The Effect of Milk Intolerance on the Consumption of Milk by Slaves in 1860

Abstract

Consumption of Milk by Slaves in I860 Fogel and Engerman compare the average daily food consumption of slaves on large plantations in 860 with the average daily food consumption of the entire population in I879, the earliest date for which such data are available. They find that slaves consumed 86 percent as much meat, 185 percent as much potatoes, I59 percent as much grain, but only 46 percent as much milk.1 Sutch, an outspoken critic of Fogel and Engerman, is the only other scholar to have exhausitvely examined the composition of the slave diet. Using his figures, the corresponding percentages are II6, I21, 171, and 29.2 In this paper we suggest that the relatively low consumption of milk found by both studies can be explained by a high incidence of milk intolerance among adult blacks, a much higher incidence than among adult whites. A major component of milk is lactose (milk sugar). To be digested, lactose must first be broken down into its monosaccharide components. This is accomplished by the enzyme lactase. A person who is lactase-deficient does not have enough lactase to break down lactose at a reasonable rate.3 Such a person can cope with a relatively small amount of milk with no ill effects.4 However, if the lactase-deficient person drinks more than a threshold amount of milk, which typically varies for different lactase-deficient people from about a glass to about a quart, then he will become