Associations of Dietary Long-Chain ω-3 Polyunsaturated Fatty Acids and Fish Consumption With Endometrial Cancer Risk in the Black Women's Health Study

Research on Health Disparities: Strategies and Findings From the Black Women's Health Study

The American Journal of Epidemiology has been a platform for findings from the Black Women's Health Study (BWHS) that are relevant to health disparities. Topics addressed have included methods of follow-up of a large cohort of Black women, disparities in health-care delivery, modifiable risk factors for health conditions that disproportionately affect Black women, associations with exposures that are highly prevalent in Black women, and methods for genetic research. BWHS papers have also highlighted the importance of considering social context, including perceived experiences of racism, in understanding health disparities. In the future, BWHS investigators will contribute to documentation of the role that structural racism plays in health disparities.

Dietary polyunsaturated fatty acids intake, air pollution, and the risk of lung cancer: A prospective study in UK biobank

BACKGROUND

Epidemiological evidence on the association between specific types of polyunsaturated fatty acids (PUFAs) intake and lung cancer risk is limited. However, whether dietary-specific PUFAs intake can modify the association between air pollutants and incident lung cancer remains unknown.

METHODS

Cox proportional hazard models and restricted cubic spline regression were used to evaluate the associations of omega-3 PUFAs, omega-6 PUFAs and the ratio of omega-6 PUFAs to omega-3 PUFAs intake with lung cancer risk. Furthermore, we evaluated the associations between air pollutants and incident lung cancer, and whether dietary-specific PUFAs intake would modify the relationship using stratification analyses.

RESULTS

This study found significant associations between the risk of lung cancer and omega-3 PUFAs intake (hazard ratio [HR], 0.82; 95 % confidence interval [CI], 0.73-0.93; per 1 g/d), and omega-6 PUFAs intake (HR, 0.98; 95 % CI, 0.96-0.99; per 1 g/d). We did not observe an association between the omega-6 to omega-3 PUFAs intake ratio and incident lung cancer. With regard to air pollution, omega-3 PUFAs intake attenuated the positive relationship between nitrogen oxides (NOx) pollution and lung cancer risk, and an increased incidence of lung cancer was found only in the low omega-3 PUFAs intake group (p < 0.05). Surprisingly, PUFAs intake (regardless of omega-3 PUFAs, omega-6 PUFAs, or in total) reinforced the pro-carcinogenic effects of PM_2.5 on lung cancer, and a positive association between PM_2.5 pollutants and incident lung cancer was observed only in the high PUFAs groups (p < 0.05).

CONCLUSIONS

Higher dietary omega-3 and omega-6 PUFAs intake was associated with a decreased risk of lung cancer in the study population. As omega-3 PUFAs have different modification effects on NO_X and PM_2.5 air pollution related lung cancer incidence, precautions should be taken when using omega-3 PUFAs as health-promoting dietary supplements, especially in high PM_2.5 burden regions.

Dietary fatty acids and endometrial cancer risk within the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Diet may impact important risk factors for endometrial cancer such as obesity and inflammation. However, evidence on the role of specific dietary factors is limited. We investigated associations between dietary fatty acids and endometrial cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

This analysis includes 1,886 incident endometrial cancer cases and 297,432 non-cases. All participants were followed up for a mean of 8.8 years. Multivariable Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) of endometrial cancer across quintiles of individual fatty acids estimated from various food sources quantified through food frequency questionnaires in the entire EPIC cohort. The false discovery rate (q-values) was computed to control for multiple comparisons.

RESULTS

Consumption of n-6 γ-linolenic acid was inversely associated with endometrial cancer risk (HR comparing 5th with 1st quintileQ5-Q1=0.77, 95% CI = 0.64; 0.92, ptrend=0.01, q-value = 0.15). This association was mainly driven by γ-linolenic acid derived from plant sources (HRper unit increment=0.94, 95%CI= (0.90;0.98), p = 0.01) but not from animal sources (HRper unit increment= 1.00, 95%CI = (0.92; 1.07), p = 0.92). In addition, an inverse association was found between consumption of n-3 α-linolenic acid from vegetable sources and endometrial cancer risk (HRper unit increment= 0.93, 95%CI = (0.87; 0.99), p = 0.04). No significant association was found between any other fatty acids (individual or grouped) and endometrial cancer risk.

CONCLUSION

Our results suggest that higher consumption of γ-linolenic acid and α-linoleic acid from plant sources may be associated with lower risk of endometrial cancer.

Dietary omega-3 fatty acids and endometrial cancer risk in the Epidemiology of Endometrial Cancer Consortium: An individual-participant meta-analysis

BACKGROUND

Limited data from prospective studies suggest that higher dietary intake of long-chain omega-3 polyunsaturated fatty acids (LCn3PUFA), which hold anti-inflammatory properties, may reduce endometrial cancer risk; particularly among certain subgroups characterized by body mass and tumor pathology.

