Through a systematic search in Pubmed for literature, on links between calcium malnutrition and risk of chronic diseases, we found the highest degree of evidence for osteoporosis, colorectal and breast cancer, as well as for hypertension, as the only major cardiovascular risk factor. Low calcium intake apparently has some impact also on cardiovascular events and disease outcome. Calcium malnutrition can causally be related to low activity of the extracellular calcium-sensing receptor (CaSR). This member of the family of 7-TM G-protein coupled receptors allows extracellular Ca2+ to function as a "first messenger" for various intracellular signaling cascades. Evidence demonstrates that Ca2+/CaSR signaling in functional linkage with vitamin D receptor (VDR)-activated pathways (i) promotes osteoblast differentiation and formation of mineralized bone; (ii) targets downstream effectors of the canonical and non-canonical Wnt pathway to inhibit proliferation and induce differentiation of colorectal cancer cells; (iii) evokes Ca2+ influx into breast cancer cells, thereby activating pro-apoptotic intracellular signaling. Furthermore, Ca2+/CaSR signaling opens Ca2+-sensitive K+ conductance channels in vascular endothelial cells, and also participates in IP(3)-dependent regulation of cytoplasmic Ca2+, the key intermediate of cardiomyocyte functions. Consequently, impairment of Ca2+/CaSR signaling may contribute to inadequate bone formation, tumor progression, hypertension, vascular calcification and, probably, cardiovascular disease.

In recent years an increasing number of observational studies have suggested that a low vitamin D status contributes to the development of all sorts of chronic diseases. In reality, however, studies that had been adequately controlled for confounding factors ruled out any link between vitamin D insufficiency and, for example, metabolic disorders, arterial hypertension, multiple sclerosis or cognitive dysfunction. Furthermore, a role of vitamin D insufficiency in autoimmune diseases is evident only in animal models but has not yet been established in humans. In respect to many malignancies, vitamin D insufficiency is only one out of many risk factors and its specific impact on disease incidence has never been assessed. There is convincing evidence, however, that vitamin D insufficiency is a major risk factor for osteoporosis, colorectal and breast cancer as well as for cardiovascular disease and mortality. However, it is debatable that circulating 25-hydroxyvitamin D concentrations of 100-150 nmol l(-1) are required for optimal health outcomes. These are overestimates which would afford to raise vitamin D intake to 4000 IU day(-1). In reality, high doses of vitamin D can cause serious health problems because of the U-shaped dose-response relationships that exist in some cases. Data from large cohort studies clearly indicate that serum 25-(OH)D concentrations around 50 nmol l(-1) are sufficient to minimize the risk of osteoporotic fractures, colorectal and breast cancer, and cardiovascular mortality. The fact that the risk-reducing potential of vitamin D depends on adequate calcium nutrition is widely ignored. I here summarize the evidence that efficient disease prevention does not require intake of more vitamin D and calcium than currently recommended for maintaining optimal bone health.

Previous studies on the significance of vitamin D insufficiency and chronic inflammation in colorectal cancer development clearly indicated that maintenance of cellular homeostasis in the large intestinal epithelium requires balanced interaction of 1,25-(OH)2D3 and prostaglandin cellular signaling networks. The present study addresses the question how colorectal cancer pathogenesis depends on alterations of activities of vitamin D hydroxylases, i.e., CYP27B1-encoded 25-hydroxyvitamin D-1a-hydroxylase and CYP24A1-encoded 25-hydroxyvitamin D-24-hydroxylase, and inflammation-induced cyclooxygenase-2 (COX-2). Data from 105 cancer patients on CYP27B1, VDR, CYP24A1, and COX-2 mRNA expression in relation to tumor grade, anatomical location, gender and age were fit into a multivariate model of exploratory factor analysis. Nearly identical results were obtained by the principal factor and the maximum likelihood method, and these were confirmed by hierarchical cluster analysis: Within the eight mutually dependent variables studied four independent constellations were found that identify different features of colorectal cancer pathogenesis: (i) Escape of COX-2 activity from restraints by the CYP27B1/VDR system can initiate cancer growth anywhere in the colorectum regardless of age and gender; (ii) variations in COX-2 expression are mainly responsible for differences in cancer incidence in relation to tumor location; (iii) advancing age has a strong gender-specific influence on cancer incidence; (iv) progression from well differentiated to undifferentiated cancer is solely associated with a rise in CYP24A1 expression.

