The danger of giving honey to infants arises from their developing gut microbiome—the community of microorganisms, including bacteria and archaea, that live in and on the human body, aid in digestion, and influence various bodily functions. In children under one year old, the gut bacteria are not mature enough to prevent certain harmful bacteria from taking hold. One such bacterium, Clostridium botulinum, can produce toxins that cause infant botulism and is sometimes present in both raw and processed honey. Research from 1998 found that up to a quarter of honey samples contained spores of this bacterium.
Infant botulism can produce serious symptoms. These include muscle weakness, making the baby appear limp and unable to move their arms or legs, and in severe cases, it can affect breathing. While the illness itself does not cause long-term damage, severe symptoms require prompt medical treatment. Most affected infants recover quickly after receiving an antitoxin. However, the most effective way to prevent infection is to avoid feeding honey to children under one year of age.)