I am highly susceptible to colon polyps & at 30 had a hgd adenoma removed, is a high or low fibre diet best for me to reduce frequency of the polyps?

More complex...: Than that. In general, high fiber diet (not simply bran or fiber supplements) may be helpful ( conflicting data). Adequate calcium, especially from dairy (low fat/no fat) may be helpful. Low sat fat (low meat, especially processed/sausage type) may be helpful. Aspirin or nsaids may be helpful. Need to discuss your particulars, including fam hx, polyp hx, w/ md. Follow surveillance scopes.