Taking Supplements? Watch Out for These Common Interactions

Vitamins, minerals and herbs play a role in many people’s daily health routine. However, it’s important to keep in mind that “natural” doesn’t always mean risk-free. Whether it’s for better sleep, thicker hair or improved gut health, supplements can often interact with each other – as well as with commonly prescribed medications.

Jacob Wolf, ND, LAc, Dipl. OM, a naturopathic doctor at University Hospitals Connor Whole Health, explains what you need to know to stay safe while allowing supplements to work most effectively.

Timing Is Everything

Many people don’t realize that supplements can compete for absorption in the stomach. For example, calcium, magnesium, zinc and iron are all absorbed via the same pathways. “It’s not a direct interaction,” says Dr. Wolf. “But if you’re taking them at the same time, you have multiple molecules competing and your body may not absorb as much of each one.”

This is especially important if you have a diagnosed vitamin deficiency. “If you’re low in iron and taking it with calcium, you might not absorb enough iron,” says Dr. Wolf. He recommends spreading out supplements across different times of day, for example by taking calcium in the morning and magnesium at night, which can offer the added bonus of supporting better sleep.

Calcium, magnesium and iron can also block thyroid hormone absorption, so if you’re taking a medication for hypothyroidism, Dr. Wolf recommends taking it on an empty stomach, then spacing out other supplements by a few hours.

While staggering supplements can help avoid interactions and improve absorption, Dr. Wolf adds another note of caution if you have an iron deficiency. “The tannins in green or black tea bind to iron, blocking its absorption,” he says. “So drink your tea at a different time of the day than when you are taking your iron.”

The Hidden Risks of St. John’s Wort

Extra caution should be taken when adding herbal supplements to your daily regimen. One standout is St. John’s Wort, often recommended for mild-to-moderate depression.

St. John’s Wort not only interacts with other popular mood supplements like 5-HTP and SAMe, it can also interfere with how your liver processes any medication. “It interacts with almost every prescription medication and supplement you can think of,” says Dr. Wolf. For that reason, he generally advises against using St. John’s Wort if you’re taking any other prescription drugs.

Gingko Biloba and Omega-3

Ginkgo biloba and omega-3 fatty acids from fish oil are popular supplements, often praised for their brain-boosting and heart-healthy benefits. However, both have mild blood-thinning effects. While not usually dangerous on their own, combining them with each other – or with prescription blood thinners or aspirin – can raise your risk of bruising or bleeding.

Dr. Wolf advises checking with your doctor before mixing gingko and omega-3 supplements, especially if you’re already on a blood-thinning medication such as coumadin. In addition, special care needs to be taken before any surgical procedures. Your surgeon will likely recommend you stop these supplements a few days to a week before your procedure.

Collagen and Biotin

Many supplements make big promises, but the science behind them can be murky. Take collagen, for instance. It’s having a moment, with claims that it boosts hair, nails, skin and joint health. In fact, it’s unlikely to be well-absorbed enough to stand up to those claims. “Collagen is a good protein source and may support gut health, but whole collagen molecules are large and don’t get absorbed directly into your joints or hair,” says Dr. Wolf. Look for collagen peptides or hydrolyzed collagen for better absorption.

What’s more, people may not be aware that another favorite supplement for hair health – biotin – can have an unintended consequence: interfering with routine lab tests. “Biotin can actually cause lab machines to give incorrect results, especially on thyroid tests,” he says. If you’re taking biotin, stop a few days before you have any blood work done to avoid misleading results.

Vitamin D

One supplement Dr. Wolf does recommend without reservation for most people is vitamin D – especially in regions that don’t get much sun. “In places with a winter season, people generally can’t make vitamin D from sunlight between October and March,” he explains. While vitamin D is generally safe, Dr. Wolf suggests getting your levels checked if you plan to take high doses.

Making Sense of Supplements

The bottom line when it comes to supplements: If you decide to try them, check first with your doctor or pharmacist to see if there are any known interactions with other medications or supplements you take. Look for high-quality, professional-grade brands with fewer fillers and binders in their ingredients lists. And keep in mind, while some supplements can be beneficial, they’re not magic bullets.

“Good health starts with good habits,” says Dr. Wolf. “Supplements are just one piece of the puzzle.”

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The integrative health experts at University Hospitals Connor Whole Health use evidence-based therapies and lifestyle approaches to help people achieve optimal health and healing.