Caloric restriction and bone health -
Interestingly, the difference in bone volume between the CR and AD groups disappeared after 1 yr of age, and mice and rats on an additional extension of CR to natural death maintained higher bone mass than the AD groups, with reduced bone turnover, suggesting that CR slows skeletal aging by regulating the rate of bone turnover.
This is the first report, to our knowledge, that has examined the effects of lifelong CR on bone metabolism and trabecular microstructure and documents its contrasting effects during maturation vs. the postmaturational, involutional period.
FRAGILITY FRACTURES DUE to osteoporosis is a serious cause of morbidity and mortality and imposes a major economic burden in aged societies 1.
Osteoporosis is a multifactorial disease, and lifestyle as well as genetic factors contribute to age-related bone loss and fragility 2 , 3. In addition to low bone mineral density, clinical factors including age, female sex, premature menopause, previous fracture, a family history of fracture, low body mass index, glucocorticoid use, excessive alcohol consumption, and cigarette smoking constitute risk factors for bone fragility and fracture 3.
Caloric restriction CR extends the lifespan of various organisms as diverse as yeast, worms, flies, and mammals and delays the progression of geriatric disorders, such as malignancy, neurodegenerative disease, renal disease, cataract, and immune disease 4.
How CR affects bone metabolism is controversial, and little is known of the long-term effects of CR per se. It has been reported that CR ameliorates age-related bone loss in male Fisher F rats through a prevention of secondary hyperparathyroidism 5.
On the other hand, others report that CR results in bone loss in aging male rats 6 and rhesus monkeys 7. Little is known about the effects of CR on bone cell activity, and the mechanism by which CR affects bone remodeling remains to be clarified. The results indicate that CR exerts biphasic effects on bone depending on the duration of the restriction; until 1 yr of age, CR decreases bone mass, mainly through a suppression of bone formation, which activity involves leptin signaling and elevated sympathetic nervous tone.
In contrast, CR for more than 2 yr has a protective effect against age-related bone loss through reducing the rate of bone turnover. This is the first report, to our knowledge, that clarifies the effects of CR on bone physiology throughout life and may have implications for optimizing nutritional programs for human bone health.
Tetracycline hydrochloride and calcein were purchased from Sigma-Aldrich Corp. Louis, MO. Tokyo, Japan and raised at Oriental Bio-service Kyoto, Japan. CR was started at the age of 3 months by alternate-day feeding; mice and rats were fed three times per week Monday, Wednesday, and Friday , a commonly used method in aging research 8.
The animal experiments were carried out in accordance with the ethical guidelines for animal care of NCGG, and the experimental protocols were approved by the animal care committee. Total RNA was isolated from the mouse hypothalamus with TRIzol reagent Invitrogen, San Diego, CA.
For quantitative RT-PCR, total RNA 1 μg was reverse transcribed using Superscript III Invitrogen , and samples were analyzed using a Light Cycler system Roche Diagnostics, Basel, Switzerland.
Serum leptin, insulin, and IGF-I concentrations were determined by using rat leptin RIA and rat insulin RIA kits Linco Research, Inc. Serum albumin and calcium and urinary calcium concentrations were determined by using an autoanalyzer Hitachi , Japan.
Micro-CT scanning was performed on proximal tibiae using a μCT scanner SCANCO Medical AG, Bassersdorf, Switzerland with a resolution of 12 μm, and microstructure parameters were calculated three-dimensionally as described previously The proximal tibia was positioned to be scanned craniocaudally using slices with 12μm increments at 55 kVp and 72 μA.
On the original three-dimensional 3D image, morphometric indices, including bone volume BV , tissue volume TV , trabecular thickness Tb. Th , trabecular separation Tb. Sp , and trabecular number Tb. N , were directly determined from the binarized volume of interest.
Nonmetric parameters, such as structure model index SMI and connectivity density Conn-Dens. Sections were prepared and stained with Villanueva Goldner to discriminate between mineralized and unmineralized bone and to identify cellular components.