Although it is well known that body mass index (BMI) and bone mineral density (BMD) are positively correlated, the mechanisms by which adiposity reduces the risk of osteoporotic fractures are not fully understood. The present study was initiated to gain deeper insight into the mechanisms underlying the osteoprotective effect of adiposity, and to assess particularly the relevance that BMI-associated changes in circulating hormone levels could have for the build-up of additional bone mineral density. Using data from a previous study on a large cohort of healthy adult Austrians, we analyzed correlations of BMI with (i) BMD at sites in the lumbar spine and hip region, (ii) bone resorption and formation markers, (iii) circulating levels of vitamin D, parathyroid hormone, testosterone and estrogen, and (iv) rates of daily vitamin D and calcium intake. After adjustment for age, positive correlations between BMI and BMD were highly significant (P<0.0001) at all skeletal sites across the entire study cohort. Associations were stronger in post-menopausal women than in pre-menopausal women and in men. In absolute values, the gain in BMD at the lumbar spine from an incremental rise of BMI in post-menopausal women was 1.5-fold higher than in pre-menopausal women, and three times of that observed in men (P<0.05). Inverse relations between BMI and β-crosslaps were consistently found in men (P<0.01) and in women before and after menopause (P<0.01 and P<0.05, respectively), suggesting that inhibition of osteoclastic bone resorption is responsible at least in part for the positive effect of high BMI on BMD. Sub-group analysis revealed that increasing BMI was associated with a significant fall of testosterone in men (P<0.05), and of 25-(OH)D in pre- and post-menopausal women (P<0.001 and P<0.05, respectively), but with a significant rise in PTH (P<0.01) in women before menopause. Since all these hormonal changes would cause bone loss, this excludes their playing any role in the osteoprotective effect of adiposity.

Both the "canonical" Wnt signaling pathway with beta-catenin as its key downstream effector as well as the "non-canonical" Wnt/Ca++ pathway, which uses intracellular Ca++ as "second messenger", play a key role in the control of bone remodeling. The Wnt signaling cascades coordinate the multiple phases in the process of bone formation (from osteogenic differentiation of pluripotent mesenchymal stem cells to matrix maturation and mineralization by fully differentiated osteoblasts and osteocytes), and also regulate differentiation and activation of osteoclasts. Accrual and maintenance of bone mass is genetically determined, mainly through expression of the genes that encode the components of the Wnt/beta-catenin signaling pathway, particularly the Wnt co-receptor LRP5. Modulation of efficiency of Wnt-activated pathways, e. g. by costimulatory signals from pathways activated by RANK/RANKL, PTH, 1,25-(OH)(2)D-3/VDR, and Ca++/CaR, or by blocking Wnt-lnhibitors like Dkk-1 and sclerostin, respectively, provides a means for prevention and therapy of primary and secondary osteoporosis.

ZusammenfassungSowohl der „kanonische” Wnt-Signalweg mit β-Catenin als terminalem Effektor als auch der „nicht-kanonische” Wnt/Ca++-Weg, in dem intrazelluläres Ca++ als „second messenger” fungiert, spielen beim kontinuierlichen Umbau des Knochens („bone remodeling”) eine wichtige Rolle: Sie koordinieren die einzelnen Phasen der Knochenneubildung (von der osteogenen Differenzierung pluripotenter mesenchymaler Stammzellen bis zur Bildung einer mineralisierten Matrix durch reife Osteoblasten bzw. Osteozyten), regulieren aber auch die Differenzierung und Aktivierung von Osteoklasten. Aufbau und Erhalt der Knochenmasse ist weitgehend genetisch determiniert, und zwar durch das Ausmaß der Expression der für die einzelnen Komponenten der Wnt/β-Catenin-Signalkaskade, insbesondere für den Wnt-Korezeptor LRP5, kodierenden Gene. Sowohl über die Schnittstellen mit anderen Signalwegen, die z. B. von RANK/ RANKL, PTH, 1,25-(OH)2D3/VDR oder Ca++/CaR aktiviert werden, als auch durch Blockade der Wnt-Inhibitoren Dkk-1 und Sklerostin ergeben sich zahlreiche Möglichkeiten, die Effektivität der Wnt/β-Catenin-Signalkaskade positiv zu beeinflussen, was zur Prävention und Therapie der verschiedenen Formen der Osteoporose genutzt werden kann.

