document: mouse lifespan , weight , and food consumption were monitored as described in detail previously ( 15 ) . 
   briefly , male b6c3f1 mice ( harlan breeders ; indianapolis ) were randomly assigned to treatment groups at 12 months of age . 
   two hundred ninety - seven control mice were shifted from ad libitum chow feeding ( diet # 5001 , purina mills , richmond , in ) to daily feeding with 13.3 kcal / day / mouse of control diet [ american institute of nutrition ( ain)-93 m diet ; diet no . 
   four groups of 18 mice each were shifted to daily feeding with an identical quantity of control diet supplemented with ndga at either 1.5 , 2.5 , 3.5 , or 4.5 g per kg diet ( approximately 1.59 , 2.65 , 3.71 , 4.77mg / kg body weight / day , respectively ) . 
   food consumption and health were monitored at the time of feeding , and any uneaten food noted . with few exceptions , 
   ndga was mixed with the powdered diet and cold - pressed into 1 g pellets by bio - serv . 
   the mice had ad libitum access to tap water , which was acidified ( ph 4.0 ) to reduce colonization by pseudomonas ( 16,17 ) . 
   the health of the mice was examined twice daily by laboratory staff and weekly by a veterinarian . 
   this study was approved by the institutional animal care and use committee at the university of california , riverside . 
   these lifespan studies utilized an unbalanced statistical design to minimize the number of mice per test group while maintaining statistical power ( 18 ) . 
   unbalanced designs have economic and logistic advantages for comparing multiple treatments to a common control ( 18 ) . 
   the group sizes in this study are similar to those required for a weibull survival analyses with a 75% probability of detecting an 10% increase in mean lifespan with a 1% probability of a false positive (   .01 ) . 
   the weibull analysis is more stringent than the comparison of kaplan  meier survival curves using the mantel 
   cox or gehan  breslow  wilcoxon tests , implemented in graphpad prism 5.01 , which are used here . 
   the significance of the differences in body weights between the treated and control groups was judged using a linear mixed effects model ( 19,20 ) as described previously ( 15 ) . in brief , we modeled the mean response by a set of fixed effects assumed to be shared by mice and a set of random effects that are unique to a particular mouse . additionally , our model imposed a common intercept since all mice were on the same diet at the time of the first measurement . to determine which group weights were significantly different than those of the controls , a bayesian information criterion ( bic ) 
   model selection criteria , a likelihood ratio test ( lrt ) , and an akaike s information criterion ( aic ) model selection criteria were used ( table 1 and results ) . 
   food consumption was determined by totaling the amount eaten by each treatment group during each time period , adjusted for the number of mice . 
   summary of the statistical analysis of mouse group weights ( figure 2 ) using bic model selection removing each diet individually 
   akaike s information criterion . 
   drosophila ( wild - type oregon - r - c ; bloomington drosophila stock center , department of biology , indiana university , bloomington , in ) lifespan determinations were performed as described in detail previously ( 21,22 ) , using 0 , 1 , or 3mg / ml ndga . 
   capillary feeder ( cafe ) assays ( 23 ) and fecal plaque assays ( fpas ( 24,25 ) ) were performed as described ( 26 ) . 
   the effect of ndga on fpa plaque size was determined as described ( 21,22 ) . 
   the effects of ndga on locomotor activity were determined as described previously ( 26 ) . 
   briefly , one day old male flies were exposed to 3 mm ndga in dmso or vehicle treatments in 9525 mm glass vials for 3 days ( at 25 c with 12 hour light / dark cycle ) . 
   after 3 days , movement of the flies was monitored for 72 hours using a trikinetics locomotor activity monitor ( lam 32 ) . 
   means  sem were calculated for 30 minutes time increments over the entire 72 hour trial ( 144 recordings ) . 
   an unpaired , two - sample t test was used to determine the significance of differences between experimental and control treatments using graphpad prism 5 . 
   mouse lifespan , weight , and food consumption were monitored as described in detail previously ( 15 ) . 
   briefly , male b6c3f1 mice ( harlan breeders ; indianapolis ) were randomly assigned to treatment groups at 12 months of age . 