Histomorphometric parameters were measured at the Ito Bone Science Institute Niigata, Japan. Nomenclature and units were used according to the recommendation of the nomenclature committee of the American Society for Bone and Mineral Research.
Bone strength was assessed in femurs by the four-point bending test, according to the previously reported methods 12 , Mechanical tests were performed at the Japan Fine Ceramics Center Nagoya, Japan using a materials testing machine type ; Instron, Norwood, MA.
Specimens were loaded in the anterior-posterior plane at a constant displacement rate of 0. The distances between the upper loading and lower support points were 4 and 8 mm, respectively.
A N load cell was used to measure the load applied to the specimens, and displacement was measured with a linear variable differential transducer.
Load and displacement data were collected using Merlin software Instron. Data are expressed as means ± sem. CR was started when animals reached 3 months of age. As shown in Fig. Body weight changes in CR mice and rats. Body weight was measured every week until 28 wk and every 4—5 wk thereafter.
The time scale is provided as both time after the start of CR upper values and the age of animals lower values in weeks. at the age of 9 months. In addition, detailed microstructure analysis of trabecular bone of mice and rats revealed that after 6 months of CR, Tb.
N and Tb. Th as well as Conn. decreased significantly, whereas SMI and Tb. Sp increased Fig. Assessment of maximal load by the four-point bending test indicated that bone strength in the femurs of CR group was indeed significantly weaker than that of the control AD group Fig.
Chronic CR induces reduced bone mass, deteriorated trabecular structure, and decreased bone strength. A and B, Representative micro-CT images of trabecular bone at the proximal tibiae of AD feeding vs.
CR mice A and AD vs. CR rats B at the age of 9 months i. after 6 months of CR. C, Microstructural parameters derived from micro-CT analysis of trabecular bone at the proximal tibiae of AD vs. CR mice. D, Bone strength after 6 months of CR was determined by maximal load at the femur by the four-point bending test.
E, Reduced bone mass by CR is not due to a concomitant reduction in calcium intake. Micro-CT scanning of proximal tibia again revealed the 3D BV decreased by this continuous CR for 6 months, as with the CR by alternate-day feeding Fig.
To examine whether the decreased bone mass after chronic CR was due to suppressed bone formation, accelerated bone resorption, or a combination of both mechanisms, histomorphometric analyses were performed at the tibial metaphysis.
When CR mice aged 9 months were switched to AD feeding, the suppression of the BFR was reversed Fig. CR causes suppression of bone formation with transiently elevated bone resorption.
A, Results of histomorphometric analysis at the proximal tibiae of AD vs. CR mice after 6 months of CR. Data are normalized for the BS.
B, Reversibility of the effects of CR on bone mass. C, Continuous suppression of bone formation by CR. The time scale is provided as both the time after the start of CR upper values and the age of the animals lower values in months M.
The suppressive effect of CR on bone formation was observed as early as 1 month after the initiation of CR and consistently for at least 9 months Fig. On the other hand, a consistent change in bone resorption was not observed; osteoclast surface Oc.
Collectively, these data suggest that the decreased bone mass after chronic CR is mainly due to suppressed bone formation, although a transient increase in bone resorption may have helped enhance the effect.
Biochemical markers of energy metabolism were assessed after 6 months of CR in the blood samples of rats due to the availability of a larger volume of samples.
There was no significant difference in serum calcium concentrations between the AD and CR groups Fig. Accordingly, serum leptin concentrations as well as insulin, IGF-I, and blood sugar levels were significantly reduced after long-term CR Fig. It is conceivable, therefore, that an altered signaling of these hormones may have affected bone metabolism under CR.
Blood biochemical characteristics under long-term CR. The results of serum, whole blood, and plasma biochemistry in AD white bars vs. CR black bars rats is shown. Blood was collected at the age of 9 months i.