Zusammenfassung An rachitischen Küken konnte mittels Immuno-Präzipitation nachgewiesen werden, daß Goldhafer auch dann in der Lage ist, Kalzium-bindendes Protein zu bilden, wenn die Synthese des aktiven Metaboliten des Vitamin D, 1,25 (OH)2 D3, in der Niere durch Strontiumfütterung gehemmt wird. Goldhafer enthält daher eine 1,25-Dihydroxycholecalciferol-artige Substanz, die geeignet ist, binnen 11 Tagen (13% Goldhafer) den rachitischen Zustand bei 32 Tage alten Küken einer weitgehenden Besserung zuzuführen, wie durch histopathologische Untersuchung der Knochen beweisbar ist. Am von Vitamin D3 depletierten Küken entfalten 2,5% Goldhaferheu keine antirachitische Wirkung, während 5%, 9% und 13% lyophilisierten Goldhafers eine von der Dosis und Verabreichungsdauer abhängige antirachitische Wirkung entfalten. An von Vitamin D3 depletierten Wachteln läßt sich, untersucht an der Kalziumausscheidung über das Eischalentrockengewicht je Tier und Tag, nachweisen, daß Goldhafer eine dem Vitamin D3 analoge Wirkung besitzt. Die in 10% lyophilisiertem Goldhafer (3. Aufwuchs) enthaltene Wirkstoffmenge entspricht rund 22200 i. E. Vitamin D3/kg Trockensubstanz in dem von uns untersuchten Goldhafer. Summary Calcinosis of cattle in Austria VI. Demonstration of a 1.25-dihydroxycholecalciferol-like substance as the cause of the antirachitic effect of Trisetum flavescens in chicks and quails In rachitic chicks it was possible by immuno-precipitation to show that Goldhafer is also able to produce a calcium-binding protein if the synthesis of active metabolites of vitamin D, 1.25 (OH)3 in the kidney is inhibited by feeding strontium. Goldhafer thus contains a 1.25-dihydroxycholecalciferol-like substance which is able within 11 days (13% Goldhafer) to result in considerable improvement in the rachitic condition of 32-day-old chicks, as shown by histological examination of their bones. In chicks depleted of vitamin D3 2.5% Goldhafer had no antirachitic effect, whereas levels of 5%, 9% and 13% of lyophilised Goldhafer hay had an antirachitic that was related to its dose and length of feeding. In quails depleted of vitamin D3 studies of calcium excretion in terms of dry eggshell weight per bird per day showed that Goldhafer possesses a vitamin D3 analogue effect. The amount of effective substance in 10% lyophilised Goldhafer (3rd crop) represented about 22,200 i. u. vitamin D3/kg. of dry matter in the Goldhafer examined. Résumé A propos de la calcinose du bovin en Autriche VI. Mise en évidence d'une substance du genre 1,25 — dihydroxycholecalciferol à l'origine d'une action antirachitique de l'avoine dorée (Trisetum flavescens) chez des poussins et des cailles On a pu mettre en évidence grâce à l'immunoprécipitation chez des poussins rachitiques que l'avoine dorée peut également former une protéine liant le calcium lorsque la synthèse du métabolite actif de la vitamine D, 1,25 (OH)3, est inhibée dans les reins lors d'une alimentation contenant du strontium. L'avoine dorée contient une substance du genre 1,25-dihydroxycholecalciferol qui est capable en l'espace de 11 jours (13% d'avoine dorée) d'améliorer nettement l'état rachitique de poulets âgés de 32 jours, ce qui a été démontré histologiquement au niveau du squelette. 2,5% defoin d'avoine dorée n'a développé aucune action antirachitique chez des poussins carencés en vitamine D3, alors que 5%, 9% et 13% d'avoine dorée lyophilisée ont montré une action antirachitique en relation avec la dose et la durée de la cure. Une action analogue de l'avoine dorée avec la vitamine D3 a été constatée chez des cailles carencées en vitamine D3 lorsqu'on a examiné la sécrétion du calcium par le poids de la coquille de l'oeuf par animal et par jour. La quantité de substance dans 10% d'avoine dorée (troisième croissance) lyophilisée a correspondu à 22200 IE de vitamine D3/kg de substance sèche pour l'avoine dorée qui a été examinée. Resumen Sobre la calcinosis de los vacunos en Austria VI. Identificación de una substancia similar al 1,25-dihidroxicolecalciferol como etiología de la acción antirraquítica de la avena dorada (Trisetum flavescens) en pollitos y codornices Se pudo demostrar en pollitos raquíticos, mediante inmunoprecipitación, que la avena dorada también es capaz de formar proteína fijadora de calcio cuando se inhibe la síntesis del metabolito activo de la vitamina D, 1,25 (OH)3, en el riñón por medio de alimentación de estroncio. Cierto es que la avena dorada contiene una substancia similar al 1,25-dihidroxicolecalciferol, la cual es capaz de llevar en el plazo de 11 días (13% avena dorada) el estado raquítico en pollitos de 32 días de edad a una mejoría amplia, como se puede demostrar mediante el examen histopatológico de los huesos. En pollitos depletados de vitamina D3 no despliega 2,5% de heno de avena dorada ninguna acción antirraquítica, mientras que 5, 9 y 13% de avena dorada liofilizada despliegan una acción antirraquítica dependiente de la dosis y tiempo de administración. En codornices depletadas de vitamina D3 se puede probar, examinando en la excreción de calcio a través del peso seco de la cáscara de huevo por animal y día, que la avena dorada posee un efecto análogo al de la vitamina D3. La cantidad de substancia activa contenida en 10% de avena dorada liofilizada (tercer crecimiento) corresponde aprox. a 22.000 u. i. de vitamina D3/kg. substancia seca en la avena dorada examinada por nosotros.

