PUFA levels in erythrocyte membrane phospholipids are differentially associated with colorectal adenoma risk

Association between polyunsaturated fatty acids in adipose tissue and mortality of colorectal cancer patients

INTRODUCTION

Nutritional intake and dysregulation of fatty acid metabolism play a role in the progression of various tumors, but the consumption of fatty acids is difficult to assess accurately with dietary questionnaires. Biomarkers can objectively assess intake, storage and bioavailability.

OBJECTIVE

We studied the association between the polyunsaturated fatty acid (PUFA) composition of abdominal subcutaneous adipose tissue (good indicator of dietary intake over 2-3 years) and all-cause mortality.

METHODS

In the multicenter AGARIC study, samples from 203 patients with colorectal cancer (CRC) undergoing curative surgery, were harvested from subcutaneous adipose tissue, which were then analyzed for PUFA composition.

RESULTS

After a median follow-up of 45 months, 76 patients died. These patients were more often men (72.4% versus 57.5%, P = 0.04), diabetic (32.9% versus 13.4%, P = 0.001), old (median: 74.5 versus 66.6 years, P < 0.001) and with high alcohol consumption (47.4% versus 30.7%, P = 0.005). An increased risk of death was observed with higher levels of 20:2 ω-6 (hazard ratiotertile3 vstertile1 (HRT3vsT1) 2.12; 95% confidence interval (CI) 1.01-4.42; p-trend = 0.04), 22:4 ω-6 (HRT3vsT1 = 3.52; 95% CI = 1.51-8.17; p-trend = 0.005), and 22:5 ω-6 (HRT3vsT1 = 3.50; 95% CI = 1.56-7.87; p-trend = 0.002). Conversely, the risk of death seemed lower when higher concentrations of 18:3 ω-6 (HRT3vsT1 = 0.52; 95% CI = 0.27-0.99; p-trend = 0.04) and the essential fatty acid, α-linolenic acid 18:3 ω-3 (HRT3vsT1 = 0.47; 95% CI = 0.24-0.93; p-trend = 0.03) were observed.

CONCLUSION

The risk of death was increased in CRC patients with higher concentrations of certain ω-6 PUFAs and lower concentrations of α-linolenic acid in their subcutaneous adipose tissue. These results reflect dietary habits and altered fatty acid metabolism. Our exploratory results warrant confirmation in larger studies with further exploration of the mechanisms involved.

Understanding the Role of Polyunsaturated Fatty Acids in the Development and Prevention of Cancer

Polyunsaturated fatty acids (PUFAs), notably omega-3 (n-3) and omega-6 (n-6), have received much attention owing to their multifaceted effects not only in the management of diverse pathological conditions but also in the maintenance of overall health of an individual. A disproportionately high n-6 to n-3 ratio contributes to the development of various disorders including cancer, which ranks as a leading cause of death worldwide with profound social and economic burden. Epidemiological studies and clinical trials combined with the animal and cell culture models have demonstrated the beneficial effects of n-3 PUFAs in reducing the risk of various cancer types including breast, prostate and colon cancer. The anti-cancer actions of n-3 PUFAs are mainly attributed to their role in the modulation of a wide array of cellular processes including membrane dynamics, apoptosis, inflammation, angiogenesis, oxidative stress, gene expression and signal transduction pathways. On the contrary, n-6 PUFAs have been shown to exert pro-tumor actions; however, the inconsistent findings and controversial data emphasize upon the need to further investigation. Nevertheless, one of the biggest challenges in future is to optimize the n-6 to n-3 ratio despite the genetic predisposition, age, gender and disease severity. Moreover, a better understanding of the potential risks and benefits as well as the cellular and molecular mechanisms of the basic actions of these PUFAs is required to explore their role as adjuvants in cancer therapy. All these aspects will be reviewed in this chapter.

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.

Mediation analysis of erythrocyte lipophilic index on the association between BMI and risk of oral cancer

Aims

To explore the relationship between the fatty acid lipophilic index (LI) of the erythrocyte membrane and oral cancer risk, as well as to evaluate the possibility of LI acting as a mediator of the association between body mass index (BMI) and oral cancer.

Method

Twenty-three fatty acids (FAs) of the erythrocyte membrane were measured using gas chromatography in 380 patients with oral cancer and 387 control subjects. The LI was calculated based on the FA proportion and FA melting points. The association of BMI and erythrocyte LI with oral cancer risk was analysed using logistic regression. The mediation effect of LI on the association between BMI and oral cancer risk was evaluated using mediation analysis.

