Dietary calcium intake, vitamin D levels, and breast cancer risk: a dose–response analysis of observational studies

A Randomized Trial of Calcium Plus Vitamin D Supplementation and Risk of Ductal Carcinoma In Situ of the Breast

Background

The effect of calcium plus vitamin D (CaD) supplementation on risk of ductal carcinoma in situ (DCIS) of the breast, a nonobligate precursor of invasive ductal carcinoma, is not well understood. In this secondary analysis, we examined this association in the Women’s Health Initiative CaD trial over approximately 20 years of follow-up.

Methods

A total of 36 282 cancer-free postmenopausal women (50-79 years) were randomly assigned to daily (d) calcium (1000 mg) plus vitamin D (400 IU) supplementation or to a placebo. Personal supplementation with vitamin D (≤600 IU/d, subsequently raised to 1000 IU/d) and calcium (≤1000 mg/d) was allowed. The intervention phase (median = 7.1 years), was followed by a postintervention phase (additional 13.8 years), which included 86.0% of the surviving women. A total of 595 incident DCIS cases were ascertained. Hazard ratios (HRs) plus 95% confidence intervals (CIs) were calculated.

Results

The intervention group had a lower risk of DCIS throughout follow-up (HR = 0.82, 95% CI = 0.70 to 0.96) and during the postintervention phase (HR = 0.76, 95% CI = 0.61 to 0.94). The group that used CaD personal supplements in combination with the trial intervention had a lower risk of DCIS compared with the trial placebo group that did not use personal supplementation (HR = 0.72, 95% CI = 0.56 to 0.91).

Conclusions

CaD supplementation in postmenopausal women was associated with reduced risk of DCIS, raising the possibility that consistent use of these supplements might provide long-term benefits for the prevention of DCIS.

The Association between Dietary Calcium Intake and Breast Cancer Risk among Iranian Women

No information is available from Middle Eastern countries linking dietary calcium intake and odds of breast cancer.

OBJECTIVE

This study was conducted to investigate the association between dietary calcium intake and odds of having breast cancer among Iranian women.

In this population-based case-control study, 350 newly diagnosed breast cancer cases were recruited and 700 age-matched subjects were enrolled as controls. Dietary intakes were examined by the use of a 106-item validated FFQ. Total dietary calcium intake of each participant was computed by summing up calcium intake from all foods and dishes. The quartile cutoff points of energy-adjusted calcium intake was obtained in the control group. These cutoff points were used to classify all study participants into quartiles in terms of dietary calcium intake.

After adjustment for age and energy intake, we found that individuals in second quartile of calcium intake were 43% less likely to have breast cancer compared with those in the bottom quartile (OR: 0.57; 95% CI: 0.38-0.86). This significant association disappeared after further controlling for other potential confounders including dietary factors and BMI (OR: 0.91; 95% CI: 0.57-1.45). When the analyses were done by menopausal status, premenopausal women with the greatest calcium intake were 60% less likely to have breast malignancy than those with the lowest intake (OR: 0.40; 95% CI: 0.16-0.99). Adjustment for potential confounders did not substantially influence this finding (OR: 0.32; 95% CI: 0.11-0.95). The association remained significant even after additional controlling for dietary covariates (OR: 021; 95% CI: 0.06-0.72) and BMI (OR: 0.21; 95% CI: 0.04-0.93). No significant association was found between dietary calcium intakes and odds of breast cancer in postmenopausal women.

Dietary calcium intake was protectively associated with odds of breast cancer in premenopausal women, but not in postmenopausal women. Further prospective investigations are needed to confirm these findings.

