Dietary intake of fish, ω-3 and ω-6 fatty acids and risk of colorectal cancer: A prospective study in U.S. men and women

Dietary intake and tissue biomarkers of omega-6 fatty acids and risk of colorectal cancer in adults: a systematic review and dose-response meta-analysis of prospective cohort studies

Findings on the associations of dietary/tissue levels of omega-6 polyunsaturated fatty acids (n-6 PUFAs) with the risk of colorectal cancer (CRC) are conflicting. We conducted a dose-response meta-analysis to assess the associations of dietary/tissue levels of n-6 PUFAs [total, linoleic acid (LA), and arachidonic acid (AA)] with CRC risk in adults. Twenty prospective cohort studies with a total sample size of 787,490 participants were included. Comparing extreme intake levels of LA revealed the summary relative risks (RR) of 1.15 (95% confidence interval (CI): 1.05-1.27) for CRC, and 1.30 (95% CI: 1.00-1.68) for rectal cancer, indicating a significant positive association for LA. However, neither total n-6 PUFAs nor AA were associated with cancers. A significant positive association was also found between a 1 gr/day increase in dietary LA intake and risk of colon cancer (RR: 1.01, 95% CI: 1.00-1.02). There were no significant associations between tissue levels of total n-6 PUFAs (RR: 0.94, 95% CI: 0.75-1.19), LA (RR: 0.93, 95% CI: 0.61-1.41), and AA (RR: 0.97, 95% CI: 0.70-1.33) and CRC risk. In conclusion, these findings suggest that dietary intake, but not tissue levels, of LA was associated with an increased risk of colorectal, colon, and rectal cancers. (PROSPERO registration: CRD42024516584).

Associations of dietary fat types (MUFA, PUFA, SFA) and sources (animal, plant) with colorectal cancer risk: A comprehensive systematic review and dose-response meta-analysis of prospective cohort studies

BACKGROUND AND OBJECTIVES

While dietary fat intake has long been implicated as a risk factor for colorectal cancer, evidence from prospective cohort studies remains inconsistent. Moreover, previous meta-analyses examining the link between dietary fat intake and risk of colorectal cancer have not explored the dose-response relationships. Therefore, the current systematic review and meta-analysis was conducted to assess the dose-response associations of intakes of specific types (MUFA, PUFA and SFA) and sources (animal, plant) of dietary fat with the risk of colorectal, colon or rectal cancer.

METHODS

A comprehensive literature search of relevant online databases was performed to detect eligible studies until May 2023, identifying 21 prospective cohort studies with a total sample size of 2311,737 participants. The follow-up periods ranged from 7 to 19.4 years, during which 21,125 cases of colorectal, colon or rectal cancer were recorded.

RESULTS

Comparing extreme intake levels of total fat revealed the summary relative risk (RR) of 1.05 (95 % CI: 0.96-1.15) for colorectal cancer, 0.99 (95 % CI: 0.87-1.11) for colon cancer, and 1.09 (0.95 % CI: 0.93-1.13) for rectal cancer, indicating no significant association. Neither animal nor plant fat intake was associated with the risk of cancers. While no significant findings were also observed for MUFA or PUFA, the highest versus lowest comparison showed that a high intake of SFA was associated with a reduced risk of both colorectal 0.91 (95 % CI: 0.85-0.99) and colon cancer 0.86 (95 % CI: 0.75-0.98). However, in the non-linear dose-response analysis, the inverse association was seen within a certain range (<40 g/day).

CONCLUSIONS

These findings suggest that dietary SFA intake, less than 40 g/day, may have a protective effect against colorectal cancer. Further studies are needed to confirm our findings.

Associations of plasma omega-6 and omega-3 fatty acids with overall and 19 site-specific cancers: A population-based cohort study in UK Biobank

Previous epidemiological studies on the associations between polyunsaturated fatty acids (PUFAs) and cancer incidence have been inconsistent. We investigated the associations of plasma omega-3 and omega-6 PUFAs with the incidence of overall and 19 site-specific cancers in a large prospective cohort. 253,138 eligible UK Biobank participants were included in our study. With a mean follow-up of 12.9 years, 29,838 participants were diagnosed with cancer. The plasma levels of omega-3 and omega-6 PUFAs were expressed as percentages of total fatty acids (omega-3% and omega-6%). In our main models, both omega-6% and omega-3% were inversely associated with overall cancer incidence (HR per SD = 0.98, 95% CI = 0.96-0.99; HR per SD = 0.99, 95% CI = 0.97-1.00; respectively). Of the 19 site-specific cancers available, 14 were associated with omega-6% and five with omega-3%, all indicating inverse associations, with the exception that prostate cancer was positively associated with omega-3% (HR per SD = 1.03, 95% CI = 1.01-1.05). Our population-based cohort study in UK Biobank indicates small inverse associations of plasma omega-6 and omega-3 PUFAs with the incidence of overall and most site-specific cancers, although there are notable exceptions, such as prostate cancer.

Plasma n-3 Polyunsaturated Fatty Acid Levels and Colorectal Cancer Risk in the UK Biobank: Evidence of Nonlinearity, as Well as Tumor Site- and Sex-Specificity

BACKGROUND

The relationship between omega-3 polyunsaturated fatty acid (n-3 PUFA) intake and colorectal cancer risk is unclear. Blood n-3 PUFA concentration is a biomarker of dietary n-3 PUFA intake. We examined the relationship between plasma n-3 PUFA concentrations and colorectal cancer risk in UK Biobank (UKBB) participants.

METHODS

We analyzed the relationship between tertiles (T) of plasma total n-3 PUFAs and n-3 PUFA docosahexaenoic acid (DHA) levels, and overall colorectal cancer (also stratified by tumor location and sex) risk. Cox proportional hazards regression models were adjusted for clinical covariates. Nonlinearity was tested by restricted cubic splines.

RESULTS

There were 2,602 incident colorectal cancer cases in 234,598 UKBB participants with baseline plasma fatty acid data (mean follow-up 13.4 years). There was an inverse association between the plasma total n-3 PUFA level [T2 HR = 0.88 (95% confidence interval, 0.80-0.97) compared with the T1 reference; T3 = 0.91 (0.83-1.00)], as well as the plasma DHA concentration [T2 = 0.89 (0.80-0.98); T3 = 0.91 (0.82-1.00)], and colorectal cancer risk. The relationship was nonlinear [P for nonlinearity = 0.14 (total n-3 PUFAs) and 0.008 (DHA)], with a plateau effect at the highest n-3 PUFA concentrations. The relationship was more pronounced for proximal colon cancer [T2 = 0.82 (0.69-0.97); T3 = 0.76 (0.64-0.90) for DHA] and was evident for males [T2 = 0.84 (0.74-0.95); T3 = 0.89 (0.78-1.00)], but not for females.

CONCLUSIONS

Higher plasma n-3 PUFAs are associated with reduced colorectal cancer risk in the UKBB.

IMPACT

Nonlinearity, as well as tumor site and sex specificities, of the inverse relationship between plasma n-3 PUFA levels and colorectal cancer risk, if confirmed in other diverse populations, has significant implications for nutritional prevention guidelines.

Fish oil supplement use modifies the relationship between dietary oily fish intake and plasma n-3 PUFA levels: an analysis of the UK Biobank

Observational evidence linking dietary n-3 PUFA intake and health outcomes is limited by a lack of robust validation of dietary intake using blood n-3 PUFA levels and potential confounding by fish oil supplement (FOS) use. We investigated the relationship between oily fish intake, FOS use and plasma n-3 PUFA levels in 121 650 UK Biobank (UKBB) participants. Ordinal logistic regression models, adjusted for clinical and lifestyle factors, were used to quantify the contribution of dietary oily fish intake and FOS use to plasma n-3 PUFA levels (measured by NMR spectroscopy). Oily fish intake and FOS use were reported by 38 % and 31 % of participants, respectively. Increasing oily fish intake was associated with a higher likelihood of FOS use (P < 0·001). Oily fish intake ≥ twice a week was the strongest predictor of high total n-3 PUFA (OR 6·7 (95 % CI 6·3, 7·1)) and DHA levels (6·6 (6·3, 7·1). FOS use was an independent predictor of high plasma n-3 PUFA levels (2·0 (2·0, 2·1)) with a similar OR to that associated with eating oily fish < once a week (1·9 (1·8, 2·0)). FOS use was associated with plasma n-3 PUFA levels that were similar to individuals in the next highest oily fish intake category. In conclusion, FOS use is more common in frequent fish consumers and modifies the relationship between oily fish intake and plasma n-3 PUFA levels in UKBB participants. If unaccounted for, FOS use may confound the relationship between dietary n-3 PUFA intake, blood levels of n-3 PUFAs and health outcomes.

