Altered gut microbiota is associated with heart attacks and strokes. A Swedish study published in the December issue of Nature Communications showed that the gut microflora in people with stroke had less capacity to produce carotenoids and could be part of the reason why they suffered from a stroke.
Carotenoid supplements show mixed results in stroke prevention. Perhaps what protects best is a microflora that produces high levels of carotenoids plus other unknown factors. It could be that carotenoid production may be a maker for stroke protection.