Figure 2.  Dietary cholesterol content significantly modified the effect of protein and carbohydrate content on lifespan and reproduction.

Lowering cholesterol most severely compromised lifespan as protein levels increased and as carbohydrate levels decreased. In general, increasing protein and decreasing carbohydrate drove increasing levels of egg production, and this was enhanced by increasing dietary cholesterol levels. Lines show the relationship between the cumulative eggs laid per female (left Y axis) or median survival (days) (right Y axis) and dietary protein or carbohydrate levels across each cholesterol level. (0 g/l (a, b), 0.15 g/l (c, d), 0.3 g/l (e, f), 0.6 g/l (g, h)). Cumulative eggs laid per female are represented as triangles while median survival (days) are shown as circles. Statistical analysis reported in Supplementary files 5 and 6.

Figure 2—figure supplement 1. Changing dietary protein and cholesterol concentrations modify Drosophila lifespan (a–c), while changing protein, cholesterol and carbohydrate concentrations modify egg production (d–f).

Diets varying in protein and carbohydrate concentration were each made at 4 levels of cholesterol (b, e) 0 g/l, 0.15 g/l, 0.3 g/l and 0.6 g/l. (a) Lifespan is reduced at both low and high protein concentrations, (b) was improved by increasing dietary cholesterol concentration, and (c) was unchanged by changing dietary carbohydrate concentration. Egg laying was improved by increasing protein (d) and cholesterol concentrations, but decreased with carbohydrate concentration (f).

Figure 2—figure supplement 2. Dietary energy intake (calories) does not mediate lifespan or egg production in Drosophila (a, b), while changing P:C ratio and cholesterol do (a, b).

Diets varying in protein and carbohydrate concentration were each made at three alternate P:C ratios, four levels of cholesterol (a, b) 0 g/l, 0.15 g/l, 0.3 g/l and 0.6 g/l, and five caloric concentrations (a, b). Lifespan is reduced when the P:C ratio is high and the dietary cholesterol concentration is low, while egg laying was improved by increasing the P:C ratio and cholesterol concentration (a, b). These effects are independent of calories (a, b).