Article Long-Chain Omega-3 Fatty Acids Are Conditionally Essential Substrates in Children: Effects on Visual Function in Children with Phenylketonuria 4 min read Add to favorite You need to log in or register to add to your favorites. Share Long-Chain Omega-3 Fatty Acids Are Conditionally Essential Substrates in Children: Effects on Visual Function in Children with Phenylketonuria (full doc) Berthold Koletzko