The Hyperglycemia and Hyperketonemia Impaired Bone Microstructures: A Pilot Study in Rats

The effects of popular diets on bone health in the past decade: a narrative review

Bone health encompasses not only bone mineral density but also bone architecture and mechanical properties that can impact bone strength. While specific dietary interventions have been proposed to treat various diseases such as obesity and diabetes, their effects on bone health remain unclear. The aim of this review is to examine literature published in the past decade, summarize the effects of currently popular diets on bone health, elucidate underlying mechanisms, and provide solutions to neutralize the side effects. The diets discussed in this review include a ketogenic diet (KD), a Mediterranean diet (MD), caloric restriction (CR), a high-protein diet (HP), and intermittent fasting (IF). Although detrimental effects on bone health have been noticed in the KD and CR diets, it is still controversial, while the MD and HP diets have shown protective effects, and the effects of IF diets are still uncertain. The mechanism of these effects and the attenuation methods have gained attention and have been discussed in recent years: the KD diet interrupts energy balance and calcium metabolism, which reduces bone quality. Ginsenoside-Rb2, metformin, and simvastatin have been shown to attenuate bone loss during KD. The CR diet influences energy imbalance, glucocorticoid levels, and adipose tissue, causing bone loss. Adequate vitamin D and calcium supplementation and exercise training can attenuate these effects. The olive oil in the MD may be an effective component that protects bone health. HP diets also have components that protect bone health, but their mechanism requires further investigation. In IF, animal studies have shown detrimental effects on bone health, while human studies have not. Therefore, the effects of diets on bone health vary accordingly.

Effects of very low carbohydrate ketogenic diets on skeletal health

PURPOSE OF REVIEW

Very low carbohydrate ketogenic diet (KD) therapy has been associated with skeletal demineralization in children with drug-resistant epilepsy, but the cause of this association is unclear. Recently, interest in the KD has grown owing to its potential benefits for other illnesses including cancer, type 2 diabetes, obesity, and polycystic kidney disease. Summaries of the best available evidence regarding effects of a KD on skeletal health are lacking.

RECENT FINDINGS

Recent rodent studies found that a KD can harm the growing skeleton, which corroborates most but not all studies in pediatric patients. Proposed mechanisms include chronic metabolic acidosis and depressed osteoanabolic hormones. Relative to other weight-reducing diets, a weight-reducing KD for treatment of obesity and/or type 2 diabetes in adults has not been associated with adverse skeletal effects. By contrast, recent evidence suggests that adaptation to a eucaloric KD may impair bone remodeling in elite adult athletes. Discrepancies in the literature may relate to differences between study populations and in diet formulation.

SUMMARY

Attention to skeletal health is warranted when using KD therapy given the uncertainty in the literature and suggestive harms in certain populations. Future research should focus on potential mechanisms of injury.

Analysis of high-intensity interval training on bone mineral density in an experimental model of type 2 diabetes

PURPOSE

To analyze the effect of high-intensity interval training (HIIT) on bone mineral density (BMD) in a model of type 2 diabetes mellitus.

METHODS

Thirty-two male, adult, 12-week-old rats (Rattus norvegicus), of the Wistar lineage, were used. The animals induced to the experimental model received a high fat diet for 10 days and, after that period, intraperitoneal injection of streptozotocin (40 mg·kg-1), dissolved in 20 mmol·L-1 sodium citrate solution (pH = 4.5). The experimental group of diabetes was formed by the animals that, 48 h after the injection of streptozotocin, had fasting blood glucose > 250 mg·dL-1). The animals were randomly divided into four groups with eight animals each: HIIT experimental diabetes; HIIT control; sedentary experimental diabetes and sedentary control. The animals in the HIIT group performed an aerobic exercise protocol on a treadmill inclined at an angle of 15° to the horizontal, with interspersed intensity. Five weekly sessions, lasting 49 min each, were held for 6 weeks. The analysis of cortical bone density (CBD) and BMD were performed by X-ray images using the In-Vivo Xtreme II/Bruker system.