Results

Among the control group, 46.0% were overweight or obese, which was significantly higher than that of oral cancer patients (29.5%). Significant differences in erythrocyte membrane saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) were observed between the patient and control groups. The proportion of C18:1 n-9 from the MUFA family increased in oral cancer patients (12.67%) compared with controls (12.21%). While the total proportion of n-3 PUFAs decreased in oral cancer patients compared with controls, with C20:5 n-3 decreasing from 0.66 to 0.47%, and C22:6 n-3 decreasing from 5.82 to 4.86%. The LI was lower in the control participants (M = 27.6, IQR: 27.3–27.9) than in the oral cancer patients (M = 28.2, IQR: 27.9–28.5). BMI was inversely associated with oral cancer risk with a fully adjusted OR of 0.59 (95% CI: 0.43–0.83), while LI was positively associated with oral cancer risk with a fully adjusted OR of 1.99 (95% CI:1.36–2.94). LI explained 7% of the variance in the relationship between BMI and oral cancer risk.

Conclusions

The distribution of the FA profile in erythrocyte membranes differed between the oral cancer patients and the control group. The LI derived from the profile of FAs was positively associated with the risk of oral cancer, and the associations between BMI and oral cancer risk can be explained, at least in part, by LI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01704-z.

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.

Therapeutic potential of melatonin in colorectal cancer: Focus on lipid metabolism and gut microbiota

Colorectal cancer (CRC) is one of the most common gastrointestinal malignancies. The occurrence and development of CRC are complicated processes. Obesity and dysbacteriosis have been increasingly regarded as the main risk factors for CRC. Understanding the etiology of CRC from multiple perspectives is conducive to screening for some potential drugs or new treatment strategies to limit the serious side effects of conventional treatment and prolong the survival of CRC patients. Melatonin, a natural indoleamine, is mainly produced by the pineal gland, but it is also abundant in other tissues, including the gastrointestinal tract, retina, testes, lymphocytes, and Harder's glands. Melatonin could participate in lipid metabolism by regulating adipogenesis and lipolysis. Additionally, many studies have focused on the potential beneficial effects of melatonin in CRC, such as promotion of apoptosis; inhibition of cell proliferation, migration, and invasion; antioxidant activity; and immune regulation. Meaningfully, gut microbiota is the main determinant of all aspects of health and disease (including obesity and tumorigenesis). The gut microbiota is of great significance for understanding the relationship between obesity and increased risk of CRC. Although the current understanding of how the melatonin-mediated gut microbiota coordinates a variety of physiological and pathological activities is fairly comprehensive, there are still many unknown topics to be explored in the face of a complex nutritional status and a changeable microbiota. This review summarizes the potential links among melatonin, lipid metabolism, gut microbiota, and CRC to promote the development of melatonin as a preventive and therapeutic agent for CRC.

A Protective Role for Arachidonic Acid Metabolites against Advanced Colorectal Adenoma in a Phase III Trial of Selenium

Oxylipins derived from arachidonic acid (ARA) have been implicated in the development of colorectal adenomas and colorectal cancer. The primary purpose of this work was to determine the relationship between plasma levels of oxylipins and colorectal adenoma characteristics at study entry, as well as with the development of a new adenoma during follow-up within a Phase III adenoma prevention clinical trial with selenium (Sel). Secondarily, we sought to determine whether the selenium intervention influenced plasma oxylipin levels. Four oxylipins were quantified in stored plasma samples from a subset of Sel study subjects (n = 256) at baseline and at 12-months. There were significantly lower odds of an advanced adenoma at baseline with higher prostaglandin E₂ (PGE₂), with an OR (95% CI) of 0.55 (0.33–0.92), and with 5-hydroxyeicosatetraenoic acid (5-HETE) ((0.53 (0.33–0.94)); and of a large adenoma with higher PGE₂ ((0.52 (0.31–0.87)). In contrast, no associations were observed between any oxylipin and the development of a new adenoma during follow-up. Selenium supplementation was associated with a significantly smaller increase in 5-HETE after 12 months compared to the placebo, though no other results were statistically significant. The ARA-derived oxylipins may have a role in the progression of non-advanced adenoma to advanced, but not with the development of a new adenoma.

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.