Clinical significance of serum 25 hydroxyvitamin D in breast cancer: An Indian scenario

Recent evidences suggest a protective mechanism of vitamin D signaling against breast cancer by the autocrine/paracrine manner and may modestly reduce the risk of breast cancer. Despite lots of sunshine, vitamin D deficiency is widespread in India. Moreover, there are limited studies from Indian population regarding circulatory 25(OH) D and breast cancer risk. Thus, the aim of the present study is to investigate circulatory 25(OH) D in relation to breast cancer risk and its association with various clinico-pathological parameters from Indian population. Total 297 subjects, comprising of 157 controls and 140 breast cancer patients were enrolled for the study. Circulatory 25(OH) D was analyzed by HPLC. Statistical analysis was carried out by SPSS software version 15. Further, subjects were categorized into severe, moderate, mild vitamin D deficiency and sufficiency. The prevalence of severe and moderate 25(OH) D deficiency was higher in breast cancer patients as compared to controls. Mean values of 25(OH) D were lower in breast cancer patients as compared to controls in mild, moderate and severe deficient groups (p = 0.07, p = 0.003 and p = 0.001). Moreover, 25(OH) D was significantly lower in postmenopausal breast cancer patients as compared to premenopausal breast cancer patients, particularly in severe deficient group. The levels of 25(OH) D were lower in ER and PR negative receptor status as compared to the positive receptor in severe deficient category (p = 0.06 and p = 0.09 respectively). Whereas, the mean values of 25(OH) D were lower in HER 2 negative receptor status as compared to positive receptor status in the moderate deficient category (p = 0.09). Further, severe deficient group showed significantly lower levels of 25(OH) Din TNBC as compared to luminal A subtype (p = 0.01). Thus, Results indicate that 25(OH) D deficiency might be associated with increased risk of breast cancer. Moreover, severe 25(OH) D deficiency is associated with aggressive behavior of breast cancer.

A multicenter case control study of association of vitamin D with breast cancer among women in Karachi, Pakistan

Background

The prevalence of vitamin D inadequacy and breast cancer are both high among women living in Karachi, Pakistan.

Methods

A matched case control study was conducted in two hospitals of Karachi, Pakistan to evaluate the association of vitamin D (serum 25-hydroxyvitamin D) concentrations, vitamin D supplementation and sun exposure with breast cancer among Pakistani women. A total of 411 newly diagnosed histologically confirmed primary breast cancer cases were enrolled and 784 controls, free of breast and any other cancers, were matched by age (year of birth ± 5 years), residence in the same geographic area and study site. Information was collected on sociodemographic history, history of vitamin D supplementation, past medical and obstetrical history, family history of breast cancer, sun exposure history, histopathology reports and anthropometric measurement and venous blood was collected to measure serum 25-hydroxyvitamin D (25(OH)D) concentration.

Results

Compared to patients with sufficient serum vitamin D (>30 ng/ml), women with serum vitamin D deficiency (<20ng/ml), had a higher risk of breast cancer (OR = 1.65, 95%CI: 1.10, 2.50). Women with history of vitamin D supplementation one year prior to enrollment, had significant protective effect against breast cancer (OR = 0.32, 95% CI: 0.24, 0.43).

Conclusions and recommendation

Serum vitamin D deficiency was associated with increased risk of breast cancer, while vitamin D supplementation was associated with decreased risk of breast cancer. In Pakistani women, where vitamin D deficiency is common, raising and maintaining serum vitamin D at population level is a safe and affordable strategy. It may play a role in reducing the incidence of both vitamin D deficiency and breast cancer, particularly among poor women where the breast cancer mortality is highest due to limited resources for early detection, diagnosis, and treatment. The effects of vitamin D with regard to breast cancer risk in Karachi Pakistan should be further evaluated.

Vitamin D intake, blood vitamin D levels, and the risk of breast cancer: a dose-response meta-analysis of observational studies

Epidemiological studies have indicated that blood vitamin D levels are linked to cancer. Here we conducted a dose-response meta-analysis based on published observational studies to evaluate the association of vitamin D intake and blood vitamin D levels with breast cancer susceptibility. PubMed, EMBASE, and Web of Science databases were searched up to January 2019. The pooled odds ratio (OR) and 95% confidence intervals (CIs) were extracted to estimate the risk. We identified 70 relevant studies on blood vitamin D levels (50 studies) and vitamin D intake (20 studies), respectively. Linear and nonlinear trend analyses were performed and showed that an increase in blood vitamin D levels by 5 nmol/l was associated with a 6% decrease in breast cancer risk (OR = 0.94, 95% CI = 0.93-0.96). Similar results were obtained for premenopausal (OR = 0.96, 95% CI = 0.93-0.99) and postmenopausal women (OR = 0.96, 95% CI = 0.94-0.98). The pooled OR of breast cancer risk for a 400IU/day increase in vitamin D intake was 0.97 (95% CI = 0.92-1.02). In conclusion, we found that breast cancer risk was inversely related to blood vitamin D levels; however, no significant association was observed in vitamin D intake.

