Nutrition and Bone: It is More than Calcium and Vitamin D

Cod Liver Oil, but Not Retinoic Acid, Treatment Restores Bone Thickness in a Vitamin A-Deficient Rat

Vitamin A plays a prominent role for maintaining optimal bone status, but its impact upon the bone in response to vitamin A deficiency is not well defined. The purpose of this study was to evaluate how replenishing vitamin A by either whole food cod liver oil (COD) or the active metabolite of vitamin A, retinoic acid (RA), altered bone thickness of vitamin A-deficient (VAD) rats. Weanling rats were administered a control diet (CTRL) or VAD diet for 9 weeks. This was followed by four weeks of treatment in which the VAD group was divided into the following 4 subgroups: (1) VAD (9 weeks)-VAD (4 weeks); (2) VAD-CTRL; (3) VAD-COD; and (4) VAD-RA. Compared to controls, VAD rats had thicker bones which showed marked dysplasia. VAD-rats treated with COD produced a thinner bone that was not significantly different from that of untreated rats. In contrast, RA did not significantly change the thicker bone, and also had significantly greater periosteal and endosteal osteoblast numbers compared to VAD-COD. Active osteoclasts were not detected in VAD rats, nor during the treatment period. These findings suggest that the abnormal bone thickness in VAD rats appears to be more effectively restored to bone thickness of untreated control rats when treated with COD.

Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis

Context

The numbers of vegans and vegetarians have increased in the last decades. However, the impact of these diets on bone health is still under debate.

Objective

This systematic review and meta-analysis sought to study the impact of vegetarian and vegan diets on bone mineral density (BMD) and fracture risk.

Data Sources

A systematic search was conducted of PubMed, Scopus, and Science Direct, covering the period from the respective start date of each database to November 2017.

Data Extraction

Two investigators evaluated 275 studies against the inclusion criteria (original studies in humans, written in English or Spanish and including vegetarian or vegan diets and omnivorous diets as factors with BMD values for the whole body, lumbar spine, or femoral neck and/or the number of fractures as the outcome) and exclusion criteria (articles that did not include imaging or studies that included participants who had suffered a fracture before starting the vegetarian or vegan diet). The quality assessment tool for observational cohort and cross-sectional studies was used to assess the quality of the studies.

Results

Twenty studies including 37 134 participants met the inclusion criteria. Compared with omnivores, vegetarians and vegans had lower BMD at the femoral neck and lumbar spine and vegans also had higher fracture rates.

Conclusions

Vegetarian and vegan diets should be planned to avoid negative consequences on bone health.

Systematic Review Registration

PROSPERO registration no. CRD42017055508.

Association Between Dietary Fiber Intake and Bone Loss in the Framingham Offspring Study

Dietary fiber may increase calcium absorption, but its role in bone mineralization is unclear. Furthermore, the health effect of dietary fiber may be different between sexes. We examined the association between dietary fiber (total fiber and fiber from cereal, fruits, vegetables, nuts, and legumes) and bone loss at the femoral neck, trochanter, and lumbar spine (L2 to L4 ) in older men and women. In the Framingham Offspring Study, at baseline (1996-2001), diet was assessed using the Willett food-frequency questionnaire, and bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Follow-up BMD was measured in 2001-2005 and 2005-2008 among 792 men (mean age 58.1 years; BMI 28.6 kg/m2 ) and 1065 women (mean age 57.3 years; BMI 27.2 kg/m2 ). We used sex-specific generalized estimating equations in multivariable regressions to estimate the difference (β) of annualized BMD change in percent (%ΔBMD) at each skeletal site per 5 g/d increase in dietary fiber. We further estimated the adjusted mean for bone loss (annualized %ΔBMD) among participants in each higher quartile (Q2, Q3, or Q4) compared with those in the lowest quartile (Q1) of fiber intake. Higher dietary total fiber (β = 0.06, p = 0.003) and fruit fiber (β = 0.10, p = 0.008) was protective against bone loss at the femoral neck in men but not in women. When examined in quartiles, men in Q2-Q4 of total fiber had significantly less bone loss at the femoral neck versus those in Q1 (all p < 0.04). For women, we did not observe associations with hip bone loss, although fiber from vegetables appeared to be protective against spine bone loss in women but not men. There were no associations with cereal fiber or nut and legume fiber and bone loss in men or women. Our findings suggest that higher dietary fiber may modestly reduce bone loss in men at the hip. © 2017 American Society for Bone and Mineral Research.

Alternative therapies for the prevention and treatment of osteoporosis

Osteoporosis is a medical condition that affects millions of men and women. People with this condition have low bone mass, which places them at increased risk for bone fracture after minor trauma. The surgeries and treatments required to repair and heal bone fractures involve long recovery periods and can be expensive. Because osteoporosis occurs frequently in the elderly, the financial burden it places on society is likely to be large. In the United States, the Food and Drug Administration has approved several drugs for use in the prevention and treatment of osteoporosis. However, all of the currently available agents have severe side effects that limit their efficacy and underscore the urgent need for new treatment options. One promising approach is the development of alternative (nonpharmaceutical) strategies for bone maintenance, as well as for the prevention and treatment of osteoporosis. This review examines the currently available nonpharmaceutical alternatives that have been evaluated in in vitro and in vivo studies. Certain plants from the following families have shown the greatest benefits on bone: Alliceae, Asteraceae, Thecaceae, Fabaceae, Oleaceae, Rosaceae, Ranunculaceae, Vitaceae, Zingiberaceae. The present review discusses the most promising findings from studies of these plant families.

