In patients with systemic lupus erythematosus (SLE), high intake of n-3 anti-inflammatory fatty acids may favorably affect patient-reported outcomes, including lupus activity and quality of sleep, according to research published in Arthritis Care and Research.

Researchers used data from the Michigan Lupus Epidemiology and Surveillance Cohort, a population-based cohort of people with SLE in southeastern Michigan, to assess the relationship between dietary intake of n-3 and n-6 fatty acids and self-reported SLE outcomes, including disease activity, quality of life, fatigue, pain, and sleep.

Using an abbreviated version of the Diet History Questionnaire II, investigators assessed participants’ dietary intake, focusing on estimates of n-3 and n-6 fatty acid intake. They used the Systemic Lupus Activity Questionnaire (SLAQ) to assess SLE disease activity.

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In all, 456 (93.2% women) participants completed the dietary questionnaire and were included in the current study. Researchers found that the mean fat energy-adjusted dietary intake of n-3 was 3.1 ± 0.9 g/1000 Kcal (range, 0.7-7.2); mean n-6 intake was 20.1 ± 7.5 g/1000 Kcal (range, 5-36.7), and mean n-6:n-3 ratio was 6.9 ± 2.9 (range, 1.2-18). Flaxseed and/or fish oil supplementation was noted in 26.8% of participants.

According to the researchers, self-reported disease activity was significantly associated with intake of polyunsaturated fatty acids, illustrated by an increase in mean SLAQ score by 0.3 (95% CI, 0.1-0.6; P =.013) points for each unit increase in n-6:n-3 ratio. The association between greater absolute n-3 intake and reduction in SLE activity was borderline significant, with SLAQ score reduction of 0.8 points/U increase of n-3 intake (regression coefficient β =−0.8; 95% CI, −1.6 to 0; P =.055).

Three dimensions of pain were assessed in the study, but no significant associations between polyunsaturated fatty acid intake and these measures — Survey Criteria for Fibromyalgia, the RAND Medical Outcomes Study 36-Item Short-Form Survey Instrument, and the Lupus Quality of Life Questionnaire — were noted.

Investigators identified an inverse association between n-3 intake and comorbid fibromyalgia (odds ratio 0.82; 95% CI, 0.66-1.02; P =.07). Perceived sleep quality was also significantly associated with polyunsaturated fatty acid intake, with each unit increase of n-3 linked with a lower mean Patient-Reported Outcome Measurement Information System Sleep Disturbance score by −1.1 point (95% CI, −2 to −0.2; P =.017).

The investigators noted several limitations to the study. First, the Diet History Questionnaire II primarily captured intake of polyunsaturated fatty acids from cooking oil, seafood, beans, and eggs, which may have underestimated absolute intake.

Second, this questionnaire limited the researchers from “calculating a global measure of diet quality,” as dietary questionnaires are typically subject to recall bias and are less quantitative in nature than biomarker measurements.

“In this population-based, cross-sectional study, lower ratios of n-6 (inflammatory) to n-3 (anti-inflammatory) fatty acids, and higher levels of n-3 fatty acid intake, were significantly associated with improved self-reported lupus disease activity,” the researchers concluded. “Future research should focus on examination of [polyunsaturated fatty acid] intake from all dietary sources and supplements.”

Reference

Charoenwoodhipong P, Harlow SD, Marder W, et al. Dietary omega polyunsaturated fatty acid intake and patient-reported outcomes in systemic lupus erythematosus: the Michigan Lupus Epidemiology & Surveillance (MILES) program [published online May 10, 2019]. Arthritis Care Res. doi:10.1002/acr.23925