The mechanism, which is sound
Ordinary metabolism produces reactive oxygen species. In excess they damage proteins, lipids and DNA. Nerve tissue is unusually exposed: high metabolic rate, high lipid content, and limited capacity to replace cells.
Which makes oxidative stress one of the better-supported explanations for how nerve tissue wears with age. That much is widely accepted.
The leap, which is where it gets thinner
From “oxidative damage contributes to ageing in nerve tissue” to “swallowing an antioxidant reduces that damage enough to change cognitive outcomes” is a large step, and the human evidence for it is far weaker than the mechanism's popularity suggests.
The clearest cautionary case is vitamin E. It was trialled extensively for exactly this reasoning. The results were disappointing, and at high doses some trials raised safety concerns. A plausible mechanism is not a result.
The three antioxidants in this formula
Curcumin from turmeric. The cognitive trial is Small 2018 — forty adults, eighteen months, ahead of placebo on memory and attention. Positive, small, slow. Covered in full here.
EGCG from green tea. Good laboratory evidence of antioxidant activity. Direct human cognitive outcome data at the amounts found in a formula capsule is limited.
Lutein and zeaxanthin from marigold. Accumulate in nerve tissue; Hammond's 2017 trial found an attention benefit after twelve months in 51 analysable participants.
Three of six ingredients, all on the same slow clock, with one reasonable trial between them and a great deal of mechanism.
Why you will never feel it
There is no sensation attached to reduced oxidative load. None. No week in which something shifts, nothing to notice, nothing to measure at home.
This matters practically: it means you cannot evaluate this part of a formula by experience. Anyone describing a noticeable antioxidant effect is describing something else, probably the caffeine.
The diet comparison, made honestly
Dietary patterns rich in these compounds — vegetables, fruit, olive oil, fish — have better evidence for cognitive outcomes than isolated supplements do. The usual caveat applies: those patterns correlate with a great deal else about how people live, and untangling it is difficult.
Still, if the choice is between adding vegetables and adding a capsule, the vegetables have the stronger case. The capsule is a supplement to that, which is what the word means.
What a reasonable expectation looks like
Slow, imperceptible, uncertain, and plausibly worth doing alongside things with better evidence. That is less exciting than the marketing and closer to the literature. The benefits page places it fifth of six for exactly this reason.