Role of dietary intake of specific polyunsaturated fatty acids (PUFAs) on colorectal cancer risk in Iran

High-fat diets have been associated with colorectal cancer (CRC) risk, and the role of polyunsaturated fatty acids (PUFAs) has been reported to vary based on the length of PUFAs. We explored the association between dietary omega-6 and omega-3 PUFAs intake and CRC. We analyzed 865 CRC patients and 3206 controls from a case-control study of Iran (IROPICAN study). We used multivariate logistic regression models to calculate the odds ratios (OR) and 95% confidence intervals (CI) for the association between PUFAs intake and CRC risk. Our results showed that gamma-linolenic acid (18:3 n-6, GLA), arachidonic acid (20:4n-6, ARA), a-linolenic acid (Cis-18:3n-3, ALA), eicosapentaenoic acid (20:5n-3, EPA), docosahexaenoic acid (22:6n-3, DHA) consumption was not associated with the risk of CRC. However, the OR of linoleic acid (18: 2n-6, LA) intake was 1.47 (95% CI 1.01-2.14, p = 0.04) for proximal colon and that of docosapentaenoic acid (22:5n-3, DPA) intake was 1.33 (95% CI 1.05-1.69, p = 0.01) for rectum. This study indicates a high level of LA is associated with an increased risk of proximal colon cancer, and DPA intake was positively associated with rectum cancer risk. Furthermore, our study noted a high intake of n-6 (from vegetable oils) compared to n-3 PUFAs (from fish and seafood) in this population. Public awareness and government support is needed to increase fish and seafood production and consumption in Iran.

Associations of plasma omega-6 and omega-3 fatty acids with overall and 19 site-specific cancers: a population-based cohort study in UK Biobank

Background

Previous epidemiological studies of the associations between polyunsaturated fatty acids (PUFAs) and cancer incidence have been inconsistent. We investigated the associations of plasma omega-3 and omega-6 PUFAs with the incidence of overall and 19 site-specific cancers in a large prospective cohort.

Methods

253,138 eligible UK Biobank participants were included in our study. With a mean follow-up of 12.9 years, 29,838 participants were diagnosed with cancer. The plasma levels of omega-3 and omega-6 PUFAs were expressed as percentages of total fatty acids (omega-3% and omega-6%).

Results

In our main models, both omega-6% and omega-3% were inversely associated with overall cancer incidence (HR per SD = 0.98, 95% CI = 0.96-0.99; HR per SD = 0.99, 95% CI = 0.97-1.00; respectively). Of the 19 site-specific cancers available, 14 were associated with omega-6% and five with omega-3%, all indicating inverse associations, with the exception that prostate cancer was positively associated with omega-3% (HR per SD = 1.03, 95% CI = 1.01 - 1.05).

Conclusions

Our population-based cohort study in UK Biobank indicates small inverse associations of plasma omega-6 and omega-3 PUFAs with the incidence of overall and most site-specific cancers, although there are notable exceptions, such as prostate cancer.

Serum levels of n-3 PUFA and colorectal cancer risk in Chinese population

Circulating n-3 PUFA, which integrate endogenous and exogenous n-3 PUFA, can be better used to investigate the relationship between n-3 PUFA and disease. However, studies examining the associations between circulating n-3 PUFA and colorectal cancer (CRC) risk were limited, and the results remained inconclusive. This case–control study aimed to examine the association between serum n-3 PUFA and CRC risk in Chinese population. A total of 680 CRC cases and 680 sex- and age-matched (5-year interval) controls were included. Fatty acids were assayed by GC. OR and 95 % CI were calculated using multivariable logistic regression after adjustment for potential confounders. Higher level of serum α-linolenic acid (ALA), docosapentaenoic acid (DPA), DHA, long-chain n-3 PUFA and total n-3 PUFA were associated with lower odds of CRC. The adjusted OR and 95 % CI were 0·34 (0·24, 0·49, Pfor trend < 0·001) for ALA, 0·57 (0·40, 0·80, Pfor trend < 0·001) for DPA, 0·48 (0·34, 0·68, Pfor trend < 0·001) for DHA, 0·39 (0·27, 0·56, Pfor trend < 0·001) for long-chain n-3 PUFA and 0·31 (0·22, 0·45, Pfor trend < 0·001) for total n-3 PUFA comparing the highest with the lowest quartile. However, there was no statistically significant association between EPA and odds of CRC. Analysis stratified by sex showed that ALA, DHA, long-chain n-3 PUFA and total n-3 PUFA were inversely associated with odds of CRC in both sexes. This study indicated that serum ALA, DPA, DHA, long-chain n-3 PUFA and total n-3 PUFA were inversely associated with odds of having CRC in Chinese population.

Anti-Inflammatory and Immune Properties of Polyunsaturated Fatty Acids (PUFAs) and Their Impact on Colorectal Cancer (CRC) Prevention and Treatment

Colorectal cancer (CRC) remains a leading cause of death from cancer worldwide, with increasing incidence in the Western world. Diet has become the focus of research as a significant risk factor for CRC occurrence, and the role of dietary polyunsaturated fatty acids (PUFAs) has become an area of interest given their potential role in modulating inflammation, particularly in the pro-carcinogenic inflammatory environment of the colon. This work reviews the main types of PUFAs, their characteristics, structure, and physiologic role. We then highlight their potential role in preventing CRC, their signaling function vis-à-vis tumorigenic signaling, and their subsequent potential role in modulating response to different treatment modalities. We review pre-clinical and clinical data and discuss their potential use as adjunct therapies to currently existing treatment modalities. Given our understanding of PUFAs' immune and inflammation modulatory effects, we explore the possible combination of PUFAs with immune checkpoint inhibitors and other targeted therapies.

Impact of Diet on Colorectal Cancer Progression and Prevention: From Nutrients to Neoplasms

Colorectal cancer (CRC), one of the most common cancers worldwide, continues to increase in incidence and mortality rates. This trend is closely linked to changes in dietary habits, which are major risk factors for colorectal cancer. The increase in the incidence of CRC in countries previously considered low-risk and with low socioeconomic status is most likely due to lifestyle and dietary changes. Understanding the influence of dietary factors on the onset of colorectal cancer is essential for prevention and treatment. This review explores the complex interplay between dietary factors and colorectal cancer, focusing on the key nutrients and dietary habits that influence disease onset and progression. The impact of diet on colorectal microbiota and the influence of diet on early-onset colorectal cancer are also reviewed, reviewing recent research on how dietary interventions affect the treatment and recurrence of colorectal cancer. Finally, the future research directions for developing and applying effective dietary intervention strategies are discussed.

Food Intake and Colorectal Cancer

Colorectal cancer (CRC) accounts for considerable mortalities worldwide. Several modifiable risk factors, including a high intake of certain foods and beverages can cause CRC. This review summarized the latest findings on the intake of various foods, nutrients, ingredients, and beverages on CRC development, with the objective of classifying them as a risk or protective factor. High-risk food items include red meat, processed meat, eggs, high alcohol consumption, sugar-sweetened beverages, and chocolate candy. Food items that are protective include milk, cheese and other dairy products, fruits, vegetables (particularly cruciferous), whole grains, legumes (particularly soy beans), fish, tea (particularly green tea), coffee (particularly among Asians), chocolate, and moderate alcohol consumption (particularly wine). High-risk nutrients/ingredients include dietary fat from animal sources and industrial trans-fatty acids (semisolid/solid hydrogenated oils), synthetic food coloring, monosodium glutamate, titanium dioxide, and high-fructose corn sirup. Nutrients/ingredients that are protective include dietary fiber (particularly from cereals), fatty acids (medium-chain and odd-chain saturated fatty acids and highly unsaturated fatty acids, including omega-3 polyunsaturated fatty acids), calcium, polyphenols, curcumin, selenium, zinc, magnesium, and vitamins A, C, D, E, and B (particularly B6, B9, and B2). A combination of micronutrients and multi-vitamins also appears to be beneficial in reducing recurrent adenoma incidence.

Comprehensive Investigation on Associations between Dietary Intake and Blood Levels of Fatty Acids and Colorectal Cancer Risk

BACKGROUND

Increasingly, studies have discovered that different fatty acids (Fas) are linked to colorectal cancer (CRC) risk.

