FIGURE 4. Improved metabolic activity of mice placed on dietary folate restriction late in life.

(A) Photographs of male mice on the indicated diet were taken at 85 weeks of age. Signs of graying were visible on the coat of mice on the F/C+ diet (left) but not on the coat of mice on the F/C− diet (right). (B) The respiratory exchange rate (RER) values (y-axis) were from 6–8 mice in each indicated group at 108 weeks of age. The measurements were taken after the animals were acclimated for two days in the metabolic cages. The period between the red vertical lines corresponds to night-time when mice are active. Loess curves and the std errors at a 0.95 level are shown.