Polyphenols and omega‑3 fatty acids are thought to have beneficial effects in Alzheimer's disease, the most common cause of dementia. Seeds of chia (Salvia hispanica L.) are highly rich in these nutrients, and thus, the present study investigated the effects of chia seeds on behavior and cognition in an aluminum‑induced Alzheimer's disease model in rats. Experimental animals received chia supplementation either during the generation of the model (i.e., pretreatment) or after the model was established (i.e., treatment). A battery of behavioral and cognitive tests were performed, including open‑field, elevated plus maze, Porsolt's forced swim, and Morris' water maze, to evaluate anxiety‑ and depression‑like behaviors, and learning and memory. Results showed that chia supplementation was ineffective against Alzheimer's‑related anxiety, whereas depression‑like behaviors were attenuated with both pretreatment and treatment. There was no improvement in learning and memory with chia treatment. Rather, cognitive performance in chia‑pretreated animals was remarkably worse as compared to their non‑treated disease‑induced counterparts. Hippocampal concentrations of amyloid-β42, amyloid precursor protein, and total tau protein were similarly increased in all disease‑induced animals (despite chia supplementation), as compared to the controls. Based on these findings, chia supplementation during the progression of Alzheimer's disease may exacerbate the disease. Although the results presented here emerge from an experimental/preclinical study, we suggest cautious and careful use of chia, especially in early‑stage Alzheimer's patients, until future research in different experimental settings is conducted.