Differences in erythrocyte phospholipid membrane long-chain polyunsaturated fatty acids and the prevalence of fatty acid desaturase genotype among African Americans and European Americans

Numerous studies have reported an association between genetic variants in fatty acid desaturases (FADS1 and FADS2) and plasma or erythrocyte long chain polyunsaturated fatty acid (PUFA) levels. Increased levels of n-6 PUFAs have been associated with inflammation and several chronic diseases, including diabetes and cancer. We hypothesized that genetic variants of FADS that more efficiently convert precursor n-6 PUFA to arachidonic acid (AA) may explain the higher burden of chronic diseases observed in African Americans. To test this hypothesis, we measured the level of n-6 and n-3 PUFAs in erythrocyte membrane phospholipids and genotyped the rs174537 FADS variants associated with higher AA conversion among African American and European American populations. We included data from 1,733 individuals who participated in the Tennessee Colorectal Polyp Study, a large colonoscopy-based case-control study. Erythrocyte membrane PUFA percentages were measured using gas chromatography. Generalized linear models were used to estimate association of race and genotype on erythrocyte phospholipid membrane PUFA levels while controlling for self-reported dietary intake. We found that African Americans have higher levels of AA and a higher prevalence of GG allele compared to whites, 81% vs 43%, respectively. Homozygous GG genotype was negatively associated with precursor PUFAs (linoleic [LA], di-homo-γ-linolenic [DGLA]), positively associated with both product PUFA (AA, docosahexaenoic acid [DHA]), product to precursor ratio (AA to DGLA), an indirect measure of FADs efficiency and increased urinary isoprostane F2 (F2-IsoP) and isoprostane F3 (F3-IsoP), markers of oxidative stress. Increased consumption of n-6 PUFA and LA resulting in increased AA and subsequent inflammation may be fueling increased prevalence of chronic diseases especially in African descent.

Fatty acid composition of the erythrocyte membrane and risk of hepatocellular carcinoma in cirrhotic patients

BACKGROUND

Disturbances in fatty acid (FA) metabolism have been reported in cirrhosis, but the role of FAs in the development of hepatocellular carcinoma (HCC) is still unclear. Biomarkers are a promising means to explore the associations between exogenous intake or endogenous production of FAs and cancer risk.

AIM

To estimate the relationship between fatty acid content in erythrocyte membranes and HCC risk in cirrhotic patients METHODS: The "CiRCE" case-control study recruited cirrhotic patients from six French hospitals between 2008 and 2012. Cases were cirrhotic patients with HCC (n = 349); controls were cirrhotic patients without HCC at inclusion (n = 550). FA composition of phospholipids in erythrocyte membranes was determined by high performance gas chromatography. Odds ratios for HCC risk according to FA concentrations were estimated with multivariable logistic regression.

RESULTS

HCC patients were older and more often men (P < 0.001). In both groups, saturated FAs represented more than 39% of all FAs in erythrocyte membranes, mono-unsaturated FAs around 14%, and polyunsaturated FAs around 46%. High levels of C15:0 + C17:0, C20:1 n-9, C18:2 n-6 and C20:2 n-6 were associated with higher risk of HCC. The levels of C18:0 and C20:4 n-6 were lower in HCC cases than in controls.

CONCLUSIONS

The FA composition of erythrocyte membranes differed according to the presence of HCC with higher levels of saturated FAs, linoleic and eicosadienoic acids, and lower levels of stearic and arachidonic acids. These alterations may reflect particular dietary patterns and/or altered FA metabolism. Further investigations are warranted.

A prospective study of erythrocyte polyunsaturated fatty acids and risk of colorectal serrated polyps and conventional adenomas

The influence of polyunsaturated fatty acids (PUFAs) on risk of colorectal cancer precursors remains largely unknown. We examined the associations of erythrocyte PUFAs, including n-3 and n-6 PUFAs, with risk of colorectal conventional adenomas and serrated polyps in 4517 participants from three US prospective cohorts who had provided a blood sample and undergone at least one endoscopic examination. We calculated the multivariable odds ratios (ORs) per 1 SD increment in individual PUFAs and the ratio of n-6/n-3 PUFAs. We considered P < .005 statistically significant to account for multiple testing. During a median of 20 years of follow-up, we documented 493 conventional adenomas and 316 serrated polyps. After adjusting for various CRC risk factors, no associations for PUFAs achieved the stringent statistical significance for either conventional adenomas or serrated polyps (ORs per 1 SD ranged from 0.90 to 1.14). Some associations achieved nominal significance (P < .05), including the association of dihomogammalinolenic acid (DGLA) (20:3, n-6) with lower risk of conventional adenomas (OR = 0.91; 95% confidence interval [CI] = 0.83-1.00), total n-6 PUFAs with higher risk of proximal serrated polyps (OR = 1.32; 95% CI = 1.01-1.74) and eicosadienoic acid (20:2, n-6) and DGLA with lower risk of advanced adenomas (OR = 0.83; 95% CI = 0.71-0.97 and OR = 0.84; 95% CI = 0.72-0.98, respectively). Our findings indicate that erythrocyte PUFAs in a typical American diet are unlikely to have a substantial influence on risk of colorectal cancer precursors. The subgroup associations require further confirmation.