METHODS

We systematically searched Embase and Medline databases to identify eligible studies that examined the associations of different types of Fas with CRC risk. The effect estimates and their 95% confidence intervals (Cis) were pooled using a random-effects model. Subgroup and sensitivity analyses were performed to examine the robustness of the study findings.

RESULTS

This study evaluated the associations of 28 dietary and 18 blood Fas with CRC risk by summarizing the most updated evidence from 54 observational and four Mendelian Randomization (MR) studies. The present findings suggested that high dietary intake of eicosapentaenoic acid (EPA), docosahexanoic acid (DHA), and docosapentaenoic acid (DPA) are related to low risk of CRC, while the n-6/n-3 PUFA ratio and trans-FA are related to high risk of CRC. The summary of all cohort studies found that a high intake of SFA and DHA was a protective factor for CRC, and a high intake of the n-6/n-3 PUFA ratio was a risk factor for CRC. In the subgroup analysis of cancer subsites, we found that the dietary intake of linoleic acid (LA) and trans-FA are risk factors, while DPA is a protective factor for colon cancer. High dietary DHA intake was associated with a lower risk of rectal cancer, while the dietary n-6/n-3 PUFA ratio was associated with a higher risk of rectal cancer. Meta-analysis of blood FA levels showed a significant reverse association between blood pentadecanoic acid and CRC risk, whilst other blood Fas showed no significant association with CRC risk. All included MR studies showed that high plasma arachidonic acid (AA) is associated with increased CRC risk.

CONCLUSIONS

Current evidence on the dietary intake and blood levels of Fas in relation to CRC risk is less consistent. Future studies are needed to investigate how the metabolism of Fas contributes to CRC development.

Association between dietary intake of n-3 polyunsaturated fatty acids and risk of colorectal cancer in the Japanese population: The Japan Collaborative Cohort Study

BACKGROUND

Epidemiological studies of the dietary intake of specific n-3 polyunsaturated fatty acids (PUFA) and anatomical subsite-specific colorectal cancer (CRC) are limited. We examined the prospective associations of total n-3 PUFA, marine-derived n-3 PUFA [combined eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA)], and alpha-linolenic acid (ALA) as plant-derived n-3 PUFA with the risk of CRC by subsite in the Japan Collaborative Cohort Study.

METHODS

The participants completed a self-administered food frequency questionnaire and had no prior history of CRC. Cox proportional hazards model was used to determine the associations between n-3 PUFAs intake and CRC risk overall and by anatomical subsite.

RESULTS

During the median 13.8-year follow-up period, 699 of the 42,536 participants aged 40-79 years developed incident CRC. An inverse association was found between dietary ALA intake and the risk of distal colon cancer; the multivariable hazard ratios and 95% confidence intervals for the highest quartiles (Q4) were 0.41 (0.21-0.81; p trend = 0.01) compared with the lowest quartiles (Q1). Marine n-3 PUFA intake was not associated with CRC risk in the overall or anatomical subsite-specific analyses.

CONCLUSION

Our findings suggest that higher ALA intake may be beneficial for lowering the risk of distal colon cancer.

Crosstalk between biological and chemical diversity with cytotoxic and cytostatic effects of Aphanothece halophytica in vitro

Different solvent extracts from Aphanothece halophytica (A. halophytica) were evaluated for their cytotoxic effects against four human cancer cell lines. The samples demonstrated different percentages of cyanobacteria species populations. The samples containing 100% A. halophytica and 90% A. halophytica showed a significant cytotoxic effect in human breast cancer cells MDA231. The cytostatic effect was demonstrated in MDA231 and human glioblastoma T98G cells regardless of the treatment, resulting in a significant cell cycle arrest in the S phase. The chemical profiles of the extracts were proven to be diverse in qualitative and quantitative compositions. This variability was dependent on the A. halophytica´s abundance in each extract. The 100% A. halophytica extract induced cytotoxic and cytostatic effects in breast cancer cells, and those could be associated with the predominance of fatty acids, hydrocarbons and phthalates, indicating that A. halophytica is an interesting source of novel compound with anticancer effect.

Association between Dietary Fatty Acid Patterns and Colorectal Cancer Risk: A Large-Scale Case-Control Study in China

Associations of dietary fatty acids with the risk of colorectal cancer (CRC) remain controversial. The objective of this study was to examine whether dietary-derived fatty acid patterns were related to CRC risk among Chinese people. A total of 2806 CRC patients and 2806 frequency-matched controls were interviewed in this case-control study between July 2010 and May 2021. A food frequency questionnaire was used to gather information on dietary intake. Four fatty acid patterns were identified using factor analysis. The even-long-chain fatty acid pattern had no statistically significant association with CRC risk (adjusted Odds ratio (aOR), 1.16; 95% confidence interval (CI), 0.97-1.39; ptrend = 0.129). However, significant inverse associations were found between the medium-chain and long-chain saturated fatty acid (SFA) pattern (aOR, 0.34; 95%CI, 0.27-0.42), the highly unsaturated fatty acid pattern (aOR, 0.73; 95%CI, 0.60-0.88), the odd-chain fatty acid pattern (aOR, 0.69; 95%CI, 0.57-0.83), and CRC risk. The interaction between fatty acid patterns and sex was observed, and the association between the highly unsaturated fatty acid pattern and CRC risk differed by subsite. In conclusion, increasing the intakes of foods rich in medium-chain SFAs, highly unsaturated fatty acids, and odd-chain fatty acids may be related to a lower risk of CRC.

Association between dietary intake of fatty acids and colorectal cancer, a case-control study

Background

The association of dietary fat and colorectal cancer (CRC) was frequently reported. However, few studies assessed the effects of different types of dietary fats on CRC. This study aimed to investigate the association between intakes of different types of dietary fatty acids with colorectal cancer risk.

Methods

This case-control study was conducted on 480 participants including 160 CRC cases and 320 healthy controls in Firoozgar Hospital, Tehran, Iran. The intake of dietary fatty acids of the participants was assessed using a semi quantitative food frequency questionnaire (FFQ).

Results

The mean intake of cholesterol (273.07 ± 53.63 vs. 254.17 ± 61.12, P = 0.001), polyunsaturated fatty acids (PUFA) (16.54 ± 4.20 vs. 15.41 ± 4.44, P = 0.012), and calorie (2,568.76 ± 404.48 vs. 2,493.38 ± 176.03, P = 0.006) was higher and the mean intake of oleic acid (5.59 ± 3.17 vs. 8.21 ± 5.46) and linoleic acid (6.03 ± 3.44 vs. 7.02 ± 4.08, P = 0.01) was lower in the case group compared to the control group. An inverse association was found between colorectal cancer (CRC) and dietary intake of oleic acid (OR: 0.85, CI 95% 0.80–0.90, P = 0.001), linoleic acid (OR: 0.85, CI 95% 0.78–0.93, P = 0.001), and α-linolenic acid (OR: 0.75, CI 95% 0.57–0.98, P = 0.04). The association remained significant after adjusting for age and sex, sleep, smoking, and alcohol consumption, and BMI.

Conclusions

The results of this study support a protective effect of oleic acid, linoleic acid, and α-linolenic acid against CRC. Further longitudinal studies are warranted to confirm these results.

Dietary Intervention for Preventing Colorectal Cancer: A Practical Guide for Physicians

Colorectal cancer (CRC) is a disease with high prevalence and mortality. Estimated preventability for CRC is approximately 50%, indicating that altering modifiable factors, including diet and body weight, can reduce CRC risk. There is strong evidence that dietary factors including whole grains, high-fiber, red and processed meat, and alcohol can affect the risk of CRC. An alternative strategy for preventing CRC is use of a chemopreventive supplement that provides higher individual exposure to nutrients than what can be obtained from the diet. These include calcium, vitamin D, folate, n-3 polyunsaturated fatty acids, and phytochemicals. Several intervention trials have shown that these dietary chemopreventives have positive protective effects on development and progression CRC. Research on chemoprevention with phytochemicals that possess anti-inflammatory and/or, anti-oxidative properties is still in the preclinical phase. Intentional weight loss by bariatric surgery has not been effective in decreasing long-term CRC risk. Physicians should perform dietary education for patients who are at high risk of cancer for changing their dietary habits and behaviour. An increased understanding of the role of individual nutrients linked to the intestinal micro-environment and stages of carcinogenesis would facilitate the development of the best nutritional formulations for preventing CRC.

