If you take your supplements first thing in the morning along with your cup of coffee, you may want to reconsider. While it’s not necessarily dangerous to take certain supplements with coffee, doing so can decrease the supplements’ absorption and bioavailability, meaning you may not get the same effects and benefits.
Here are six supplements you should avoid taking with coffee:
Coffee contains plant compounds called polyphenols. They’re known for their antioxidant properties, but polyphenols also bind to iron, limiting the amount of iron your body can absorb.
According to some research, drinking coffee with an iron-rich meal may decrease your iron absorption by about 35%. A study from 2023 that looked specifically at the absorption of iron supplements taken with coffee, with or without breakfast, found that coffee decreased people’s iron absorption by 54-66%.
This means taking iron with coffee won’t give your iron levels the same boost as intended.
To get the most benefit from your calcium supplement, it’s important to avoid taking it with coffee so your body can absorb it.
The caffeine in coffee can interfere with your body’s ability to absorb calcium from food or supplements. Coffee may also interact with vitamin D, a nutrient that helps your body absorb calcium.
Coffee is also a diuretic, meaning it increases the amount of urine you make. Your body makes urine by filtering your blood. Some research suggests that coffee’s diuretic effect filters calcium out of your body to be excreted or flushed out of your system through your urine.
Overall, research suggests that people who want to increase their vitamin D levels and get the most benefit may want to avoid taking vitamin D supplements with coffee.
For example, some research suggests that caffeine can decrease how well vitamin D works. It does this by interfering with vitamin D receptors in your body.
Other research has found that people who take in more caffeine, such as those who drink a lot of coffee, have lower levels of vitamin D in their blood. However, this research doesn’t show that coffee or caffeine causes the deficiency—just that there’s an association.
Taking B vitamins with coffee may prevent you from absorbing these nutrients as intended, or it may encourage your body to get rid of them. This means you may not get the same benefits of taking them as you might otherwise. B vitamins include:
- Thiamine
- Folate
- Folic acid
- Biotin
- Niacin
- Riboflavin
Some research has found that drinking coffee may decrease the levels of B vitamins in your blood. A study published in 2016 suggests that higher coffee intake is associated with lower thiamine levels. Research from 2018 suggests that caffeine may also interfere with folate, reducing levels in the blood.
B vitamins are also water-soluble, which means you may flush out the vitamins through your urine. Coffee can increase this effect by making you have to urinate more.
However, research is mixed. Another study notes that moderate coffee drinking, defined as one to two cups per day, is not associated with a significant change in vitamin B12 or folic acid.
Coffee may influence levels of water-soluble magnesium supplements in ways similar to how it decreases calcium and B vitamins: By increasing your urine volume, the mineral is filtered out of your body as you urinate more often.
In other words, taking magnesium with coffee means your body gets rid of the mineral more quickly, and you may not get the full effect. If you’re taking a supplement for low magnesium levels, this may mean you’re more likely to experience symptoms, like muscle cramping or fatigue.
Coffee and zinc may not be a great combination. That’s because drinking coffee may interfere with zinc’s bioavailability, or the amount of your intake that enters circulation and is able to have an active effect in your body.
This may also be due to coffee’s effect on vitamin D absorption, as vitamin D helps you absorb zinc.
When it comes to making the most of your supplements and avoiding interactions that decrease their effects, timing your coffee intake may be key. Research suggests you may be in the clear if you drink your coffee one to two hours before taking your supplements or eating vitamin-rich foods.