MATERIALS AND METHODS

Data from 12 prospective cohort studies participating in the Epidemiology of Endometrial Cancer Consortium were harmonized as nested case-control studies, including 7268 endometrial cancer cases and 26,133 controls. Habitual diet was assessed by food frequency questionnaire, from which fatty acid intakes were estimated. Two-stage individual-participant data mixed effects meta-analysis estimated adjusted odds ratios (OR) and 95% confidence intervals (CI) through logistic regression for associations between study-specific energy-adjusted quartiles of LCn3PUFA and endometrial cancer risk.

RESULTS

Women with the highest versus lowest estimated dietary intakes of docosahexaenoic acid, the most abundant LCn3PUFA in diet, had a 9% increased endometrial cancer risk (Quartile 4 vs. Quartile 1: OR 1.09, 95% CI: 1.01-1.19; P trend = 0.04). Similar elevated risks were observed for the summary measure of total LCn3PUFA (OR 1.07, 95% CI: 0.99-1.16; P trend = 0.06). Stratified by body mass index, higher intakes of LCn3PUFA were associated with 12-19% increased endometrial cancer risk among overweight/obese women and no increased risk among normal-weight women. Higher associations appeared restricted to White women. The results did not differ by cancer grade.

CONCLUSION

Higher dietary intakes of LCn3PUFA are unlikely to reduce endometrial cancer incidence; rather, they may be associated with small to moderate increases in risk in some subgroups of women, particularly overweight/obese women.

N-6 Polyunsaturated Fatty Acids and Risk of Cancer: Accumulating Evidence from Prospective Studies

Previous studies on the association between polyunsaturated fatty acids (PUFAs) and cancer have focused on n-3 PUFAs. To investigate the association between intake or blood levels of n-6 PUFAs and cancer, we searched the PubMed and Embase databases up to March 2020 and conducted a meta-analysis. A total of 70 articles were identified. High blood levels of n-6 PUFAs were associated with an 8% lower risk of all cancers (relative risk (RR) = 0.92; 95% confidence interval (CI): 0.86-0.98) compared to low blood levels of n-6 PUFAs. In the subgroup analyses by cancer site, type of n-6 PUFAs, and sex, the inverse associations were strong for breast cancer (RR = 0.87; 95% CI: 0.77-0.98), linoleic acid (LA) (RR = 0.91; 95% CI: 0.82-1.00), and women (RR = 0.88; 95% CI: 0.79-0.97). In the dose-response analysis, a 2% and 3% decrease in the risk of cancer was observed with a 5% increase in blood levels of n-6 PUFAs and LA, respectively. Thus, there was no significant association between n-6 PUFA intake and the risk of cancer. The pooled RR of cancer for the highest versus lowest category of n-6 PUFA intake was 1.02 (95% CI: 0.99-1.05). Evidence from prospective studies indicated that intake of n-6 PUFAs was not significantly associated with risk of cancer, but blood levels of n-6 PUFAs were inversely associated with risk of cancer.

The Potential for Plant-Based Diets to Promote Health Among Blacks Living in the United States

Plant-based diets are associated with reduced risks of various chronic diseases in the general population. However, it is unclear how these benefits translate to Blacks living in the United States, who are disproportionately burdened with heart disease, cancer, diabetes, obesity, and chronic kidney disease. The objectives of this study were to: (1) review the general evidence of plant-based diets and health outcomes; (2) discuss how this evidence translates to Blacks following a plant-based diet; and (3) provide recommendations and considerations for future studies in this area. Interestingly, although the evidence supporting plant-based diets in the general population is robust, little research has been done on Blacks specifically. However, the available data suggests that following a plant-based diet may reduce the risk of heart disease and possibly cancer in this population. More research is needed on cardiovascular disease risk factors, cancer subtypes, and other chronic diseases. Further, attention must be given to the unique individual, familial, communal, and environmental needs that Blacks who follow plant-based diets may have. Interventions must be culturally appropriate in order to achieve long-term success, and providing low-cost, flavorful, and nutritious options will be important.

Dietary Intake of Omega-3 fatty acids and Endocrine-related Gynecological Cancer: A Meta-Analysis of Observational Studies

Purpose

Previous observational epidemiological studies have reported inconsistent findings on the association between dietary intake of omega-3 fatty acids and endocrine-related gynecological cancer such as ovarian cancer and endometrial cancer. This study aimed to investigate this association using a meta-analysis of observational studies.

Materials and Methods

We searched PubMed, EMBASE, and Cochrane library by using key words related with the topic in April 2017. The pooled odd ratios (pORs), relative risks (pRRs), or hazard ratios (pHRs) with 95% confidence intervals (CIs) were calculated based on the random-effects model. Also, we performed subgroup meta-analysis by methodological quality, types of cancer, study design, and omega-3 fatty acids.

