To view a very informative and interactive infographic that outlines all different nail shapes and abnormalities and their possible causes, please click here. Image Source: http://3.bp.blogspot.com/-GgLKK2A4j2A/U9pJV0f-V4I/AAAAAAAAQlM/KdrZGY-uwsw/s1600/ridges-nails-final.jpg
johnrtitus: Vitamin B12 deficiency will cause your brain to shrink, you may lose memory or experience confusion. One indication that you might be deficient is the appearance of lines or ridges on your fingernails and/or the disappearance of the moons at the bottoms of your fingernails. Methylcobalamin is the bioactive form, so look on your label to make sure you have that form of B12. Also, watch your peripheral neuropathy start to ease with B12, it is nerve food!
Your moons, or lunula, are related to your Iodine levels. Low moons, small moons, or no moons indicate low iodine. Info on how to Properly supplement Iodine on this link (not my website, just good info with no sales).