Dereplication of Cytochalasans and Octaketides in Cytotoxic Extracts of Endophytic Fungi from Casearia arborea (Salicaceae)

Endophytes have been shown to be a source of novel drug prototypes. The Casearia genus is known for presenting cytotoxic clerodane diterpenes; however, there are few reports on secondary metabolites produced by its fungal microbiota. Thus, in the present study endophytic fungi obtained from the fresh leaves of C. arborea were grown in potato dextrose broth and rice to perform a secondary metabolite prospection study. The cytotoxic profile of the crude extracts at 10 µg/mL was determined by a colorimetric assay on tumor cell lines. The endophytes producing cytotoxic extracts were identified through phylogenetic analysis and belong to Diaporthe and Colletotrichum species. Metabolites present in these extracts were organized in molecular networking format based on HRMS-MS, and a dereplication process was performed to target compounds for chromatographic purification. Metabolic classes, such as lipids, peptides, alkaloids, and polyketides were annotated, and octaketide and cytochalasin derivatives were investigated. Cytochalasin H was purified from the cytotoxic Diaporthe sp. CarGL8 extract and its cytotoxic activity was determined on human cancer cell lines A549, MCF-7, and HepG2. The data collected in the present study showed that molecular networking is useful to understand the chemical profile of complex matrices to target compounds, minimizing the cost and time spent in purification processes.

On optimal two-stage testing of multiple mediators

Mediation analysis in high-dimensional settings often involves identifying potential mediators among a large number of measured variables. For this purpose, a two-step familywise error rate procedure called ScreenMin has been recently proposed. In ScreenMin, variables are first screened and only those that pass the screening are tested. The proposed data-independent threshold for selection has been shown to guarantee asymptotic familywise error rate. In this work, we investigate the impact of the threshold on the finite-sample familywise error rate. We derive a power maximizing threshold and show that it is well approximated by an adaptive threshold of Wang et al. (2016, arXiv preprint arXiv:1610.03330). We illustrate the investigated procedures on a case-control study examining the effect of fish intake on the risk of colorectal adenoma. We also apply our procedure in the context of replicability analysis to identify single nucleotide polymorphisms (SNP) associated with crop yield in two distinct environments.

Association of Dietary Intake and Biomarker of α-Linolenic Acid With Incident Colorectal Cancer: A Dose-Response Meta-Analysis of Prospective Cohort Studies

Background and Objective

There is keen interest in better understanding the impacts of alpha-linolenic acid (ALA), a plant-derived n-3 fatty acid, in ameliorating the development of cancer; however, results of several prospective cohorts present an inconsistent association between ALA intake and the incident colorectal cancer (CRC). We aimed to investigate the summary association of dietary intake and biomarkers of ALA with CRC risk based on the prospective cohorts.

Methods

Pertinent prospective cohorts were identified in Cochrane Library, PubMed, and EMBASE from inception to February 2022. Study-specific risk ratios (RRs) with 95% confidence intervals (CIs) for comparing the top with the bottom quartiles of ALA levels were combined using a random-effects model. Nonlinear dose-response relationships of ALA levels in diet and blood with CRC risk were assessed using the restricted cubic spline models, respectively.

Results

Over the duration of follow-up with a median of 9.3 years ranging from 1 to 28 years, 12,239 CRC cases occurred among 861,725 participants from 15 cohorts (11 studies on diet and 5 studies on biomarkers including 4 on blood and 1 on adipose tissue). The summary RR was 1.03 (95% CI: 0.97, 1.10; I²: 0.00%) for dietary intake and 0.83 (95% CI: 0.69, 0.99; I²: 0.00%) for biomarker. Each 0.1% increase in the levels of ALA in blood was associated with a 10% reduction in risk of CRC (summary RR: 0.90, 95% CI: 0.80, 0.99; I²: 38.60%), whereas no significant dose-response association was found between dietary intake of ALA and the incident CRC (p for non-linearity = 0.18; p for linearity = 0.24).

Conclusions

Blood levels of ALA were inversely and linearly associated with the risk of CRC, which suggested that increased intake of ALA to improve circulating levels was beneficial for CRC prevention.

Use of polyunsaturated fatty acids in prevention and treatment of gastrointestinal diseases, obesity and cancer

Fatty acids are important structural and functional elements of human body. We can distinguish several types: among others polyunsaturated fatty acids, which include omega-3 fatty acids (ω-3PUFA) and omega-6 fatty acids(ω-6PUFA). The first group has pleiotropic health-promoting effects, while the second group, ω-6PUFA, negatively affects the homeostasis of the human body and contributes to the development of numerous diseases. Both the amount and the relative ratio of these acids in the diet is an important factor affecting health and quality of life.

Laboratory and clinical studies indicate that ω-3PUFA have a positive effect on the therapy of illnesses such as obesity and inflammatory bowel disease (IBD). ω-3 PUFA supplementation also appears to have a helpful effect in the adjuvant treatment of colorectal cancer and recovery.

Inverse Association between Canned Fish Consumption and Colorectal Cancer Risk: Analysis of Two Large Case-Control Studies

Fish is among the foods exerting favourable effects on colorectal cancer (CRC), but the possible role of canned fish has been insufficiently investigated. We aimed to investigate the relationship between canned fish consumption and CRC risk. We analysed data from two case−control studies conducted between 1992 and 2010 in several Italian areas, comprising a total of 2419 incident cases and 4723 hospital controls. Canned fish consumption was analysed according to the weekly frequency of consumption as <1 serving per week (s/w) (reference category), 1 < 2 s/w, and ≥2 s/w. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression models, adjusting for several recognised confounding factors. Overall, canned fish consumption was lower among cases than among controls (23.8% vs. 28.6%). An inverse association was found between canned fish consumption and CRC risk with a significant trend in risk (OR = 0.81, 95% CI: 0.71−0.92 for intermediate consumption and OR = 0.66, 95% CI: 0.51−0.85 for the highest one), which was consistent across strata of several covariates. This study is the first to offer a basis of support for canned fish consumption as a component of a healthy diet, and it has relevant public health implications given the high ranking of CRC in incidence and mortality worldwide.

Omega-3 polyunsaturated fatty acids: moving towards precision use for prevention and treatment of colorectal cancer

Data from experimental studies have demonstrated that marine omega-3 polyunsaturated fatty acids (O3FAs) have anti-inflammatory and anticancer properties. In the last decade, large-scale randomised controlled trials of pharmacological delivery of O3FAs and prospective cohort studies of dietary O3FA intake have continued to investigate the relationship between O3FA intake and colorectal cancer (CRC) risk and mortality. Clinical data suggest that O3FAs have differential anti-CRC activity depending on several host factors (including pretreatment blood O3FA level, ethnicity and systemic inflammatory response) and tumour characteristics (including location in the colorectum, histological phenotype (eg, conventional adenoma or serrated polyp) and molecular features (eg, microsatellite instability, cyclooxygenase expression)). Recent data also highlight the need for further investigation of the effect of O3FAs on the gut microbiota as a possible anti-CRC mechanism, when used either alone or in combination with other anti-CRC therapies. Overall, these data point towards a precision approach to using O3FAs for optimal prevention and treatment of CRC based on mechanistic understanding of host, tumour and gut microbiota factors that predict anticancer activity of O3FAs.

The impact of bioactive compounds derived from marine fish on cancer

Cancer persists as the world's leading cause of mortality, thereby making it a compelling condition to research and potentially develop prevention options. Anticancer therapies such as chemotherapy, surgery and radiation therapy are becoming highly futile and tend to have achieved a clinical deficit, due to massive side effects, toxicities, and limited specificity. Anticancer agents from natural sources, such as aquatic fishes, terrestrial mammals, animal venoms, and amphibians, have mainly been focused on in recent researches. Edible marine fishes contain high contents of fatty acids, vitamins, and proteins, also having bioactive compounds. Fish derivatives are naturally having the potential to target cancer cells while being less hazardous to normal tissues, making them a better choice for cancer prevention and therapy. In this review, we mainly focused on the bioactive compounds identified from marine fishes which have significant biological properties including anticancer effects, also discuss the mechanism of action.

