Tag Archives: review

Review: Cyclists Have Low Bone Density

Abstract

Cycling and bone health: a systematic review.

Cycling is considered to be a highly beneficial sport for significantly enhancing cardiovascular fitness in individuals, yet studies show little or no corresponding improvements in bone mass.
A scientific literature search on studies discussing bone mass and bone metabolism in cyclists was performed to collect all relevant published material up to April 2012. Descriptive, cross-sectional, longitudinal and interventional studies were all reviewed. Inclusion criteria were met by 31 studies.
Heterogeneous studies in terms of gender, age, data source, group of comparison, cycling level or modality practiced among others factors showed minor but important differences in results. Despite some controversial results, it has been observed that adult road cyclists participating in regular training have low bone mineral density in key regions (for example, lumbar spine). Conversely, other types of cycling (such as mountain biking), or combination with other sports could reduce this unsafe effect. These results cannot yet be explained by differences in dietary patterns or endocrine factors.
From our comprehensive survey of the current available literature it can be concluded that road cycling does not appear to confer any significant osteogenic benefit. The cause of this may be related to spending long hours in a weight-supported position on the bike in combination with the necessary enforced recovery time that involves a large amount of time sitting or lying supine, especially at the competitive level.

Olmedillas H, González-Agüero A, Moreno LA, Casajus JA…
BMC Med 2012
PMID: 23256921 | Free Full Text

Review: Calcium, Vitamin D, K, B, C Essential for Bone Quality

Abstract

[Diabetes mellitus and osteoporosis. Dietary therapy of diabetes related osteoporosis].

Diabetic patients are prone to fracture, even when their bone mineral density (BMD) is high, suggesting that BMD is not exclusive factor for bone health. Bone strength is determined by BMD and bone quality, the latter of which could influence fracture risk in diabetic patients. Calcium, vitamin D and vitamin K are essential for increasing and/or maintaining BMD. Vitamin B group and C, which contribute to maintain bone quality, are also important. Intake of these mineral and vitamins under controlling energy consumption plays a key role for bone health.

Uenishi K
Clin Calcium Sep 2012
PMID: 22932295

Review: Vitamin K1 and MK-4 Reduce Bone Loss

Abstract

Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trials.

Observational and some experimental data suggest that low intake of vitamin K may be associated with an increased risk of fracture.
To assess whether oral vitamin K (phytonadione and menaquinone) supplementation can reduce bone loss and prevent fractures.
The search included the following electronic databases: MEDLINE (1966 to June 2005), EMBASE (1980 to June 2005), the Cochrane Library (issue 2, 2005), the ISI Web of Science (1945 to June 2005), the National Research Register (inception to the present), Current Controlled Trials, and the Medical Research Council Research Register.
Randomized controlled trials that gave adult participants oral phytonadione and menaquinone supplements for longer than 6 months were included in this review.
Four authors extracted data on changes in bone density and type of fracture. All articles were double screened and double data extracted.
Thirteen trials were identified with data on bone loss, and 7 reported fracture data. All studies but 1 showed an advantage of phytonadione and menaquinone in reducing bone loss. All 7 trials that reported fracture effects were Japanese and used menaquinone. Pooling the 7 trials with fracture data in a meta-analysis, we found an odds ratio (OR) favoring menaquinone of 0.40 (95% confidence interval [CI], 0.25-0.65) for vertebral fractures, an OR of 0.23 (95% CI, 0.12-0.47) for hip fractures, and an OR of 0.19 (95% CI, 0.11-0.35) for all nonvertebral fractures.
This systematic review suggests that supplementation with phytonadione and menaquinone-4 reduces bone loss. In the case of the latter, there is a strong effect on incident fractures among Japanese patients.

Cockayne S, Adamson J, Lanham-New S, Shearer MJ…
Arch. Intern. Med. Jun 2006
PMID: 16801507

Review: Vitamin K and Bone Health

Abstract

Chemistry, nutritional sources, tissue distribution and metabolism of vitamin K with special reference to bone health.