Association between the Healthy Eating Index and bone turnover markers in US postmenopausal women aged ≥45 y

BACKGROUND

Some studies have reported that overall diet quality affects bone status in postmenopausal women; however, the findings are inconsistent.

OBJECTIVES

Our primary objective was to examine the association between overall diet quality and bone turnover markers (BTMs) in postmenopausal women aged ≥45 y by using the Healthy Eating Index 2005 (HEI-2005)-a diet quality-assessment tool-developed by the US Department of Agriculture. Our secondary objective was to explore the associations between the components of the HEI-2005 and the MyPyramid food groups and BTMs.

DESIGN

We used cross-sectional data from NHANES 1999-2002. Multiple regression models with adjustments for relevant confounders were used to examine the relation between the total HEI-2005 score and its components and food groups and serum bone-specific alkaline phosphatase (BAP), a biomarker of bone formation, and urinary N-telopeptides/creatinine (uNTx/Cr), a biomarker of bone resorption.

RESULTS

No association was found between the total HEI-2005 score and BTMs. The milk group component of HEI-2005 had a significant negative linear relation with uNTx/Cr. Women in the lowest tertile of the MyPyramid milk group had the highest uNTx/Cr. Those in the highest tertile of energy-adjusted added sugar intake had the highest BAP.

CONCLUSIONS

Our results support the ability of a healthy diet with adequate dairy intake to promote bone health in aging women. However, we found that the HEI-2005 is not a good measure of healthy eating for optimal bone health. Further research is needed to develop an overall dietary assessment tool in relation to bone health for postmenopausal women.

Cortical and trabecular bone, bone mineral density, and resistance to ex vivo fracture are not altered in response to life-long vitamin A supplementation in aging rats

High vitamin A (VA) intakes have been correlated with increased risk of bone fracture. Over 50% of the U.S. adult population reports use of dietary supplements, which can result in VA intakes > 200% of the RDA. In this study, 2 experiments were designed to determine the effect of dietary VA on cortical and trabecular bone properties and resistance to ex vivo fracture. In Expt. 1, we investigated whether orally administered VA accumulates in bone. Seven-week-old rats were treated daily with VA (6 mg/d for 14 d). Total retinol increased in both the tibia and femur (P < 0.01). In Expt. 2, we conducted a longitudinal study in which rats were fed 1 of 3 levels of dietary VA (marginal, adequate, and supplemented, equal to 0.35, 4, and 50 μg retinol/g diet, respectively) from weaning until the ages of 2-3 mo (young), 8-10 mo (middle-age), and 18-20 mo (old). Tibial trabecular and cortical bone structure, bone mineral density, and resistance to fracture were measured using micro-computed tomography and material testing system analysis, respectively. The VA-marginal diet affected measures of cortical bone dimension, suggesting bone remodeling was altered. VA supplementation increased medullary area and decreased cortical thickness in young rats (P < 0.05), but these changes were not present during aging. VA supplementation did not affect resistance to fracture or bone mineral content in old rats. From these results, we conclude that VA-marginal status affects trabecular bone more than cortical bone, and VA supplementation at a moderate level over the lifetime is unlikely to increase the risk of age-related bone fracture in rats.

Safety and toxicological evaluation of AlgaeCal (AC), a novel plant-based calcium supplement

The present study was conducted to examine the safety of a novel plant-based calcium supplement, derived from marine algae and containing high levels of calcium, magnesium, and other bone supporting minerals (commercially known as AlgaeCal (AC)). The present study evaluated the broad-spectrum safety of AC using a variety of toxicological assays including acute oral, acute dermal, primary skin irritation, and primary eye irritation toxicity. Under the conditions of the study, the acute oral LD(50) of AC was found to be greater than 5000 mg/kg body weight in rats, while the single acute dermal LD(50) was greater than 2000 mg/kg body weight. The primary skin irritation index of AC was found to be 0.4 and classified as slightly irritating to the skin. In primary eye irritation studies, the maximum mean total score of AC was observed to be 13.7 and classified as mildly irritating to the eye. Furthermore, another independent set of studies was conducted to obtain preliminary data for the teratogenic effects of AC in pregnant rats likely to arise from repeated gestational exposure, via oral gavage, over a test period of implantation through gestation (gestation days 5-19). Under the conditions of this pilot study, the effect of daily administration of AC by oral gavage at dose levels of 0, 500, 2500, and 5000 mg/kg/day during gestation days 5-19 of a 21-day pregnancy has appeared to result in no adverse toxicological effects to the pregnant rat or its developing offspring. A slight, non-significant increase in the incidence of incomplete sterna ossification (5(th) center) was observed. Under the conditions of the study, a no-observed-adverse effect level (NOAEL) of 5000 mg/kg/day of AC during pregnancy of the rat was observed. Overall, no significant toxicities of AC were observed in these toxicity models. Therefore, the results from the current study demonstrate a broad-spectrum safety profile of AC.