Keeping up with CR

As before, the calorie restriction (CR) literature has accumulated faster than we could blog about it. Here, without comment, are excerpted abstracts from the last couple of months. I’ve tried to include in the excerpts only the essential conclusion/”money shot” of the study, and not much else — for more detail, click through the links to the full abstracts. Abstracts are ordered in rough order of decreasing interest to me (so you might want to start at the bottom).

Nerve function & structure: The molecular architecture of myelinated peripheral nerves is supported by calorie restriction with aging, Rangaraju et al.:

Age-associated reduction in the expression of the major myelin proteins and widening of the nodes of Ranvier are attenuated by the dietary intervention, which is paralleled with the maintenance of a differentiated Schwann cell phenotype. The improvements in nerve architecture with diet restriction, in part, are underlined by sustained expression of protein chaperones and markers of the autophagy-lysosomal pathway. Together, the in vitro and in vivo results suggest that there might be an age-limit by which dietary intervention needs to be initiated to elicit a beneficial response on peripheral nerve health.

Inflammation: Effect of short term calorie restriction on pro-inflammatory NF-kB and AP-1 in aged rat kidney, Jung et al.:

To compare the effect of short-term calorie restriction (CR) on aging with that of already known long-term CR, the anti-inflammatory efficacy of 10-day CR was explored in aged rat kidney…. Reactive species (RS), lipid peroxides and COX-2 activity were measured. … We report for the first time that 10-day CR can attenuate the altered signaling transduction for inflammatory processes which is mediated through RS-induced NF-kB and AP-1 in aged kidney.

Metabolism and metabolomics: Metabolic shifts due to long-term caloric restriction revealed in nonhuman primates, Rezzi et al.:

The metabolic profile and the associated pathways are compatible with our previous findings that CR-induced gene transcriptional changes in tissue suggest the critical regulation of peroxisome proliferator-activated receptors as a key mechanism. The metabolic phenotyping provided in this study can be used to define a reference molecular profile of CR-associated health benefits and longevity in symbiotic superorganisms and man.

Insulin signaling: Reducing Grb2 Expression Mediates the Insulin Sensitizing Effect of Calorie Restriction, Liu et al.:

To determine whether Grb2 down-regulation contributes to increased insulin sensitivity in the regulation of glucose metabolism, we generated C2C12 cell lines in which the expression of Grb2 is suppressed by RNA interference. … Reduced IRS-1 serine phosphorylation is also found in Grb2+/- heterozygous knockout mice, which is associated with enhanced insulin signaling and resistance to high fat diet-induced glucose and insulin intolerance. All together, our results suggested that reducing the expression levels of Grb2 provides a mechanism by which CR increases insulin sensitivity in vivo.

CR+exercise vs. exercise alone: Effects of Exercise and Caloric Restriction on Insulin Resistance and Cardiometabolic Risk Factors in Older Obese Adults—A Randomized Clinical Trial, Yassine et al.:

We examined the effect of exercise alone (EX) or exercise combined with moderate caloric restriction (–500 kcal, EX + CR) on metabolic and cardiovascular risk factors. … With the exception of weight loss and subcutaneous fat, there was no difference in the magnitude of improvement between the interventions. … These data suggest that exercise alone is an effective nonpharmacological treatment strategy for insulin resistance, metabolic syndrome, and cardiovascular disease risk factors in older obese adults.

Aging and memory: Caloric restriction improves memory in elderly humans, Witte et al.:

We found a significant increase in verbal memory scores after caloric restriction (mean increase 20%; P < 0.001), which was correlated with decreases in fasting plasma levels of insulin and high sensitive C-reactive protein …

Intermittent fasting and reproduction: Gonadal Transcriptome Alterations in Response to Dietary Energy Intake: Sensing the Reproductive Environment, Martin et al.:

The transcriptional activity of the gonadal response to these variations in dietary energy intake was assessed at the individual gene level as well as at the parametric functional level. … Our data show that at the level of gonadal gene responses, the male rats on the IF regime adapt to their environment in a manner that is expected to increase the probability of eventual fertilization of females that the males predict are likely to be sub-fertile due to their perception of a food deficient environment.

Alternate-day fasting vs. CR: Improvements in body fat distribution and circulating adiponectin by alternate-day fasting versus calorie restriction, Varady et al.:

he present study evaluated the effects of ADF versus CR on body fat distribution and circulating adiponectin levels and examined the kinetic mechanisms that underlie changes in fat distribution. … These findings indicate that ADF (both modified and true) produces similar beneficial modulations in body fat distribution and adiponectin levels as daily CR.