Coffee lovers know there’s something magical about a cup of joe: the rich aroma, the comforting warmth, and the complex flavors that make it a cherished part of the day. As a dietitian and a devoted coffee enthusiast myself, I also appreciate the potential health benefits coffee can offer, like its antioxidant properties, its ability to perk us up, and its link to a reduced risk of developing dementia.
Rest assured, I’m not here to tell you to give up your beloved coffee habit. However, we do need to talk about what you might be pairing with that morning brew that you really, really shouldn’t.
Many people enjoy the convenience of taking their daily vitamins or supplements alongside their coffee; it feels like a productive way to combine two healthy habits. But here’s the catch: Certain compounds in coffee may interfere with the absorption or effectiveness of some nutrients and compounds. This means that if you’re washing down some supplements with your dark roast, you might not be getting the full benefits you’re expecting.
Here, we’ll explore how coffee impacts nutrient absorption and highlight which supplements you may want to keep separate from your morning mug—and when to take them instead.
Why coffee and supplements don’t always mix
To understand why coffee and certain supplements clash, we need to look at the chemistry of your drink. Coffee is complex, containing hundreds of different compounds. Two of these compounds are primarily responsible for impacting nutrient absorption: tannins and caffeine.
Tannins are a type of polyphenol found in coffee, true tea, and wine. While they act as antioxidants, they also function as “anti-nutrients.” Tannins bind to certain minerals in your digestive tract. When they do this, they form complexes that are much harder for your body to absorb. This can reduce the amount of the nutrient that enters your bloodstream, with the unabsorbed portion passing through your digestive system.
Caffeine brings its own set of challenges to your morning vitamin routine. It stimulates your digestive system, mildly increasing how quickly food and supplements move through your gastrointestinal tract. While this effect is usually too mild to significantly impact nutrient absorption, excessive caffeine intake or preexisting digestive issues could reduce the time your intestines have to absorb certain nutrients.
4 supplements to keep away from your coffee cup
If you are investing in supplements and want to get the full nutritional punch you paid for, you may need to separate your coffee from your medicine cabinet. Here are the four supplements I tell people to try and avoid mixing with your morning brew.
Iron
If you take iron supplements to combat iron deficiency or support energy production, it’s important to know that coffee and iron don’t mix well. The tannins in coffee bind to non-heme iron (the type found in most supplements) and form complexes that are difficult for your body to absorb. Research suggests that drinking coffee with an iron-rich meal or supplement can reduce non-heme iron absorption by up to 54%, depending on the coffee’s polyphenol content and strength. Stronger brews with higher polyphenol levels are likely to have a greater inhibitory effect than lighter roasts or weaker cups—good to know!
Calcium
Calcium is essential for keeping your bones strong, your teeth healthy, and your muscles and nerves functioning properly. And the good news is that for most generally healthy people, enjoying your morning coffee alongside your calcium supplement isn’t a big concern. While caffeine can have a small impact on calcium balance, like slightly increasing calcium excretion through urine or mildly reducing absorption, these effects are minimal and unlikely to cause harm if you’re meeting your daily calcium needs.
That said, for certain individuals, like those with low calcium intake, osteoporosis, or other bone health concerns, it’s worth paying closer attention. Caffeine’s diuretic effect and its potential to interfere with calcium absorption, while minor, could add up over time if your calcium levels are already low.
Magnesium
Magnesium is a powerhouse mineral, supporting everything from muscle recovery to sleep and blood sugar regulation. But pairing magnesium with coffee might not be the best idea if you’re trying to maximize its benefits.
Data shows that caffeine can slightly increase magnesium excretion, meaning you might lose a small amount of this vital mineral through urine after your morning coffee. While this isn’t a huge deal for most people with a balanced diet, it may be worth pairing your magnesium supplement with water instead of java, especially if you’re addressing a deficiency or aiming to optimize absorption.
Zinc
Zinc is a go-to supplement during cold and flu season, thanks to its powerful immune-supporting properties. However, like iron, zinc absorption can be impacted by the tannins in coffee. These compounds bind to zinc, forming complexes that your body may have difficulty absorbing. As a result, you may not be reaping the full immune-boosting benefits of your supplement when taking it with coffee. (It’s also best to avoid taking zinc with foods high in phytates, by the way—like whole grains, legumes, and seeds—as they can interfere with absorption too.)
What about tea and decaf coffee?
If you’re thinking of swapping your coffee for tea or decaf to avoid nutrient absorption issues, it’s worth knowing that these drinks aren’t entirely off the hook either.
True teas, like black, green, white, and oolong, contain tannins just like coffee. While true teas generally have less caffeine than coffee, the tannins alone can still interfere with nutrient absorption. So if you’re sipping on a cup of green tea with your iron or zinc supplement, you might not be getting the full benefits.
Herbal teas, on the other hand, are a different story. Since they’re made from herbs, flowers, or fruits rather than tea leaves, most don’t contain tannins. And herbal teas are naturally sans-caffeine, eliminating any potential concerns the stimulant can have on nutrient utilization. This makes them a better choice if you’re looking to avoid interference with your supplements. However, always check the ingredients, as some blends may include true tea leaves or other compounds that could still impact absorption.
As for decaf coffee, it’s not a free pass either. While it contains far less caffeine, it still has tannins, so you run into the same potential concerns you may have when you sip on OG coffee when it comes to taking iron and zinc supplements.
How to time your supplements and coffee
If you love your morning coffee and your supplements, the good news is that you don’t have to pick sides. With a little smart scheduling, you can enjoy your daily brew while still reaping all the benefits of your vitamins and minerals.
The golden rule of supplement timing is to wait at least two hours since you had your last cup. This allows the caffeine and tannins enough time to clear your upper digestive tract, reducing their impact on nutrient absorption. However, the exact ideal timing may vary depending on the individual and the specific supplement.
Alternatively, you can consider moving your supplements to a completely different part of the day. I generally recommend my clients take magnesium supplements before bedtime, and iron on an empty stomach for maximum absorption. Ideally, people are waiting two hours before or after taking an iron supplement before drinking coffee.
And if you don’t want to budge on your morning routine—we get it, sometimes it’s easier to check it off first thing—try a tannin and caffeine-free drink like chicory coffee or a herbal tea.
By timing your coffee and supplements thoughtfully, you can enjoy the best of both worlds: the comfort of your morning ritual and the full nutritional punch of your supplementation routine. It’s a simple tweak that may have a profound impact on your health.
Originally published on SELF.
