The influence of dietary fat on the toxicity of orally ingested lead in rats.

The influence of dietary fat on the toxicity of orally ingested lead was investigated. Groups of ten male weanling Wistar rats were maintained on diets providing 11.5, 20, 40 or 60% of energy from fat for 8 wk. All diets were supplemented with a low level of lead--1.25 mg Pb (as lead acetate) per 1000 kJ energy in the diet. Groups receiving 11.5 and 20% of energy as fat had similar lead levels for each tissue studied. Raising the fat level to 40 or 60% of energy resulted in significant increases in tissue-lead concentrations with each increment in dietary fat. The groups receiving 60% of energy as fat had more than twice the level of lead in the femur, kidney, liver and brain than the control rats maintained on the diet containing 11.5% energy as fat, even though the amount of lead ingested was the same for all groups. delta-Aminolaevulinic acid dehydratase activity was not affected when dietary fat was increased from 11.5 to 20%. There was a significant reduction in activity when fat was increased to 40 or 60% of energy. Free erythrocyte protoporphyrin was not affected by the level of dietary fat. This work demonstrates that increasing the level of dietary fat significantly increases lead toxicity and indicates the need for further research on the interaction between dietary factors and lead toxicity.