The salutary effect of milk on amoebiasis and its reversal by iron.

Observations among milk-drinking African nomads showed an unusual freedom from infection with Entamoeba histolytica compared with similar nomads taking a mixed diet. A controlled study among Maasai pastoralists showed that the administration of iron to correct their dietary iron deficiency sharply increased their susceptibility to amoebiasis. Examination of the milk of their Zebu cattle showed that it not only had a concentration of iron below the minimum necessary for the growth of E histolytica but also contained partly saturated lactoferrin and transferrin, which may actively compete with the parasite in the colon for ambient iron. These observations suggest the possibility of a long-standing ecological compromise between nomads, their milk diet, and E histolytica.