Results

A total of ten observational studies with six case-control and four cohort studies were included in the final meta-analysis. In the meta-analysis of all the studies, dietary intake of total omega-3 fatty acids was not significantly associated with the risk of endometrial and ovarian cancers (pOR/HR, 0.87; 95% CI, 0.73-1.04; I²=67.2%) (highest versus lowest intake). In the subgroup meta-analysis by type of study, there was no significant association between them in cohort studies (pHR, 1.03; 95% CI, 0.63-1.67, I²=81.9%), whereas its reduced risk was observed in case-control studies (pOR, 0.81; 95% CI, 0.67 to 0.98, I²=55.7%).

Conclusion

The current meta-analysis of observational studies suggests that there is no higher level of evidence to support the protective effect of dietary omega-3 fatty acids on endocrine-related gynecological cancer. Further prospective studies should be conducted to confirm the association.

Long-chain omega-3 fatty acids and cancer: any cause for concern?

PURPOSE OF REVIEW

Recently, concerns have been raised with regard to the recommended doses of marine long-chain omega-3 polyunsaturated fatty acids (LC-omega-3 PUFAs) especially in relation to cancer risk and treatment. There is urgent need to clarify this point. This review considers the most recent evidence related to the potential risk of developing cancer with high LC-omega-3 PUFA intakes, and possible research strategies to better elucidate this matter.

RECENT FINDINGS

The latest published recommendations have still highlighted the usefulness of an increased dietary intake of LC-omega-3 PUFAs for the prevention of some cardiovascular diseases. However, LC-omega-3 PUFAs have been related to the potential development and progression of cancer, and considerable debate exists on this issue.

SUMMARY

The use of biomarkers reflecting the intake of LC-omega-3 PUFAs as cancer risk markers is discussed, as well as the possibility that the reported beneficial/deleterious effects may be confined to specific subpopulations on the basis of genetic, metabolic, and nutritional characteristics. Recent advances on new strategies for a safer intake of LC-omega-3 PUFAs will be considered, as their dietary sources may be contaminated by toxic/carcinogenic compounds. Potentially future directions in this important research area are also discussed.

Recommendations of the Spanish Menopause Society on the consumption of omega-3 polyunsaturated fatty acids by postmenopausal women

The consumption of long-chain omega-3 polyunsaturated fatty acids (LCO3-PUFAs) has shown a great variety of beneficial effects, including cardiovascular, metabolic and inflammatory effects, which make them interesting for the postmenopausal woman. Because LCO3-PUFAs could be effective and safe during this period, a panel of experts from the Spanish Menopause Society met to establish a set of recommendations for their use in postmenopausal women based on the best available evidence. The decrease in triglycerides is the most consistent effect observed with LCO3-PUFAs (at doses greater than 3g/day). In addition, LCO3-PUFAs have antiarrhythmic effects, reduce blood pressure, improve depressive and psychotic symptoms, and do not increase the risk of cancer. However, further studies are needed to confirm the benefit of LCO3-PUFAs in the relief of menopause symptoms and osteoporosis.

Dietary n-3 polyunsaturated fatty acids, fish consumption, and endometrial cancer risk: a meta-analysis of epidemiological studies

The relationship between intake of fish and n-3 fatty acids and endometrial cancer risk has not been consistent across epidemiological studies. We quantitatively assessed the aforementioned association through a systematic review and meta-analysis. PubMed and Embase were searched through March 2017 for eligible epidemiological studies. Fixed or random-effects models were used to pool relative risks (RRs) and 95% confidence intervals (CIs). The dose-response relationship was also evaluated. Based on the literature search, five prospective studies and 11 case-control studies were identified. All 16 studies were categorized as high-quality studies. After pooling available risk estimates, no significant association was detected between overall fish intake and endometrial cancer risk. In subgroup analyses, every one additional serving/week of fish intake was significantly associated with inversed endometrial cancer risk in studies adjusted for smoking (RR (95% CI): 0.95 (0.91-1.00)), or studies performed in Europe (RR (95% CI): 0.90 (0.84-0.97)), but not in other tested subgroups. In studies conducted in Asia, there was significant positive association (RR (95% CI): 1.15 (1.10-1.21)). Regarding n-3 PUFA intake, marginally inverse associations of high EPA or DHA intake were detected (EPA: RR (95% CI) = 0.79 (0.61-1.04); DHA: RR (95% CI) = 0.85 (0.64-1.11)). Dose-response analyses suggested a significant nonlinear relationship between DHA intake and endometrial cancer risk (p: 0.04). Overall, this meta-analysis suggests that intake of n-3 PUFA may be inversely associated with endometrial cancer risk at some level of evidence, although the exact relationship, especially for fish intake, needs further characterization. Further well-designed studies are warranted.