Fish Consumption and Colorectal Cancer Risk: Meta-Analysis of Prospective Epidemiological Studies and Review of Evidence from Animal Studies

Background: Epidemiological studies on the association between fish consumption and colorectal cancer (CRC) risk have yielded inconsistent results, despite evidence from preclinical studies that long-chain ω-3 polyunsaturated fatty acids inhibit colorectal carcinogenesis. We conducted a meta-analysis of prospective epidemiological studies investigating the association between fish consumption and CRC risk among humans and reviewed studies examining the link between fish components and colorectal carcinogenesis in animal models. Methods: We included studies published until November 2020. We calculated the summary risk ratio (SRR) and 95% confidence intervals (CI) through random effects meta-analysis models in order to summarize evidence from studies among humans. Results: Twenty-five prospective epidemiological studies encompassing 25,777 CRC cases were included. Individuals in the highest (vs. lowest) category of fish consumption had a significantly reduced risk of CRC (SRR 0.94, 95%CI 0.89-0.99). In dose-response meta-analysis, a 50-g increment in the daily consumption of fish was associated with a statistically significant 4% reduction in CRC risk (SRR 0.96, 95%CI 0.92-0.99). Preclinical studies (n = 25) identified multiple mechanisms of action of fish and fish components on colorectal carcinogenesis. Conclusions: Dietary recommendations for cancer prevention should take into account the evidence from epidemiological and preclinical studies that increasing fish consumption may be effective in preventing CRC.

Dietary Fat Intake and KRAS Mutations in Colorectal Cancer in a Moroccan Population

Epidemiologic data support an association between diet and mutations in the Kirsten-ras (KRAS) gene involved in colorectal cancer (CRC) development. This study aimed to explore the associations between fat intake and KRAS mutations in codons 12 and 13 in cases of CRC in the Moroccan population. A multicenter case-series study nested in a large-scale Moroccan CRC case-control study was conducted. Among all CRC cases recruited, 151 specimens were available for the DNA mutation analysis. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (Cis) for KRAS mutation status according to the fat intake variables. A KRAS mutation was detected in the CRC tumor of 34.4% of the patients among whom 65.4% had a single mutation at codon 12 and 34.6% had a single mutation at codon 13. Compared to low levels of consumption, a positive association was observed between high polyunsaturated fatty acids (PUFA) consumption (>16.9 g/day) and prevalence of KRAS mutations (OR = 2.15, 95% CI = 1.01-4.59). No statistically significant associations were observed for total fat, monounsaturated fatty acids, saturated fatty acids and KRAS mutations. The results of this study suggest that PUFA may be relevant in the etiology of CRC, possibly through the generation of G > A transitions at the KRAS oncogene. Further studies are needed to verify and explain this finding.

Dietary patterns with combined and site-specific cancer incidence in Alberta's Tomorrow Project cohort

BACKGROUND/OBJECTIVES

Poor diet quality has been associated with an increased risk of cancer. Here, we examine the association between dietary patterns derived with two methods, and combined and site-specific cancer incidence in Canada.

SUBJECTS/METHODS

Dietary data were obtained from participants enrolled in Alberta's Tomorrow Project, a prospective cohort study, between 2000 and 2008. Principle component analysis (PCA) and reduced rank regression (RRR) were used to derive dietary patterns, and data linkage with the Alberta Cancer Registry was used for incident cancer cases. Cox proportional hazard regressions were used to estimate multivariable-adjusted models for the association between each dietary pattern score with combined and site-specific cancer incidence.

RESULTS

PCA revealed three dietary patterns ("western", "prudent", and "sugar, fruits, and dairy") and RRR resulted in four patterns ("dietary fiber", "vitamin D", "fructose", and "discretionary fat"). Five cancer sites were included in our site-specific analysis: lung, colon, breast, prostate, and endometrial cancers. The most protective dietary patterns for combined cancer sites were the "Prudent" pattern (HR = 0.82, CI = 0.73-0.92) and the "Dietary fiber" pattern (HR = 0.82, CI = 0.69-0.97). The "Fructose" pattern was associated with increased risk of combined cancers (HR = 1.14, CI = 1.02-1.27). Three dietary patterns were protective against colon cancer ("Prudent", "Dietary fiber", and "Discretionary fats"), and other risk reductions were seen for the "sugar, fruit, and dairy" pattern (lung cancer), and the "Dietary fiber" pattern (prostate cancer).

CONCLUSIONS

These results support cancer prevention strategies for a diet high in vegetables, fruits, fish, and whole grains. Further studies should explore the possible association between discretionary fats and colon cancer.

Changes in Serum, Red Blood Cell, and Colonic Fatty Acids in a Personalized Omega-3 Fatty Acid Supplementation Trial

This study evaluated changes in fatty acids from sera, red blood cells, and colonic biopsies from a phase Ib clinical trial of personalized ω-3 fatty acid dosing in 47 healthy volunteers. The trial aimed to reduce colonic prostaglandin E₂ (PGE₂), a pro-inflammatory product of arachidonic acid (AA) oxidation. The personalized doses ranged 2-10 grams/day (54% eicosapentaenoic acid, EPA, 24% other ω-3 fatty acids). In colon, increases in ω-3 highly unsaturated fatty acids (HUFA) and EPA:AA ratios each were correlated with decreases in PGE₂. Changes in either colonic EPA:AA ratios or ω-3 HUFA were significantly correlated with changes in the same fatty acid measures in red blood cells or serum. The only blood-based measure significantly correlated with changes in colonic PGE₂ was change in red blood cell ω-3 HUFA (ρ = -0.39), and the increase in red blood cell ω-3 HUFA was significantly greater in participants who had at least a median reduction in colonic PGE₂ vs. those who did not. In summary, fatty acid changes in blood did reflect fatty acid changes in the colon, but additional factors will be needed for optimizing dosing models that seek to predict the anti-inflammatory effects of ω-3 fatty acids on the colon.

Colorectal Cancer and Diet: Risk Versus Prevention, Is Diet an Intervention?

Colorectal cancer is the third most common cause of cancer in men and women in the world. Epidemiologic research approximates that half of colon cancer risk is preventable by modifiable risk factors, including diet. This article reviews prior studies involving certain food items and their relation to colorectal cancer, to elucidate whether diet can be a potential intervention.

Dietary fatty acids and colorectal cancer risk in men: A report from the Shanghai Men's Health Study and a meta-analysis

Evidence from animal models suggests that dietary fatty acids have both anticancer and tumor-promoting effects. Whether dietary fatty acids are associated with colorectal cancer (CRC) in humans remains inconclusive. We investigated associations between dietary fatty acids and risk of CRC among 59 986 men who participated in the Shanghai Men's Health Study (SMHS), an ongoing population-based prospective cohort study. We identified 876 incident CRC cases in the SMHS during a mean follow-up of 9.8 years. Associations between dietary fatty acid intake and CRC risk were evaluated by Cox proportional hazard regression analyses. Consumption of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) was not significantly associated with CRC risk. Multivariate hazard ratios (HRs) and respective 95% confidence intervals (CIs) for Quartile 4 vs Quartile 1 were 0.92 (0.74-1.14; Ptrend = 0.47) for SFA, 0.95 (0.79-1.16; Ptrend = 0.74) for MUFA and 1.18 (0.95-1.46; Ptrend = 0.21) for PUFA. No significant associations were found for total n-6 PUFA or total n-3 PUFA. Additionally, we performed a meta-analysis to summarize results from the present study and 28 reports from 26 additional cohorts, which supported the overall null association between dietary fatty acid intake and CRC risk among men. Docosahexanoic acid and eicosapentaenoic acid were associated with 11% to 12% reduced risk, and linoleic acid a 19% increased risk, of CRC in the meta-analysis of combined sexes. In conclusion, this population-based prospective study and meta-analysis of cohort studies found little evidence that dietary fatty acid intake was associated with risk of CRC in men.

Tumor-infiltrating T-regulatory cells adapt to altered metabolism to promote tumor-immune escape

Tumor mass and its microenvironment alter host immune system in various ways to promote tumor growth. One of the modifications is evasion of immune surveillance by augmenting the number of Tregs in tumor vicinity. Elevated levels of Tregs are seen in peripheral circulation and tumor tissue of cancer patients. Cancer cells release several chemokines to attract Tregs in tumor-site. Infiltration of Tregs has clinical significance because being immunosuppressive infiltrating Tregs suppress other immune cells making the tumor microenvironment favorable for tumor growth. On the other hand, infiltrating Tregs show metabolic alteration in tumor microenvironment which allows their selective survival over the others. Persistence of Tregs in the tumor microenvironment and subsequent immunosuppression makes Tregs a potential therapeutic obstacle and the reason behind the failure of immunotherapy. In this review, we emphasize the recent development in the metabolic adaptation of tumor-infiltrating Tregs and the therapeutic approaches to boost immunity against cancer.