CR reduces bone mass through leptin signaling and sympathetic nervous tone. CR black bar regimen for 4 months. Representative micro-CT images are shown to the right. D, Expression of NMU in the hypothalamus of CR vs. AD mice. RNA was extracted from the hypothalamus after CR for the indicated periods in months, M and subjected to quantitative RT-PCR.
E, Involvement of the sympathetic nervous system. The decrease in bone mass by CR was prevented by propranolol Pro , a β-blocker, whereas isoproterenol Iso , a β-stimulant, reduced BV in AD mice.
Consistent with this notion are the results that the expression of neuromedin U NMU , a mediator of the antiosteogenic action of leptin in the hypothalamus 15 , was increased in the hypothalamus of CR mice in the face of reduced circulating leptin concentrations, compared with the AD group Fig.
It has been demonstrated that the suppression of bone formation induced by leptin is mediated through an increased sympathetic nervous tone and signaling through the β2-adrenergic receptor expressed on osteoblasts To examine the involvement of the sympathetic nervous system in the suppressive effect of CR on bone, the effect of blocking adrenergic tone on bone mass under the CR regimen was examined.
Conversely, when mice were treated with isoproterenol, a β-stimulant, BV decreased, even in the AD group, down to the CR level Fig. Treatment with isoproterenol did not cause a further reduction in BV in CR mice Fig.
These results are consistent with our concept that the reduced BV by CR is mediated through increased activity of the sympathetic nervous system. We examined the time course of the effects of CR on 3D BV. After CR was initiated at the age of 3 months, there was a significant decrease in bone mass at 3 months of CR i.
at the age of 6 months , and a clear-cut reduction in BV was also observed after 6—9 months of CR i. at the age of 9—12 months Fig. However, the effect of CR on BV became more and more obscure thereafter, and after 13—17 months of CR i. at the age of 16—20 months , BV was indistinguishable between CR and AD mice Fig.
In fact, after 24 months of CR i. at the age of 27 months , CR mice exhibited a modestly but significantly higher bone mass than the AD control group Fig. CR protects against age-related bone loss by reducing bone turnover. A, Changes in the 3D BV fraction at the proximal tibiae of AD white bars vs.
CR black bars mice, as determined by micro-CT, were followed at the indicated times. The time scale is provided as both the time after the start of CR upper values and the age of mice in months lower values. B, Representative micro-CT images of trabecular bone in the proximal tibiae of AD vs.
CR mice at natural death at the indicated age in months M. C, Microstructural parameters derived from micro-CT analysis of trabecular bone at the proximal tibiae of life-long CR mice black bars. The age at death is provided below in months M as the mean ± sem. D, Results of histomorphometric analysis of the proximal tibiae of AD white bars vs.
CR black bars mice after 24 months of CR. Oc, Number of osteoclasts. Because CR extends the maximal lifespan, the average age of CR mice at death was higher than that of the control AD group Detailed microstructure analysis indicates that the higher bone mass in CR mice was associated with increased Tb.
Th and connectivity and decreased SMI Fig. The protective effects of lifelong CR on age-related bone loss and microstructural deterioration were also confirmed in F rats Fig.
CR protects against age-related bone loss and microstructural deterioration in F rats. A, Representative micro-CT images of trabecular bone at the proximal tibiae of AD vs. CR F rats at natural death at the indicated age in months M. B, Microstructural parameters derived from micro-CT analysis of trabecular bone at the proximal tibiae of AD white bars vs.
CR black bars F rats. The age at death is provided below in months M as mean ± sem for each group. Finally, to gain some insight into the mechanism by which CR countered age-related bone loss, histomorphometric analysis was performed at the tibiae at the age of 27 months i.
after 2 yr of CR. The results indicate that the number of osteoclasts N. With respect to indices of bone formation, the osteoblast surface Ob. These data suggest that the higher bone turnover rate in aged AD animals is mitigated by CR and that CR counters the aging-related bone loss by reducing bone turnover.
Thus, regulation of bone turnover appears to be a protective strategy deployed by CR against skeletal aging. Nutrition, especially the intake of calcium and vitamin D, is an important remedy for maintaining bone health. The present study demonstrates that under physiological conditions, the amount of total caloric intake per se has a profound impact on bone remodeling.
