Timing of Iron Supplements After Coffee Consumption
Wait at least 1-2 hours after drinking coffee before taking iron supplements to avoid significant inhibition of iron absorption. 1, 2
Evidence for Coffee's Impact on Iron Absorption
Coffee is a powerful inhibitor of iron absorption and should be strictly avoided around the time of iron supplementation:
Coffee reduces iron absorption by approximately 54% when consumed with iron supplements, representing a substantial decrease in the amount of iron your body can utilize. 3
When coffee is consumed with breakfast alongside iron supplements, absorption decreases by 66%, even when vitamin C (approximately 90 mg) is present in the meal. 3 This demonstrates that coffee's inhibitory effect is so strong that it overwhelms the absorption-enhancing benefits of vitamin C.
The American Gastroenterological Association explicitly recommends avoiding coffee for at least 1-2 hours after taking iron to maximize absorption and minimize the need for higher doses or prolonged treatment. 1
Optimal Iron Supplementation Strategy
To maximize the effectiveness of your iron supplements:
Take iron in the morning on an empty stomach (1-2 hours before or after meals), as this is when absorption is highest due to lower hepcidin levels. 1, 2, 3
Consume iron with approximately 100-500 mg of vitamin C (such as a vitamin C tablet or a glass of orange juice) to enhance absorption by approximately 30%. 1, 3
Avoid tea as well as coffee, as both are powerful inhibitors of iron absorption and should not be consumed within 1 hour after taking iron. 4, 1
Take iron with plain water if vitamin C or citrus juice is unavailable, but never with milk, tea, coffee, or calcium-containing foods. 2
Practical Timing Recommendations
The safest approach to ensure adequate separation:
If you drink coffee in the morning, take your iron supplement at least 1-2 hours later. 1
Alternatively, take your iron supplement first thing in the morning with vitamin C and water, then wait at least 1 hour before drinking coffee. 1
If you must have morning coffee, consider taking iron supplements in the late morning or early afternoon (though morning dosing on an empty stomach remains optimal for absorption). 2, 3
Common Pitfall to Avoid
- Do not assume that adding extra vitamin C will compensate for coffee consumption. Even with 90 mg of vitamin C present, coffee still reduced iron absorption by 66% in clinical studies. 3 The inhibitory effect of coffee is simply too strong to overcome with vitamin C supplementation.