   two hundred ninety - seven control mice were shifted from ad libitum chow feeding ( diet # 5001 , purina mills , richmond , in ) to daily feeding with 13.3 kcal / day / mouse of control diet [ american institute of nutrition ( ain)-93 m diet ; diet no . 
   four groups of 18 mice each were shifted to daily feeding with an identical quantity of control diet supplemented with ndga at either 1.5 , 2.5 , 3.5 , or 4.5 g per kg diet ( approximately 1.59 , 2.65 , 3.71 , 4.77mg / kg body weight / day , respectively ) . 
   food consumption and health were monitored at the time of feeding , and any uneaten food noted . with few exceptions , 
   ndga was mixed with the powdered diet and cold - pressed into 1 g pellets by bio - serv . 
   the mice had ad libitum access to tap water , which was acidified ( ph 4.0 ) to reduce colonization by pseudomonas ( 16,17 ) . 
   the health of the mice was examined twice daily by laboratory staff and weekly by a veterinarian . 
   this study was approved by the institutional animal care and use committee at the university of california , riverside . 
   these lifespan studies utilized an unbalanced statistical design to minimize the number of mice per test group while maintaining statistical power ( 18 ) . 
   unbalanced designs have economic and logistic advantages for comparing multiple treatments to a common control ( 18 ) . 
   the group sizes in this study are similar to those required for a weibull survival analyses with a 75% probability of detecting an 10% increase in mean lifespan with a 1% probability of a false positive (   .01 ) . 
   the weibull analysis is more stringent than the comparison of kaplan  meier survival curves using the mantel 
   cox or gehan  breslow  wilcoxon tests , implemented in graphpad prism 5.01 , which are used here . 
   the significance of the differences in body weights between the treated and control groups was judged using a linear mixed effects model ( 19,20 ) as described previously ( 15 ) . in brief , we modeled the mean response by a set of fixed effects assumed to be shared by mice and a set of random effects that are unique to a particular mouse . additionally , our model imposed a common intercept since all mice were on the same diet at the time of the first measurement . to determine which group weights were significantly different than those of the controls , a bayesian information criterion ( bic ) 
   model selection criteria , a likelihood ratio test ( lrt ) , and an akaike s information criterion ( aic ) model selection criteria were used ( table 1 and results ) . 
   food consumption was determined by totaling the amount eaten by each treatment group during each time period , adjusted for the number of mice . 
   summary of the statistical analysis of mouse group weights ( figure 2 ) using bic model selection removing each diet individually 
   akaike s information criterion . 
   drosophila ( wild - type oregon - r - c ; bloomington drosophila stock center , department of biology , indiana university , bloomington , in ) lifespan determinations were performed as described in detail previously ( 21,22 ) , using 0 , 1 , or 3mg / ml ndga . 
   capillary feeder ( cafe ) assays ( 23 ) and fecal plaque assays ( fpas ( 24,25 ) ) were performed as described ( 26 ) . 
   the effect of ndga on fpa plaque size was determined as described ( 21,22 ) . 
   the effects of ndga on locomotor activity were determined as described previously ( 26 ) . 
   briefly , one day old male flies were exposed to 3 mm ndga in dmso or vehicle treatments in 9525 mm glass vials for 3 days ( at 25 c with 12 hour light / dark cycle ) . 
   after 3 days , movement of the flies was monitored for 72 hours using a trikinetics locomotor activity monitor ( lam 32 ) . 
   means  sem were calculated for 30 minutes time increments over the entire 72 hour trial ( 144 recordings ) . 
   an unpaired , two - sample t test was used to determine the significance of differences between experimental and control treatments using graphpad prism 5 . 
   male mice were fed ndga in their food at 1.5 , 2.5 , 3.5 , or 4.5g / kg diet ( 160 , 267 , 373 , 480mg / kg bw / d ) , beginning at 12 months of age . 
   median lifespan was extended by 12% at 373mg / kg bw / d ( ~13.5mg / mouse / day ; mantel 
   cox p = .008 ; gehan  breslow  wilcoxon p = .009 ; figure 1 ) . 
