Dark fingernails/"stripes" on fingernails - what is it a sign of?

Hi,

Throughout my life, I have had fingernails that seemed darker or more pigmented than usual. As a youth growing up - there seemed to be one fingernail that was especially affected: one of my thumbs seemed to have a very-broad, dark "stripe" in the middle of it. And my other fingernails had dark stripes on it - some stripes were narrow, others broad (although the dark stripes on my other nails didn't seem to be quite as noticeable as the one on my thumb).

In adulthood - either the problem got somewhat better, or my eyes just became used to it. My nails don't look as "weird" to me as they did when I was young - but I can look at my nails right now and still see many of the same pigmented stripes that have always been there. They just seem lighter or more "faded" than they used to be - especially the thumb.

Growing up - I just thought of myself as having very weird, unusual-looking nails. Even other people noticed it - although I can only recall one incident in detail. In about the 7th grade, a classmate looked at my nails and told me that those dark areas indicated an iron deficiency (if I'm recalling this correctly - I *think* iron was the mineral that she cited). I blew-off/dismissed her comment as some folk mythology. I told her what my mom (who was a nurse & had actual medical training) had told me: that it was just "hereditary" and that it didn't indicate any kind of "health" issue. (Supposedly I "inherited" these nails from my Dad).

But in recent years - as I have become much more of a believer in "alternative stuff" - I have wondered. Do my dark nails indicate some type of health issue? Are they a sign of a nutritional deficiency or some type of metabolism issue? Or what?

I also have the same issue with my toenails - at least some of them. Some of the pigmented "stripes" on my toenails are darker than the ones on my fingernails. Actually - the nature and the location of those dark areas on my toenails seem to be a bit different than those on my thumb. Some of my toenails have very dark areas on the edges/perimeter of the nail, and some toenails seem to be (almost) entirely darkened.

Is there any health significance to this - or is it just harmless "heredity"? Any feedback is appreciated - TIA! Tweet