Vitamin K occurs in nature as a series of compounds with a common 2-methyl- 1,4 naphthoquinone nucleus and differing isoprenoid side chains at the 3 position. They comprise a single major plant form, phylloquinone with a phytyl side chain and a family of bacterially synthesized menaquinones (MKs) with multiprenyl side chains. The major dietary source to humans is phylloquinone for which the chief food contributors are green, leafy vegetables followed by certain vegetable oils (soybean, rapeseed and olive oils). Recent analyses by high pressure liquid chromatography are now providing a wide-ranging database of phylloquinone in foods. Menaquinones are found in moderate concentrations in only a few foods such as cheeses (MK-8 and MK-9). A wider spectrum of MKs is synthesized by the gut microflora, and their intestinal absorption probably accounts for most of the hepatic stores, particularly those with very long side chains (MKs-10-13) synthesized by members of the genus Bacteroides. The site of absorption of floral MKs is not known, but reasonable concentrations are found in the terminal ileum where bile salt-mediated absorption is possible. Both phylloquinone and menaquinones are bioactive in hepatic gamma-carboxylation but long-chain MKs are less well absorbed. Liver stores of vitamin K are relatively small and predominantly MKs-7-13. The hepatic reserves of phylloquinone (approximately 10% of the total) are labile and turn over at a faster rate than menaquinones. Trabecular and cortical bone appear to contain substantial concentrations of both phylloquinone and menaquinones. A majority (approximately 60-70%) of the daily dietary intake of phylloquinone is lost to the body by excretion, which emphasizes the need for a continuous dietary supply to maintain tissue reserves.

Shearer MJ, Bach A, Kohlmeier M
J. Nutr. Apr 1996
PMID: 8642453 | Free Full Text

At the present time the human requirements for vitamin K are based solely on its classical function in coagulation being listed as a Recommended Dietary Allowance (RDA) in the United States (Suttie 1992) and a Safe and Adequate Intake in the United Kingdom (Department of Health Report 1991). In both cases these requirements were set at a value of 1 mcg/kg/d. If, as argued by Vermeer et al. and Kohlmeier et al. in this volume, vitamin K is important to bone health and its requirements for this bone function are greater than for its hepatic function, a great challenge to researchers and future committees alike is to determine whether these putative extra demands can be quantified more precisely. Finally, it should be noted that the concept of reexamining the optimal intake of a vitamin with respect to the extra health benefits, which may be conferred by giving amounts over and above those required to protect against the originally discovered deficiency disease, is not new. There is already a recognition of the newer and often unexpected roles played by several other vitamins including in some cases the beneficial effects of extra intakes (Sauberlich and Machlin 1992).

Review: Statins and Bone Formation

Abstract

Statins, bone formation and osteoporosis: hope or hype?

Osteoporosis is a major health problem affecting both men and women. Statins, besides their action as lipid-lowering agents, seem to have additional pleiotropic properties, among them a beneficial effect on bone mineral density. The entirety of experimental and the majority of clinical studies as well as the only relevant meta-analysis suggest that statins have an anabolic effect on bone metabolism. Statins, osteoporosis and adipogenesis share the same pathway, RANKL/OPG. It would appear that an imbalance in this pathway could be responsible for the manifestation of some metabolic disorders such as diabetes mellitus, atherogenesis, multiple myeloma, osteoporosis. Possibly in the future, drugs which can intervene in this biochemical and pathophysiological cascade, like statins, in a variety of doses, could be used for the management of ectopic ossification syndromes and other bone disorders, even as an additive treatment. Until then, further large longitudinal randomized controlled studies for each statin separately are required to confirm this hypothesis.

