Several points are important when choosing a spermidine supplement: 1. Whether the supplement content in mg is clarified per pack or per capsule and without counting other ingredients. 2. Whether the total content of supplement such as Fisetin, Quercetin & Ca-AKG  matches what is claimed on the packaging.  3. Whether the product is made in a GMP certified facility and not certified by unknown laboratory. 4. Whether the product quality is stable, the longer the expiration date, the more stable the quality is tested for.   7. Whether it’s in powder form and in white or off white in color.  8. Whether the packaging is light-proof and not in a transparent bottle or pack. 9. Whether the purity is clarified as the top standard of at least 1% and not anything less 0.3% nor the impossible 100%.Ca