Sucrose intake as a function of its cost and the cost of chow

The avid consumption of pure carbohydrate solutions, which often results in a distortion of nutrient balance, is generally presumed to be driven by their taste. In the first of two experiments, we examined the effect of consumption cost on rats' intake of three concentrations of sucrose solution (8%, 16%, and 32%) when a nutritionally complete chow was concurrently freely available. In the second experiment, we examined the intake of 24% sucrose solution and chow as the consumption costs of both were varied. Increasing the cost of sucrose resulted in a reduction in the percent calories taken from sucrose; the steepness of the decline in intake with price was inversely related to the sucrose concentration and to the cost of chow. Chow calories were substituted for relatively expensive sucrose calories. An increase in the cost of chow resulted in a reduction in the percent of calories taken from chow and a protein-poor diet. The cost of sucrose did not affect the slope of the chow intake curve, presumably because, despite its sweet taste, sucrose was not a substitute for the protein, fat, and micronutrients in chow. Total caloric intake was conserved in all cases. Thus, the avid consumption of sucrose solution is curtailed when it is costly; but the degree of change in intake with cost depends on the cost of an alternative food. These results suggest that diet selection involves a comparison not only of the taste and post-ingestive consequences of available foods, but also of the cost of calories and nutrients in the foods. Selection appears to be guided first by caloric requirements and the relative cost of calories, then by nutrient requirements and the relative cost of nutrients, and finally by taste. (C) 2000 Elsevier Science Inc. Ail rights reserved.