ω-3 Polyunsaturated Fatty Acids on Colonic Inflammation and Colon Cancer: Roles of Lipid-Metabolizing Enzymes Involved

Substantial human and animal studies support the beneficial effects of ω-3 polyunsaturated fatty acids (PUFAs) on colonic inflammation and colorectal cancer (CRC). However, there are inconsistent results, which have shown that ω-3 PUFAs have no effect or even detrimental effects, making it difficult to effectively implement ω-3 PUFAs for disease prevention. A better understanding of the molecular mechanisms for the anti-inflammatory and anticancer effects of ω-3 PUFAs will help to clarify their potential health-promoting effects, provide a scientific base for cautions for their use, and establish dietary recommendations. In this review, we summarize recent studies of ω-3 PUFAs on colonic inflammation and CRC and discuss the potential roles of ω-3 PUFA-metabolizing enzymes, notably the cytochrome P450 monooxygenases, in mediating the actions of ω-3 PUFAs.

A systematic review of the determinants of seafood consumption

Although seafood is considered to be an important part of a balanced diet, many national food consumption surveys suggest that seafood is not consumed in sufficient amounts. As consumers are moving to diversify their diet from animal-based protein, it is important to understand the factors influencing consumption of marine foods. This review aims to assess the characteristics of seafood consumers as well as the influences on seafood consumption in Europe, USA, Canada, Australia and New Zealand. Systematic search strategies were used to identify relevant journal articles from three electronic databases (PubMed, Web of Science and Embase). Three searches were carried out and identified 4405 unique publications from which 121 met the criteria for the review process. The reviewed studies revealed that seafood consumers were more likely to be older, more affluent and more physically active and were less likely to smoke compared with non-seafood consumers. Sex and BMI did not appear to have a directional association with seafood consumption. The most commonly reported barriers to seafood consumption were cost, followed by sensory or physical barriers, health and nutritional beliefs, habits, availability and cooking skills. The most commonly reported influences were beliefs about the contribution of seafood to health, environmental influences and personal preferences. Based on the findings of this review, future intervention strategies to increase seafood consumption may need to consider affordability and education in terms of health, nutrition and cooking skills. More research is needed to explore the effectiveness of specific interventions at increasing the consumption of seafood.

Dual Behavior of Long-Chain Fatty Acids and Their Cyclooxygenase/Lipoxygenase Metabolites on Human Intestinal Caco-2 Cell Growth

Etiology of colorectal cancer (CRC) is related, at least in part, with nutritional profile and epidemiological data indicating a key role of dietary fat on CRC pathogenesis. Moreover, inflammation and eicosanoids produced from arachidonic acid might have a pivotal role in CRC development. However, the effect of specific fatty acids (FAs) on intestinal epithelial cell growth is not completely studied now. By this reason, the aim of this work is to unravel the effect of different saturated and unsaturated long-chain fatty acids (LCFA) and some LCFA metabolites on CRC cell line growth and their possible mechanisms of action. Our results demonstrated that oleic acid is a potent mitogenic factor to Caco-2 cells, at least in part, through 10-hydroxy-8-octadecenoic synthesized by lipoxigenase pathway, whereas polyunsaturated FAs such as eicosapentaenoic (EPA) acid has a dual behavior effect depending on its concentration. A high concentration, EPA induced apoptosis through intrinsic pathway, whereas at low concentration induced cell proliferation that could be related to the synthesis of eicosanoids such as prostaglandin E₃ and 12-hydroxyeicosapentaenoic acid and the subsequent induction of mitogenic cell signaling pathways (ERK 1/2, CREB, p38α). Thus, this study contributes to understand the complicated relationship between fat ingest and CRC.

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.

Omega-3 and -6 Fatty Acid Intake and Colorectal Cancer Risk in Swedish Women's Lifestyle and Health Cohort

PURPOSE

We aimed to assess the association between the dietary intake of fish-derived omega-3 polyunsaturated fatty acids and the risk of colorectal cancer among Swedish women.

MATERIALS AND METHODS

A total of 48,233 women with information on dietary intake were included in the analysis. Participants were followed for incident colorectal cancer until 31 December 2012. Cox proportional hazard models were used to assess the association between baseline fatty acid intake and colorectal cancer risk. All analyses were stratified by colon and rectal cancers.

RESULTS

During a median of 21.3 years of follow-up, a total of 344 colorectal cancer cases were ascertained. Although there was no overall association between omega-3 fatty acid intake and colorectal cancer risk, high intake of fish-derived docosahexaenoic acid was associated with reduced risk of rectal cancer (hazard ratios for the third and the highest quartiles were 0.59 (95% confidence interval [CI], 0.37 to 0.96) and 0.62 (95% CI, 0.39 to 0.98), respectively).

CONCLUSION

In conclusion, we found only limited support for an association between omega-3 polyunsaturated fatty acids and colorectal cancer in a large Swedish cohort of middle-aged women.

Dietary Intake of N-3 and N-6 Polyunsaturated Fatty Acids and Risk of Cancer: Meta-Analysis of Data from 32 Studies

BACKGROUND

Large epidemiological studies have yielded conflicting results regarding the relationship between polyunsaturated fatty acids (PUFAs) and cancers. Here, we performed a meta-analysis to examine the link between dietary intake of n-3 and n-6 PUFAs and cancer risk.

MATERIALS AND METHODS

We performed a search on PubMed, EMBASE, and the Cochrane Library. Studies that reported adjusted relative risk (RR) estimates with 95% confidence intervals (CI) for the associations of interest were included.

RESULTS

Thirty-two studies involving 1,445,732 participants were included. Colorectal, breast and prostate cancer had been analyzed in our study. Specifically, for colorectal cancer, total n-3 PUFAs, marine n-3 PUFAs, α-linolenic acids (ALA) and n-6 PUFAs were not associated with the risk of it (RR 1.04, 95%CI 0.85-1.28; RR 0.99, 95%CI 0.89-1.09; RR 1.05, 95%CI 0.93-1.19; RR 1.02, 95%CI 0.94-1.11, respectively). For breast cancer, only marine n-3 PUFAs, but not total n-3 PUFAs, ALA, and n-6 PUFAs, was associated with a lower risk of it (RR 0.70, 95%CI 0.55-0.91). For prostate cancer, ALA and n-6 PUFAs also have no association with the risk of it.

CONCLUSIONS

Most subtypes of PUFAs are probably not related to cancers. However, additional high-quality trials are warranted to corroborate the findings of this meta-analysis.

Mendelian Randomization of Circulating Polyunsaturated Fatty Acids and Colorectal Cancer Risk

BACKGROUND

Results from epidemiologic studies examining polyunsaturated fatty acids (PUFA) and colorectal cancer risk are inconsistent. Mendelian randomization may strengthen causal inference from observational studies. Given their shared metabolic pathway, examining the combined effects of aspirin/NSAID use with PUFAs could help elucidate an association between PUFAs and colorectal cancer risk.

METHODS

Information was leveraged from genome-wide association studies (GWAS) regarding PUFA-associated SNPs to create weighted genetic scores (wGS) representing genetically predicted circulating blood PUFAs for 11,016 non-Hispanic white colorectal cancer cases and 13,732 controls in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Associations per SD increase in the wGS were estimated using unconditional logistic regression. Interactions between PUFA wGSs and aspirin/NSAID use on colorectal cancer risk were also examined.

RESULTS

Modest colorectal cancer risk reductions were observed per SD increase in circulating linoleic acid [ORLA = 0.96; 95% confidence interval (CI) = 0.93-0.98; P = 5.2 × 10-4] and α-linolenic acid (ORALA = 0.95; 95% CI = 0.92-0.97; P = 5.4 × 10-5), whereas modest increased risks were observed for arachidonic (ORAA = 1.06; 95% CI = 1.03-1.08; P = 3.3 × 10-5), eicosapentaenoic (OREPA = 1.04; 95% CI = 1.01-1.07; P = 2.5 × 10-3), and docosapentaenoic acids (ORDPA = 1.03; 95% CI = 1.01-1.06; P = 1.2 × 10-2). Each of these effects was stronger among aspirin/NSAID nonusers in the stratified analyses.

CONCLUSIONS

Our study suggests that higher circulating shorter-chain PUFAs (i.e., LA and ALA) were associated with reduced colorectal cancer risk, whereas longer-chain PUFAs (i.e., AA, EPA, and DPA) were associated with an increased colorectal cancer risk.

IMPACT

The interaction of PUFAs with aspirin/NSAID use indicates a shared colorectal cancer inflammatory pathway. Future research should continue to improve PUFA genetic instruments to elucidate the independent effects of PUFAs on colorectal cancer.

