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All, Al posted a new review article  which discusses all the available evidence relating calorie restriction, protein restriction, and methionine restriction to bone health. It basically goes over many of the things we've discussed here before - like the fact that DEXA bone scanners aren't well-calibrated for very thin people, and that CRed organisms have lighter bones, but not necessarily bones that are lower in quality, or more fragile. I like the way they summarize in the free full text: In the pursuit of survival with enhanced growth and development, human beings have come to suffer the negative effects of excessive nutrition.Currently, it may be appropriate to reevaluate the possibility that dietary restriction actually shapes a skeletal system to a size or mass suitable for the organism rather than causes an unfavorable loss of bone mineral. A philosophy of achieving optimal bone quality may be more important than preserving maximal bone size/mass when considering skeletal health under various dietary restrictions. As I said, nothing really new, but it's nice to see all the reassuring evidence suggesting our skeletons aren't crumbling away as a result of CR. --Dean ------------  Ann N Y Acad Sci. 2016 Feb 16. doi: 10.1111/nyas.13004. [Epub ahead of print] Dietary restrictions, bone density, and bone quality. Huang TH(1), Ables GP(2). Author information: (1)Laboratory of Exercise, Nutrition and Bone Biology, Institute of Physical Education, Health and Leisure Studies, National Cheng Kung University, Tainan, Taiwan. (2)Orentreich Foundation for the Advancement of Science, Cold Spring-on-Hudson, New York. Free full text: http://onlinelibrary.wiley.com/doi/10.1111/nyas.13004/epdf Caloric restriction (CR), protein restriction (PR), and specific amino acid restriction (e.g., methionine restriction (MR)) are different dietary interventions that have been confirmed with regard to their comprehensive benefits to metabolism and health. Based on bone densitometric measurements, weight loss induced by dietary restriction is known to be accompanied by reduced areal bone mineral density, bone mass, and/or bone size, and it is considered harmful to bone health. However, because of technological advancements in bone densitometric instruments (e.g., high-resolution X-ray tomography), dietary restrictions have been found to cause a reduction in bone mass/size rather than volumetric bone mineral density. Furthermore, when considering bone quality, bone health consists of diverse indices that cannot be fully represented by densitometric measurements alone. Indeed, there is evidence that moderate dietary restrictions do not impair intrinsic bone material properties, despite the reduction in whole-bone strength because of a smaller bone size. In the present review, we integrate research evidence from traditional densitometric measurements, metabolic status assays (e.g., energy metabolism, oxidative stresses, and inflammatory responses), and biomaterial analyses to provide revised conclusions regarding the effects of CR, PR, and MR on the skeleton. © 2016 New York Academy of Sciences. PMID: 26881697
Michael R posted a topic in CR Science & TheoryAll: Those of you who have been CR Society members and/or followers of the old CR Society email listserv may remember the CRONA study, a UCSF study on human CR that recruited CR Society members (overlapping significantly with Dr. Luigi Fontana's studies at WUSTL). The study was intended to serve the diverse research interests of the investigators: most of the investigators, including Dr. Tomiyama (who was really leading the effort and responsible for subjects on a day-to-day basis) are psychologists, and primarily working in obesity and eating disorder fields, and wanted to better understand what makes long-term CR people so darned successful at maintaining fairly severe (by human standards) CR for years and years, when in practice the attrition rate from weight loss programs based on reducing *excess* Calorie intake (despite the fact that people on diets of the latter sort don't even "need" the extra Calories the way we do). Data on this were published in (1), which are now freely available in full-text thanks to the wise use of the tax dollars of American taxpayers. However, the part that they talked up the most in their press coverage and in their recruitment efforts was the effect of CR on "telomere lengths," because telomere