Under these conditions, bone resorption and subsequently bone formation are stimulated, with a net balance such that the former exceeds the latter, resulting in bone loss and structural deterioration. CR with relatively increased calcium content failed to reverse the reduction in bone mass, which lends further support to our conclusion that a reduction in caloric, not calcium intake, is responsible for the decreased bone formation and bone mass induced by CR.
Bone remodeling, performed by bone-resorbing osteoclasts and bone-building osteoblasts, functions under hormonal 19 , 20 , neuronal 21 , immunological 22 , and mechanical 23 , 24 control. Recently, much attention has been focused on the central control of bone remodeling Mice harboring genetic mutations in leptin signaling and the sympathetic nervous system have provided powerful tools in dissecting molecular pathways that link energy homeostasis to bone remodeling 16 , However, the physiological conditions under which the pathway operates have been elusive.
Our data suggest that changes in leptin signaling may be involved in the suppression of bone formation and osteopenia after chronic CR.
The effects of leptin on bone metabolism appear to be complex and to depend on the site and type of bone analyzed. In addition, leptin treatment partially prevents the bone loss induced by ovariectomy in the trabecular bone of the proximal tibia in rats 27 and counters the inhibition of the longitudinal effects of calorie deprivation in young mice Leptin can affect bone metabolism not only through the central nervous system 16 but also through a peripheral pathway by acting directly on the cells in bone 29 , A recent study demonstrates that NMU-deficient mice exhibit high bone mass with increased bone formation and are resistant to the antiosteogenic effects of leptin and isoproterenol, suggesting that NMU is a mediator of the antiosteogenic action of the leptin-sympathetic nervous system The data show that treatment with propranolol blocked the suppressive effect of CR on bone.
Taken together with the link between central leptin signaling and the peripheral sympathetic nervous system 17 , one plausible hypothesis is that leptin signaling regulates bone metabolism in response to CR through increased activity of the sympathetic nervous system.
However, the data cannot rule out the possibility that the adrenergic receptor responds to CR independently of leptin signaling. Importantly, this study discloses another and unexpected aspect of CR, namely a protective effect against age-related bone loss during the latter half of life.
Histomorphometric analysis of 1- vs. Although CR animals had gained less bone during young adulthood, they maintained a higher bone mass after 27 months of age. This protection from skeletal aging is likely to be attained by reducing bone turnover, because reduced osteoclast number and activity with a reduced bone formation rate was observed in aged CR mice compared with the AD group.
At present, there is no evidence for the involvement of leptin signaling in the slower age-related bone loss in the CR group, and more studies are required to identify which factor s specifically elicited by the CR regimen provides protection against skeletal aging by reducing bone turnover.
In conclusion, if the present results were to extrapolate to humans, it would follow that excessive dieting during young adulthood would be discouraged, whereas a mild reduction in calorie intake after middle age would be encouraged to help slow the aging of the skeleton.
It remains to be determined whether CR during the latter half of life alone has a protective effect or a whether combination of AD and CR, i. AD feeding until 1 yr of age followed by CR thereafter, would be even more effective in maintaining skeletal health in rodents, both by increasing peak bone mass and by slowing the rate of age-related bone loss.
As such, it is sometime referred to as CRON, for "calorie restriction with optimal nutrition. Leanne M. Redman, from Pennington Biomedical Research Center in Baton Rouge, Louisiana, and colleagues conclude. These results are based on a study of 46 subjects who were randomly assigned to one of four diets: a normal healthy diet; a percent calorie restriction diet; a percent calorie restriction plus aerobic exercise diet; or a low-calorie diet followed by weight maintenance.
The average loss of body weight ranged from 1. With the calorie restriction diet, the average loss was Compared with the healthy diet, none of the other diets were associated with significant changes in bone thickness. SOURCE: Archives of Internal Medicine, September 22, Read Next.