Tsartsalis AN, Dokos C, Kaiafa GD, Tsartsalis DN…
Hormones (Athens)
PMID: 22801558 | Free Full Text

All the available data from the literature, including evidence from experimental studies as well as from the vast majority of observational studies and the results of a single meta-analysis, suggested that there is a positive effect of statins on BMD, although another meta-analysis by Bauer et al72 showed evidence that the beneficial effects on BMD and on fracture risk are observational, while many limitations and the placebo-controlled trials did not demonstrate any clear-cut benefit. However, the in vitro and some clinical studies (Chuengsamarn et al71) suggest that statins inhibit bone resorption and stimulate bone formation, having a dual action on bone metabolism. Therefore, in the future statins might gain a position among drugs used for the prevention and management of osteoporosis, taking into account that clinicians already have a good deal of experience in prescribing statins, for other indications, and feel familiar with this drug family. Their anabolic and anti-resorptive effects on bone make them an ideal candidate for osteoporosis treatment.

Review: Fish Oil Mechanisms of Action on Bone

Abstract

Long-chain polyunsaturated fatty acids: selected mechanisms of action on bone.

Evidence presented over the past 20 years has shown that long-chain polyunsaturated fatty acids (LCPUFAs), especially the n-3 fatty acids such as eicospentaenoic acid (EPA) and docosahexaenoic acid (DHA) are beneficial for bone health. Some studies in humans indicate that LCPUFAs can increase bone formation, affect peak bone mass in adolescents and reduce bone loss as measured using bone mineral densitometry. The cellular mechanisms of action of the LCPUFAs, however, are complex and involve modulation of fatty acid metabolites such as prostaglandins, resolvins and protectins, several signalling pathways, cytokines and growth factors. LCPUFAs affect receptor activator of nuclear factor κβ (RANK), a receptor found on the osteoclast, the cell causing bone resorption, which controls osteoclast formation. Lipoxygenase (LOX) generated lipid mediators (resolvins, lipoxins, protectins and docosanoids) have both anti-inflammatory and pro-resolving activities. Both resolvins and lipoxins inhibit inflammation-induced bone resorption. Arachidonic acid significantly upregulates inducible NO synthase (iNOS) mRNA expression in human osteoblast-like cells, thereby possibly enhancing osteoclastic activity. The protective effect of EPA on osteoblastogenesis could be mediated by the biphasic cross-talk between PGE(2) and NO production involving COX-2 and iNOS pathways. Other mediators of osteoblast maturation include PPARα ligands such as linoleic acid and possibly DHA in association with bone morphogenic proteins. Since DHA is a weaker ligand for PPARγ, more uncommitted mesenchymal stem cells are thought to differentiate into osteoblasts rather than adipocytes. This review addresses selected cellular mechanisms that may explain the beneficial effects of the LCPUFAs on bone.

Kruger MC, Coetzee M, Haag M, Weiler H
Prog. Lipid Res. Oct 2010
PMID: 20600307

Review: Fish Oil Effects on Bone

Abstract

The impact of omega-3 fatty acids on osteoporosis.

The essential polyunsaturated fatty acids (PUFAs) comprise 2 main classes: n-6 and n-3 fatty acids. The most common source of n-6 fatty acids is linoleic acid (LA) which is found in high concentrations in various vegetable oils. Arachidonic acid (AA), the 20-carbon n-6 fatty acid, is obtained largely by synthesis from LA in the body. The n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) are found in fish and fish oils. Long-Chain polyunsaturated fatty acids (LCPUFAs) and lipid mediators derived from LCPUFAs have critical roles in the regulation of a variety of biological processes including bone metabolism. There are different mechanisms by which dietary fatty acids affect bone: effect on calcium balance, effect on osteoblastogenesis and osteoblast activity, change of membrane function, decrease in inflammatory cytokines such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha), modulation of peroxisome proliferators-activated receptor gamma (PPARgamma). Animal studies have shown that a higher dietary omega-3/omega-6 fatty acids ratio is associated with beneficial effects on bone health. In spite of increasing evidence of the positive effects of dietary fats on bone metabolism from animal and in vitro studies, the few studies conducted in humans do not allow us to draw a definitive conclusion on their usefulness in clinical practice.

Maggio M, Artoni A, Lauretani F, Borghi L…
Curr. Pharm. Des. 2009
PMID: 20041817

Review: Homocysteine in Bone Remodeling

Abstract

The role of homocysteine in bone remodeling.