   wilcoxon test gives more weight to deaths at early time points , while the mantel - cox test gives equal weight to all time points . despite its effects on median lifespan 
   , we found no effect of 373 mg of ndga / kg bw / d ( 3.5g / kg diet ) on maximum lifespan using the method of gao et al . 
   maximum lifespan is variously defined as the lifespan of the longest lived 10% or 20% of a cohort . here , we eliminated the lifespan data below a pooled quantile of 0.8 . the resulting mann 
   shown are the lifespans of mice consuming ain-93 m diet without additions ( filled circles ; median survival 983 days ) ; mice consuming 1.5 g of ndga / kg ain-93 m diet ( open circles ; median survival 969 days ; mantel 
   cox p = .769 ; gehan  breslow  wilcoxon p = .991 ) ; mice consuming 2.5 g of ndga / kg diet ( open squares ; median survival 1059 days ; mantel - cox p = .528 ; gehan  breslow  wilcoxon p = .490 ) ; mice consuming 3.5 g of ndga / kg diet ( open upward pointing triangles ; median survival 1099 days ; mantel - cox p = .008 ; gehan 
   breslow  wilcoxon p = .009 ) ; and mice consuming 4.5 g of ndga / kg diet ( open downward pointing triangles ; median survival 995 days ; mantel  cox p = .963 ; gehan  breslow  wilcoxon p = .647 ) . 
   the dose of ndga which extended median lifespan is within 12% of that initially reported to extend the lifespan of the nih - itp mice ( ~417mg / kg bw / d ( 12 ) ) . in our study , only this dose extended lifespan ( figure 1 ) . 
   recently , the nih - itp reported lifespan extension using censored data at higher and lower dosages . further study will be needed to resolve these differences . 
   the statistical design and animal husbandry used in these studies have been described in detail elsewhere ( 15,18,26,28 ) . 
   food consumption and body weight food consumption and body mass were monitored throughout the study ( figure 2 ) . 
   the mice ate essentially all their food each day , with the exception of a single excursion by the 1.5g / kg diet group late in life . 
   this is consistent with the instability of the weights in late life due to the smaller number of mice and the presence of more age - related pathologies . 
   shown is the body weight of the control ( closed black circles ) ; 40% cr fed ( closed orange circles ) ; 20% cr fed ( closed fuchsia circles ) ; 1.5 g ndga / kg diet ( closed gold circles ) ; 2.5 g ndga / kg diet ( closed green circles ) ; 3.5 g ndga / kg diet ( closed purple circles ) ; and 4.5 g ndga / kg diet ( closed blue circles ) . 
   food consumption as a percent of the kcal offered with respect to the kcals consumed during the preceding month is shown for control , ( open black circles ) ; 40% cr fed ( open orange circles ) ; 20% cr fed ( open fuchsia circles ) ; 1.5 g ndga / kg diet ( open gold circles ) ; 2.5 g ndga / kg diet ( open green circles ) ; 3.5 g ndga / kg diet ( open purple circles ) ; and 4.5 g ndga / kg diet ( open blue circles ) . 
   a preliminary report of these data from 365 to 1,063 days of age was published previously ( 14 ) . 
   the weights of the mice were analyzed using a mixed effects model with a bic model selection criterion , as described previously [ table 1 ; reference ( 15 ) ] . 
   these results suggest that the weights of the 2.5 and 4.5g / kg diet - treated mice , as well as the 20% and 40% cr mice were reduced significantly relative to those of the control group ( figure 2 ; table 1 ) . 
   the differences between the weights of the control and the 1.5 and 3.5g / kg diet - treated groups were close to significance by this test ( table 1 ) . 
   a lrt suggests that the weights of all the groups except the 1.5g / kg diet group differed significantly from those of the control group . 
   an aic model selection criteria suggests that all the diets groups differed significantly from the control group ( table 1 ) . 
   the group consuming the highest dose of ndga weighed less than the 20% calorically restricted ( 20% cr ) group at younger ages , when the data were more accurate due to sample sizes . 
   pathologies associated with mortality death - related pathology has not been reported previously ( 1012 ) . 
   the results of the necropsies from our study are summarized in tables 2 and 3 . 
