The Effects of Calcium, Vitamins D and K co-Supplementation on Markers of Insulin Metabolism and Lipid Profiles in Vitamin D-Deficient Women with Polycystic Ovary Syndrome

Green strength: The role of micronutrients in plant-based diets for athletic performance enhancement

This review examines the correlation between plant-based diets and athletic performance, with a specific emphasis on the vital aspect of optimizing micronutrients for athletes. In light of the increasing prevalence of plant-based nutrition among athletes due to its perceived advantages in terms of health, ethics, and the environment, this study investigates the ability of these diets to satisfy the demanding nutritional requirements essential for achieving optimal performance and facilitating recovery. The article emphasizes the significance of essential micronutrients such as iron, vitamin B12, calcium, vitamin D, zinc, and omega-3 fatty acids and also addressing the challenges with their absorption and bioavailability from plant sources. The review consolidates existing scientific knowledge to propose strategies for improving micronutrient consumption, comparing the effects of supplements against whole foods, and highlighting the significance of enhancing bioavailability. The proposal supports the implementation of personalized meal planning, with the assistance of sports nutritionists or dietitians, and is substantiated by case studies showcasing the success of plant-based athletes. Future research directions examine the long-term effects of plant-based diets on micronutrient status and athletic performance, as well as developing nutritional trends and technology. The review concludes that plant-based diets can meet athletes' nutritional demands and improve peak performance while aligning with personal and ethical values with strategic planning and professional guidance. This study intends to help athletes, coaches, and nutritionists understand plant-based nutrition for enhanced athletic performance.

Efficacy of antioxidant supplementation in improving endocrine, hormonal, inflammatory, and metabolic statuses of PCOS: a meta-analysis and systematic review

Background and aim: A large number of recent studies have reported on the use of antioxidants in patients with polycystic ovary syndrome (PCOS). This study aimed to evaluate the antioxidant effects on PCOS. Methods: We searched PubMed, Embase, Web of Science, and The Cochrane Library to identify randomized controlled trials investigating the use of antioxidants in treating PCOS. Statistical analysis was performed using Review Manager 5.4. Stata17.0 software was used to conduct sensitivity analyses. Results: This meta-analysis included 49 articles and 62 studies. The sample comprised 1657 patients with PCOS from the antioxidant group and 1619 with PCOS from the placebo group. The meta-analysis revealed that the fasting blood glucose levels [standardized mean difference (SMD): -0.31, 95% confidence interval (CI): -0.39 to -0.22, P < 0.00001], the homeostatic model assessment of insulin resistance (SMD: -0.68, 95% CI: -0.87 to -0.50], P < 0.00001), and insulin levels (SMD: -0.68, 95% CI: -0.79 to -0.58, P < 0.00001) were significantly lower in patients with PCOS taking antioxidants than those in the placebo group. Further, total cholesterol levels (SMD: -0.38, 95% CI: -0.56 to -0.20, P < 0.001), low-density lipoprotein cholesterol levels (SMD: -0.24, 95% CI: -0.37 to -0.10, P = 0.0008), and very low-density lipoprotein levels (SMD: -0.53, 95% CI: -0.65 to -0.41, P < 0.00001) were lower in patients with PCOS taking antioxidant supplements compared with the placebo group. Total testosterone (TT) level (SMD: -0.78, 95% CI: -1.15 to -0.42, P < 0.0001), dehydroepiandrosterone level (SMD: -0.42, 95% CI: -0.58 to -0.25, P < 0.00001), and mean standard deviation modified Ferriman-Gallway (MF-G scores) (SMD: -0.63, 95% CI: -0.98 to -0.28, P = 0.0004) were lower in patients taking antioxidant supplements. C-reactive protein (CRP) levels (SMD: -0.48, 95% CI: -0.63 to -0.34, P < 0.000001), body mass index [mean difference (MD): -0.27, 95% CI: -0.50 to -0.03, P = 0.03], weight (MD: -0.73, 95% CI: -1.35 to -0.11, P = 0.02), and diastolic blood pressure (MD: -3.78, 95% CI: -6.30 to -1.26, P = 0.003) were significantly lower. Moreover, the levels of sex hormone-binding protein (SMD: 0.23, 95% CI: 0.07-0.38, P = 0.004), high-density lipoprotein cholesterol (SMD: 0.11, 95% CI: 0.01-0.20, P = 0.03), total antioxidant capacity (SMD: 0.59, 95% CI: 0.31-0.87, P < 0.0001), and quantitative insulin sensitivity index (SMD: 0.01, 95% CI: 0.01-0.02, P < 0.00001) were higher in patients with PCOS who took antioxidant supplements compared with the placebo group. Antioxidant supplements did not affect other analyzed parameters in these patients, including follicle-stimulating hormone, free androgen index, nitric oxide, glutathione, malondialdehyde, and diastolic blood pressure. Conclusions: Antioxidants are beneficial in treating PCOS. Our study might provide a new treatment strategy for patients with clinical PCOS. We hope that more high-quality studies evaluating the effects of antioxidants on patients with PCOS will be conducted in the future. Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42023448088.

