6 Supplements You Should Never Take With Coffee, According to Nutrition Experts

When used consistently, supplements can help fill nutritional gaps in your diet. However, if you prefer taking them in the morning, it's worth being mindful of your coffee intake. According to nutrition experts, coffee can negatively affect how your body absorbs certain vitamins and minerals, potentially reducing the desired effects of supplements.

Find out which supplements should not be mixed with coffee. And, learn the best way to time supplements and coffee.

Supplements to Avoid Taking With Coffee

For optimal benefits, keep the following supplements separate from coffee.

Calcium

"Caffeine, the most well-known compound found in coffee, has a minor effect upon calcium absorption," says Laura Bishop-Simo, RD, LD, registered dietitian at The Ohio State University Wexner Medical Center. "First, caffeine acts as a diuretic, which means it makes you urinate more," says Stefanie Jaskot, MS, RDN, CDCES, registered dietitian at Hackensack University Medical Center. This can modestly lower your calcium levels, as a small amount of the mineral will be eliminated in the urine. "Secondly, caffeine can slightly reduce how much calcium your body absorbs from the food you eat. It can also interfere with vitamin D, which is important for helping your body absorb calcium," notes Jaskot.

Iron

Another supplement that shouldn't be combined with coffee is iron. This is due to the polyphenols, or antioxidant compounds, in coffee. Though polyphenols provide impressive health benefits, they can interfere with the way your body takes up iron. Specifically, polyphenols can attach to the iron from plant-based foods and supplements in your stomach, says Jaskot. This can make it difficult for your body to absorb the mineral. Bishop-Simo echoes this notion, sharing that coffee polyphenols (i.e., tannins and chlorogenic acid) can substantially reduce absorption.

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Zinc

Many people take zinc supplements for immune support, as zinc is necessary for normal immune function. And while it can be tempting to start your day with the supplement, you should avoid washing it down with coffee. "Zinc is bound by tannins in coffee, creating complex compounds that limit absorption in the body," says Bishop-Simo.

B vitamins

There are eight types of B vitamins, and you might be taking one (or all eight) in supplement form. Regardless of the reason, be sure to consume them separately from coffee. Not only does coffee potentially block the absorption of many B vitamins, but it also has a mild diuretic effect, which can increase their excretion through the urine, according to Bishop-Simo.

Vitamin D

As mentioned, vitamin D helps the body absorb calcium. It's also needed for a healthy immune system and muscle strength, according to Jaskot. Supplements can be helpful as many people don't get enough vitamin D from food or sunlight exposure, notes Jaskot—though you'll want to avoid mixing them with coffee. "The caffeine in coffee can make it harder for your body to use vitamin D. It does this by reducing the effectiveness of vitamin D receptors in your cells," Jaskot says. "This means that even if you're taking vitamin D supplements, your body might not be able to use the vitamin as well as it should," she notes.

Magnesium

Magnesium supplements may be helpful for muscle cramps, heart health, and more. But if you'd like to add them to your routine, be mindful of when you drink coffee. "Caffeine acts as a diuretic, making you urinate more frequently," Jaskot says. "This increased urination can flush out essential minerals, like magnesium, before your body can fully absorb them," she says. In other words, caffeine doesn't block magnesium absorption in your stomach, but instead speeds up its removal from your system, says Jaskot.

When to Take Supplements

To ensure the aforementioned supplements are effective, it's important to wait a few hours before taking them and drinking coffee, says Jaskot. "Wait at least one hour between your supplements and your coffee," she says. "You could also try to take your supplements with a meal when you don't drink coffee, such as lunch or dinner," Jaskot says.

Note that supplements like vitamins A, E, K, and C can be taken with coffee, as the drink doesn't affect their absorption, notes Jaskot.