Possible Clues:

• Vitamin: it is swallowed by solitary person retiring
• Vitamin A; rosin oil
• Anti-aging vitamin
• Relation jittery lacking a certain vitamin
• Relation suffers, lacking a particular vitamin
• Eye cream ingredient
• Energy from tritium found in iron, rock and metal foundation or sourced in yellow and green vegetables, for example
• A serum marketed for lines and wrinkles
• Vitamin A's relation different (not A)