Folate intake, serum folate, and risk of esophageal cancer: a systematic review and dose-response meta-analysis

The dose-response relationship between folate and the risk of esophageal cancer (EC) is not clear. To further elucidate their relationships, we carried out a dose-response meta-analysis of folate intake, serum folate, and the risk of EC. PubMed, Embase, Web of Science, and China National Knowledge Infrastructure were searched for observational studies until September 2016. Then, we carried out a systematic review and dose-response meta-analysis using Stata 14.0 software. Subgroup analyses were further carried out according to study characteristics and adjustment confounders. A total of 23 studies with a total of 3886 patients were enrolled in this study. The pooled odds ratios for EC in the highest versus the lowest levels of folate intake and serum folate were 0.64 (0.54-0.76, P<0.001) and 0.45 (0.19-1.07, P=0.071), respectively. Dose-response meta-analyses were carried out to assess associations between folate intake, serum folate, and EC risk. When serum folate is 10 μg/l higher than the lowest reference dosage (3.44 μg/l), EC decreased risk with an increase in serum folate levels. When folate intake is 50 μg/day higher than the lowest reference dosage (125.21 μg/day), the EC risk is decreased with an increase in folate intake. Finally, the results support that folate can promote public health through decreasing EC risk in a certain dosage range; otherwise, the protective effects might be reduced.

Association between Dietary Vitamin E Intake and Esophageal Cancer Risk: An Updated Meta-Analysis

Epidemiological studies have provided ambiguous evidence on the association between vitamin E and esophageal cancer risk. To resolve this controversy, we performed this meta-analysis. The literature was searched by using Excerpta Medica Database (EMBASE), PubMed, the Web of Science, and the Cochrane Library from the inception to April 2018. A random effect model was utilized to calculate the odds ratio (OR) with the 95% confidence interval (95% CI). Twelve articles reporting 14 studies involving 3013 cases and 11,384 non-cases were included. By comparing the highest category with the lowest category of dietary vitamin E intake, we found that dietary vitamin E intake was inversely related to esophageal cancer risk (OR = 0.47, 95% CI: 0.36–0.60). Subgroup analysis revealed that dietary vitamin E intake had a significantly negative association with both the esophageal squamous cell carcinoma risk (OR = 0.29, 95% CI: 0.18–0.44) and the esophageal adenocarcinoma risk (OR = 0.66, 95% CI: 0.49–0.88). No study significantly affected the findings in the sensitivity analysis. Publication bias was discovered, however, the OR (95% CI) remained unchanged after the trim-and-fill analysis. This meta-analysis showed that the higher dietary vitamin E intake is associated with a lower esophageal cancer risk. However, the association still needs to be upheld by more large-scaled randomized controlled trials and prospective studies.

Folate intake, serum folate levels and esophageal cancer risk: an overall and dose-response meta-analysis

Previously reported findings on the association between folate intake or serum folate levels and esophageal cancer risk have been inconsistent. This study aims to summarize the evidence regarding these relationships using a dose-response meta-analysis approach. We performed electronic searches of the Pubmed, Medline and Cochrane Library electronic databases to identify studies examining the effect of folate on the risk of esophageal cancer. Ultimately, 19 studies were included in the meta-analysis. Summary odds ratios (ORs) were estimated using a random effects model. A linear regression analysis of the natural logarithm of the OR was carried out to assess the possible dose-response relationship between folate intake and esophageal cancer risk. The pooled ORs for esophageal cancer in the highest vs. lowest levels of dietary folate intake and serum folate were 0.63 (95% CI: 0.56-0.71) and 0.71 (95% CI: 0.55-0.92), respectively. The dose-response meta-analysis indicated that a 100 μg/day increment in dietary folate intake reduced the estimate risk of esophageal cancer by 12%. These findings suggest that dietary and serum folate exert a protective effect against esophageal carcinogenesis.

