What component of human milk is cytotoxic to parasites like Giardia lamblia?

The component of human milk that is cytotoxic to parasites such as Giardia lamblia is found in the fatty acids present. Specifically, certain free fatty acids, which are derived from the breakdown of fats in human milk, have been shown to exhibit antimicrobial properties. These fatty acids can disrupt the membrane integrity of parasites, inhibiting their growth and ability to survive in the host.

In addition to direct cytotoxic effects, fatty acids also play a role in stimulating the immune system, enhancing the body's ability to fight off infections, including those caused by parasites. This protective quality of fatty acids underscores their importance in the gut health of infants, where many parasitic infections can originate.

Understanding the role of fatty acids in human milk can help appreciate how breastfeeding contributes to an infant’s immune defense mechanisms, particularly in relation to gastrointestinal parasites.