Taking supplements with coffee? These 6 may be less effective
Coffee may reduce how well your body absorbs several common supplements
If your morning routine includes both a cup of coffee and daily supplements, you may not be getting the full benefit of certain vitamins and minerals.
According to experts, drinking coffee alongside some supplements is not necessarily harmful, but it can reduce how much your body absorbs or is able to use. The good news is that you do not have to give up coffee. Instead, adjusting when you take your supplements may help maximise their effectiveness.
Here are six supplements that may be best taken separately from your morning coffee.
1. Iron
Coffee contains plant compounds called polyphenols, which are known for their antioxidant properties. However, these compounds can also bind to iron, reducing the amount your body absorbs.
According to research, drinking coffee with an iron-rich meal may decrease iron absorption by about 35%.
A 2023 study examining iron supplements found that drinking coffee with the supplements, with or without breakfast, reduced iron absorption by 54% to 66%.
2. Calcium
Caffeine may interfere with your body's ability to absorb calcium from both food and supplements.
Coffee may also interact with vitamin D, which helps the body absorb calcium.
Because coffee has a diuretic effect, it increases urine production. Some research suggests this may cause more calcium to be filtered from the body and excreted through urine.
3. Vitamin D
Research suggests people trying to increase their vitamin D levels may benefit from avoiding coffee when taking vitamin D supplements.
Some studies indicate caffeine may interfere with vitamin D receptors, affecting how well the vitamin works in the body.
Other research has found that people with higher caffeine intake tend to have lower vitamin D levels in their blood, though the studies do not show that coffee directly causes vitamin D deficiency.
4. B vitamins
Taking B vitamins with coffee may reduce how much of these nutrients your body absorbs or increase how quickly they are eliminated.
B vitamins discussed in the research include thiamine, folate, folic acid, biotin, niacin and riboflavin.
One 2016 study linked higher coffee intake with lower thiamine levels, while research published in 2018 suggested caffeine may reduce folate levels in the blood.
Because B vitamins are water-soluble, coffee's diuretic effect may also increase their loss through urine.
However, the evidence is mixed. Another study found that drinking one to two cups of coffee per day was not associated with significant changes in vitamin B12 or folic acid levels.
5. Magnesium
Coffee may also affect magnesium supplements by increasing urine production, allowing the mineral to leave the body more quickly.
If you are taking magnesium supplements for low magnesium levels, reduced absorption may make symptoms such as muscle cramping or fatigue more likely to persist.
6. Zinc
Coffee may reduce zinc's bioavailability, meaning less of the mineral enters the bloodstream where it can be used by the body.
Researchers also note this may be linked to coffee's effect on vitamin D, which plays a role in zinc absorption.
When should you drink coffee?
Research suggests timing may help reduce these interactions.
Experts recommend drinking coffee one to two hours before taking supplements or eating vitamin-rich foods to help maximise nutrient absorption.
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. It is based on user-generated content from social media, and the claims have not been independently verified.
