Safety is the first real question, and it deserves a calm, conservative answer. Resveratrol has been described in broader toxicology and safety pharmacology literature as having a favorable profile in subchronic oral toxicity contexts, with cardiovascular safety considerations discussed in preclinical settings (Johnson WD, 2011). Separately, high-purity trans-resveratrol has been tested in experimental animals and is often reported as well-tolerated, with minimal adverse effects observed (Williams LD, 2009).
But cats are a special case. Their metabolism of trans-resveratrol differs, including an absence of certain glucuronidation products, which is one reason veterinarians may be more cautious about dose selection and long-term use (Burnett K, 2017). If your cat has liver disease, is on multiple medications, is pregnant, or is medically fragile, treat any resveratrol supplement for cats as a vet-supervised decision.