20 Nov 09

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Author: Dr. Karen (8 Articles)

Patient: A couple of my fingernails are curling downward as they grow. Is this due to a poor diet?

Optional Information
Gender: female
Age: 60
Already Tried: nothing

Doctor: Fingernail changes are due to SO many things, it is hard to say without a picture.

But in general, if your fingernails are strong, but curling this is less of a concern than if they are weak and “bendy”.


Curling down is very much associated with respiratory problems- asthma, chronic bronchitis, emphysema and the like.

Iron deficiency will produce pale nails which can curl.

There are many other causes-

See this site at Mayo-


There has not been shown that any dietary change can produce real changes.

However, it depends on what exactly is wrong.

Here is a site talking more about nutrition- but in general, protein, calcium, Vit, B and C have all been used to give better nail health.



You want to be examined- think of the nails as the windows to your body-

Some blood tests or even a chest Xray may be needed (esp if you smoke).

After this- you can rest easy than nothing major is wrong.

Feel free to ask anything else regarding this-

I am happy to add more color where you think it may be relevant

Patient: My nails are not weak or bendy. It is just within the last year that they have started to grow in this curved way. I have no respiratory problems although I do smoke. My mother’s nails did the same thing in her later years and she never smoked.

Doctor: It may be nothing- but with a history of smoking, you just want to make sure the lungs are OK. That is numero uno.

Aside from that, simply checking the nails general health and related lab tests if needed is the next step.

I misspoke- it is NOT just when they are weak and bendy that there is a concern with curling. Typical curling nails with lung disease (called clubbing) usually show thicker curling nails.

Make an appointment and ease your (and my) concerns.

The best to you

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  • salli says:

    I have a toenail that is bending over, is there a way you straighten it back out over time?
    Thank you.


    i have my fingernails bending over and weak,what could be the problem.

  • Teresa Kiernan says:

    I have noticed for awhile now that my middle fingernails bend and they are not that long…they are soft …I thought it was from years of biting them previously …but as a smoker and reading about curved nails was wondering if its worth visting my doctor!

  • Rhonda says:

    My nails curl also, I have actually gone to the doctor about it and been tested and what I found out is that it was a vitamin d deficiency. I have only been taking the vitamin d for a couple of months now and I can notice a little change but not much as of yet. And by the way I am a smoker also and my doctor knows this so I don’t think it has anything to do with smoking.

  • Mystica says:

    My fingernails have curled over the ends of my fingers most of my life. I was diagnosed as asthmatic at age 19 (I’m now 55). my fingernails are pink, but without the little “half-moon” shapes at the bottoms (except my thumb nails). One thumb nail is very strong and solid; the other one tends to separate and peel. Most of my nails have longitudinal stria (lines and ridges). I recently began taking a women’s multivitamin, which seems to have fixed the peeling/separating of the one nail, and some of the stria seem to be smoothing out. Most of the nails still curl over, though, either in the center (ring fingers) or to the inside (medial) sides of the nail. At least, now I understand the curling, so thank you! :-)

  • Sharon says:

    I have a very similar issue with my nails that Mystica talks about, so similar that I could have written her comment myself. I always thought I was alone in the world. However, I was never diagnosed with any kind of breathing disorder. I have had this problem with my nails for as long as I can remember and I am in my mid 40’s. I would include pics in my comment but don’t see that its possible so I will very descriptive about my nail conditions. I do not have much of a half moon on my nails either except for the thumbs. The other nails have just a tiny sliver at the cuticle. My index finger nails curl on the thumb side of the nails while the other side grows straight. My middle and ring finger nails are wide and flat and curl around the end of the finger tip. I wouldn’t say they are clubbing though as my fingers themselves are not wider at the tip than the rest of the finger. My nails also have the raised lines running the length of the nail from the cuticle to the end of the nail. I do not have any indentations in the nails however. My nails are somewhat strong but are also thin. Thin enough that you can kind of see through them. I always thought they should be solid in color and not opaque. I am embarrassed by them at times. I usually keep them cut short but I do like to try to grow them out a little until I get frustrated with them only to cut them short again. I have tried several times to wear fake nails, but because of their width and the way they naturally grow, fake nails usually pop off after a few days. Are these issues due to a vitamin deficiency as well? If so, which vitamins am I lacking? Or is this an indication of a more severe health problem thats been undetected for my whole life?

  • Katie says:

    My nails are strong but have recently started to curl as they grow out. I just had a baby about 10 months ago and I am breastfeeding him. That’s the only medical change in my life. I am not a smoker and do not have any know lung problems. Do you think this is from breastfeeding? Am I not getting enough vitamins, that he’s getting them all through my milk and not leaving any for me? Any help would be super appreciated! Thanks!

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