Depressive symptoms and diet: their effects on prospective inflammation levels in the elderly

It has been reported that a Mediterranean-type diet in old age is protective against inflammation in Italians with depressive symptoms. In the present study, we explore this hypothesis in a non-Mediterranean, elderly sample, and further disentangle whether it is a Mediterranean diet per se or a healthy diet, in general, that confers this protective effect. The sample is a cohort of people born in 1936, who were assessed on diet and depressive symptoms at age 70. Inflammatory markers, C-reactive protein, fibrinogen and albumin, were collected at ages 70 and 73, while Interleukin-6 transferrin and ferritin were measured at the second time-point only. Controlling for confounding factors (e.g., CVD risk factors, medication) no interaction effect of depressive symptoms and Mediterranean diet was observed on inflammation. However, a main effect of Mediterranean diet on change in C-reactive protein was significant (β=-0.10, p=0.03), and so too was an effect of the 'Health Aware' diet on ferritin (β=-0.12, p=0.02). An interaction between depressive symptoms and a Health Aware diet on transferrin levels showed that there was an association between increased depressive symptoms and inflammation in those following a Health Aware diet. Our results indicate that there are advantages of a Mediterranean diet over a Health Aware diet with respect to the progression of inflammation in old age and that depressive symptoms compound inflammatory burden only for specific biomarkers and under specific dietary conditions unrelated to the Mediterranean diet.