Can blood cause dark-brown flecks in stool?

Hello doctor,

I have noticed dark (do not know if they are dark-brown, more greenish, or black) flecks in what looks like otherwise very normal stool. Can this be blood, or does blood typically only present as fully-black, tarry stool? Also, I have PKU, and my supplemental food contains 4g Ferrous Sulfate per serving. Could this cause discoloration in my stool from time-to-time?I am 43 years old with a history of anxiety, 6'2", 190, decent health. Non-smoker. Light drinker. In no pain.

Thank you doctor,

I did want to follow up with this: I do not so much tend to notice any of the flecks in the toilet. I notice these things more on the toilet paper. They sometimes very much appear to be undigested food (I tend to have nervous bowels and there is a huge history of IBS on my mother'ss

side of the family), but even when they don't so much appear to be undigested food, I'm only noticing them on the toilet paper. I have, in the past, passed dark stool, but rarely, and without accompanying pain, and almost every time it's happened, I've been able to think of dietary reasons. (along with my PKU diet, I'm allowed fruits, veggies, and junk food, and I I tend to eat a fair amount of chocolate-y things). Anyway, my whole point was that, with the flecks, I only notice them when I wipe. I guess, I'm wondering, also, isn't it very natural that stool can exit our body in a variety of dark and light shades of brown as well? Thanks again, so much, Chris