Dietary calcium consumption and astrocytic glioma: the San Francisco Bay Area Adult Glioma Study, 1991-1995

Association between dietary minerals and glioma: A case-control study based on Chinese population

Background

As one of the essential nutrients for the human body, minerals participate in various physiological activities of the body and are closely related to many cancers. However, the population study on glioma is not sufficient.

Objective

The purpose of this study was to evaluate the relationship between five dietary minerals and glioma.

Methods

A total of 506 adult patients with glioma and 506 healthy controls were matched 1:1 according to age (±5 years) and sex. The food intake of the subjects in the past year was collected through the food frequency questionnaire, and the intakes of calcium, magnesium, iron, zinc, and copper in the diet were calculated. The logistic regression model was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI) for dietary minerals to gliomas.

Results

After adjusting for confounders, higher intakes of calcium (OR = 0.65, 95% CI: 0.57-0.74), magnesium (OR = 0.18, 95% CI: 0.11-0.29), iron (OR = 0.04, 95% CI: 0.02-0.11), zinc (OR = 0.62, 95% CI: 0.54-0.73), and copper (OR = 0.22, 95% CI: 0.13-0.39) were associated with a significantly decreased risk of glioma. Similar results were observed in gliomas of different pathological types and pathological grades. The restriction cubic spline function suggested significant linear dose-response relationships between intakes of five minerals and the risk of glioma. When the dietary minerals exceeded a particular intake, the risk of glioma stabilized.

Conclusion

Our study suggests that higher dietary intakes of calcium, magnesium, iron, zinc, and copper are associated with a decreased risk of glioma. However, the results of this study require further exploration of potential mechanisms in the future better to elucidate the effects of mineral intake on gliomas.

A Meta-Analysis of Calcium Intake and Risk of Glioma

BACKGROUND

A meta-analysis was conducted to investigate the correlation between calcium intake and the risk of brain tumors (especially glioma).

METHODS

The PubMed, Web of Science, and Embase databases were searched for relevant papers on the association between calcium intake and glioma as of August 22, 2021. The odds ratio (OR) with a 95% confidence interval (CI) was calculated using a random-effects model. Egger's test was conducted to assess publication bias.

RESULTS

The meta-analysis includes four studies. The meta-analysis showed that calcium intake and the risk of brain tumors have a significant negative relationship (OR = 0.28; 95% CI: 0.11 to 0.72; P = 0.008). Dose-response analysis showed that for every 100 mg/day increase in calcium intake, the risk of glioma decreased by 7% (OR = 0.93; 95% CI: 0.88 to 0.98). In addition, compared with humans without calcium intake, when calcium intake is 455 mg/day, 800 mg/day and 1000 mg/day, the risk of glioma is 0.65 (95% CI 0.43, 0.97), 0.55 (95% CI 0.37, 0.82) and 0.37 (95% CI 0.15, 0.86).

CONCLUSION

There is a significant negative association between calcium intake and brain tumors (especially gliomas), but more high-quality studies are needed to verify these results.

Health Effects of Calcium: Evidence From Mendelian Randomization Studies

Calcium is widely used in conjunction with vitamin D to prevent osteoporosis. The use of calcium supplementation is also promoted for its potential benefits in lowering the risk for metabolic syndromes and cancers. However, the causal link between calcium and various health outcomes remains unclear. This review focuses on the evidence from 24 Mendelian randomization (MR) studies that were designed to minimize bias from confounding and reverse causation. These MR studies evaluated the effect of lifelong genetically higher serum calcium levels on various health outcomes. Overall, available MR studies found no conclusive effects of serum calcium levels on bone mineral density and fracture, ischemic stroke and heart failure, cancers, type 2 diabetes, Parkinson disease, or offspring birth weight. However, a higher serum calcium concentration was reported to have estimated causal effects on increased risks for coronary artery disease (especially myocardial infarction), migraine, renal colic, allergy/adverse effect of penicillin, and reduced risks for osteoarthrosis and osteoarthritis. In conclusion, supplementation of calcium in individuals from the general population is not predicted to influence the risk of most investigated diseases to date. Moreover, long-term high serum calcium concentrations may result in adverse health outcomes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

