Fish consumption, not fatty acid status, is related to quality of life in a healthy population

Abstract

Depressive symptoms in the community have a considerable impact on quality of life. Although long-chain polyunsaturated fatty acids (LCPUFA) have frequently been implicated in depressed mood, their relationship with quality of life has scarcely been investigated.

This study examined the cross-sectional associations between fish consumption and plasma phospholipid LCPUFA status on the one hand, and quality of life, as measured by the Short Form 36 questionnaire, on the other in a population-based sample. The mental health component of quality of life was not associated with LCPUFA status or fish consumption. Fish consumption showed a positive association with physical well-being, which remained significant after correction for LCPUFA status, suggesting that the relationship between fish consumption and physical well-being is independent of the LCPUFA content of fish. These findings indicate that fish consumption may serve as a proxy for a healthy lifestyle or a favorable nutritional status, which is reflected in better quality of life.

Introduction

Depressive symptoms are highly prevalent in the general population [1]. Subclinical depressive symptoms not only significantly increase the risk of developing major depression [2], [3], but are also associated with considerable functional impairment [2], [4]. The negative impact of subclinical depressive symptoms on both physical and mental functioning is generally reflected in a reduction of quality of life [5], [6]. From a public health perspective, it is important to identify the factors involved in the development of depressive symptoms and the concomitant decrease in quality of life.

It has often been suggested that long-chain polyunsaturated fatty acids (LCPUFA), which are primarily found in fish, may lower the risk of developing depressive symptoms [7], [8], [9]. Strikingly, the relationship between LCPUFA status and quality of life has scarcely been investigated—only one study has addressed this issue to date. In a community-based study, Crowe et al. [10] examined the associations between serum phospholipid LCPUFA status and the physical and mental health components of quality of life. Although the authors did not find any associations between mental well-being and the two LCPUFA that are predominant in fish, i.e. eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), they did find a positive relationship between EPA concentration and physical well-being. In addition, Silvers and Scott [11] addressed the relationships between fish consumption and the physical and mental health dimensions of quality of life in a population-based sample. Interestingly, this study reported a positive relationship between fish consumption and self-reported mental health, but not physical well-being.

Unfortunately, the two above-mentioned studies solely focused on either LCPUFA status or fish consumption, which makes it difficult to compare their results. An additional limitation of the study by Silvers and Scott is the crude distinction between fish consumers and non-consumers, without taking into account the frequency and/or the kind of fish consumption.

The aim of the present study was to investigate the cross-sectional relationships between LCPUFA status, fish intake, and quality of life in a population-based sample. In order to compensate for the limitations of the above-mentioned studies, we included detailed measurements of both fish consumption and plasma phospholipid LCPUFA concentrations in our study.