Erythrocyte membrane polyunsaturated fatty acid profiles are associated with systemic inflammation and fish consumption in systemic lupus erythematosus: a cross-sectional study

Objective

This study aimed to assess polyunsaturated fatty acid (PUFA) status and association with systemic inflammation and fish consumption in systemic lupus erythematosus (SLE).

Methods

Parameters of PUFA status including the proportion of omega-6 and -3 fatty acids in highly unsaturated fatty acids (omega-6%, omega-3%), essential fatty acids linoleic acid (LA) and alpha-linolenic acid (ALA), the omega-6 PUFA arachidonic acid (ARA) and the sum of key omega-3 PUFA eicosapentaenoic acid+docosahexaenoic acid (omega-3 status) were measured by gas chromatography in 68 SLE patients (88.2% female, aged 45.7±12.5 years). Associations with serum CRP, disease activity, damage and fish consumption were assessed by linear regression modelling adjusted for age, sex and body mass index. Associations are reported in terms of regression coefficients (β).

Results

Omega-6 PUFA were associated with higher CRP: omega-6% (β = 0.052, p = 0.02), the ratio of LA/ALA (β = 0.007, p = 0.02) and ARA (β = 0.308, p = 0.001). Conversely, omega-3% was associated with lower CRP (β = −0.051, p = 0.02). Increased dietary PUFA consumption from fish (g/day) was linked to a higher omega-3 status (β = 2.21, p = 0.02) and lower self-reported damage (Brief Index of Lupus Damage; β = −3.22, p = 0.02).

Conclusions

Omega-3 and omega-6 fatty acid status differentially reflect systemic inflammation in SLE and are linked to fish consumption.

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.

Arachidonic acid and colorectal adenoma risk: a Mendelian randomization study

BACKGROUND

Previous studies have shown a link between increased dietary intake of arachidonic acid (ARA) and colorectal neoplasms. It has been shown that erythrocyte phospholipid membrane concentrations of ARA are strongly determined by genetic variation. Fatty acid desaturase (FADS) controls the rate limiting step in ARA production, and FADS variant rs174537 has been shown to be responsible for up to 18.6% of the variation seen. To determine if a causal association exists between erythrocyte membrane ARA concentrations and colorectal adenomas, we conducted a Mendelian randomization (MR) analysis using rs174537 as an instrumental variable (IV). MR analysis was chosen because it is less susceptible to bias and confounding.

PATIENTS AND METHODS

A case-control study was performed using the Tennessee Colorectal Polyps Study. Patients were matched on age, gender, race, facility site, and year of colonoscopy. Cases were defined as any colorectal adenoma on colonoscopy (n=909) and controls were polyp free (n=855). A two-stage logistic regression was conducted using rs174537 as the IV with the dependent variable being the presence of a colorectal adenoma on colonoscopy.

RESULTS

Cases were older (59 vs 57 years of age, P<0.0001), and more likely to use alcohol (47.4% vs 19.8%, P=0.001) and to smoke (77.0% vs 66.9%, P<0.0001). There was no statistically significant difference in: age, sex, alcohol use, body mass index (BMI), or NSAID use when stratified by the rs174537 alleles. Genotype was strongly associated with erythrocyte membrane ARA concentrations (P<0.0001). We found no evidence of an association between our IV (rs174537) and colorectal adenomas (P=0.41).

CONCLUSION

In our MR study increased erythrocyte ARA concentrations were not associated with the risk of colorectal adenomas.

Serum ω-3 Polyunsaturated Fatty Acids and Potential Influence Factors in Elderly Patients with Multiple Cardiovascular Risk Factors

Recent clinical trials failed to demonstrate that ω-3 polyunsaturated fatty acid (PUFA) supplement reduced cardiovascular events, which contradicted previous evidence. However, serum ω-3 PUFA concentrations of participants remained unclear in those studies. We aimed to investigate the definite relationship between serum concentrations of ω-3 PUFAs and coronary artery disease (CAD), and to explore the potential influence factors of ω-3 PUFAs. We selected Chinese in-patients (n = 460) with multiple cardiovascular risk factors or an established diagnosis of CAD. Serum ω-3 PUFAs, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were measured by liquid chromatography mass spectrometry. Serum concentrations of ω-3 PUFAs in CAD patients were lower than that in patients with cardiovascular risk factors. Furthermore, high serum DHA concentration was an independent protective factor of CAD after adjustment for confounding factors (OR: 0.52, p = 0.014). Alcohol intake (p = 0.036) and proton pump inhibitor (PPI) usage (p = 0.027) were associated with a decreased serum ω-3 PUFA concentration. We conclude that serum concentrations of ω-3 PUFAs may associate with a decreased CAD proportion, and DHA may serve as a protective factor of CAD. Serum ω-3 PUFA concentrations may be reduced by alcohol intake and certain drugs like PPIs.