A case-control study on dietary calcium intake and risk of glioma

Limited evidence exists regarding the association between dietary calcium intake and risk of glioma. The objective of this study was to determine the relationship between dietary calcium intake and risk of glioma in Iranian adults. In this hospital-based case-control study, we enrolled 128 newly-diagnosed cases of glioma and 256 age- and sex-matched controls. Patients with pathologically confirmed glioma (without any other cancers) were selected. Dietary intakes of study participants were collected through a validated 126-item food-frequency questionnaire. Dietary calcium intake was computed from dairy products in the questionnaire. Participants were categorized into quartiles of dietary calcium intake. Binary logistic regression was used to examine the association between dietary calcium intake and glioma. Higher dietary intake of calcium was associated with younger age, long duration of cell phone use, and frequent canned foods intake. After taking age, sex, and energy intake into account, participants with the greatest dietary calcium intake had 84% lower odds of glioma than those with the lowest intake [odds ratio (OR): 0.16; 95% confidence interval (CI), 0.07-0.37]. Further adjustment for other potential confounders including nutrient intakes did not significantly alter the association (OR: 0.22; 95% CI, 0.08-0.64). Even after additional adjustment for BMI, we found a significant inverse association between dietary calcium intake and odds of glioma (OR: 0.23; 95% CI, 0.08-0.65). We found an inverse protective association between high dietary calcium intake and odds of glioma. Further prospective cohort studies are needed to confirm these findings.

The Association Between Index of Nutritional Quality (INQ) and Glioma and Evaluation of Nutrient Intakes of These Patients: A Case-Control Study

INTRODUCTION

Glioma is the most common adult brain tumors. Dietary factors may play a role in the etiology of glioma. The Index of Nutritional Quality (INQ) provides a general overview for the nutrient content of a food or a diet. This study aimed to investigate the association between INQ and glioma and nutrient intakes.

MATERIAL AND METHODS

This study was included 128 patients and 256 controls. Dietary intakes of the subjects were evaluated by a food frequency questionnaire (FFQ) and FFQ-derived dietary data were used to calculate INQ scores. Logistic regression was used to calculate the odds ratios and 95% confidence intervals.

RESULTS

Cases had higher intake of total fat, saturated fatty acid (SFA), meats, hydrogenated oils and controls had higher intake of monounsaturated fatty acid, polyunsaturated fatty acid, calcium, dairy, fruits, and nuts. Only the INQ of vitamin C, vitamin E, calcium, and fiber are higher in controls. An inverse association was observed between glioma and INQ of calcium, vitamin E, vitamin C, and fiber.

CONCLUSION

The results of this study propose a healthy diet such as high intake of vitamins C and E, calcium, fiber, food groups like fruits and vegetables, and low-fat milk and nuts; and low consumption of total fat, SFA, and red meat may be protective against glioma.

Epidemiology

More than 250,000 new cases of primary malignant brain tumors are diagnosed annually worldwide, 77% of which are gliomas. A small proportion of gliomas are caused by the inheritance of rare high-penetrance genetic variants or high-dose radiation. Since 2009, inherited genetic variants in 10 regions near eight different genes have been consistently associated with glioma risk via genome-wide association studies. Most of these variants increase glioma risk by 20-40%, but two have higher relative risks. One on chromosome 8 increases risk of IDH-mutated gliomas sixfold and another that affects TP53 function confers a 2.5-fold increased risk of glioma. Functions of some of the other risk variants are known or suspected, but future research will determine functions of other risk loci. Recent progress also has been made in defining subgroups of glioma based on acquired alterations within tumors. Allergy history has been consistently associated with reduced glioma risk, though the mechanisms have not yet been clarified. Future studies will need to be large enough so that environmental and constitutive genetic risk factors can be examined within molecularly defined, etiologically homogeneous subgroups.

Modulation of glioma risk and progression by dietary nutrients and antiinflammatory agents

Gliomas are tumors of glial origin formed in the central nervous system and exhibit profound morphological and genetic heterogeneity. The etiology of this heterogeneity involves an interaction between genetic alterations and environmental risk factors. Scientific evidence suggests that certain natural dietary components, such as phytoestrogens, flavonoids, polyunsaturated fatty acids, and vitamins, may exert a protective effect against gliomas by changing the nature of the interaction between genetics and environment. Similarly, certain antiinflammatory drugs and dietary modifications, such as methionine restriction and the adoption of low-calorie or ketogenic diets, may take advantage of glioma and normal glial cells' differential requirements for glucose, methionine, and ketone bodies and may, therefore, be effective as part of preventive or treatment strategies for gliomas. Treatment trials of glioma patients and chemoprevention trials of individuals with a known genetic predisposition to glioma using the most promising of these agents, such as the antiinflammatory drugs curcumin and gamma-linolenic acid, are needed to validate or refute these agents' putative role in gliomas.