Controversial Impact of Vitamin D Supplementation on Reducing Insulin Resistance and Prevention of Type 2 Diabetes in Patients with Prediabetes: A Systematic Review

BACKGROUND

Prediabetes has become a worldwide health problem. Multiple clinical trials have been conducted to determine the potential benefits of vitamin D supplementation in preventing the conversion to diabetes, but the results are inconsistent. The aims of this study were to evaluate the current knowledge and to suggest recommendations for researchers on designing future trials regarding that matter.

METHODS

Four databases were searched for randomized control trials from the last 10 years about vitamin D and insulin resistance. The systematic electronic literature search identified 2645 studies, of which thirty-eight qualified for full-text reading and discussion. Finally, eight trials were included.

RESULTS

Final results of seven trials reported that supplementation of vitamin D does not reduce insulin resistance nor reduces the risk of diabetes mellitus type 2 development in prediabetes. Only one trial showed improvements in fasting glucose and HOMA-IR.

CONCLUSIONS

Due to the great variation and biases in study designs, an unambiguous interpretation of the results is not possible. To eliminate those vulnerabilities in the future, we made certain suggestions for study design. Long-term and well-designed studies are still required.

Low Maternal Serum 25-Hydroxyvitamin D Concentration Is Associated With Postpartum Hemorrhage: A Retrospective Observational Study

OBJECTIVE

The primary aim of this study is to investigate the relationship between vitamin D serum level and the incidence of postpartum hemorrhage (PPH). The secondary objective is to determine the relative risk of low vitamin D associated with PPH.

METHODS

This was a retrospective observational study. A total of 600 women who had delivered their babies in a single tertiary teaching hospital were enrolled. Serum blood test for 25(OH)D was performed at 35 + 0 to 36 + 6 weeks of pregnancy to measure vitamin D. A 25(OH)D level < 20 ng/mL was defined as vitamin D deficient, and a level 21-29 ng/mL as insufficient.

RESULTS

Vitamin D levels were deficient in 145 (24.1%) and insufficient in 254 (42.3%) of the women tested. Women with deficient and insufficient vitamin D levels were significantly younger than those with sufficient vitamin D levels (p < 0.001). The overall rates of PPH in the deficient and insufficient groups were 6.9% (10/145) and 6.7% (17/254), respectively, and were significantly higher than the rate of the normal vitamin D group (1.5%, p = 0.009). Women with sufficient vitamin D levels had significantly higher hemoglobin levels than those with low vitamin D levels. Higher vitamin D levels were associated with a significantly low risk of PPH (AOR: 0.93, CI: 0.89-0.98, p = 0.006).

CONCLUSION

Our results suggest that a low vitamin D level is a risk factor for PPH. Low vitamin D also related to high risk of low hemoglobin before delivery. Thus, antepartum care should include vitamin D supplements for all women if possible.

