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Higher dietary folate intake reduces the breast cancer risk: a systematic review and meta-analysis.

Chen P, Li C, Li X, Li J, Chu R, Wang H - Br. J. Cancer (2014)

Bottom Line: Women with daily dietary folate intake between 153 and 400 μg showed a significant reduced breast cancer risk compared with those <153 μg, but not for those >400 μg.Increased dietary folate intake reduced breast cancer risk for women with higher alcohol intake level, but not for those with lower alcohol intake.No significant association between circulating folate level and breast cancer risk was found when the results of 8 identified studies with 5924 participants were pooled.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, People's Republic of China.

ABSTRACT

Background: Many epidemiological studies have investigated the association between folate intake, circulating folate level and risk of breast cancer; however, the findings were inconsistent between the studies.

Methods: We searched the PubMed and MEDLINE databases updated to January, 2014 and performed the systematic review and meta-analysis of the published epidemiological studies to assess the associations between folate intake level, circulating folate level and the overall risk of breast cancer.

Results: In all, 16 eligible prospective studies with a total of 744 068 participants and 26 205 breast cancer patients and 26 case-control studies with a total of 16 826 cases and 21 820 controls that have evaluated the association between folate intake and breast cancer risk were identified. Pooled analysis of the prospective studies and case-control studies suggested a potential nonlinearity relationship for dietary folate intake and breast cancer risk. Prospective studies indicated a U-shaped relationship for the dietary folate intake and breast cancer risk. Women with daily dietary folate intake between 153 and 400 μg showed a significant reduced breast cancer risk compared with those <153 μg, but not for those >400 μg. The case-control studies also suggested a significantly negative correlation between the dietary folate intake level and the breast cancer risk. Increased dietary folate intake reduced breast cancer risk for women with higher alcohol intake level, but not for those with lower alcohol intake. No significant association between circulating folate level and breast cancer risk was found when the results of 8 identified studies with 5924 participants were pooled.

Conclusions: Our studies suggested that folate may have preventive effects against breast cancer risk, especially for those with higher alcohol consumption level; however, the dose and timing are critical and more studies are warranted to further elucidate the questions.

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Related in: MedlinePlus

The pooled RR of breast cancer for women in the highest category of daily total folate intake level compared with those in the lowest category for the prospective studies.
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fig3: The pooled RR of breast cancer for women in the highest category of daily total folate intake level compared with those in the lowest category for the prospective studies.

Mentions: From the meta-analysis of the prospective studies, no significant association between dietary folate intake and breast cancer risk was found (pooled RR=0.95; 95% CI=0.87–1.03; Figure 2) for those in the highest category of dietary intake compared with those in the lowest category (Table 1). However, Egger's test suggested that significant publication bias existed (P=0.023). When we applied the trim and fill methods to adjust for the publication bias, we still found no significant reduced breast cancer risk for those with highest category dietary folate intake (pooled RR=1.04; 95% CI=0.94–1.15). The higher total folate intake also showed no reduction of breast cancer risk (pooled RR=0.97; 95% CI=0.87–1.08; Figure 3) under the random-effects model. Participants who took folate supplements had no reduced breast cancer risk compared with those who did not (pooled RR=1.07; 95% CI=0.95–1.21; Table 1). In the stratification analysis of folate intake and breast cancer risk by the quality of the studies, menopausal status of the women, the ethnicity of the participants, oestrogen receptor (ER) status for the breast cancer patients and whether the estimate was adjusted for the alcohol intake in the individual studies, we found no statistically significant heterogeneity for the summary estimate between the stratifications (Table 1).


Higher dietary folate intake reduces the breast cancer risk: a systematic review and meta-analysis.

Chen P, Li C, Li X, Li J, Chu R, Wang H - Br. J. Cancer (2014)

The pooled RR of breast cancer for women in the highest category of daily total folate intake level compared with those in the lowest category for the prospective studies.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4007237&req=5

fig3: The pooled RR of breast cancer for women in the highest category of daily total folate intake level compared with those in the lowest category for the prospective studies.
Mentions: From the meta-analysis of the prospective studies, no significant association between dietary folate intake and breast cancer risk was found (pooled RR=0.95; 95% CI=0.87–1.03; Figure 2) for those in the highest category of dietary intake compared with those in the lowest category (Table 1). However, Egger's test suggested that significant publication bias existed (P=0.023). When we applied the trim and fill methods to adjust for the publication bias, we still found no significant reduced breast cancer risk for those with highest category dietary folate intake (pooled RR=1.04; 95% CI=0.94–1.15). The higher total folate intake also showed no reduction of breast cancer risk (pooled RR=0.97; 95% CI=0.87–1.08; Figure 3) under the random-effects model. Participants who took folate supplements had no reduced breast cancer risk compared with those who did not (pooled RR=1.07; 95% CI=0.95–1.21; Table 1). In the stratification analysis of folate intake and breast cancer risk by the quality of the studies, menopausal status of the women, the ethnicity of the participants, oestrogen receptor (ER) status for the breast cancer patients and whether the estimate was adjusted for the alcohol intake in the individual studies, we found no statistically significant heterogeneity for the summary estimate between the stratifications (Table 1).

Bottom Line: Women with daily dietary folate intake between 153 and 400 μg showed a significant reduced breast cancer risk compared with those <153 μg, but not for those >400 μg.Increased dietary folate intake reduced breast cancer risk for women with higher alcohol intake level, but not for those with lower alcohol intake.No significant association between circulating folate level and breast cancer risk was found when the results of 8 identified studies with 5924 participants were pooled.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, People's Republic of China.

ABSTRACT

Background: Many epidemiological studies have investigated the association between folate intake, circulating folate level and risk of breast cancer; however, the findings were inconsistent between the studies.

Methods: We searched the PubMed and MEDLINE databases updated to January, 2014 and performed the systematic review and meta-analysis of the published epidemiological studies to assess the associations between folate intake level, circulating folate level and the overall risk of breast cancer.

Results: In all, 16 eligible prospective studies with a total of 744 068 participants and 26 205 breast cancer patients and 26 case-control studies with a total of 16 826 cases and 21 820 controls that have evaluated the association between folate intake and breast cancer risk were identified. Pooled analysis of the prospective studies and case-control studies suggested a potential nonlinearity relationship for dietary folate intake and breast cancer risk. Prospective studies indicated a U-shaped relationship for the dietary folate intake and breast cancer risk. Women with daily dietary folate intake between 153 and 400 μg showed a significant reduced breast cancer risk compared with those <153 μg, but not for those >400 μg. The case-control studies also suggested a significantly negative correlation between the dietary folate intake level and the breast cancer risk. Increased dietary folate intake reduced breast cancer risk for women with higher alcohol intake level, but not for those with lower alcohol intake. No significant association between circulating folate level and breast cancer risk was found when the results of 8 identified studies with 5924 participants were pooled.

Conclusions: Our studies suggested that folate may have preventive effects against breast cancer risk, especially for those with higher alcohol consumption level; however, the dose and timing are critical and more studies are warranted to further elucidate the questions.

Show MeSH
Related in: MedlinePlus