Coffee consumption can lead to iron deficiency anemia. Coffee interferes with the absorption of iron supplemental. Interference with iron absorption is due to the polyphenols present in coffee. Although the inhibition of iron absorption can cause an iron deficiency.
may cause heartburn.
Moderate amounts of coffee (50–100 mg of caffeine or 5–10 g of coffee powder a day) are well tolerated by most elderly people.
Excessive amounts of coffee, however, can, in many individuals, cause very unpleasant, exceptionally even life-threatening adverse effects.
Coffee containing caffeine can cause insomnia, nervousness, stomach upset, nausea and vomiting, increased heart and breathing rate, and other side effects.
Consuming large amounts of coffee might also cause headache, anxiety, agitation, ringing in the ears, and irregular heartbeats.