Dietary vitamin C intake and the risk of hip fracture: a dose-response meta-analysis

The meta-analysis suggested that dietary vitamin C was statistically inversely associated with the risk of hip fracture (overall OR = 0.73, 95% CI = 0.55-0.97, I ² = 69.1%) and with the increase of 50 mg/day vitamin C intake, the risk of hip fracture will reduce by 5% (OR = 0.95, 95% CI 0.91-1.00, P = 0.05).

INTRODUCTION

Previous studies had inconsistent findings regarding the association between vitamin C intake and the risk of hip fracture. Therefore, we conducted a meta-analysis to evaluate the association of dietary vitamin C intake and the risk of hip fracture.

METHODS

Relevant studies were identified by searching PubMed, Embase, and Web of Science up to December 2016. Additional articles were identified from reviewing the reference lists of relevant articles. The summary relative risks (RRs) or odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by random effects model. Funnel plot and Egger's test were used to test publication bias.

RESULTS

The total six articles containing 7908 controls and 2899 cases of hip fracture were included in this meta-analysis. By comparing the highest versus the lowest categories of vitamin C intake, we found that dietary vitamin C was statistically correlated with the risk of hip fracture [overall OR = 0.73, 95% CI = 0.55-0.97, I ² = 69.1%]. A linear dose-response association showed that the increase with vitamin C intake of 50 mg/day statistically reduced by 5% (OR = 0.95, 95% CI 0.91-1.00, P = 0.05) the risk of hip fracture.

CONCLUSIONS

In conclusion, the results of current meta-analysis strongly support that increasing dietary vitamin C intake can decrease the risk of hip fracture. In order to verify the association of vitamin C intake and hip fracture risk, further well-designed largely randomized controlled trials (RCTs) are needed.

Phytotherapy and Nutritional Supplements on Breast Cancer

Breast cancer is the most frequent type of nonskin malignancy among women worldwide. In general, conventional cancer treatment options (i.e., surgery, radiotherapy, chemotherapy, biological therapy, and hormone therapy) are not completely effective. Recurrence and other pathologic situations are still an issue in breast cancer patients due to side effects, toxicity of drugs in normal cells, and aggressive behaviour of the tumours. From this point of view, breast cancer therapy and adjuvant methods represent a promising and challenging field for researchers. In the last few years, the use of some types of complementary medicines by women with a history of breast cancer has significantly increased such as phytotherapeutic products and nutritional supplements. Despite this, the use of such approaches in oncologic processes may be problematic and patient's health risks can arise such as interference with the efficacy of standard cancer treatment. The present review gives an overview of the most usual phytotherapeutic products and nutritional supplements with application in breast cancer patients as adjuvant approach. Regardless of the contradictory results of scientific evidence, we demonstrated the need to perform additional investigation, mainly well-designed clinical trials in order to establish correlations and allow for further validated outcomes concerning the efficacy, safety, and clinical evidence-based recommendation of these products.

Calcium Intake and the Risk of Ovarian Cancer: A Meta-Analysis

Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain controversial. Thus, we performed a meta-analysis to explore the association between calcium intake and the risk of ovarian cancer. Pubmed, Embase and Web of Science were searched for eligible publications up to April 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Small-study effect was estimated using Egger's test and the funnel plot. Among 15 epidemiological studies involving 493,415 participants and 7453 cases eligible for this meta-analysis, 13 studies were about dietary calcium intake, 4 studies about dairy calcium intake and 7 studies about dietary plus supplemental calcium intake. When comparing the highest with the lowest intake, the pooled RRs of ovarian cancer were 0.80 (95% CI 0.72-0.89) for dietary calcium, 0.80 (95% CI 0.66-0.98) for dairy calcium and 0.90 (95% CI 0.65-1.24) for dietary plus supplemental calcium, respectively. Dietary calcium was significantly associated with a reduced risk of ovarian cancer among cohort studies (RR = 0.86, 95% CI 0.74-0.99) and among case-control studies (RR = 0.75, 95% CI 0.64-0.89). In subgroup analysis by ovarian cancer subtypes, we found a statistically significant association between the dietary calcium (RR = 0.78, 95% CI 0.69-0.88) and the risk of epithelial ovarian cancer (EOC). This meta-analysis indicated that increased calcium intake might be inversely associated with the risk of ovarian cancer; this still needs to be confirmed by larger prospective cohort studies.