RESULTS

For CBD and BMD, when comparing diabetes and control groups, a significant difference was seen between groups in relation to HIIT (p = 0.007). Animals submitted and not submitted to HIIT in the same group showed a significant difference between groups in relation to diabetes (p < 0.001).

CONCLUSIONS

The HIIT experimental diabetes group had increased CBD and BMD in comparison with the sedentary experimental diabetes group.

Dietary Complex and Slow Digestive Carbohydrates Promote Bone Mass and Improve Bone Microarchitecture during Catch-Up Growth in Rats

Catch-up growth is a process that promotes weight and height gains to recover normal growth patterns after a transient period of growth inhibition. Accelerated infant growth is associated with reduced bone mass and quality characterized by poor bone mineral density (BMD), content (BMC), and impaired microarchitecture. The present study evaluated the effects of a diet containing slow (SDC) or rapid (RDC) digestible carbohydrates on bone quality parameters during the catch-up growth period in a model of diet-induced stunted rats. The food restriction period negatively impacted BMD, BMC, and microarchitecture of appendicular and axial bones. The SDC diet was shown to improve BMD and BMC of appendicular and axial bones after a four-week refeeding period in comparison with the RDC diet. In the same line, the micro-CT analysis revealed that the trabecular microarchitecture of tibiae and vertebrae was positively impacted by the dietary intervention with SDC compared to RDC. Furthermore, features of the cortical microstructure of vertebra bones were also improved in the SDC group animals. Similarly, animals allocated to the SDC diet displayed modest improvements in growth plate thickness, surface, and volume compared to the RDC group. Diets containing the described SDC blend might contribute to an adequate bone formation during catch-up growth thus increasing peak bone mass, which could be linked to reduced fracture risk later in life in individuals undergoing transient undernutrition during early life.

The Comparative Study on the Status of Bone Metabolism and Thyroid Function in Diabetic Patients with or without Ketosis or Ketoacidosis

PURPOSE

This study aims to identify changes in bone turnover markers and thyroid function in diabetic ketosis (DK) and diabetic ketoacidosis (DKA).

MATERIALS AND METHODS

We compared data from the Department of Endocrinology at Shanghai Pudong Hospital from 2018 to 2020 on the pancreatic status and previous glucose control, bone transformation, calcium homeostasis, and thyroid function in groups with diabetes (DM alone, n=602), DK (n=232), and DKA (n=60). Similar comparisons were made in recurrent DK (A) (n=17) and single DK (A) (n=272).

RESULTS

The fasting C-peptide level decreased significantly, but hemoglobin A1c (HbA1c) levels were higher in DK or DKA (p<0.05). Blood calcium and 25-hydroxyvitamin D3 (25-OH-VitD3) levels were significantly lower in DKA (p<0.05), but parathyroid hormone (PTH) levels remained constant across all three groups. The N-terminal middle molecular fragment of osteocalcin (N-MID) and β-C terminal cross-linking telopeptide of type 1 collagen (β-CTX) showed significant inverse alterations in DKA, regardless of gender or age (p<0.05). Otherwise, DKA significantly inhibited thyroid function (p<0.05). Furthermore, Spearman correlation analyses revealed a relationship between N-MID and HbA1c in DM alone (r=-0.27, p<0.01), while total triiodothyronine (TT3, r=0.62, p<0.01) or free T3 (FT3, r=0.61, p<0.01) in DK, and DKA (TT3, r=0.45, p<0.01; FT3, r=0.43, p<0.01). Multilinear regression analyses revealed that β-CTX (β=0.564), HbA1c (β=-0.196), TT3 (β=0.183), and 25-OH-VitD3 (β=-0.120) were the only independent determinants of N-MID in DM, whereas FT3 (β=0.491), β-CTX (β=0.315) in DK, and FT3 (β=0.420), β-CTX (β=0.367), TG (β=-0.278) in DKA. Only 25-OH-VitD3 was found to be significantly lower in recurrent DK (A) than in single onset DK (A) (p<0.05), and β-CTX (β=0.745) was found to be significantly independently associated with N-MID.

