Most commercially sold honey in the United States contains a label warning consumers not to feed honey to infants less than one year of age. This is because honey often contains spores of a bacterium called Clostridium botulinum, the spore-producing bacterium responsible for botulism.
C. botulinum feed on dead and decaying organic matter and is commonly found in soils and sediments throughout the world. Honey is contaminated with C. botulinum spores when bees, while collecting pollen, come into contact with dirt and dust particles that contain the spores. Bees then transport the contaminants back to the hive, where honey is produced. C. botulinum spores are not pathogenic on their own, but will germinate in an ideal environment. Underdeveloped, low-oxygen conditions like a baby’s stomach allow spores to produce a neurotoxic protein called botulin. Botulin, the toxin that causes botulism, interferes with the way nerves tell muscles to contract, causing a loss of muscle tone called flaccid paralysis. Infants with botulism may have droopy eyelids, loss of head control, and limpness associated with flaccid paralysis. If respiratory muscles, like the diaphragm muscle in the chest, no longer contract, infants can have difficulty breathing and eventually suffer from respiratory failure. Symptoms of botulism can appear in infants 3 to 30 days after ingesting contaminated food. Infant botulism is most common in babies 6 weeks to 6 months old, although babies up to a year old can be affected. This is why labels specify that infants less than one year old should not consume honey.
So why not sterilize honey? C. botulinum exists in soils worldwide and bees have a wide foraging range, making contaminated products almost impossible to individually identify. The spores and subsequent toxins are heat sensitive, but difficult to destroy. Toxins can be destroyed by exposure to boiling temperatures for 10-20 minutes, but spores must be exposed to boiling temperatures for 6 hours before being destroyed, and some spores can survive boiling.
Furthermore, the risk of children and adults developing botulism is relatively low. C. botulinum spores will not germinate in acidic conditions (< pH 4.6). Because honey is acidic (pH ~3.9) and hygroscopic (does not absorb moisture from the air), spores cannot germinate in honey and the botulin toxin cannot develop. The spores will remain dormant until they come in contact with a more hospitable environment. Consequentially, the botulism toxin has never been found in honey, just C. botulinum spores. If adults consume contaminated honey, their immune systems and digestive microbiomes are usually both developed enough and strong enough to destroy the spores.
Botulism in adults is rare. In 2014, the Center for Disease Control reported 161 cases of botulism in the United States1. Foodborne botulism, caused by consuming food that contains the botulin toxin, accounted for only 9% of those cases. Eating improperly sterilized canned foods was the most common cause of foodborne botulism in adults, and contaminated honey was not responsible for any botulism case. Wound botulism, caused when C. botulinum spores infect a wound and produce the botulin toxin, accounted for 10% of cases. Infant botulism accounted for the remaining 80% of cases.
Fortunately, no infants died from botulism in 2014. This is likely due to early diagnosis and effective medical treatment. Infant botulism is treated with an antitoxin called botulism immune globulin intravenous (BIG-IV). The product contains purified immunoglobulin, a protein present in immune system cells to destroy pathogens like bacteria. The immunoglobulin in BIG-IV is derived from the blood plasma of adults who were immunized against botulism and had high levels of an antibody that works well to destroy the botulin toxin. If taken immediately, most infants make a full recovery.
The warning labels on honey jars are not an example of governmental overreach or health lobbyists dictating what to feed your child. Giving infants honey in their first year of life could lead to a preventable, life-threatening illness. It’s only a year: what’s the rush?
- World Health Organization, 2016. Botulism. Link.