The US National Library of Medicine has concluded that daily use of Niacinamide (Vitamin B3) improves skin tone and texture.
The B vitamins niacinamide and panthenol have been shown to reduce many signs of skin aging, including hyperpigmentation and redness.
Adult women 30-60 years of age with epidermal hyperpigmentation were recruited in Mumbai and randomly assigned to apply a test or control lotion to the face daily for 10 weeks. Effects on skin tone were measured using an image capturing system and associated software. Skin texture was assessed by expert graders. Barrier function was evaluated by transepithelial water loss measurements. Subjects and evaluators were blinded to the product assignment.
To learn about their results, you can read the full article here.