Randomized Study Design to Test Effects of Vitamin D and Omega-3 Fatty Acid Supplementation as Adjuvant Therapy in Colorectal Cancer Patients

This study examines the effects of vitamin D and omega-3 fatty acid co-supplementation on inflammation and nutritional status in colorectal cancer patients. Patients were randomly assigned into four groups: (1) controls, receiving placebos; (2) omega-3 fatty acid arm, receiving two 330 mg omega-3 fatty acid capsules daily and placebo (for vitamin D₃) weekly; (3) vitamin D arm, receiving a 50,000 IU vitamin D₃ soft gel weekly and two placebos (for omega-3 fatty acids) daily; and (4) co-supplementation arm, receiving a 50,000 IU vitamin D₃ soft gel weekly and two 330 mg omega-3 fatty acids capsules daily for 8 weeks. As outcomes, we measure height; weight; fat-free mass (FFM); serum levels of 25(OH)D, TNF-α, and IL-6; C-CRP; and albumin, before and after the intervention. The presented results show that vitamin D₃ plus omega-3 fatty acid co-supplementation in colorectal cancer patients has beneficial impacts on inflammation and nutritional status.

Consumption of Fish and Long-chain n-3 Polyunsaturated Fatty Acids Is Associated With Reduced Risk of Colorectal Cancer in a Large European Cohort

BACKGROUND & AIMS

There is an unclear association between intake of fish and long-chain n-3 polyunsaturated fatty acids (n-3 LC-PUFAs) and colorectal cancer (CRC). We examined the association between fish consumption, dietary and circulating levels of n-3 LC-PUFAs, and ratio of n-6:n-3 LC-PUFA with CRC using data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

METHODS

Dietary intake of fish (total, fatty/oily, lean/white) and n-3 LC-PUFA were estimated by food frequency questionnaires given to 521,324 participants in the EPIC study; among these, 6291 individuals developed CRC (median follow up, 14.9 years). Levels of phospholipid LC-PUFA were measured by gas chromatography in plasma samples from a sub-group of 461 CRC cases and 461 matched individuals without CRC (controls). Multivariable Cox proportional hazards and conditional logistic regression models were used to calculate hazard ratios (HRs) and odds ratios (ORs), respectively, with 95% CIs.

RESULTS

Total intake of fish (HR for quintile 5 vs 1, 0.88; 95% CI, 0.80-0.96; Ptrend = .005), fatty fish (HR for quintile 5 vs 1, 0.90; 95% CI, 0.82-0.98; Ptrend = .009), and lean fish (HR for quintile 5 vs 1, 0.91; 95% CI, 0.83-1.00; Ptrend = .016) were inversely associated with CRC incidence. Intake of total n-3 LC-PUFA (HR for quintile 5 vs 1, 0.86; 95% CI, 0.78-0.95; Ptrend = .010) was also associated with reduced risk of CRC, whereas dietary ratio of n-6:n-3 LC-PUFA was associated with increased risk of CRC (HR for quintile 5 vs 1, 1.31; 95% CI, 1.18-1.45; Ptrend < .001). Plasma levels of phospholipid n-3 LC-PUFA was not associated with overall CRC risk, but an inverse trend was observed for proximal compared with distal colon cancer (Pheterogeneity = .026).

CONCLUSIONS

In an analysis of dietary patterns of participants in the EPIC study, we found regular consumption of fish, at recommended levels, to be associated with a lower risk of CRC, possibly through exposure to n-3 LC-PUFA. Levels of n-3 LC-PUFA in plasma were not associated with CRC risk, but there may be differences in risk at different regions of the colon.

Diet and Gut Microbes Act Coordinately to Enhance Programmed Cell Death and Reduce Colorectal Cancer Risk

Diet is an important risk factor for colorectal cancer (CRC), and several dietary constituents implicated in CRC are modified by gut microbial metabolism. Microbial fermentation of dietary fiber produces short-chain fatty acids, e.g., acetate, propionate, and butyrate. Dietary fiber has been shown to reduce colon tumors in animal models, and, in vitro, butyrate influences cellular pathways important to cancer risk. Furthermore, work from our group suggests that the combined effects of butyrate and omega-3 polyunsaturated fatty acids (n-3 PUFA) may enhance the chemopreventive potential of these dietary constituents. We postulate that the relatively low intakes of n-3 PUFA and fiber in Western populations and the failure to address interactions between these dietary components may explain why chemoprotective effects of n-3 PUFA and fermentable fibers have not been detected consistently in prospective cohort studies. In this review, we summarize the evidence outlining the effects of n-3 long-chain PUFA and highly fermentable fiber with respect to alterations in critical pathways important to CRC prevention, particularly intrinsic mitochondrial-mediated programmed cell death resulting from the accumulation of lipid reactive oxygen species (ferroptosis), and epigenetic programming related to lipid catabolism and beta-oxidation-associated genes.

Preferential uptake of polyunsaturated fatty acids by colorectal cancer cells

Although a growing body of evidence suggests that colorectal cancer (CRC) is associated with alterations of fatty acid (FA) profiles in serum and tumor tissues, available data about polyunsaturated fatty acid (PUFA) content in CRC patients are inconclusive. Our study showed that CRC tissues contained more PUFAs than normal large intestinal mucosa. However, serum levels of PUFAs in CRC patients were lower than in healthy controls. To explain the mechanism of PUFA alterations in CRC, we measured FA uptake by the colon cancer cells and normal colon cells. The levels of PUFAs in colon cancer cell culture medium decreased significantly with incubation time, while no changes were observed in the medium in which normal colon cells were incubated. Our findings suggest that the alterations in tumor and serum PUFA profiles result from preferential uptake of these FAs by cancer cells; indeed, PUFAs are essential for formation of cell membrane phospholipids during rapid proliferation of cancer cells. This observation puts into question potential benefits of PUFA supplementation in CRC patients.

Effect of Supplementation With Marine ω-3 Fatty Acid on Risk of Colorectal Adenomas and Serrated Polyps in the US General Population: A Prespecified Ancillary Study of a Randomized Clinical Trial

Importance

Marine ω-3 fatty acid has been suggested to protect against colorectal cancer.

Objective

To assess the effect of daily marine ω-3 fatty acid supplementation on the risk of colorectal cancer precursors, including conventional adenomas and serrated polyps.

Design, Setting, and Participants

This study was a prespecified ancillary study of the placebo-controlled randomized clinical trial VITAL (Vitamin D and Omega-3 Trial). An intention-to-treat analysis was used to examine the effect of daily marine ω-3 supplements among 25 871 adults in the US general population (including 5106 African American persons) free of cancer and cardiovascular disease at enrollment. Randomization was from November 2011 to March 2014, and intervention ended as planned on December 31, 2017.

Interventions

Marine ω-3 fatty acid, 1 g daily (which included eicosapentaenoic acid, 460 mg, and docosahexaenoic acid, 380 mg) and vitamin D3 (2000 IU daily) supplements.

Main Outcomes and Measures

Risk of conventional adenomas (including tubular adenoma, tubulovillous adenoma, villous adenoma, and adenoma with high-grade dysplasia) or serrated polyps (including hyperplastic polyp, traditional serrated adenoma, and sessile serrated polyp). In a subset of participants who reported receiving a diagnosis of polyp on follow-up questionnaires, endoscopic and pathologic records were obtained to confirm the diagnosis. Odds ratios (ORs) and 95% CIs were calculated using logistic regression, after adjusting for age, sex, vitamin D treatment assignment, and use of endoscopy. Secondary analyses were performed according to polyp features and participants' characteristics.

Results

The demographic characteristics of participants at randomization were well balanced between the treatment and placebo groups; for example, 50.6% vs 50.5% were women, and 19.7% vs 19.8% were African American persons were included in each group. The mean (SD) age was 67.1 (7.1) years in the placebo group and 67.2 (7.1) in the ω-3 treatment group. During a median follow-up of 5.3 years (range, 3.8-6.1 years), 294 cases of conventional adenomas were documented in the ω-3 group and 301 in the control group (multivariable OR, 0.98; 95% CI, 0.83-1.15) (1:1 ratio between number of cases and number of participants). In addition, 174 cases of serrated polyps were documented in the ω-3 group and 167 in the control group (OR, 1.05; 95% CI, 0.84-1.29). Null associations were found for polyp subgroups according to size, location, multiplicity, or histology. In secondary analyses, marine ω-3 treatment appeared to be associated with lower risk of conventional adenomas among individuals with low plasma levels of ω-3 index at baseline (OR, 0.76; 95% CI, 0.57-1.02; P = .03 for interaction by ω-3 index). A beneficial association of supplementation was also noted in the African American population (OR, 0.59; 95% CI, 0.35-1.00) but not in other racial/ethnic groups (P = .11 for interaction).

