However, if you take vitamin or mineral supplements with your morning coffee, you might want to consider how coffee affects their absorption.
Namely, caffeine, polyphenols, and the mild diuretic effect of coffee can interfere with the way the body uses certain nutrients. “For example, iron absorption can be slowed down due to caffeine, and its diuretic properties also affect the balance of other minerals,” explains pharmacist Dr. Filip Ngo.
Pharmacists have revealed how coffee affects supplement absorption – and what you can do to make your morning routine as effective as possible, reports nova.rs.
1. Iron
Iron is essential for growth, hormone production, and proper cell function. Since iron deficiency is very common, doctors often recommend supplements.
“If you take iron with coffee or with breakfast containing caffeine, your body can absorb up to 54% less iron,” notes Dr. Bo Wang. The cause is not caffeine itself but chlorogenic acid, a polyphenol found in coffee and tea, which inhibits the absorption of non-heme iron (from plant sources and supplements).
Tip: Take iron at least one hour before or after coffee, and pair it with vitamin C-rich foods like oranges or lemons, which improve absorption.
2. Vitamin D
Vitamin D is difficult to obtain solely from food, but the body can produce it with the help of sunlight. However, research shows that caffeine can reduce the expression of vitamin D receptors, which may lead to lower blood levels.
A 2021 study linked higher caffeine intake to lower vitamin D concentrations, although further research is needed.
Tip: Take vitamin D at least one hour away from coffee, ideally with a meal containing healthy fats – since this vitamin is fat-soluble.
3. B Vitamins
This group of vitamins (including B1, B2, B7, B9, and B12) plays a key role in energy production, nervous system health, and the formation of red blood cells. Since they are water-soluble, the body doesn’t store them in large amounts.
Caffeine’s diuretic effect can speed up the excretion of these vitamins through urine. As a result, regular coffee drinkers often have lower levels of B vitamins.
Tip: Avoid taking B vitamins with coffee or tea. Wait at least an hour. These vitamins can be taken with or without food, but many people tolerate them better after a meal.
4. Magnesium
Magnesium is a mineral that supports protein synthesis, blood sugar balance, blood pressure, and sleep quality. Although found in beans, nuts, and yogurt, many people don’t get enough through diet.
Caffeine can increase magnesium excretion through urine, further lowering its levels.
Tip: If you take magnesium as part of your evening routine for better sleep, avoid caffeine for several hours before bedtime so as not to reduce the supplement’s effect – either on sleep or mineral balance.
5. Calcium
Similar to magnesium, calcium excretion can also be increased by caffeine via the kidneys. Although the clinical significance of this effect is still being studied, one study found that participants who consumed caffeine excreted up to 77% more calcium.
Tip: Adding milk to coffee can help offset calcium loss. Take supplements at least one hour after coffee, or two hours before, for optimal absorption.
Expert Conclusion
Coffee can affect the absorption of certain nutrients, but simple timing adjustments can help significantly. A one-hour gap between coffee and supplements is often enough to avoid interference in absorption.
However, it’s important to know that not all supplements are necessary. “Supplements are, as the name suggests, an addition to the diet,” says Dr. Ngo. “For a person in good health who eats a varied diet, it might not be necessary to invest in supplements unless there is a proven deficiency.”
So, before you drink your vitamins with your morning coffee next time, it might be worth “separating” them. Or even better – talk to your doctor and do tests to find out what you really need.
