Dietary Omega Polyunsaturated Fatty Acid Intake and Patient-Reported Outcomes in Systemic Lupus Erythematosus: The Michigan Lupus Epidemiology and Surveillance Program

Abstract

Objective: To examine associations between dietary intake of omega-3 (n-3; generally antiinflammatory) and omega-6 (n-6; generally proinflammatory) fatty acids and patient-reported outcomes in systemic lupus erythematosus (SLE).

Methods: This study was based on the population-based Michigan Lupus Epidemiology and Surveillance cohort. Estimates of n-3 and n-6 intake were derived from Diet History Questionnaire II items (past year with portion size version). Patient-reported outcomes included self-reported lupus activity (Systemic Lupus Activity Questionnaire [SLAQ]). Multivariable regression, adjusted for age, sex, race, and body mass index, was used to assess associations between absolute intake of n-3 and n-6, as well as the n-6:n-3 ratio, and patient-reported outcomes.

Results: Among 456 SLE cases, 425 (93.2%) were female, 207 (45.4%) were African American, and the mean ± SD age was 52.9 ± 12.3 years. Controlling for potential confounders, the average SLAQ score was significantly higher by 0.3 points (95% confidence interval [95% CI] 0.1, 0.6; P = 0.013) with each unit increase of the n-6:n-3 ratio. Both lupus activity and Patient-Reported Outcomes Measurement Information System (PROMIS) sleep disturbance scores were lower with each 1-gram/1,000 kcal increase of n-3 fatty acids (SLAQ regression coefficient β = -0.8 [95% CI -1.6, 0.0]; P = 0.055; PROMIS sleep β = -1.1 [95% CI -2.0, -0.2]; P = 0.017). Higher n-3 intakes were nonsignificantly associated with lower levels of depressive symptoms and comorbid fibromyalgia, and with higher quality of life, whereas results for the n6:n3 ratio trended in the opposite direction.

Conclusion: This population-based study suggests that higher dietary intake of n-3 fatty acids and lower n-6:n-3 ratios are favorably associated with patient-reported outcomes in SLE, particularly self-reported lupus activity and sleep quality.

Figure 1

Associations between dietary polyunsaturated fatty acid intake (n‐3, n‐6, and ratio n‐6:n‐3) and patient‐reported outcome measures for lupus activity (Systemic Lupus Activity Questionnaire [SLAQ]), sleep quality (Patient‐Reported Outcomes Measurement Information System [PROMIS] sleep disturbance), and depression (PROMIS depression), from separate multivariable models. The circle, square, and triangle markers indicate regression (beta) coefficients, which represent mean outcome changes associated with each 1‐unit increase of the respective polyunsaturated fatty acid variable; horizontal lines indicate 95% confidence intervals. Lower scores for the SLAQ and PROMIS measures indicate better outcomes (coefficients below 0 indicate favorable associations, and above 0 indicate unfavorable associations). The n‐3 and n‐6 fatty acid variables were fat energy–adjusted (grams/1,000 kcal). Multivariable models were adjusted for the covariates sex, age, race, and body mass index. coeff = coefficient.

Figure 2

Associations between dietary fatty acid intake (n‐3, n‐6, and ratio n‐6:n‐3) and fulfillment of fibromyalgia (FM) survey criteria, from separate multivariable models. The circle, square, and triangle markers designate odd ratios (ORs), and horizontal lines indicate 95% confidence intervals. ORs below 1 indicate favorable associations, and above 1 indicate unfavorable associations. The n‐3 and n‐6 fatty acid variables were fat energy–adjusted (grams/1,000 kcal). Multivariable models were adjusted for the covariates sex, age, race, and body mass index.

Figure 3

Associations between dietary fatty acid intake (n‐3, n‐6, and ratio n‐6:n‐3) and health related quality of life, measured by the Medical Outcomes Study Short Form 36 (MOS SF‐36), from separate multivariable models. The circle, square, and triangle markers indicate regression (beta) coefficients, which represent mean outcome changes associated with each 1‐unit increase of the respective polyunsaturated fatty acid variable; horizontal lines indicate 95% confidence intervals. Higher scores indicate better health‐related quality of life. The n‐3 and n‐6 fatty acid variables were fat energy–adjusted (grams/1,000 kcal). Multivariable models were adjusted for the covariates sex, age, race, and body mass index. fx = functioning; coeff = coefficient.

Figure 4

Associations between dietary fatty acid intake (n‐3, n‐6, and ratio n‐6:n‐3) and lupus‐specific quality of life, measured by the Lupus Quality of Life Questionnaire (LQoL), from separate multivariable models. The circle, square, and triangle markers indicate regression (beta) coefficients, which represent mean outcome changes associated with each 1‐unit increase of the respective polyunsaturated fatty acid variable; horizontal lines indicate 95% confidence intervals. Higher scores indicate better health‐related quality of life. The n‐3 and n‐6 fatty acid variables were fat energy–adjusted (grams/1,000 kcal). Multivariable models were adjusted for the covariates sex, age, race, and body mass index. coeff = coefficient.