Nutritional Supplements and Complementary Therapies in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) affects 1 in 5 women of reproductive age, and is characterized by menstrual irregularities, clinical or biochemical hyperandrogenism, and the presence of polycystic ovary morphology. One of the recommended treatment strategies in the international evidence-based guidelines is lifestyle modification, which includes diet and exercise, with the aim of improving a range of health outcomes. The incurable nature of PCOS reinforces the importance of developing novel and innovative symptomatic relief strategies, which are currently the only available approaches for improving quality of life for these women. Women with PCOS tend to be nutrient deficient in many common vitamins and minerals, thought to be associated with the psychological (depression, anxiety, etc.) and physiological (insulin resistance, diabetes, infertility, etc.) sequelae of the condition. Nutrient supplementation and the integration of complementary medicine as adjuncts to traditional lifestyle-based therapies in PCOS could therefore provide additional benefits to these women. In this review, we synthesize the evidence regarding nutrient supplementation and complementary therapies in PCOS, predominantly from randomized controlled trials, systematic reviews, and meta-analyses, to provide an overview of the state of knowledge in this field. The evidence to date suggests that specific vitamins (B-12, inositols, folate, vitamins D, E, and K), vitamin-like nutrients (bioflavonoids and α-lipoic acid), minerals (calcium, zinc, selenium, and chromium picolinate), and other formulations (melatonin, ω-3 fatty acids, probiotics, and cinnamon), as well as some complementary approaches such as acupuncture and yoga may be beneficial in PCOS. However, there remain areas of uncertainty and key limitations in the literature that must be overcome before these therapies can be integrated into routine clinical practice.

PCOS and nutritional approaches: Differences between lean and obese phenotype

Polycystic Ovary Syndrome (PCOS) is an endocrine/metabolic disorder with an ever-increasing prevalence. It has various clinical characteristics; the cardinals are androgen excess, oligo-anovulatory infertility, polycystic ovaries, insulin resistance (IR), and cardiometabolic alterations. These disturbances are a consequence of PCOS's complex etiology. PCOS is mainly related to women with obesity; however, there are many PCOS lean patients too. Even though they share some aspects in their metabolic profiles, each group has individual differences in body composition and other parameters. Thus, in order to achieve successful therapeutic strategies, they should be tailored to these details. The authors reviewed PubMed's updated and related publications about body composition and nutritional strategies for PCOS lean and obese patients. As previous reports have determined, dietary patterns are essential in PCOS treatment. Several diets have been studied to control and improve IR, infertility, and cardiometabolic dysfunctions in PCOS. This review will explain the specific features in metabolic characterization and body composition among these patients. Finally, the diverse nutritional strategies used in women with PCOS will be analyzed depending on their lean or obese phenotype.

The Treatment with Complementary and Alternative Traditional Chinese Medicine for Menstrual Disorders with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a frequent gynecological female endocrinopathy, characterized by chronic anovulation, hyperandrogenism, and insulin resistance (IR). Menstrual disorders are one of the main clinical manifestations of PCOS. Other symptoms include hirsutism and/acne. At present, the treatment of PCOS with irregular menstruation is mainly based on oral contraceptives, but there are some side effects and adverse reactions. In recent years, more and more attention has been paid to the complementary and alternative medicine (CAM), which has been widely used in clinical practice. Modern Western medicine is called "conventional medicine" or "orthodox medicine," and the complementary and alternative medicine is called "unconventional medicine" or "unorthodox medicine." CAM includes traditional medicine and folk therapy around the world. Around 65-80% of world health management business is classified into traditional medicine by the World Health Organization, which is used as alternative medicine in Western countries. In our country, Chinese medicine, acupuncture, and other therapies are commonly used due to their significant efficacy and higher safety. Therefore, this review aims to summarize and evaluate the mechanisms and the effect of current complementary replacement therapy in the treatment of menstrual disorders caused by PCOS, so as to provide guidance for the following basic and clinical research.

Polycystic ovary syndrome and obesity: clinical aspects and nutritional management

INTRODUCTION

Polycystic Ovary Syndrome (PCOS) is a multifactorial endocrine and metabolic disorder characterized by androgen excess, oligo-anovulatory infertility, polycystic ovaries in ultrasound examination, insulin resistance, and cardiometabolic disorders, with overweight/obesity and visceral adiposity. This review aims to provide an overview of the clinical characteristics and nutritional therapy of PCOS and obesity.

METHODS

The authors analyzed the updated and relevant publications found on Pubmed about clinical aspects and nutritional management of PCOS and obesity in studies done in animal and human models.

