45 yo male, exercise/nutrition fanatic. finally getting more than a few gray hairs. is there any nutritional or topical way to restore color?

Not yet!: Technically hair coloring is a topical solution but even as we begin to crack the secrets of cellular aging we've learned very little about loss of hair pigment . A better solution revolves around self image and how you truly appear to others. Don't underestimate the attraction to intelligent, strong, fit, wise, & distinguished appearing men. For many, lack of at least some grey is a deal breaker.