The primary aim of this study was to examine the quality of dietary intakes in adults with diagnosed mood disorders using comparisons to national and international nutrition standards as well as regional nutrition survey data. Our results were consistent with others [22
] that have revealed many indications of poor diet quality in this population.
The low intakes of grains, vegetables and fruit, and meat and alternatives coupled with the high intakes of foods with excess sugar and fat may compromise mental health status [23
]. Comparison of carbohydrate (main sources are plants) intakes with the AMDRs showed that more than a quarter of the sample (28%) were below the lower boundary; two participants consumed less than the EAR which is based on the amount needed to produce enough glucose for essential brain activities. About 10% of the sample had intakes of protein less than the EAR, suggesting that important neurotransmitter precursors such as tryptophan may be lacking in the diets of some individuals. Nutrients commonly associated with good mental health include polyunsaturated fatty acids (particularly the omega 3 types), minerals such as zinc, magnesium, and iron, a range of B vitamins particularly folate, and antioxidant vitamins such as C and E most of which are found in diets rich in dark green leafy and orange-coloured vegetables and whole grains. Evidence is accumulating that the combination of polyunsaturated fats, minerals and vitamins may help to relieve the symptoms of some mental illnesses and improve the effectiveness of medication for some conditions [25
Closer examination of the intakes of the major nutrients suggests many implications for negative mental health effects in this population. The high total and saturated fat diets found in this sample have been associated with reduced hippocampal levels of neurotrophic factor, a crucial modulator of synaptic plasticity [27
], which can induce cognitive dysfunction [28
]. Low intakes of omega-3 fatty acids impair astrocyte-mediated vascular coupling that contributes to reduced gray matter volume in the prefrontal cortex [29
] and research has suggested that lipid profiles comprising a low docosahexaenoic acid percentage and omega-3 proportions predicted risk of suicidal behaviour among depressed patients over a 2-year period [30
]. The high proportion of participants with hypercholesterolemia (further suggesting excess fat intakes) also has mental health implications. Studies of people with elevated blood cholesterol levels have shown that global severity of psychological symptoms is worsened with high fat, low-complex carbohydrate diets [31
]. Lipid-lowering medications are standard treatment for hypercholesterolemia, however, these drugs can form complexes with lipoproteins, alter the medication's pharmacokinetics and lead to deterioration of mental symptoms [32
]; dietary interventions do not present these risks.
The limitations of this study include biases related to recall, sample selection (i.e., participants were drawn mainly from an urban sample of a non-profit network), and misclassification (i.e., with AMDRs). Males were under-represented, which may limit generalizability. The samples compared (i.e., study versus BCNS) did differ on some variables (e.g., income levels) that can affect food choice, however both samples were drawn based on random selection. Finally, this cross-sectional study cannot determine the temporal sequence of disease and nutrient intake.
One of the study's strengths is that it provided quantified comparisons of nutrient intakes to the general local population, which have never been reported previously for mood disorders. This investigation also determined the prevalence of various nutrition-related factors in a mood disorder sample and is therefore useful for future hypothesis generation and planning of health services.
Dietary intakes in this sample of adults with mood disorders tended to consist of a high proportion of foods associated with neuronal impairment (e.g., high fat, high sugar) and limited dietary components associated with neuro-protection (e.g., fibre, antioxidants). People with mood disorders have a greater frequency of poor diet for several reasons such as the occurrence of depressive episodes that exacerbate a sedentary lifestyle associated with lack of exercise, weight gain, and cardiovascular disease and diabetes risk, or manic episodes that may be associated with treatment non-adherence. Other factors such as food insecurity, co-existing medical problems, or substance use may also explain the association between mood disorders and poor nutrition status. The negative impact of poor dietary intake in individuals with mood disorders may be exacerbated by the fact that health providers are unlikely to discuss diet habits with them, according to patient report [33