Bone remodeling is a very complex process. Homocysteine (Hcy) is known to modulate this process via several known mechanisms such as increase in osteoclast activity, decrease in osteoblast activity and direct action of Hcy on bone matrix. Evidence from previous studies further support a detrimental effect on bone via decrease in bone blood flow and an increase in matrix metalloproteinases (MMPs) that degrade extracellular bone matrix. Hcy binds directly to extracellular matrix and reduces bone strength. There are several bone markers that can be used as parameters to determine how high levels of plasma Hcy (hyperhomocysteinemia, HHcy) affect bone such as: hydroxyproline, N-terminal collagen 1 telopeptides. Mitochondrion serves an important role in generating reactive oxygen species (ROS). Mitochondrial abnormalities have been identified during HHcy. The mechanism of Hcy-induced bone remodeling via the mitochondrial pathway is largely unknown. Therefore, we propose a mitochondrial mechanism by which Hcy can contribute to alter bone properties. This may occur both through generations of ROS that activate MMPs and could be extruded into matrix to degrade bone matrix. However, there are contrasting reports on whether Hcy affects bone density, with some reports in favour and others not. Earlier studies also found an alteration in bone biomechanical properties with deficiencies of vitamin B12, folate and HHcy conditions. Moreover, existing data opens speculation that folate and vitamin therapy act not only via Hcy-dependent pathways but also via Hcy-independent pathways. However, more studies are needed to clarify the mechanistic role of Hcy during bone diseases.

Vacek TP, Kalani A, Voor MJ, Tyagi SC…
Clin. Chem. Lab. Med. Mar 2013
PMID: 23449525

Review: Cardiovascular Disease and Osteoporosis Strategies

Abstract

Cardiovascular disease and osteoporosis: balancing risk management.

In this narrative review of the current literature, we examine the traditional risk factors and patient profiles leading to cardiovascular disease and osteoporosis. We discuss the interrelationships between risk factors and common pathophysiological mechanisms for cardiovascular disease and osteoporosis. We evaluate the increasing evidence that supports an association between these disabling conditions. We reveal that vascular health appears to have a strong effect on skeletal health, and vice versa. We highlight the importance of addressing the risk benefit of preventative interventions in both conditions. We discuss how both sexes are affected by these chronic conditions and the importance of considering the unique risk of the individual. We show that habitual physical activity is an effective primary and secondary preventative strategy for both cardiovascular disease and osteoporosis. We highlight how a holistic approach to the prevention and treatment of these chronic conditions is likely warranted.

Warburton DE, Nicol CW, Gatto SN, Bredin SS
Vasc Health Risk Manag 2007
PMID: 18078019 | Free Full Text

Review: Genetics of Cardiovascular Diseases and Osteoporosis

Abstract

Genetic determinants of osteoporosis: common bases to cardiovascular diseases?

Osteoporosis is the most common and serious age-related skeletal disorder, characterized by a low bone mass and bone microarchitectural deterioration, with a consequent increase in bone fragility and susceptibility to spontaneous fractures, and it represents a major worldwide health care problem with important implications for health care costs, morbidity and mortality. Today is well accepted that osteoporosis is a multifactorial disorder caused by the interaction between environment and genes that singularly exert modest effects on bone mass and other aspects of bone strength and fracture risk. The individuation of genetic factors responsible for osteoporosis predisposition and development is fundamental for the disease prevention and for the setting of novel therapies, before fracture occurrence. In the last decades the interest of the Scientific Community has been concentrated in the understanding the genetic bases of this disease but with controversial and/or inconclusive results. This review tries to summarize data on the most representative osteoporosis candidate genes. Moreover, since recently osteoporosis and cardiovascular diseases have shown to share common physiopathological mechanisms, this review also provides information on the current understanding of osteoporosis and cardiovascular diseases common genetic bases.

Marini F, Brandi ML
Int J Hypertens 2010
PMID: 20948561 | Free Full Text