   focusing on the aggregated results for the pathologies for all the groups , there was a highly or very highly significant increase in liver and lung tumors , enlarged thymuses ( indicative of thymomas or lymphomas ) , and hemorrhage into the peritoneum ( hemorrhagic diathesis ; table 2 ) . 
   response relationship for these pathologies , likely due to the relatively small group sizes . however , even the lowest dose of ndga produced significant pathologies ( table 2 ) . 
   ndga decreased the size of liver tumors by 24% relative to those found in the control mice , suggesting that it may decrease the rate of tumor growth . 
   however , the total mass of the tumors per mouse was unchanged , suggesting it may increase hepatic tumorigenesis ( tables 2 and 3 ; see discussion below ) . 
   necropsy results from the mouse longevity studies shown in figure 1 
    * number of necropsied mice in each treatment group . 
   significance of the differences from the control values were determined using fisher s exact test . for convenience , 
   liver tumor mass of the mice shown in table 2 and figure 1 * tumor mass was calculated as ( /6 )  l  w  h  1.0 g , where l is length , w is width , and h is the height of each tumor . 
   significant changes are in bold . in view of the clinical evidence of hepatotoxicity and nephrotoxicity in humans and rodents consuming ndga , we investigated whether ndga produced signs of toxicity at the concentrations used in these lifespan studies . 
   male b6c3f1 mice were treated with ndga or control diet for 9 weeks , and clinical chemistries performed . 
   alanine transaminase ( alt ) was significantly decreased by the higher doses of ndga , which is the opposite of what would be expected if the drug was toxic to the liver or kidneys . 
   aspartate transaminase ( ast ) , alkaline phosphatase , bilirubin , and creatinine levels , which can also be signs of toxicity if elevated , were unchanged . 
   con = control ; p = p - value . * eight male b6c3f1 mice were treated with ndga at each dosage or with control diet for 8 weeks . at 21 months of age 
   clinical chemistries were performed on the 68 mice in each group with no obvious signs of pathology at necropsy . 
   blood glucose levels were measured with the freestyle lite blood glucose monitoring system ( abbot laboratories ) . 
   the other blood tests were performed by the comparative pathology laboratory , university of california , davis . 
   all , results and p - values for all ndga treated groups considered together ; two lowest , the number of pathologies and the p - values for the 1.5 and 2.5g / kg diet fed mice considered together ; two highest , the number of pathologies and p - values for the 3.5 and 4.5g / kg diet fed mice considered together . 
   calculated using unpaired two - sample t tests for convenience , significant changes are indicated in bold . 
   however , the elevated triglyceride and glucose levels seem more likely to have resulted from the alterations in energy homeostasis evinced by the decrease in body weight in the absence of a change in caloric consumption ( figure 2 ; table 1 ) . 
   conservation of the lifespan response to further characterize the effects of the drug , we investigated its effects on the lifespan of drosophila . 
   optimum oral treatment with ndga at 3.0mg / ml medium increased the median lifespan of the flies by approximately 23% ( figure 3 ) . 
   these results suggest that at least some of the target(s ) of ndga action are phylogenically conserved between mice and flies . 
   the relatively short lifespans of the control flies are the result of using large flybottles , which induce more flight time ( 29 ) , male flies only ( 30 ) , mildly elevated incubation temperatures ( 31 ) , and food with a high protein concentration ( 3234 ) . 
   each of these parameters somewhat shortens lifespan , although the flies remain responsive to compounds that lengthen lifespan [ e.g. references ( 21,22,26 ) ] . 
   shown is the survival of drosophila fed diets containing either vehicle alone ( closed circles ; median survival 20 days ) , vehicle containing 1.0mg / ml ndga ( upward pointing triangles ) , or vehicle containing 3.0mg / ml ndga ( downward pointing triangles ; median survival 26 days ; both mantel  cox and gehan  breslow 
   because drug induced cr or reduced locomotor activity might increase drosophila lifespan ( 29,35 ) , we investigated these parameters in ndga - treated flies . 
   we found no effect of ndga on food consumption ( tables 5 and 6 ) , body weight ( table 7 ) , or locomotor activity ( table 8) . food consumption was quantified in two ways . 