DISCUSSION

It is crucial an early detection and intervention in PCOS patients to avoid the more challenging control of the onset of more impaired-health conditions that this pathology causes. It is presented evidence that clearly shows the close interaction among oxidative stress, low-grade inflammation, and PCOS. It is also analyzed the relevance of treating metabolic and nutritional correlations of PCOS with a complete therapeutic strategy that includes individualized medication, diet, and healthy habits.

CONCLUSIONS

By an integral approach and treatment that includes not only medications for PCOS symptoms, supplementation of minerals and vitamins to control PCOS complications but an antiinflammatory diet, nutritional education, exercise individualized program, lifestyle changes, it is possible to improve insulin resistance, sustained weight loss, ovulation rates, among other goals for the management of this disease. Further studies are needed to clarify mechanisms, beneficial effects, and doses of supplements and precise medication to determine the best combination of diets and exercise programs according to these patients' specific requirements.

Glycemic control improvement in individuals with type 2 diabetes with vitamin K2 supplementation: a randomized controlled trial

PURPOSE

This study aimed to investigate the effects of vitamin K₂ supplementation in the form of menaquinone-7 (MK-7) on glucose, insulin, and lipid metabolism in patients with type 2 diabetes mellitus (T2DM).

METHODS

In this double-blinded, placebo-controlled, randomized trial, 68 insulin-independent people with diabetes received either 180 µg MK-7 twice a day or placebo for 12 weeks. We assessed fasting plasma glucose (FPG) and insulin concentrations (primary outcomes), glycated hemoglobin (HbA1c), insulin sensitivity indices, and lipid profiles (secondary outcomes) at baseline and end of the trial.

RESULTS

At the end of the trial, FPG (effect size (ES) = - 0.68; p-adjusted = 0.031) and HbA1c (ES = - 0.36; p-adjusted = 0.004) were significantly lower in the vitamin K₂ group compared with the placebo at the end of the trial. The number of participants achieved the target levels of glycemic control based on FPG, and HbA1c concentrations were significantly higher in the vitamin K₂ group compared to the placebo group. Insulin concentrations (ES = - 0.29; p = 0.019) and homeostatic model assessment for insulin resistance (HOMA-IR) significantly decreased in the vitamin K₂ group (ES = - 0.29; p = 0.019) compared to baseline, but their values were not significantly different compared to the placebo group at the end of the trial. No significant variation was observed in lipid profiles.

CONCLUSION

Daily intake of 360 µg Vitamin K₂ in the form of MK-7 for 12-weeks reduces FPG and HbA1c in patients with T2DM but does not have a lipid-lowering effect.

Beneficial health effects of Menaquinone-7 on body composition, glycemic indices, lipid profile, and endocrine markers in polycystic ovary syndrome patients

OBJECTIVE

The aim of this study was to investigate the effect of oral vitamin K2 (Menaquinone-7 [MK-7]) on clinical and biochemical parameters in polycystic ovary syndrome (PCOS) patients.

METHODS

In this randomized, double-blind, placebo-controlled clinical trial, 84 PCOS patients were randomly assigned into the treatment (90 µg Menaquinone-7 daily for 8 weeks) and placebo groups. Insulin resistance, lipid profile, endocrine biomarkers, and body composition of the participants were measured before and after the intervention. This study was performed in Ghadir Mother & Child Hospital affiliated to Shiraz University of Medical Sciences, Shiraz, Iran.

RESULTS

Menaquinone-7 supplementation, when compared to placebo, significantly decreased serum fasting insulin (p = .002), homeostasis model of assessment insulin resistance (p = .002), and homeostasis model of assessment β-cell function (p = .02) in addition to a significant increase in quantitative insulin sensitivity check index (p = .001). Also, MK-7 administration led to significant declines in serum triglyceride (p = .003) and dihydrotestosterone (DHT; p = .03) levels, free androgen index (p < .001), waist circumference (p = .03), and body fat mass (p < .001) as well as significant increases in skeletal muscle (p < .001) and sex hormone binding globulin (SHBG, p < .001).

