Extent of Unidentified Complaints and Depression Is Inversely Associated with Fish and Shellfish Intake in Young Japanese Women

Abstract

Background/Objectives: Vague physical complaints with no corresponding organic disease background are called unidentified complaints. The symptoms of patients with unidentified complaints closely resemble medically unexplained or persistent physical symptoms, with the onset sometimes masked by mental disorders. Over the past 50 years, numerous studies have connected unfavorable eating habits to these symptoms; however, no study has systematically examined the association between the symptoms and specific nutrients or food items. Methods: We conducted a cross-sectional study of young Japanese women, using questionnaire surveys, to assess their nutritional intake, quantify unidentified complaints and depression, and identify nutrients/food items primarily associated with the severity of these conditions. Results: Our findings indicate that participants with high scores for unidentified complaints, depression, or both had lower intake levels of eicosapentaenoic acid, docosahexaenoic acid, vitamin D, and vitamin B₁₂ than those with low scores, alongside reduced fish and shellfish consumption. Notably, the median fish and shellfish intake in the group with high scores for both unidentified complaints and depression was less than one-fourth of that in the low-score group. Conclusions: The results align with previous findings, demonstrating a modest inverse association between fish intake and depression risk, and suggesting the involvement of fish and shellfish intake in the occurrence of unidentified complaints.

Keywords: depression; docosahexaenoic acid; eicosapentaenoic acid; food frequency questionnaire; medically unexplained symptoms; unidentified complaints; vitamin B12; vitamin D.

Figure 1

Distribution of MDCQ (a) and BDI-II (b) scores among participants. Red lines indicate the cutoff between low- and high-score groups.

Figure 2

Comparison of EPA (a), DHA (b), vitamin D (c), vitamin B₁₂ (d), and fish and shellfish (e) intake between the LC (≤26 of MDCQ score) and HC (≥27 of MDCQ score) groups by box plots. The bottom of the box is the 25th percentile, the line that intersects the box is the median, the multiplication sign within the box is the mean, and the top of the box is the 75th percentile. Whiskers above and below the box represent the 10th and 90th percentiles, and the points above and below the whiskers indicate the outliers. The p-values from the Mann–Whitney U-test for the LC and HC groups are displayed in the top square brackets. EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid; MDCQ, micronutrient deficiency-related complaints questionnaire; LC, low complaint; HC, high complaint.

Figure 3

Comparison of EPA (a), DHA (b), vitamin D (c), vitamin B₁₂ (d), and fish and shellfish (e) intake between the LD (≤13 of BDI-II score) and HD (≥14 of BDI-II score) groups by box plots. The bottom of the box is the 25th percentile, the line that intersects the box is the median, the multiplication sign within the box is the mean, and the top of the box is the 75th percentile. Whiskers above and below the box represent the 10th and 90th percentiles, and the points above and below the whiskers indicate the outliers. The p-values from the Mann–Whitney U-test for the LD and HD groups are displayed in the top square brackets. EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid; LD, low depression; HD, high depression; BDI-II, Beck Depression Inventory, Second Edition.

Figure 4

Frequency of participants in the HD (≥14 of BDI-II score) and LD (≤13 of BDI-II score) groups within the HC (≥27 of MDCQ score) and LC (≤26 of MDCQ score) groups. The frequency of HD associated with HC and the p-value from the chi-square test results are shown. BDI-II, Beck Depression Inventory, Second Edition; MDCQ, micronutrient deficiency-related complaints questionnaire; LC, low complaint; HC, high complaint; LD, low depression; HD, high depression.

Figure 5

Comparison of EPA (a), DHA (b), vitamin D (c), vitamin B₁₂ (d), and fish and shellfish (e) intake between the LC-LD (≤26 of MDCQ score and ≤13 of BDI-II score) and HC-HD (≥27 of MDCQ score and ≥14 of BDI-II score) groups by box plots. The bottom of the box is the 25th percentile, the line that intersects the box is the median, the multiplication sign within the box is the mean, and the top of the box is the 75th percentile. Whiskers above and below the box represent the 10th and 90th percentiles, and the points above and below the whiskers indicate the outliers. The p-values from the Mann–Whitney U-test for the LC-LD and HC-HD groups are displayed on the top square brackets. EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid; MDCQ, micronutrient deficiency-related complaints questionnaire; BDI-II, Beck Depression Inventory, Second Edition; LC, low complaint; HC, high complaint; LD, low depression; HD, high depression.