   we used our modifications of the cafe assay ( table 5 ) and the fecal plaque assay [ fpa ; table 6 ; references ( 21,22 ) ] . no effect on food consumption 
   long - term ndga treatment also did not change body weight ( table 7 ) . 
   locomotor activity was quantified using a lam 32 activity monitor ( trikinetics ) as described previously [ table 8 ; reference ( 26 ) ] . 
   there was no significant difference between the activity of flies consuming food containing ndga or an equivalent volume of vehicle . 
   together , these results indicate that the effects of ndga on drosophila lifespan were not due to cr or altered locomotor activity . 
   further , we did not detect a disequilibrium between food intake and weight in this species as we did in the mice . 
   ndga does not alter food consumption in drosophila as measured using cafe assays * one day old male flies were starved for 2 hours and exposed to capillary tubes containing a solution of 5% sucrose and 5% yeast extract with the addition 1% by volume of either 3 mm ndga dissolved in dmso , or dmso alone . a small volume of red food coloring was added to the food to aid in the visualization of the liquid . for a complete description see methods . 
   consumption per fly is the mean  sem of the difference between the initial volume in the capillary pipets at the start and completion of assay conducted with flies present less the average amount of liquid loss to evaporation in control assays conducted in the absence of flies , divided by the number of flies in the assays . 
   four bottles per condition ( 50 flies per bottle ) . each bottle had four capillary tubes inserted into its sides . 
   nul control bottles were identical except for the absence of flies . 
   the significance of the difference in food consumption between the treated and control flies was determined using an unpaired , two - sample t test . 
   two day old flies were starved for 2 hours and exposed to capillary tubes containing a solution of 5% sucrose and 5% yeast extract with the addition 1% by volume of either 3 mm ndga dissolved in dmso , or dmso alone . a small volume of red food coloring was added to the food to aid in the visualization of the fecal plaques . 
   the significance of the differences between the treated and control groups was determined using an unpaired two - sample t test . 
   * one day old flies were fed for 7 days with food containing either 3 mm ndga or an equal volume of vehicle ( dmso ) . 
   a total of 7 groups ( n ) of 25 flies were weighed for each treatment condition . 
   mean weight  sem was calculated by dividing the total weight in milligrams of each group of flies by the number of individuals in the group . 
   the significance of the differences in weight was determined using unpaired two - sample t tests . 
   * flies were treated with either 3 mm ndga , dissolved in dmso , or medium containing an equal volume of dmso alone for 3 days , followed by 72 hours of monitoring at 25 c in a lam 32 activity monitor ( trikinetics ) . 
   ten flies in each of 10 vials were monitored simultaneously for each condition . 
   the average number of infrared beam disruptions per 72-hour period by the groups of 10 flies . 
   the significance of the differences in the mean number of beam breaks for treated and control flies determined using unpaired two - sample t tests . 
   the results presented here show that ndga can extend murine and drosophila lifespan . in our study , 
   ndga consumption , even at doses below its therapeutic dose , was associated with an increase in multiple tumor types and hemorrhagic diathesis . 
   the drug also increased the lifespan of drosophila , suggesting its target(s ) and mechanism(s ) of action may be phylogenetically conserved . 
   however , aspects of the response in flies were unlike those in mice . in flies 
   , ndga did not appear to affect energy uptake or utilization . in our studies , 
   3.5g / kg diet ( 373 mg ndga / kg bw / d ) extended lifespan , but higher and lower dosages were ineffective . 
   the nih - itp found that ndga extended male mouse lifespan at 2.5 g ndga / kg diet , which they estimated supplied approximately 417mg / kg bw / d ( 10,11 ) . 
   however , the actual dose was uncertain because food intake was not continuously measured in this study . 
   more recently , they report that ndga at 0.8 or 5.0g / kg food produced lifespan effects similar to that of 2.5g / kg diet . 
   these data were censored at 30% survival , and thus further study will be required to determine the dose response range of the lifespan effect in mice ( 12 ) . 
   the nih - itp did not report necropsy or toxicity studies for their ndga - treated mice ( 10,12 ) . 