Bone-mineral homeostasis (homoióstasis = equilibrium in Greek) is the result of the interplay of two intertwined endocrine circuits formed by the feedback-regulated actions of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and parathyroid hormone (PTH). Partially divergent effects of two hormones on calcium and phosphate fluxes in the classical target organs (intestine, kidney, and bone) have to be carefully orchestrated at any time during the life of a vertebrate organism to meet the ever-changing demands of bone growth and functions. This can only be achieved if the input into the system from the outside will allow it to adjust itself to different functional levels, i.e., to promote longitudinal growth during development, to build up an adequate peak bone mass through appositional bone growth until 20-30 years of age, to meet the specific challenge for bone-mineral homeostasis during pregnancy, and finally to maintain structural and functional integrity as long as possible in the face of continuous involutional bone loss throughout adulthood.

Sporadic colorectal cancer is a disease of advancing age and the percentage of the population which reaches an advanced age is strongly increasing. Multiple factors are responsible for the etiology of this cancer since the colorectal mucosa is directly influenced by nutrients reaching the colonic lumen and impacting on mucosal cells. The vitamin D system appears to be central to several preventative molecular pathways. Insufficiency of the serum precursor 25-hydroxyvitamin D3 has been linked by epidemiology to enhanced colon tumor incidence, most likely because it is a major determinant of 1,25-dihydroxyvitamin D3 synthesis in colonic mucosal cells. Bound to its receptor, vitamin D regulates colonic proliferation, differentiation and apoptosis in an autocrine/paracrine manner. During early malignancy, vitamin D synthesis is enhanced to counteract hyperproliferation, whereas in high-grade tumors catabolism by far surpasses synthesis. The colonic vitamin D system is regulated by several known natural factors. One of the most important ones is nutritional calcium that, if supply is low, will result in enhanced catabolism of colonic 1,25-dihydroxyvitamin D3. Estrogenic compounds can increase expression and activity of the synthesizing 25-hydroxyvitamin D-1alpha-hydroxylase. Due to enhanced synthesis of the active metabolite, this can lead to protection against colorectal tumors in women. During tumor progression, expression of 25-hydroxyvitamin D-1alpha-hydroxylase as well as of the catabolizing 25-hydroxyvitamin D-24-hydroxylase appears to be under epigenetic control as demonstrated by studies with phytoestrogens and folate. It is commonly accepted that sporadic colorectal cancer pathogenesis is multifactorial and these are just a few examples of the regulatory capacity of natural (nutrient) substances for improving the colonic vitamin D system. However, protection by vitamin D might have central importance, with nutrients increasing the efficiency of the vitamin D system in a targeted manner. This could result in prevention of hyperproliferation or retardation of progression to clinically manifest primary colonic tumors.