Conclusions and Relevance

Supplementation with marine ω-3 fatty acids, 1 g per day, was not associated with reduced risk of colorectal cancer precursors. A potential benefit of this supplementation for individuals with low baseline ω-3 levels or for African American persons requires further confirmation.

Trial Registration

ClinicalTrials.gov identifier: NCT01169259.

Intake or Blood Levels of n-3 Polyunsaturated Fatty Acids and Risk of Colorectal Cancer: A Systematic Review and Meta-analysis of Prospective Studies

BACKGROUND

Previous results of the association between n-3 polyunsaturated fatty acids (PUFA) and colorectal cancer were inconsistent. We conducted a systematic review and meta-analysis of prospective studies.

METHODS

The PubMed and Embase databases were searched through July 10, 2019, followed by a manual search. A random-effects model was used.

RESULTS

Twenty prospective studies, including 18,102 cases and 1,360,046 participants, were included. The pooled RR of colorectal cancer for the highest versus lowest category of n-3 PUFA intake was 0.97 [95% confidence interval (CI), 0.90-1.04]. Regarding the type of n-3 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intakes were inversely associated with 11% (RR = 0.89; 95% CI, 0.80-0.99) and 12% (RR = 0.88; 95% CI, 0.81-0.96) lower colorectal cancer risks, respectively, in the comparison of the highest versus lowest category. Increments of 0.1 g/day of EPA (RR = 0.95; 95% CI, 0.92-0.98) and DHA (RR = 0.97; 95% CI, 0.95-0.99) intakes were associated with a lower colorectal cancer risk. Regarding the blood levels of n-3 PUFAs, the pooled RR of colorectal cancer for the highest versus lowest category of blood levels of n-3 PUFAs was 0.79 (95% CI, 0.64-0.98). The risk of colorectal cancer decreased by 4% for every 1% increase in blood n-3 PUFA levels (RR = 0.96; 95% CI, 0.92-1.00).

CONCLUSIONS

High blood n-3 PUFA levels are inversely associated with colorectal cancer risk, and high n-3 PUFA intake is suggestively associated with lower colorectal cancer risk.

IMPACT

Our findings suggest that high blood n-3 PUFA levels may be associated with reduced colorectal cancer risk, but further studies are needed.

Association of CD44 gene rs187115 polymorphism with colorectal cancer risk and prognosis in Chinese Han population: a case-control study

The cell surface adhesion receptor CD44 reportedly affects the development and progression of cancers. Moreover, CD44 gene rs187115 polymorphism appears to be genetic determinant of cancer susceptibility. We investigated whether CD44 rs187115 polymorphism is associated with colorectal cancer (CRC) risk and prognosis. We enrolled 669 CRC cases and 826 controls in this three-center case-control study in a Chinese Han population. All individuals were genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Cross-over analysis, multivariate logistic regression, Kaplan-Meier method, and Cox regression analysis were used for analysis. In this study, CD44 rs187115 polymorphism was associated with increased risk for CRC. Stratified analyses revealed that CD44 rs187115 polymorphism was correlated with increased risk for CRC in females, drinkers, smokers, and those aged ≥ 60 years. In addition, rs187115 polymorphism was significantly associated with TNM III+IV stage, lymph node metastasis and tumor size in CRC patients. Combined effects of CD44 rs187115 polymorphism (GG/AG vs. AA) and environmental factors (smoking and drinking) further increased the risk of CRC. GG genotype carriers showed poorer overall survival than AA genotype carriers. Cox regression analysis showed that drinking, CD44 rs187115 polymorphism, and TNM stage were independent prognostic factors affecting CRC. These findings show that CD44 rs187115 polymorphism may be a potential biomarker predictive of CRC susceptibility and prognosis.

Effects of Vitamin D and Omega-3 Fatty Acids Co-Supplementation on Inflammatory Factors and Tumor Marker CEA in Colorectal Cancer Patients Undergoing Chemotherapy: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Objectives: This study aimed to investigate the effects of vitamin D and omega-3 fatty acids co-supplementation on inflammatory factors and tumor marker CEA in colorectal cancer patients undergoing chemotherapy.Methods: In this study, 81 patients with stage ӀӀ or ӀӀӀ colorectal cancer were randomly assigned into four groups: (1) control: receiving a vitamin D placebo, weekly + two omega-3 fatty acid placebo capsules, daily; (2) omega-3 fatty acid, receiving two omega-3 fatty acid capsules (each capsule containing 330 mg of omega-3 fatty acids), daily + a vitamin D placebo, weekly; (3) vitamin D, receiving a 50,000 IU vitamin D soft gel, weekly + two omega-3 fatty acid placebo capsules, daily; (4) co-supplementation, receiving a 50,000 IU vitamin D soft gel, weekly + two omega-3 fatty acids capsules, for 8 weeks. Before and after the intervention, serum levels of 25(OH)D, TNF-α, IL-1β, IL-6, IL-8, NF-kB activity, and tumor marker CEA, were measured.Results: After 8 weeks of intervention, patients who received combined vitamin D and omega-3 fatty acids supplements compared with omega-3, vitamin D, and placebo had significantly decreased TNF-α, and IL-1β (P < .05). In addition, serum levels of TNF-α, IL-1β, IL-6, IL-8, and tumor marker CEA were decreased significantly in omega-3, vitamin D, and co-supplementation of them, compared with baseline. NF-kB activity was decreased significantly in vitamin D and co-supplementation groups, compared with baseline. Regarding CEA, there was no significant difference between the four groups at the end of intervention (P > .05).Conclusion: Results show that co-supplementation of vitamin D and omega-3 fatty acids co-supplementation, in colorectal cancer patients have beneficial impacts on inflammation and tumor marker CEA.

Association between polymorphism in the promoter region of lncRNA GAS5 and the risk of colorectal cancer

The growth arrest special 5 (GAS5), as a research hotspot of long noncoding RNAs (lncRNAs), has been reported to be associated with colorectal cancer (CRC). However, the association between polymorphisms in GAS5 and the risk of CRC was not clear. In the present study, a case–control study in 1078 CRC patients and 1175 matched healthy controls was performed to evaluate the association between the potential functional genetic variants in GAS5 and the risk of CRC. PCR-TaqMan, qPCR, dual-luciferase assay, electrophoretic mobility shift assay (EMSA), flow cytometry, migration and invasion assays were performed to evaluate the function of polymorphism. Results showed that subjects carrying the rs55829688 CT/TT genotypes had a significantly higher risk of CRC when compared with the CC genotype. Further qPCR assay confirmed that the CRC tissues with rs55829688 CT/TT genotypes had a higher GAS5 mRNA expression level. The dual-luciferase assay, qPCR and EMSA assay revealed that rs55829688 T>C polymorphism could decrease the expression level of GAS5 by impacting the binding ability of the transcription factor Yin Yang-1 (YY1) to the GAS5 promoter region. The expression of apoptosis-related proteins were detected by Western blot. Further, flow cytometry, migration, and invasion experiments showed that GAS5 repressed apoptosis and increased invasion and migration capability of CRC cells. Taken together, our findings provided evidence that the rs55829688 variant in the GAS5 promoter was associated with the risk of CRC and decreased expression of GAS5 by affecting the binding affinity of the transcription factors YY1 to GAS5.

Omega-3 polyunsaturated fatty acids as adjuvant therapy of colorectal cancer

The majority of evidence linking anti-colorectal cancer (CRC) activity with omega-3 polyunsaturated fatty acids (O3FAs) has focussed on decreased CRC risk (prevention). More recently, preclinical data and human observational studies have begun to make the case for adjuvant treatment of advanced CRC. Herein, we review latest data regarding the effect of O3FAs on post-diagnosis CRC outcomes, including mechanistic preclinical data, evidence that O3FAs have beneficial effects on efficacy and tolerability of CRC chemotherapy, and human epidemiological data linking dietary O3FA intake with CRC outcomes. We also highlight ongoing randomised controlled trials of O3FAs with CRC endpoints and discuss critical gaps in the evidence base, which include limited understanding of the effects of O3FAs on the tumour microenvironment, the host immune response to CRC, and the intestinal microbiome.