Glycemic index, glycemic load, and common psychological disorders

Potential associations between dietary glycemic index (GI) and glycemic load (GL) with psychological disorders remain uncertain.

We investigated the relations of dietary GI and GL with psychological distress, anxiety, and depression.

A total of 3363 nonacademic members of the staff of Isfahan University of Medical Sciences were included in this cross-sectional study. GI and GL were assessed by using a validated, self-administered, dish-based, semiquantitative food-frequency questionnaire. Validated Iranian versions of the Hospital Anxiety and Depression Scale and General Health Questionnaire-12 were used to assess anxiety, depression, and psychological distress.

After control for potential confounders, individuals in the top tertile of GI had greater odds of depression (OR: 1.44; 95% CI: 1.03, 2.02; P-trend = 0.03) and a trend for greater odds of anxiety (OR: 1.52; 95% CI: 0.97, 2.38; P trend = 0.06) compared with those in the first tertile. Higher GL values were linked to lower odds for mental disorders (OR: 0.66; 95% CI: 0.49, 0.90; P-trend = 0.009), depression (OR: 0.69; 95% CI: 0.51, 0.93; P-trend = 0.02), and psychological distress (OR: 0.67; 95% CI: 0.48, 0.92; P-trend = 0.01). Significant interactions were observed between GI and sex for depression (P = 0.01) and psychological distress (P = 0.046) in the crude model. In stratified analyses by sex, after control for potential confounders, a greater GI was linked to a higher odds of depression (OR: 1.52; 95% CI: 1.20, 1.94; P-trend = 0.001) and psychological distress (OR: 1.66; 95% CI: 1.28, 2.14; P-trend = 0.001) in women but not in men.

Our findings support a direct link between the odds of depression and dietary GI but inverse associations between GL and mental disorders, depression, and psychological distress. This trial was registered at clinicaltrials.gov as NCT02362113.