Vitamin D has important benefits in reducing the risk of many conditions and diseases. Those diseases for which the benefits are well supported and that have large economic effects include many types of cancer, cardiovascular diseases, diabetes mellitus, several bacterial and viral infections, and autoimmune diseases such as multiple sclerosis. Europeans generally have low serum 25-hydroxyvitamin D [25(OH)D] levels owing to the high latitudes, largely indoor living, low natural dietary sources of vitamin D such as cold-water ocean fish, and lack of effective vitamin D fortification of food in most countries. Vitamin D dose–disease response relations were estimated from observational studies and randomized controlled trials. The reduction in direct plus indirect economic burden of disease was based on increasing the mean serum 25(OH)D level to 40 ng/mL, which could be achieved by a daily intake of 2000–3000 IU of vitamin D. For 2007, the reduction is estimated at €187,000 million/year. The estimated cost of 2000–3000 IU of vitamin D3/day along with ancillary costs such as education and testing might be about €10,000 million/year. Sources of vitamin D could include a combination of food fortification, supplements, and natural and artificial UVB irradiation, if properly acquired. Additional randomized controlled trials are warranted to evaluate the benefits and risks of vitamin D supplementation. However, steps to increase serum 25(OH)D levels can be implemented now based on what is already known.

A low vitamin D status and inadequate calcium intake are important risk factors for various types of cancer. Ecological studies using solar UV-B exposure as an index of vitamin D3 photoproduction in the skin found a highly significant inverse association between UV-B and mortality in fifteen types of cancer. Of these, colon, rectal, breast, gastric, endometrial, renal and ovarian cancer exhibit a significant inverse relationship between incidence and oral intake of calcium. In addition, lung and endometrial cancer as well as multiple myeloma are considered calcium and vitamin D sensitive. Studies on tissue-specific expression of the CYP27B1-encoded 25-hdroxyvitamin D-1alpha-hydroxylase and of the extracellular calcium-sensing receptor (CaR) have led to an understanding how locally produced 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and extracellular Ca2+ act jointly as key regulators of cellular proliferation, differentiation and function. Thus, impairment of antimitogenic, proapoptotic and prodifferentiating signaling from the 1,25(OH)2D3-activated vitamin D receptor (VDR) and from the CaR in vitamin D and calcium insufficiency has been implicated in the pathogenesis of the aforementioned types of cancer. 1,25(OH)2D3 and calcium interact in modulating cell growth in different ways: (i) Signaling pathways from the VDR and the CaR converge on the same downstream elements, e.g. of the canonical Wnt pathway; (ii) high extracellular calcium modulates extrarenal vitamin D metabolism in favor of higher local steady-state concentrations of 1,25(OH)2D3; (iii) 1,25(OH)2D3 may up-regulate expression of the CaR and thus augment CaR-mediated antiproliferative responses to high extracellular Ca2+. This can explain why combined supplementation is required for optimal chemoprevention of cancer by calcium and vitamin D.

BACKGROUND:A cross-sectional study was performed on a cohort of colorectal cancer (CRC) patients to reveal any influence of age, gender, and subsite on grades of malignancy.PATIENTS AND METHODS:Data from histopathological grading according to WHO criteria were pooled into groups of low-grade (well and moderately differentiated) and high-grade (poorly and undifferentiated) cancer and analyzed for associations.RESULTS:In general, women with CRC were significantly older than men (p<0.05). In particular, women with high-grade cancer in the proximal and distal colon had a median age of 75 years and were thus 10-15 years older (p<0.01 and p<0.05, respectively) than their male counterparts. In contrast, high-grade rectal cancer developed in both genders around the early age of 60 years.CONCLUSION:Women are protected from more aggressive cancer in the colon though not in the rectum until well after menopause. This likely reflects the differential sensitivity of the mucosa at these sites against the anticancer effects triggered by activation of estrogen receptor-beta.

