women or at nighttime can respond well to topical magnesium gel.
  • Choose from capsules, chewable tablets, sprays, liquids, and oils.
  • Take magnesium apart from other minerals and preferably with food.


If you suspect you’re anemic, it’s important to confirm you have an iron deficiency via a blood test by your health care practitioner. A blood test can determine the true level of iron in your blood and whether you require an iron supplement. Professional guidance is important, as excess iron intake can be harmful. Tablets and liquid are two common types of iron supplements.

How to take it:

  • Take iron with a glass of orange juice, as vitamin C helps the body absorb iron in the gut and regulates iron uptake and metabolism.
  • If you’re on other medication, check with your health care practitioner before taking iron.
  • If you take other medication, don’t take iron with grapefruit juice; this citrus fruit can affect how some medications work.
  • Take iron with food to reduce the risk of an upset stomach.
  • Don’t take calcium supplements at the same time as iron supplements or iron-rich foods; calcium can decrease iron absorption.


Probiotics have gained popularity for their beneficial effects on the gastrointestinal and immune systems. Lactobacillus and Bifidobacteria are two popular strains of probiotic bacteria. Certain conditions respond better to certain probiotics. Research has helped uncover specific benefits for the treatment of antibiotic-associated diarrhea, irritable bowel syndrome (IBS), ulcerative colitis, and lactose intolerance.

To help ensure probiotics survive stomach acid for delivery to the intestines, researchers have developed an enteric coating or microencapsulation that is both heat and acid stable.

A benefit of liquid probiotics is that liquids distribute healthy bacteria all along the gastrointestinal tract. However, most liquid preparations require refrigeration; otherwise, the supplement will lose its potency.

How to take them:

  • Take probiotics with meals, or 30 minutes before a meal, for best absorption.
  • Take probiotics with a meal containing healthy fats to improve absorption.
  • Wash them down with milk, rather than water, to help ensure their survival in the intestinal tract.
  • Consult your health care practitioner for advice on the best strain of probiotic to take to meet your needs.


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Matthew Kadey, MSc, RDMatthew Kadey, MSc, RD