a, Robust lifespan extension in adult C. elegans by α-KG. 8 mM α-KG increased the mean lifespan of N2 by an average of 47.3% in three independent experiments (P < 0.0001 for every experiment, by log-rank test). Experiment 1, mean lifespan (days of adulthood) with vehicle treatment (m veh ) = 18.9 (n = 87 animals tested), m α-KG = 25.8 (n = 96); experiment 2, m veh = 17.5 (n = 119), m α-KG = 25.4 (n = 97); experiment 3, m veh = 16.3 (n = 100), m α-KG = 26.1 (n = 104). b, Worms supplemented with 8 mM α-KG and worms with RNAi knockdown of α-KGDH (encoded by ogdh-1) have increased α-KG levels. Young adult worms were placed on treatment plates seeded with control HT115 E. coli or HT115-expressing ogdh-1 dsRNA, and α-KG content was assayed after 24 h (see Methods). c, α-KG treatment beginning at the egg stage and that beginning in adulthood produced identical lifespan increases. Light red, treatment with vehicle control throughout larval and adult stages (m = 15.6, n = 95); dark red, treatment with vehicle during larval stages and with 8 mM α-KG at adulthood (m = 26.3, n = 102), P < 0.0001 (log-rank test); orange, treatment with 8 mM α-KG throughout larval and adult stages (m = 26.3, n = 102), P < 0.0001 (log-rank test). d, α-KG does not alter the growth rate of the OP50 E. coli, which is the standard laboratory food source for nematodes. α-KG (8 mM) or vehicle (H 2 O) was added to standard LB media and the pH was adjusted to 6.6 by the addition of NaOH. Bacterial cells from the same overnight OP50 culture were added to the LB ± α-KG mixture at a 1:40 dilution, and then placed in the 37 °C incubator shaker at 300 r.p.m. The absorbance at 595 nm was read at 1 h time intervals to generate the growth curve. e, Schematic representation of food preference assay. f, N2 worms show no preference between OP50 E. coli food treated with vehicle or α-KG (P = 0.85, by t-test, two-tailed, two-sample unequal variance), nor preference between identically treated OP50 E. coli. g, Pharyngeal pumping rate of C. elegans on 8 mM α-KG is not significantly altered (by t-test, two-tailed, two-sample unequal variance). h, Brood size of C. elegans treated with 8 mM α-KG. Brood size analysis was conducted at 20 °C. Ten L4 wild-type worms were each singly placed onto an NGM plate containing vehicle or 8 mM α-KG. Worms were transferred one per plate onto a new plate every day, and the eggs laid were allowed to hatch and develop on the previous plate. Hatchlings were counted as a vacuum was used to remove them from the plate. Animals on 8 mM α-KG showed no significant difference in brood size compared with animals on vehicle plates (P = 0.223, by t-test, two-tailed, two-sample unequal variance). Mean ± s.d. is plotted in all cases. Source data