A compromised vitamin D status, characterized by low 25-hydroxyvitamin D (25-(OH)D) serum levels, and a nutritional calcium deficit are widely encountered in European and North American countries, independent of age or gender. Both conditions are linked to the pathogenesis of many degenerative, malignant, inflammatory and metabolic diseases. Studies on tissue-specific expression and activity of vitamin D metabolizing enzymes, 25-(OH)D-1α-hydroxylase and 25-(OH)D-24-hydroxylase, and of the extracellular calcium-sensing receptor (CaR) have led to the understanding of how, in non-renal tissues and cellular systems, locally produced 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and extracellular Ca2+ act jointly as key regulators of cellular proliferation, differentiation and function. Impairment of cooperative signalling from the 1,25-(OH)2D3-activated vitamin D receptor (VDR) and from the CaR in vitamin D and calcium insufficiency causes cellular dysfunction in many organs and biological systems, and, therefore, increases the risk of diseases, particularly of osteoporosis, colorectal and breast cancer, inflammatory bowel disease, insulin-dependent diabetes mellitus type I, metabolic syndrome, diabetes mellitus type II, hypertension and cardiovascular disease. Understanding the underlying molecular and cellular processes provides a rationale for advocating adequate intake of vitamin D and calcium in all populations, thereby preventing many chronic diseases worldwide.

Vitamin D and calcium insufficiencies are risk factors for multiple chronic diseases. Data from 46 recent studies from Europe, North America, South-East Asia and the South Pacific area clearly indicate that a low vitamin D status and inadequate calcium nutrition are highly prevalent in the general population (30–80%), affecting both genders. The extent of insufficiencies is particularly high in older populations, and in some geographical areas, also in children and in young women of child-bearing age, in ethnic minorities and immigrants, as well as in people of low socio-economic status. Enrichment of cereal grain products with vitamin D and calcium would be a viable approach to increase consumption and improve health outcomes in the general population worldwide.

Background Many cancer cells produce interleukin-6 (IL-6), a cytokine that plays a role in growth stimulation, metastasis, and angiogenesis of secondary tumours in a variety of malignancies, including colorectal cancer. Effectiveness of IL-6 in this respect may depend on the quantity of basal and inducible IL-6 expressed as the tumour progresses through stages of malignancy. We therefore have evaluated the effect of IL-6 modulators, i.e. IL-1β, prostaglandin E 2 , 17β-estradiol, and 1,25-dihydroxyvitamin D 3 , on expression and synthesis of the cytokine at different stages of tumour progression. Methods We utilized cultures of the human colon carcinoma cell clones Caco-2/AQ, COGA-1A and COGA-13, all of which expressed differentiation and proliferation markers typical of distinct stages of tumour progression. IL-6 mRNA and protein levels were assayed by RT-PCR and ELISA, respectively. DNA sequencing was utilized to detect polymorphisms in the IL-6 gene promoter. Results IL-6 mRNA and protein concentrations were low in well and moderately differentiated Caco-2/AQ and COGA-1A cells, but were high in poorly differentiated COGA-13 cells. Addition of IL-1β (5 ng/ml) to a COGA-13 culture raised IL-6 production approximately thousandfold via a prostaglandin-independent mechanism. Addition of 17β-estradiol (10 -7 M) reduced basal IL-6 production by one-third, but IL-1β-inducible IL-6 was unaffected. Search for polymorphisms in the IL-6 promoter revealed the presence of a single haplotype, i.e., -597A/-572G/-174C, in COGA-13 cells, which is associated with a high degree of transcriptional activity of the IL-6 gene. IL-6 blocked differentiation only in Caco-2/AQ cells and stimulated mitosis through up-regulation of c- myc proto-oncogene expression. These effects were inhibited by 10 -8 M 1,25-dihydroxyvitamin D 3 . Conclusion In human colon carcinoma cells derived from well and moderately differentiated tumours, IL-6 expression is low and only marginally affected, if at all, by PGE 2 , 1,25-dihydroxyvitamin D 3 , and 17β-estradiol. However, IL-6 is highly abundant in undifferentiated tumour cells and is effectively stimulated by IL-1β. In case of overexpression of an IL-6 gene variant with extreme sensitivity to IL-1β, massive release of the cytokine from undifferentiated tumour cells may accelerate progression towards malignancy by paracrine action on more differentiated tumour cells with a still functioning proliferative IL-6 signalling pathway.