CONCLUSIONS

This study highlights the beneficial effects of MK-7 on insulin resistance, fat mass, skeletal muscle, and serum levels of triglyceride, DHT, and SHBG in PCOS patients. Therefore, it seems that MK-7 supplementation might be an appropriate additive treatment for PCOS patients.

Effects of vitamin D supplementation on serum lipid profile in women with polycystic ovary syndrome: A protocol for a systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is the commonest endocrine disorder in reproductive-aged women. In addition to the reproductive consequences, PCOS is also characterized by a metabolic disorder, which may play a part in the etiology of anovulation and has important implications for long-term health as well. Vitamin D deficiency is prevalent in PCOS and there is a close relationship between metabolic dysfunction and vitamin D status in women with PCOS. The purpose of this systematic analysis is to evaluate the effect of vitamin D supplementation on serum lipid profiles in patients with PCOS.

METHODS

We will search five databases for relative studies: Medline, the Cochrane Library, EMBASE, Web of Science, and ClinicalTrials.gov and identified all reports of randomized controlled trials published prior to July 2020. Two authors will independently scan the articles searched, extract the data from articles included, and assess the risk of bias by Cochrane tool of risk of bias. Disagreements will be resolved by discussion among authors. All analysis will be performed based on the Cochrane Handbook for Systematic Reviews of Interventions. Fixed-effects model or random-effects model was used to calculate pooled estimates of weighted mean difference (WMD) with 95% confidence intervals.

RESULTS

This review will be to assess the effect of vitamin D supplementation on serum lipid profiles in patients with PCOS. The results of the study will be published in a scientific journal after peer-review.

CONCLUSIONS

These findings will provide guidance to clinicians and patients on the use of vitamin D for PCOS with dyslipidemia.

ETHICS AND DISSEMINATION

This study is a protocol for a systematic review of vitamin D as a treatment of dyslipidemia in PCOS patients.

SYSTEMATIC REVIEW REGISTRATION

INPLASY202050007.

Immunophenotypic Profiles in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) a long-known endocrinopathy and one of the most common endocrine-reproductive-metabolic disorders in women, which can lead to infertility. Although the precise etiology remains unclear, PCOS is considered as a complex genetic trait, with a high degree of heterogeneity. Besides, hormones and immune cells, including both innate and adaptive immune cells, are reportedly a cross talk in PCOS. Chronic low-grade inflammation increases autoimmune disease risk. This proinflammatory condition may, in turn, affect vital physiological processes that ultimately cause infertility, such as ovulation failure and embryo implantation. Here, we review the accumulating evidence linking PCOS with inflammatory status providing an overview of the underlying hormone-mediated dysregulation of immune cells. We mainly focus on the correlational evidence of associations between immune status in women and the increased prevalence of PCOS, along with the specific changes in immune responses. Further recognition and exploration of these interactions may help elucidate PCOS pathophysiology and highlight targets for its treatment and prevention.

Vitamin K: a nutrient which plays a little-known role in glucose metabolism

PURPOSE OF REVIEW

Type 2 diabetes is one of the most important public health diseases. Type 2 diabetes pathophysiology involves multiple pathways, in which micronutrients could play a role. Among them, interest has grown concerning vitamin K. The purpose of this review is to expose the latest studies on the role of vitamin K in glucose metabolism, a poorly known function of this vitamin.

RECENT FINDINGS

Animal experimentations and human observational and interventional studies were analyzed to evaluate the role of this vitamin in glucose metabolism. Daily intake of vitamin K seems to improve glucose metabolism and low intakes could be involved in type 2 diabetes pathophysiology. Recent data show that vitamin K could act on glucose metabolism via downstream targets such as osteocalcin, growth arrest-specific 6 protein, and matrix Gla protein.

SUMMARY

This review depicts new insights into the role of vitamin K in glucose metabolism regulation and depicts also the probable mechanisms underlying this association. Further studies will be needed to determine the dose and the duration of vitamin K treatment to achieve the strongest metabolic effect. Maybe the best strategy to improve glucose metabolism would be 'cocktails' of micronutrients associating vitamin K.