CONCLUSION

Our preliminary findings show a dramatic change in bone turnover markers in DM patients with DK and DKA, and this change may be related to thyroid function.

Protective effects of low-magnitude high-frequency vibration on high glucose-induced osteoblast dysfunction and bone loss in diabetic rats

Objective

Low-magnitude high-frequency vibration (LMHFV) has been reported to be capable of promoting osteoblast proliferation and differentiation. Reduced osteoblast activity and impaired bone formation were related to diabetic bone loss. We investigated the potential protective effects of LMHFV on high-glucose (HG)-induced osteoblasts in this study. In addition, the assessment of LMHFV treatment for bone loss attributed to diabetes was also performed in vivo.

Method

MC3T3-E1 cells induced by HG only or treated with LMHFV were treated in vitro. The experiments performed in this study included the detection of cell proliferation, migration and differentiation, as well as protein expression. Diabetic bone loss induced by streptozotocin (STZ) in rats was established. Combined with bone morphometric, microstructure, biomechanical properties and matrix composition tests, the potential of LMHFV in treating diabetes bone loss was explored.

Results

After the application of LMHFV, the inhibiting effects of HG on the proliferation, migration and differentiation of osteoblasts were alleviated. The GSK3β/β-catenin pathway was involved in the protective effect of LMHFV. Impaired microstructure and biomechanical properties attributed to diabetes were ameliorated by LMHFV treatment. The improvement of femur biomechanical properties might be associated with the alteration of the matrix composition by the LMHFV.

Conclusion

LMHFV exhibited a protective effect on osteoblasts against HG by regulating the proliferation, migration and differentiation of osteoblasts. The function of promoting bone formation and reinforcing bone strength made it possible for LMHFV to alleviate diabetic bone loss.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02803-w.

Strontium-incorporated titanium implant surfaces treated by hydrothermal treatment enhance rapid osseointegration in diabetes: A preclinical vivo experimental study

OBJECTIVES

The aim of the current study was to explore effects of strontium-incorporated titanium implant surfaces by hydrothermal treatment on osseointegration in diabetic rats.

MATERIALS AND METHODS

The surface characteristics of SLA and SLA-Sr surfaces were detected by related instruments. Thirty-six male Sprague-Dawley rats were induced into diabetes, and thirty-six rats were normal. SLA and SLA-Sr implants were, respectively, inserted into bilateral tibial metaphysis of each rat. Percentage of bone-to-implant contact (BIC%) and percentage of bone area (BA%) were analyzed at 4 and 8 weeks after implantation. Immunohistochemistry of osteoprotegerin (OPG) and Wnt5a were conducted at 1 and 4 weeks. Gene expression levels of inflammatory cytokines and related signaling molecules in peri-implant bone tissue were detected at 3 and 7 days.

RESULTS

Strontium was uniformly distributed on SLA-Sr surfaces, and it was released in an effective concentration range. SLA-Sr surfaces showed significantly higher BIC% in diabetic rats at 4 (p < .05) and 8 weeks (p < .05). Besides, it displayed higher BIC% at 4 weeks (p < .05) in normal rats. Also, SLA-Sr surfaces upregulated expression of OPG at 4 weeks (p < .05) in diabetic rats. What's more, SLA-Sr surfaces downregulated inflammation (TNF-α, IL-1β, and IL-6; p < .01) in diabetic rats at 3 days. In addition, expression of Wnt5a and ROR2 was upregulated (p < .05) at 7 days after implantation under diabetes.

CONCLUSION

It is suggested that strontium-incorporated titanium implant surfaces by hydrothermal treatment could enhance implant osseointegration as compared with SLA implant surfaces in diabetic rats.