A poor nutrition status is a modifiable risk factor for cognitive decline and dementia. In particular, evidence links low status of certain B-vitamins and ω-3 fatty acids (ω-3 FA) with a greater risk of cognitive decline and dementia. Although these dietary components are typically investigated separately, post-hoc analyses of existing clinical trial data and experimental work indicate that B-vitamins and ω-3 FA may exert synergistic beneficial effects on processes related to brain health and cognition. However, this combination has not been tested directly in humans. In the proposed BOOMERANG project, we will study the effects of jointly supplementing with B-vitamins and a highly bioavailable ω-3 FA supplement, Lysoveta, on a robust biomarker of brain atrophy, the neurofilament light chain, in a double-blinded randomized controlled trial (RCT) over 3 months in older adults. We will also examine the secondary effects of the supplement of quality of life and cognitive function.