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Uncountable restricfion care calric, clinicians, and individuals are Nutrient timing for vitamins and minerals to prevent calooric and the many chronic medical caloriic linked to it by advocating a rextriction lifestyle that includes measures such as reducing dietary restricfion intake i. Although these caloric restriction and bone health are traditionally considered healthy, their Lentils soup recipe impact on restritcion health has yet to be established, and some studies have reported that they have negative effects on bone outcomes. Although data on this subject are limited to small studies and there is no information specifically referring to fractures, CR, but not IF, seems to reduce BMD but does not seem to affect bone quality. Vegetarian diets particularly vegan ones are associated with significantly lower BMD values with respect to omnivorous ones and could, potentially, increase the risk of fractures. This is a preview of subscription content, log in via an institution to check access. Rent this article via DeepDyve. Institutional subscriptions.An restriction, especially hwalth caloric restriction and bone health with exercise, restdiction make bones smaller and weaker, according Hunger relief organizations new anc in mice. In contrast, exercising while on a full calorie restrictkon can benefit bone cqloric, say Hypertension and vitamin D levels researchers.
They heath their investigation and its results in a recent Journal bobe Bone and Mineral Helath paper. Hralth Styner, an restrition professor of medicine at caloric restriction and bone health University of North Carolina at Chapel Hill.
Resstriction is not hone inert material but very much alive; it caloric restriction and bone health continually renewing itself. During Electrolyte Balance Maintenance, new bone restricfion happens faster than annd caloric restriction and bone health old bone, resulting Fiber and gut microbiome bigger, heavier, healt denser bones.
Bone formation continues outpacing bone heaalth until restrkction the age of 20—30 years, during which time it peaks anc most people. They boen do this by acloric regular exercise, not smoking, not claoric too much adn, and retriction that they restrlction a jealth amount of an D and calcium in healty diet.
Osteoporosis caloricc when restrictionn formation is too slow, when removal is too quick, or both. The condition, which caloirc to affect females more often than calori, weakens bones and makes them more restruction to reetriction. Scientists suggest that one reason osteoporosis is more common Grape Vine Pest Control Methods females Nutrient absorption process in the intestines because their bones tend to be smaller calorif thinner.
Another healfh could bome because menopause brings on a sudden drop in acloricresteiction hormone that can protect andd. Styner suggests that the new findings could nad particularly relevant for women caolric as they age, their bone caloric restriction and bone health starts to deteriorate naturally.
In their investigation, Dr. Styner and colleagues calofic on bone marrow fat. Scientists do not erstriction understand how this Prevention programs and initiatives of fat works. They suspect restrichion it is harmful caloric restriction and bone health Fasting for weight loss in humans and other mammals.
Skincare for sun-damaged skin studies have suggested calpric lower levels of bone marrow fat are usually an indication of good heaoth health.
In earlier work, Dr. Adn had examined how Vehicle Fuel Monitoring consumption relates to bone marrow fat and anf exercise restrictiom influence this link. Those studies showed, for example, that levels of bone marrow fat go up when excess calorie consumption leads to obesity.
They also found that when mice of a normal weight and mice with obesity exercised, it caused a drop in their bone marrow fat and improved their bone density.
The purpose of the new study was to find out what happens to bone marrow fat and bone health during calorie restriction. The researchers split mice into two groups. The calorie restricted mice received supplements of minerals and vitamins so that these nutrient intakes matched those of the mice on the normal diet.
The team then split the mice again, into sedentary and exercise subgroups, and monitored them for 6 weeks. The results showed that although the calorie restricted mice lost weight, their bone marrow fat levels went up significantly. These mice also experienced a decrease in bone quantity.
The researchers conclude that the bone loss in the calorie restricted mice was due to calorie reduction alone and not lack of nutrients, since the mice had the same vitamin and mineral intake as their regular diet counterparts.
The team found that, as expected from previous studies, adding exercise to calorie restriction led to a reduction in bone marrow fat.
