I have history of diverticulitis and wanted to know if its ok to take grapefruit seed extract daily as part of my diet to avoid another attack?

Diverticulitis: High fibre diet is recommended for longterm management of the condition. Some authorities though would recommend avoiding high fibre, high residue foods during flareups. The extract is not typically advised in conventional medicine. Safest thing here is to discuss with surgeon, doctor or dietician licensed in your area. https://patient.info/health/diverticula-including-diverticulosis-diverticu

Assuming that: you had sigmoid diverticulitis, a high fiber diet is generally recommended. However, it is at best marginally effective especially in the short term. Grapefruit seed extract seems harmless enough to me, but you should consult with your doctor or gi specialist, just to make sure.