Dietary calcium status during maternal pregnancy and lactation affects lipid metabolism in mouse offspring

Calcium plays important roles in lipid metabolism and adipogenesis, but whether its status in early life affects later lipid profiles needs to be clarified. Three to four-week old C57BL/6J female mice were fed with three different reproductive diets containing normal, low (insufficient) and high (excessive) calcium concentrations respectively throughout pregnancy and lactation. At postnatal 21 days, the weaning male and female pups from each group were sacrificed for experiments and the remaining were fed with the normal chow diet for 16 weeks. Meanwhile, some of the weaning female pups from maternal low calcium diet group were fed with the normal calcium, low calcium and high calcium mature diets respectively for 8 weeks. Maternal insufficient or excessive calcium status during pregnancy and lactation programmed an abnormal expression of hepatic and adipose genes (PPAR-γ, C/EBP-α, FABP4, Fasn, UCP2, PPAR-α, HMG-Red1, Acc1, and SREBP-1c) in the offspring and this may lead to dyslipidemia and accumulation of hepatic triglyceride (TG) and total cholesterol (TC) in later life. The effects of maternal calcium status on lipid metabolism were found only in the female adult offspring, but were similar between offspring males and females at postnatal 21 days. Additionally, the dyslipidemia and hepatic lipid accumulation caused by insufficient calcium status in early life may be reversed to some extent by dietary calcium supplementation in later life.

The Role of Vitamin D Oral Supplementation in Insulin Resistance in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate the effect of vitamin D supplementation (alone or with co-supplementation) on insulin resistance in patients with polycystic ovary syndrome (PCOS).

METHODS

We performed a literature search of databases (Medline, Scopus, Web of Knowledge, Cochrane Library) and identified all reports of randomized controlled trials (RCTs) published prior to April 2018. We compared the effects of supplementation with vitamin D alone (dose from 1000 IU/d to 60,000 IU/week) or with co-supplements to the administration of placebos in women diagnosed with PCOS. The systematic review and meta-analysis protocol was registered in the International Prospective Register of Systematic Reviews (Prospero) as number CRD42018090572.

MAIN RESULTS

Eleven of 345 identified studies were included in the analysis; these involved 601women diagnosed with PCOS. Vitamin D as a co-supplement was found to significantly decrease fasting glucose concentrations and the HOMA-IR value. HOMA-IR also declined significantly when vitamin D was supplemented with a dose lower than 4000 IU/d.

CONCLUSIONS

Evidence from RCTs suggests that the supplementation of PCOS patients with continuous low doses of vitamin D (<4000 IU/d) or supplementation with vitamin D as a co-supplement may improve insulin sensitivity in terms of the fasting glucose concentration (supplementation with vitamin D in combination with other micronutrients) and HOMA-IR (supplementation with vitamin D in continuous low daily doses or as co-supplement).

The Resulting Variation in Nutrient Intake With the Inclusion of Walnuts in the Diets of Adults at Risk for Type 2 Diabetes: A Randomized, Controlled, Crossover Trial

PURPOSE

We previously demonstrated that including walnuts in the diets of adults at risk for type 2 diabetes mellitus (T2DM) led to improved overall diet quality. This report examines the specific changes in their nutrient intake.

DESIGN

This was a randomized, controlled, modified Latin square parallel design trial with 2 treatment arms. Participants were randomized to walnut intake with, or without, dietary advice to regulate caloric intake. Within each treatment arm, they were further randomized to one of 2 sequence permutations (walnut-included/walnut-excluded or walnut-excluded/walnut-included diet), with a 3-month washout between treatment phases.

SETTING

Community hospital in Lower Naugatuck Valley in Connecticut.

PARTICIPANTS

Cohort of 112 participants (31 men and 81 women) at risk for T2DM.

INTERVENTION

Participants included 56 g (366 kcal) of walnuts in their daily diets for 6 months.

MEASURES

Nutrient intake was assessed using web-based Automated Self-Administered 24-Hour Dietary Assessment.

ANALYSIS

Data were analyzed using generalized linear models.