However, it unexpectedly also led to a reduction in overall quantity and quality of bone. The researchers were surprised to find that under conditions of calorie restriction, exercise appears to make bones more fragile — not more robust.
They are already planning further investigations to better understand the function of bone marrow fat. In particular, they wish to learn about the underlying mechanisms that cause diet and exercise to produce the effects that they found.
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Medical News Today. Health Conditions Health Products Discover Tools Connect. Calorie restriction plus exercise can make bones more fragile. By Catharine Paddock, Ph. on September 13, — Fact checked by Jasmin Collier.
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: Caloric restriction and bone health| Calorie Restriction Does Not Appear To Induce Bone Loss In Overweight Adults | ScienceDaily | Healtu Heart Inst J — PubMed PubMed Caloric restriction and bone health Google Scholar Forouhi NG, Wareham NJ Epidemiology of diabetes. Despite weight loss, the EX group did not demonstrate a decrease in BMD at any site. Trends Endocrinol Metab 14 : — Rocz Panstw Zakl Hig 65 1 :9— Purchase access. |
| Exercising While Restricting Calories Could be Bad for Bone Health | CR mice. JAMA and Archives Journals. Although there were no significant changes in bone-specific alkaline phosphatase levels from baseline within each group, the change in bone-specific alkaline phosphatase at 6 months in the EX group was greater than the corresponding changes in the CR and HL groups. decreased significantly, whereas SMI and Tb. The 3 groups did not differ on baseline demographic and clinical characteristics except for age, with the EX group being slightly older than the CR group Table 1. This resulted in varied responses by anatomical location and between cortical versus trabecular bone. The researchers were surprised to find that under conditions of calorie restriction, exercise appears to make bones more fragile — not more robust. |
| The effects of calorie restriction, intermittent fasting and vegetarian diets on bone health | Barbour KE, Lui LY, Ensrud KE et al Inflammatory markers and risk of hip fracture in older white women: the study of osteoporotic fractures. J Bone Miner Res — Ding C, Parameswaran V, Udayan R et al Circulating levels of inflammatory markers predict change in bone mineral density and resorption in older adults: a longitudinal study. J Clin Endocrinol Metab — Veronese N, Shivappa N, Hebert J et al Pro-inflammatory dietary pattern is associated with fractures in women: an eight year longitudinal cohort study. Osteoporos Int S71—S Article Google Scholar. Dennison E, Syddall H, Sayer AA et al Type 2 diabetes mellitus is associated with increased axial bone density in men and women from the Hertfordshire Cohort Study: evidence for an indirect effect of insulin resistance? Diabetologia — Veronese N, Stubbs B, Crepaldi G et al Relationship between low bone mineral density and fractures with incident cardiovascular disease: a systematic review and meta-analysis. J Bone Miner Res 32 5 — Huang T, Ables GP Dietary restrictions, bone density, and bone quality. Ann N Y Acad Sci — Soltani S, Hunter G, Kazemi A et al The effects of weight loss approaches on bone mineral density in adults: a systematic review and meta-analysis of randomized controlled trials. Osteoporos Int — Ensrud K, Vo T, Burghardt A et al Weight loss in men in late life and bone strength and microarchitecture: a prospective study. Osteoporosis Int 29 7 — Article CAS Google Scholar. Villareal DT, Fontana L, Weiss EP et al Bone mineral density response to caloric restriction-induced weight loss or exercise-induced weight loss: a randomized controlled trial. Arch Intern Med — Villareal DT, Fontana L, Das SK et al Effect of two-year caloric restriction on bone metabolism and bone mineral density in non-obese younger adults: a randomized clinical trial. Villareal DT, Kotyk JJ, Armamento-Villareal RC et al Reduced bone mineral density is not associated with significantly reduced bone quality in men and women practicing long-term calorie restriction with adequate nutrition. Aging Cell — Schoell S, Weaver A, Beavers D et al Development of subject-specific proximal femur finite element models of older adults with obesity to evaluate the effects of weight loss on bone strength. J Osteoporosis Phys Act. Davis CS, Clarke RE, Coulter SN et al Intermittent energy restriction and weight loss: a systematic review. Eur J Clin Nutr — Patterson RE, Sears