Caffeine, a primary component of coffee, can significantly impair the body’s ability to absorb key nutrients, including iron, calcium, B vitamins, vitamin D, and probiotics. This interference arises from multiple mechanisms in the digestive system.
Tannins in coffee bind to minerals like iron, forming complexes that are excreted rather than absorbed. Research shows that taking iron supplements with coffee can reduce iron absorption by up to 75%. Caffeine’s diuretic effect also promotes the rapid excretion of water-soluble nutrients, such as B vitamins, vitamin C, and magnesium, through urine, limiting their time in the body.
“Caffeine and other coffee compounds can disrupt the absorption of certain nutrients, potentially diminishing their efficacy,” said nutrition experts studying supplement interactions.
Coffee’s acidity poses a particular challenge for probiotics, which contain live bacteria sensitive to heat and acidic conditions. The hot, acidic environment of coffee can kill these beneficial microbes before they reach the intestines, reducing their health benefits.
Additionally, caffeine stimulates gastric acid secretion, which may cause stomach discomfort in sensitive individuals, especially when combined with supplements that similarly affect gastric acid levels.

Experts recommend waiting at least two hours after consuming coffee before taking supplements, though a six-to-eight-hour gap is optimal. Caffeine has a half-life of approximately four hours, with full metabolism taking up to eight hours in some individuals.
Even decaffeinated coffee carries risks, as trace amounts of caffeine and tannins may remain, potentially affecting nutrient absorption. For best results, take supplements with plain water, which poses no risk of interaction.
Iron and calcium supplements are particularly sensitive to timing, as proper absorption is essential for bone health and preventing deficiencies. Probiotics should be taken on an empty stomach with water, ideally several hours before or after coffee.
Health In News Team Haeun Oh
press@hinews.co.kr