RESULTS

Walnut inclusion led to increased intake of total fat, calcium, magnesium, thiamin, total saturated fatty acids, and monounsaturated and polyunsaturated fatty acids (379.0 ± 90.3 g vs -136.5 ± 92.7 g, P < .01; 230.7 ± 114.2 mg vs -95.2 ± 117.4 mg, P = .05; 111.0 ± 33.9 mg vs -32.3 ± 34.9 mg, P < .01; 0.28 ± 0.2 mg vs -0.47 ± 0.2 mg, P = .02; 8.6 ± 3.4 g vs -1.1 ± 3.5 g, P =.05; 6.3 ± 3.9 g vs -6.3 ± 4.0 g, P = .03; and 25.4 ± 4.0 vs -6.6 ± 4.2 g, P < .01, respectively). Vitamin C intake decreased (-65.3 ± 55.3 mg vs 98.9 ± 56.8 mg, P = .04). Protein intake increased from baseline with the inclusion of walnuts (20.0 ± 8.8 g, P < .05). Walnut inclusion led to an increase in total calories consumed when caloric intake is not regulated.

CONCLUSION

Including walnuts in the diets of these adults led to increased dietary intake of some nutrients associated with lower risk of developing T2DM and other cardiometabolic risk factors.

The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review

Vitamins D and K are both fat-soluble vitamins and play a central role in calcium metabolism. Vitamin D promotes the production of vitamin K-dependent proteins, which require vitamin K for carboxylation in order to function properly. The purpose of this review is to summarize available evidence of the synergistic interplay between vitamins D and K on bone and cardiovascular health. Animal and human studies suggest that optimal concentrations of both vitamin D and vitamin K are beneficial for bone and cardiovascular health as supported by genetic, molecular, cellular, and human studies. Most clinical trials studied vitamin D and K supplementation with bone health in postmenopausal women. Few intervention trials studied vitamin D and K supplementation with cardiovascular-related outcomes. These limited studies indicate that joint supplementation might be beneficial for cardiovascular health. Current evidence supports the notion that joint supplementation of vitamins D and K might be more effective than the consumption of either alone for bone and cardiovascular health. As more is discovered about the powerful combination of vitamins D and K, it gives a renewed reason to eat a healthy diet including a variety of foods such as vegetables and fermented dairy for bone and cardiovascular health.

Vitamin D deficiency causes insulin resistance by provoking oxidative stress in hepatocytes

Vitamin D deficiency could cause insulin resistance. However, the underlying mechanisms are unclear. The 1α-Hydroxylase [“1α(OH)ase”] is a key enzyme for activate vitamin D3 synthesis. Here, we show that 1α(OH)ase stable knockdown by targeted shRNA led to vitamin D3 depletion in L02 hepatocytes. 1α(OH)ase silence also inhibited insulin-induced downstream signaling (IRS-1, ERK and AKT) transduction and glucose transporter 4 expression. Further, 1α(OH)ase shRNA in L02 hepatocytes led to significant reactive oxygen species production, p53-p21 activation and DNA damages. Such effects were almost completely reversed with co-treatment of n-acetylcysteine, which is an established anti-oxidant. Remarkably, insulin-induced downstream signaling transduction and glucose transporter 4 expression were recovered with n-acetylcysteine co-treatment in 1α(OH)ase-silenced L02 hepatocytes. Together, our results suggest that vitamin D deficiency-induced insulin resistance is possibly caused by oxidative stress in hepatocytes.

Insulin resistance in vitamin D-deficient mice is alleviated by n-acetylcysteine

Vitamin D deficiency will lead to insulin resistance. In the current study, vitamin D3 1α-Hydroxylase [“1α(OH)ase”] knockout mice were generated to mimic vitamin D deficiency in vivo. As compared to the wild-type mice, the liver tissues of the knockout mice showed impaired insulin signaling, decreased glucose transporter 4 expression and increased reactive oxygen species production. Meanwhile, p53-p21 activation, apoptosis intensity and pro-inflammatory cytokines (IL-6, IL-1 and MIP-1α) level were significantly increased in the knockout mice livers. Significantly, such effects in the knockout mice were largely attenuated by supplement with anti-oxidant n-acetylcysteine (NAC). Remarkably, insulin resistance and metabolic abnormalities in the knockout mice were largely alleviated after treatment of NAC. Therefore, inhibition of oxidative stress by NAC alleviated insulin resistance in vitamin D-deficient mice. Oxidative stress could be the primary cause of insulin resistance by vitamin D deficiency.