   based on the mortality - related pathologies we found , there was an association between ndga consumption and an increased incidence of liver , lung , and thymus tumors , and increased hemorrhagic diathesis . 
   there was little evidence for acute liver or kidney toxicity as measured by serum chemistries . 
   however , others reported that treatment of mice with 5.0 g ndga / kg diet , a concentration reported to extend lifespan by the nih - itp , stunted the growth of male and female mice , and induced inflammatory cecal lesions , hemorrhages , and cysts in rats [ reviewed in ( 6 ) ] . 
   thus , the doses of ndga which extend murine lifespan appear to overlap the dosages which produce serious pathologies . in humans , 
   the consumption of dietary supplements containing creosote leaf and stem extracts resulted in toxic hepatitis , cirrhosis , and fulminant liver failure ( 4,7,36,37 ) . 
   however , ndga also was found to suppress signaling through the igfir and to suppress the androgen - stimulated growth of human prostate cancer cells in culture ( 3840 ) . 
   these studies led to clinical investigation of its safety and efficacy for the treatment of prostate cancer ( 41,42 ) . in humans , continuous oral dosing at up to 2.5g / d ( ~31mg / kg bw / d ) , one - tenth of the dose which extended lifespan in this study in mice , was tolerated , except for the development of elevated ast or alt ( transaminitis ) in some patients ( 42 ) . 
   drug dosages in rodents are often scaled down approximately 10-fold in mg per kg body weight for investigational studies in humans ( 14 ) . in a phase ii study of men with non - metastatic hormone - sensitive prostate cancer , oral doses of 2.0 g 
   ndga / d in 28 day cycles produced transaminitis in 8 patients ( 67% ) . 
   the development of less toxic derivatives of ndga , such as tetra - o - methyl nordihydroguaiaretic acid , are underway for potential use as cancer therapeutics ( 43,44 ) . 
   possible mechanisms for the longevity effects of ndga a large number of molecular mechanisms have been proposed to explain the presumed , but as yet largely undocumented , health benefits of ndga [ reviewed in ( 4 ) ] . 
   perhaps the most probable mechanism for the longevity effects of ndga is its inhibitory effects on the activity of mammalian target of rapamycin complex 1 ( mtorc1 ( 45 ) ) . 
   mtorc1 inhibition is a well - established mechanism for the extension of mouse and drosophila lifespan ( 22,4649 ) . 
   a recent review of the literature argues that rapamycin inhibition of mtorc1 extends mouse lifespan by suppressing cancer formation and growth ( 50 ) . 
   however , it will be important to discover whether the dosages of ndga that extend lifespan actually inhibit mtorc1 activity in tissues shown to be important to its longevity effects . in our studies , ndga decreased the mass of liver tumors by 24% relative to those found in control mice , suggesting that it decreased the rate of liver tumor growth ( table 3 ) . 
   these observations are consistent with in vitro and in vivo studies showing that ndga inhibits the growth and proliferation , and induces the apoptosis of multiple cancer cell types ( 5154 ) . 
   these effects likely result from the inhibitory effects of ndga on growth factor signaling ( 3840 ) . in mammals 
   , ndga inhibits igfir activation , igfir and her2 tyrosine kinase activity , androgen dependent growth of cultured prostate tumor cells , and growth of cultured her2-overexpressing human breast cancer cells ( 3840 ) . in our studies 
   , ndga appeared to increased hepatic tumor number ( tables 2 and 3 ) , and to increase the prevalence of lung and thymus tumors ( table 2 ) . 
   taken together , the data suggest that while ndga reduces tumor growth rates , it increases tumor formation . 
   inhibition of igfi receptor signaling can enhance rodent lifespan , although these effects are sex and background dependent ( 55,56 ) . 
   there is less of an effect on lifespan on the c57bl/6j background than on the 129/svpas background ( 56 ) . 
   female mice heterozygous null for the igf1r exhibit extended longevity , while their male counterparts do not ( 56,57 ) . 
   in other studies , neither male nor female mice with reduced igfi levels experience an increase in mean lifespan ( 55 ) . 