Epidemiology of brain tumors

Gliomas account for more than 70% of all brain tumors, and of these, glioblastoma is the most frequent and malignant histologic type (World Health Organization [WHO] grade IV). There is a tendency toward a higher incidence of gliomas in highly developed, industrialized countries. Some reports indicate that Caucasians have a higher incidence than African or Asian populations. With the exception of pilocytic astrocytomas (WHO grade I), the prognosis of glioma patients is still poor. Fewer than 3% of glioblastoma patients are still alive at 5 years after diagnosis, older age being the most significant and consistent prognostic factor of poorer outcome. Gliomas are components of several inherited tumor syndromes, but the prevalence of these syndromes is very low. Many environmental and lifestyle factors including several occupations, environmental carcinogens, and diet have been reported to be associated with an elevated glioma risk, but the only factor unequivocally associated with an increased risk is therapeutic X-irradiation. In particular, children treated with X-irradiation for acute lymphoblastic leukemia show a significantly elevated risk of developing gliomas and primitive neuroectodermal tumors, often within 10 years after therapy. Significant correlation between G:C --> A:T transitions in the TP53 gene and promoter methylation of the O6 -methylguanine-DNA methyltransferase (MGMT) gene in glio-mas have been reported in several studies, suggesting the possible involvement of O6-methylguanine DNA adducts, which may be produced by exogenous or endogenous alkylating agents in the development of gliomas.

Epidemiology of brain tumors

Brain tumors seemed to have increased in incidence over the past 30 years, but the rise probably results from use of new neuroimaging techniques. Treatments have not improved prognosis for rapidly fatal brain tumors. Established brain tumor risk factors (exposure to ionizing radiation, rare mutations of penetrant genes, and familial history) explain only a small proportion of brain tumors, and only one of these potentially is modifiable. Genetic and environmental characteristics likely play a role in familial aggregation of glioma and these factors are not identified. New concepts in brain tumor etiology and clinical management are the goal of research, with an aim at eradicating this devastating disease.

Epidemiology and molecular pathology of glioma

Gliomas account for almost 80% of primary malignant brain tumors, and they result in more years of life lost than do any other tumors. Glioblastoma, the most common type of glioma, is associated with very poor survival, so glioma epidemiology has focused on identifying factors that can be modified to prevent this disease. Only two relatively rare factors have so far been conclusively shown to affect glioma risk--exposure to high doses of ionizing radiation, and inherited mutations of highly penetrant genes associated with rare syndromes. In addition, preliminary evidence points to a lower glioma risk among people with allergic conditions and high levels of serum IgE. Recent research has focused on identifying germline polymorphisms associated with risk of glioma, and using molecular markers to classify glial tumors into more-homogenous groups. Because gene products probably interact with environmental factors or developmental signals to produce gliomas, large studies are needed to analyze associations between polymorphisms and glioma. Cohort studies of immune factors and glioma risk are being undertaken to validate the results of case-control studies. Studies of polymorphisms of genetic pathways with strong prior hypotheses are being planned, and whole-genome scans are being proposed to study high-risk families and case-control series. The Brain Tumor Epidemiology Consortium has been formed to co-ordinate these studies.

The molecular epidemiology of gliomas in adults

In this paper the authors highlight recent findings from molecular epidemiology studies of glioma origin and prognosis and suggest promising paths for future research. The reasons for variation in glioma incidence according to time period of diagnosis, sex, age, ancestry and ethnicity, and geography are poorly understood, as are factors that affect prognosis. High-dose therapeutic ionizing irradiation and rare mutations in highly penetrant genes associated with certain rare syndromes—the only two established causes of glioma—can be called upon to explain few cases. Both familial aggregation of gliomas and the inverse association of allergies and immune-related conditions with gliomas have been shown consistently, but the explanations for these associations are inadequately developed or unknown. Several bio-markers do predict prognosis, but only evaluation of loss of 1p and 19q in oligodendroglial tumors are incorporated in clinical practice. Ongoing research focuses on classifying homogeneous groups of tumors on the basis of molecular markers and identifying inherited polymorphisms that may influence survival or risk. Because most cases of glioma have yet to furnish either an environmental or a genetic explanation, the greatest potential for discovery may lie in genomic studies in conjunction with continued evaluation of environmental and developmental factors. Large sample sizes and multidisciplinary teams with expertise in neuropathology, genetics, epidemiology, functional genomics, bioinformatics, biostatistics, immunology, and neurooncology are required for these studies to permit exploration of potentially relevant pathways and modifying effects of other genes or exposures, and to avoid false-positive findings. Improving survival rates for patients harboring astrocytic tumors will probably require many randomized clinical trials of novel treatment strategies.