Dietary Fat Consumption and Non-Hodgkin's Lymphoma Risk: A Meta-analysis

OBJECTIVE

Many studies suggest that high-fat diets are linked to the etiology of non-Hodgkin's lymphoma (NHL). However, the findings are inconsistent and therefore the association between fat and non-Hodgkin's lymphoma remains unclear. In this study, we aim to quantitatively assess the association between fat consumption and the risk for NHL.

METHODS

We reviewed 221 published cohort and case-control studies that reported relative risk (RRs) and corresponding 95% confidence intervals (CIs) of NHL and fat intake using PubMed, Cochrane, EMBASE, and Google Scholar databases. A random-effects model computed summary risk estimates.

RESULTS

Based on our literature search, 10 of 221 studies (two cohort and eight case-control studies) were relevant to this meta-analysis. There was a significant association between total fat consumption and increased risk of NHL (RR = 1.26; 95% CI: 1.12-1.42); in addition, subgroup analysis showed a significant correlation with diffuse large B-cell lymphoma (RR = 1.41; 95% CI: 1.08-1.84) but not with follicular lymphoma (RR = 1.21; 95% CI: 0.97-1.52), small lymphocytic lymphoma/chronic lymphocytic leukemia (RR = 0.91; 95% CI: 0.68-1.23), nor with T cell lymphoma (RR = 1.12; 95% CI: 0.60-2.09). The funnel plot revealed no evidence for publication bias.

CONCLUSION

Total fat consumption, particularly animal fat, increases the risk for NHL.

Dietary and pharmacological compounds altering intestinal calcium absorption in humans and animals

The intestine is the only gate for the entry of Ca to the body in humans and mammals. The entrance of Ca occurs via paracellular and intracellular pathways. All steps of the latter pathway are regulated by calcitriol and by other hormones. Dietary and pharmacological compounds also modulate the intestinal Ca absorption process. Among them, dietary Ca and P are known to alter the lipid and protein composition of the brush-border and basolateral membranes and, consequently, Ca transport. Ca intakes are below the requirements recommended by health professionals in most countries, triggering important health problems. Chronic low Ca intake has been related to illness conditions such as osteoporosis, hypertension, renal lithiasis and incidences of human cancer. Carbohydrates, mainly lactose, and prebiotics have been described as positive modulators of intestinal Ca absorption. Apparently, high meat proteins increase intestinal Ca absorption while the effect of dietary lipids remains unclear. Pharmacological compounds such as menadione, dl-butionine-S,R-sulfoximine and ursodeoxycholic acid also modify intestinal Ca absorption as a consequence of altering the redox state of the epithelial cells. The paracellular pathway of intestinal Ca absorption is poorly known and is under present study in some laboratories. Another field that needs to be explored more intensively is the influence of the gene × diet interaction on intestinal Ca absorption. Health professionals should be aware of this knowledge in order to develop nutritional or medical strategies to stimulate the efficiency of intestinal Ca absorption and to prevent diseases.

Inhibition of 4NQO-Induced Oral Carcinogenesis by Dietary Oyster Shell Calcium

Oyster has gained much attention recently for its anticancer activity but it is unclear whether calcium, the major antitumor ingredient in oyster shell, is responsible for the anticarcinogenic role of the oyster. To address this issue, C57BL/6 mice were fed with the carcinogen 4-nitroquinoline-1-oxide (4NQO, 50 µg/mL) and normal diet or a diet containing oyster powder, oyster calcium, or calcium depleted oyster powder. The tongue tissue specimens isolated from these mice were histologically evaluated for hyperplasia, dysplasia, and papillary lesions, and then analyzed for proliferation and differentiation markers by immunohistochemistry. The results showed that mice on the diet containing oyster calcium significantly reduced rates of tumors in the tongue and proliferation and enhanced differentiation in the oral epithelium compared with the diet containing calcium depleted oyster powder. These results suggest that calcium in oyster plays a critical role in suppressing formation of oral squamous cell carcinoma and proliferation and promoting differentiation of the oral epithelium.

