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Base foodLow concern for people

Coffee

In pet food

Toxic to dogs and cats

Caffeine — in coffee, guarana and similar — can overstimulate a dog's or cat's heart and nervous system, causing restlessness, an irregular heartbeat, tremors or seizures. The more caffeine, the greater the risk.

Sources checked 2026-10-12. If you think a pet has eaten something harmful, contact your vet or an animal poison control line straight away. This is not veterinary advice.

In plain words

The short version

Contains both caffeine and chlorogenic acids; like tea, it lowers iron uptake from the meal it accompanies.

Why it's green

For people, coffee is widely considered safe at the amounts usually drunk — that's what the green means. Dogs and cats are different: the caffeine in it can harm them. See "In pet food" above.

Interactions

Safety profile

Chlorogenic acids bind non-haem iron much as tea tannins do, reducing absorption from the same meal. Caffeine has only a very small effect on calcium: it slightly lowers absorption, an effect offset by as little as 1–2 tablespoons of milk, and controlled balance studies found no change in total daily urinary calcium.

The detail

Sources

  1. Morck TA, Lynch SR, Cook JD. Inhibition of food iron absorption by coffee. Am J Clin Nutr 1983;37:416–420 (doi:10.1093/ajcn/37.3.416; PMID 6402915) — American Journal of Clinical Nutrition — abstract via US National Library of Medicine, 1983. Coffee lowers iron absorption from the meal; timing effect
  2. Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr 1999;81:289–295 — British Journal of Nutrition (Cambridge University Press), 1999. Chlorogenic acids in coffee inhibit non-haem iron absorption, like tea
  3. Heaney RP. Effects of caffeine on bone and the calcium economy. Food Chem Toxicol 2002;40:1263–1270 (doi:10.1016/S0278-6915(02)00094-7; PMID 12204390) — Food and Chemical Toxicology — abstract via US National Library of Medicine, 2002. Caffeine's effect on calcium is small and offset by calcium intake

Checked against these sources on .

Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.