lengths are a very "sexy" area of aging research, at least in the public imagination. Since many dieters experience a lot of subjective stress, and CR in humans, nonhuman primates, and rodents caused elevated wake-period cortisol, it isn't crazy to hypothesize that we might have SHORT telomeres; alternatively, of course, you might have expected that we would have unusually LONG telomeres as a result of a good diet and healthy lifestyle, or a CR-driven deceleration of the aging process. in reality, the logitudinal data (studies following the same person over time) don't support an association between shorter mean leukocyte telomere length (which, everyone should remember, is what is actually being studied in all of these telomere length studies -- rather than critically-short telomeres and/or the length of telomeres in solid organs) and long-term health or survival outcomes (eg, (2-4). Also, many things that are bad for you (smoking, inflammation, overweight, physical inactivity, etc) shorten your mean telomere length in the short term — yet the effects wash out in the long term (4); that clearly shows that those things are not bad for you because they reduce mean telomere lengths. It's n=1, but my mean leukocyte telomere lenthgths are unremarkable (and yes, I was of the opinion that it was an irrelevant market before I learned this ;) ; separately, long-time CR practitioner and all around great guy David Fischer got his leukocycte telomere length measured as part of a UK TV special, and it was dead average, even tho' he's a ~20-year CR practitioner with an excellent regimen and stupendous bloodwork, and who was estimated by one of the leading dermatologists in the UK to be in his mid-thirties when he was actually 51: https://www.youtube.com/watch?feature=player_detailpage&v=TElbEVlYZo4#t=5 (If that isn't an embedded video, see the Dave Fisher CR video here). We were given blood tests and a range of psycological and neurophysiological tests along with detailed verbal interviews on psychological matters, and they were quite up-front about what they were doing at every stage. ANYWAY: One part of the study was to compare the performance of the Bod Pod (a device that is based on similar principles to underwater hydrostatic weighing but is done in an airtight chamber) to DEXA, the gold standard measure of %body fat. Several subjects who are very, very lean noted that our Bod Pod results were way, way out of whack to our DEXA results, indicating that we had the typical, excessive %fats of average Americans when in fact they are similar to or lower than Olympic athletes. Now, those results have been published in free full-text,(4) and indeed, they found that Bod Pod does OK for the middle of the anthropometric range (tho' it's not great even there: see studies reviewed here), but at both extremes, it falls apart. I was alerted to this study via an update from the investigators, which includes the following on the mean leukocyte telomere length and other blood data: So: watch this space! References 1: Clues to Maintaining Calorie Restriction? Psychosocial Profiles of Successful Long-term Restrictors. Belsky AC, Epel ES, Tomiyama AJ. Appetite. 2014 Apr 16. pii: S0195-6663(14)00171-8. doi: 10.1016/j.appet.2014.04.006. [Epub ahead of print] PMID:24747211 2: Bendix L, Thinggaard M, Fenger M, Kolvraa S, Avlund K, Linneberg A, Osler M. Longitudinal changes in leukocyte telomere length and mortality in humans. J Gerontol A Biol Sci Med Sci. 2014 Feb;69(2):231-9. doi: 10.1093/gerona/glt153. Epub 2013 Oct 22. PubMed PMID: 24149432. 3: Mather KA, Jorm AF, Parslow RA, Christensen H. Is telomere length a biomarker of aging? A review. J Gerontol A Biol Sci Med Sci. 2011 Feb;66(2):202-13. doi: 10.1093/gerona/glq180. Epub 2010 Oct 28. Review. PubMed PMID: 21030466. 4: Weischer M, Bojesen SE, Nordestgaard BG. Telomere shortening unrelated to smoking, body weight, physical activity, and alcohol intake: 4,576 general population individuals with repeat measurements 10 years apart. PLoS Genet. 2014 Mar 13;10(3):e1004191. doi: 10.1371/journal.pgen.1004191. eCollection 2014 Mar. PubMed PMID: 24625632; PubMed Central PMCID: PMC3953026. 5: Lowry DW, Tomiyama AJ. Air displacement plethysmography versus dual-energy x-ray absorptiometry in underweight, normal-weight, and overweight/obese individuals. PLoS One. 2015 Jan 21;10(1):e0115086. doi: 10.1371/journal.pone.0115086. eCollection 2015. PubMed PMID: 25607661; PubMed Central PMCID: PMC4301864.