Association between vitamin C intake and lung cancer: a dose-response meta-analysis

Epidemiological studies evaluating the association between the intake of vitamin C and lung cancer risk have produced inconsistent results. We conducted a meta-analysis to assess the association between them. Pertinent studies were identified by a search of PubMed, Web of Knowledge and Wan Fang Med Online through December of 2013. Random-effect model was used to combine the data for analysis. Publication bias was estimated using Begg's funnel plot and Egger's regression asymmetry test. Eighteen articles reporting 21 studies involving 8938 lung cancer cases were included in this meta-analysis. Pooled results suggested that highest vitamin C intake level versus lowest level was significantly associated with the risk of lung cancer [summary relative risk (RR) = 0.829, 95%CI = 0.734–0.937, I² = 57.8%], especially in the United States and in prospective studies. A linear dose-response relationship was found, with the risk of lung cancer decreasing by 7% for every 100 mg/day increase in the intake of vitamin C [summary RR = 0.93, 95%CI = 0.88–0.98]. No publication bias was found. Our analysis suggested that the higher intake of vitamin C might have a protective effect against lung cancer, especially in the United States, although this conclusion needs to be confirmed.

Association of vitamin B6, vitamin B12 and methionine with risk of breast cancer: a dose-response meta-analysis

Background:

Epidemiological studies evaluating the association of vitamin B₆, vitamin B₁₂ and methionine with breast cancer risk have produced inconsistent results.

Methods:

Pertinent studies were identified by a search in PubMed and Web of Knowledge. Random-effect model was used. Dose–response relationship was assessed by restricted cubic spline.

Results:

The combined relative risk (95% confidence interval) of breast cancer for the highest vs lowest category of serum pyridoxal 5′-phosphate (PLP, active form of vitamin B₆) levels and dietary methionine intake was 0.80 (0.66–0.98, P=0.03) and 0.94 (0.89–0.99, P=0.03), respectively, and the associations of breast cancer with higher serum PLP levels and dietary methionine intake were significant among post-menopausal women, but not among pre-menopausal women. The inverse association between breast cancer risk and dietary vitamin B₆ intake, serum vitamin B₁₂ levels and dietary vitamin B₁₂ intake was not significant overall. Linear dose–response relationship was found, and the risk of breast cancer decreased by 23% (P<0.00) for every 100 pmol ml⁻¹ increment in PLP levels and 4% (P=0.05) for every 1 g per day increment in dietary methionine intake, respectively.

Conclusion:

Serum PLP levels and methionine intake might be inversely associated with breast cancer risk, especially among postmenopausal women, which need to be confirmed.

Calcium intake is not related to breast cancer risk among Singapore Chinese women

There is experimental evidence that calcium protects against breast cancer development. Prospective epidemiologic studies supporting a protective effect of calcium on breast cancer risk have mainly been limited to Western populations. We examined the association between calcium intake and breast cancer risk in the Singapore Chinese Health Study, a large population-based prospective cohort. Calcium intake and supplement use was assessed by in-person interviewer using a validated food frequency questionnaire. After a mean follow-up of 14.2±3.5 years, 823 cohort participants developed invasive breast cancer. Multivariate proportional hazards regression models were fitted to examine the associations between calcium intake and breast cancer risk. Vegetables were the primary food source of calcium in this study population, followed by dairy products, grains and soy foods. Calcium intake was not associated with breast cancer risk, comparing highest quartile (>345.6 mg/1,000 kcal/day) to lowest quartile (<204.5 mg/1,000 kcal/day) of intake. There was no evidence of effect modification by menopausal status, body mass index, dietary vitamin D or stage of disease at diagnosis. Our findings do not support a hypothesis for calcium in breast cancer chemoprevention, contrary to findings from previous studies among Western populations with higher calcium intake primarily from dairy products and supplements.