Epidemiology and etiology of gliomas

Gliomas of astrocytic, oligodendroglial and ependymal origin account for more than 70% of all brain tumors. The most frequent (65%) and most malignant histological type is the glioblastoma. Since the introduction of computerized tomography and magnetic resonance imaging, the incidence rates of brain tumors have been rather stable, with a tendency of higher rates in highly developed, industrialized countries. Some reports indicate that Caucasians have higher incidence than black or Asian populations, but to some extent, this may reflect socio-economic differences and under-ascertainment in some regions, rather than a significant difference in genetic susceptibility. With the exception of pilocytic astrocytomas, the prognosis of glioma patients is still poor. Less than 3% of glioblastoma patients are still alive at 5 years after diagnosis, higher age being the most significant predictor of poor outcome. Brain tumors are a component of several inherited tumor syndromes, but the prevalence of these syndromes is very low. Several occupations, environmental carcinogens, and diet (N-nitroso compounds) have been reported to be associated with an elevated glioma risk, but the only environmental factor unequivocally associated with an increased risk of brain tumors, including gliomas, is therapeutic X-irradiation. In particular, children treated with X-irradiation for acute lymphoblastic leukemia show a significantly elevated risk of developing gliomas and primitive neuroectodermal tumor (PNET), often within 10 years after therapy. TP53 mutations are frequent in low-grade gliomas and secondary glioblastomas derived therefrom. Approximately 60% of mutations are located in the hot spot codons 248 and 273, and the majority of these are G:C-->A:T transitions at CpG sites. TP53 mutations are significantly more frequent in low-grade astrocytomas with promoter methylation of the O(6)-methylguanine-DNA methyltransferase repair gene, suggesting that, in addition to deamination of 5-methylcytosine, exogenous or endogenous alkylation in the O(6) position of guanine may contribute to the formation of these mutations.

Mutant, wild type, or overall p53 expression: freedom from clinical progression in tumours of astrocytic lineage

Abnormalities of the p53 tumor-suppressor gene are found in a significant proportion of astrocytic brain tumours. We studied tumour specimens from 74 patients evaluated over 20 years at the Massachusetts General Hospital, where clinical outcome could be determined and sufficient pathologic material was available for immunostaining. p53 expression studies employed an affinity-purified p53 monoclonal antibody, whose specificity was verified in absorption studies and, in a minority of cases, a second antibody recognising a different epitope of p53. Significant overexpression of p53 protein was found in 48% of the 74 tumours included in this series and high levels of expression were associated with higher mortality from astrocytic tumours (P<0.001, log rank). Multivariate analyses revealed that immunohistochemically detected p53 was an independent marker of shortened progression-free and overall actuarial survival in patients with astrocytic tumours, suggesting that increased expression of p53 plays an important role in the pathobiology of these tumours. In a subset of 36 cases, coding regions of the p53 gene were completely sequenced via SSCP and direct DNA sequencing, revealing that overexpression of p53 protein is not always associated with point mutations in conserved exons of the p53 gene. Finally, we confirmed p53 protein expression in early-passage human glioma cell lines of known p53 mutational status and immunostaining scores. Although grade continues to be the strongest prognostic variable, the use of p53 staining as a prognostic indicator, in contrast to mutational DNA analyses, may be a useful adjunct in identifying patients at higher risk of treatment failure.

The potential benefits of dietary and/or supplemental calcium and vitamin D

Osteoporosis is a significant problem in women and men. In addition, as osteoporosis has garnered more attention there should be more attention than ever placed on the potential benefits of calcium and vitamin D. Clinicians need to inform patients that there are numerous healthy dietary sources of calcium and vitamin D. Calcium and vitamin D supplements seem to act synergistically to reduce fracture risk in men and women; therefore, they need to be taken together to impact fracture risk. In addition, almost every randomized trial of an effective osteoporosis drug therapy has utilized calcium and vitamin D to enhance the efficacy of the drug itself. Several forms of calcium supplements are commercially available today and clinicians need to understand the similarities and differences between them. Calcium and vitamin D in moderation also have a good safety profile and may actually have benefits far beyond osteoporosis therapy. For example, calcium may increase high-density lipoprotein (HDL), prevent colon polyps, reduce blood pressure, reduce kidney stone recurrence, and may promote weight loss. Vitamin D may reduce the risk of some cancers, provide an enhanced response to some chemotherapeutic agents, prevent type I diabetes, and may reduce tooth loss along with calcium. Clinicians need to encourage individuals to receive the recommended daily allowance of these two agents because they seem to have an impact on numerous health conditions besides osteoporosis.