DD Metabolic effects of intermittent fasting. Annu Rev Nutr — Bahijri SM, Ajabnoor GM, Borai A et al Effect of Ramadan fasting in Saudi Arabia on serum bone profile and immunoglobulins. Ther Adv Endocrinol Metab — Barnosky A, Kroeger CM, Trepanowski JF et al Effect of alternate day fasting on markers of bone metabolism: an exploratory analysis of a 6-month randomized controlled trial. Nutr Healthy Aging — Pilis W, Stec K, Zych M et al Health benefits and risk associated with adopting a vegetarian diet. Rocz Panstw Zakl Hig 65 1 :9— PubMed Google Scholar. Sabaté J, Wien M Vegetarian diets and childhood obesity prevention. Am J Clin Nutr S—S. Rizzo NS, Sabaté J, Jaceldo-Siegl K et al Vegetarian dietary patterns are associated with a lower risk of metabolic syndrome: the adventist health study 2. Diabetes Care — Snowdon DA, Phillips RL Does a vegetarian diet reduce the occurrence of diabetes? Am J Public Health — Kwok CS, Umar S, Myint PK et al Vegetarian diet, seventh day adventists and risk of cardiovascular mortality: a systematic review and meta-analysis. Int J Cardiol — Fraser GE Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California seventh-day adventists. Am J Clin Nutr s— s. Craig WJ Health effects of vegan diets. Veronese N, Solmi M, Caruso MG et al Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. Am J Clin Nutr — Abid Z, Cross AJ, Sinha R Meat, dairy, and cancer. Institute of Medicine US Standing Committee on the Scientific Evaluation of Dietary Reference Intakes Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. National Academies Press US , Washington DC. Google Scholar. Tucker KL Vegetarian diets and bone status. Ho-Pham LT, Nguyen ND, Nguyen TV Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. Iguacel I, Miguel-Berges ML, Gómez-Bruton A et al Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis. Nutr Rev — Shams-White MM, Chung M, Du M et al Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation, 2. CAS PubMed Google Scholar. Weaver CM, Proulx WR, Heaney R Choices for achieving adequate dietary calcium with a vegetarian diet. Tai V, Leung W, Grey A et al Calcium intake and bone mineral density: systematic review and meta-analysis. BMJ h Roman-Garcia P, Quiros-Gonzalez I, Mottram L et al Vitamin B dependent taurine synthesis regulates growth and bone mass. J Clin Investig — Burckhardt P The role of low acid load in vegetarian diet on bone health: a narrative review. Although fat in the bone is poorly understood, to date it is thought to be harmful to bones of mammals, including humans, because it makes bone weaker. Less fat is usually an indication of better bone health. Exercise in both obese and normal weight mice decreased bone marrow fat and improved the density of bones. The latest study looked at what happens to bone marrow fat and overall bone health when restricting calories. There were four groups of mice in all — a group on a regular diet RD , a group on a calorie-restricted CR diet, a RD group that exercised RD-E , and a CR group that exercised CR-E. Mice in the CR group ate 30 percent less than what RD mice ate. A 30 percent reduction would equal a diet of 1, calories per day, which is around the amount suggested to most women trying to lose weight at a rate of one pound a week. Both CR groups of mice were given supplements of vitamins and minerals to match the amount the RD group received from the extra food they ate. This, Styner says, is an indication that the effect on bone health was from calorie restriction, and not a lack of nutrients. These factors inform about the activity of osteoblasts and osteoclasts, which themselves are regulated by numerous systemic and local regulators such as leptin, parathyroid hormone PTH , calcitriol, calcitonin, growth hormone GH , insulin-like growth factor 1 IGF-1 , glucocorticoids, thyroid hormones, estrogens, androgens, transforming growth factor TGF -beta, and cytokines 17, In this section, we discuss the existing studies examining the impact of caloric restriction on bone health with an emphasis on molecular markers of bone remodeling. Studies in this area vary widely in the 1 specific caloric restriction employed, 2 duration of dietary restriction, and 3 species or strain studied. Hamrick et al. studied the effects of increasing caloric restriction with time on bone health in mice [19]. This resulted in varied responses by anatomical location and between cortical versus trabecular bone. Compared to mice fed ad libitum, calorie-restricted mice displayed decreased femoral and vertebral cortical thickness whereas trabecular