Phelan D, Prado-Cabrero A, Nolan JM. Nutrients. October 2017.
Summary: Oils and Powder Analysis of stability and potency in commercially available products. All powder filled products (n = 3) failed to comply with label claim (L: 19–74%; Z: 57–73%; MZ: 83–97%); however, the oil filled soft gel products (n = 5) met or were exceeded label claim (L: 98–122%; Z: 117–162%; MZ: 97–319%). The carotenoid content of the oil filled capsules were stable over time (e.g., L average percentage change: −1.7%), but the powder filled supplements degraded over time (e.g., L average percentage change: −17.2%). These data are consistent with previous work, and emphasize the importance of using carotenoid interventions in oil based formulas rather than powder filled formulas.