If you want to incorporate both ingredients, alternate their use on different nights or use AHA/BHAs in the morning and retinol at night
Signs and symptoms of vitamin B12 deficiency can include fatigue, pale skin, headaches, shortness of breath, fast heartbeat, gastrointestinal issues, mouth inflammation, paresthesias (abnormal sensations), decreased cognitive ability, depression, muscle weakness, imbalance and incoordination, vision problems, and erectile dysfunction
Nat Chem Biol 10:917 Hwang C, Sinskey AJ, Lodish HF (1992) Oxidized redox state of glutathione in the endoplasmic reticulum
There are all kinds of claims being made
Preliminary research suggests the peptide stimulates proteoglycan synthesis in cartilage, which may benefit osteoarthritis (Metabolic Pharmaceuticals, 2010)