   together , these results suggest that if a lifespan effect is observed when igfr activity is inhibited , females , rather than males respond . 
   thus , this response is the opposite of that found with ndga , where males rather than females respond . 
   thus , reduced igfir activity alone is unlikely to be the major mechanism by which ndga extends murine lifespan . 
   hormetic stimuli are thought to produce molecular damage at low doses , which stimulate increased maintenance and repair , and thereby increased longevity ( 58 ) . at high doses 
   masoro and others have proposed that cr is a hormetic agent ( 35,59,60 ) . in one example , the genic profiles produced by a group of progeroid mutations recapitulate the profiles produced by the prolongevity treatments of cr and gh deficiency in mice ( 60 ) . 
   the data regarding ndga are not sufficiently developed to indicate whether it is a hormetic longevity agent . 
   it appears to produce molecular damage at its optimum dosage for increasing lifespan , as evinced by the induction of cancers ( table 2 ) and modest liver and kidney toxicity in humans ( 41,42 ) and mice ( table 4 ) . 
   an unanswered question is whether the less toxic derivatives of ndga such as tetra - o - methyl nordihydroguaiaretic acid will also be capable of extending murine and drosophila lifespan ( 43,44 ) . 
   one theory proposes that ndga exerts positive effects on health because it is a potent scavenger of activated oxygen and nitrogen species in vitro and in vivo ( 4 ) . 
   however , exogenous antioxidants have not been shown to reproducibly extend mammalian lifespan , and they can shorten it ( 15,28,6164 ) . 
   further , the consumption of agents that increase oxidative stress , rather than reduce it , appear to be associated with enhanced longevity in mammals and other species ( 65 ) . 
   ndga reportedly suppresses proinflammatory gene expression and prostaglandin e 2 production and thereby inhibits arachidonic acid 5-lipoxygenase and cytokine - stimulated activation of microglia and macrophages ( 66,67 ) . 
   some data support an inverse correlation between inflammation and lifespan ( 68 ) . however , correlative evidence has been misleading in the context of oxidative stress ( 61 ) . in the absence of direct evidence for an association between reduced inflammation and extended lifespan , 
   inhibition of oxidative phosphorylation can increase rodent and fly lifespan ( 69,70 ) . however , decreased rates of oxidative phosphorylation are not consistent with the dose responsive loss of body weight observed in our mice ( figure 2 ; table 1 ) . 
   inhibition of oxidative phosphorylation should preserve body weight , since it reduces the utilization of calories . in flies 
   , ndga had no effect on body weight , physical activity , or food consumption ( tables 58 ) . 
   thus , our data are inconsistent with the extension of lifespan through inhibition of oxidative phosphorylation . 
   the funders had no role in study design , data collection or analysis , decision to publish , or preparation of the manuscript .
summary: mesonordihydroguaiaretic acid ( ndga ) extends murine lifespan . 
   the studies reported here describe its dose dependence , effects on body weight , toxicity - related clinical chemistries , and mortality - related pathologies . in flies 
   , we characterized its effects on lifespan , food consumption , body weight , and locomotion . 
   b6c3f1 mice were fed ain-93 m diet supplemented with 1.5 , 2.5 , 3.5 , or 4.5 g ndga / kg diet ( 1.59 , 2.65 , 3.71 and 4.77mg / kg body weight / day ) beginning at 12 months of age . only the 3.5mg / kg diet produced a highly significant increase in lifespan , as judged by either the mantel 
   cox log - rank test ( p = .008 ) or the gehan  breslow 
   wilcoxon test ( p = .009 ) . 
   ndga did not alter food intake , but dose - responsively reduced weight , suggesting it decreased the absorption or increased the utilization of calories . 
   ndga significantly increased the incidence of liver , lung , and thymus tumors , and peritoneal hemorrhagic diathesis found at necropsy . 
   however , clinical chemistries found little evidence for overt toxicity . 
   while ndga was not overtly toxic at its therapeutic dosage , its association with severe end of life pathologies does not support the idea that ndga consumption will increase human lifespan or health - span . 
   the less toxic derivatives of ndga which are under development should be explored as anti - aging therapeutics .