bone in both locations was unchanged femora or increased vertebrae. Importantly, calorie-restricted mice had reduced femoral fracture strength. These changes were associated with a decrease in both serum leptin and IGF-1 in response to caloric restriction. These results are generally consistent with Delvin et al. Compared to mice fed ad libitum, calorie-restricted mice displayed impaired skeletal growth resulting in smaller body size and low bone mass. These changes were associated with reduced bone formation rate with increased bone resorption rate and decreased levels of serum leptin and IGF Interestingly, one study using mice and rats suggests that the effects of prolonged caloric restriction on bone mass appear impacted by age, with chronic caloric restriction preventing age-related bone loss. It is unclear if this finding is due to the prolonged nature of this intervention or if short duration caloric restriction in aged mice or rats impacts bone health Studies on the impact of caloric restriction in human subjects have produced inconsistent findings. For instance, Riedt et al. Although leading to weight loss, this intervention did not impact bone mineral density or serum bone turnover markers In contrast, Villareal et al. Notably, individuals on a high protein diet plus caloric restriction experience less bone loss than caloric restriction alone 29 , suggesting that the amount of bone loss during caloric restriction may be mitigated by specifically increasing protein intake. In this section, we discuss the relatively limited data examining the impact of intermittent fasting on bone health. For instance, Clayton et al. examined how fasting for twenty-four hours affects bone turnover markers in humans during the re-feeding period and found no impact on bone turnover markers between fasting and control subjects This is generally consistent with Barnosky et al. in which they compared six months of alternate-day fasting compared to caloric restriction on bone metabolism in obese adults. Bone mineral density and bone turnover markers were unchanged in either group compared to individuals on the control diet In contrast, Bahijri et al. examined the effects of intermittent fasting on bone markers during the Muslim holiday of Ramadan in which observers fast from sunrise until sunset and found decreased evening PTH levels after two weeks of IF. This study did not include an assessment of bone mineral density and it is unclear if this effect is due to caloric restriction, sleep disturbance, or other factors such as alteration in mineral intake with evening serum calcium significantly higher during Ramadan Significant discrepancies exist within this literature, especially with regard to the length of intervention, degree of restriction, etc. A relatively small sample size is an additional limitation, particularly for the human subject trials. This underscores the need for future work to replicate previous study designs and provide independent corroboration of findings in diverse patient populations. That said, it is generally consistent across species and multiple studies that caloric restriction negatively influences bone mass; at present, it appears that intermittent fasting may not. It is important to note, however, that bone mass is only one aspect of fracture risk and measurements of fracture rate, bone strength, and bone quality are generally lacking in the studies detailed here. Future study is required to address this important limitation of the current literature. These articles were screened by CH and AE for relevance to the topic, eliminating publications. Intramural funds for the publication of this work were provided to JWL by Marian University. Copyright: © Lowery JW. This article is distributed under the terms of the Creative Commons Attribution 4. Home Articles Article Details. Introduction Osteoporosis is a chronic condition characterized by low bone mass and places individuals at increased risk for fracture. Bone Remodeling and Bone Health Bone matrix is produced by cells called osteoblasts and resorbed by cells called osteoclasts. Caloric Restriction and Bone Health In this section, we discuss the existing studies examining the impact of caloric restriction on bone health with an emphasis on molecular markers of bone remodeling. Intermittent Fasting and Bone Health In this section, we discuss the relatively limited data examining the impact of intermittent fasting on bone health. Conflict of Interest The authors declare no conflicts of interest. |
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