Horizontal lines (Beau’s lines): These can suggest past illness, significant stress, or chronic conditions such as diabetes or circulation issues.

Vertical ridges: While common with aging, unusually deep or uneven ridges could point to nutritional deficiencies like iron or vitamin B12 shortage.

Dark streaks: Sudden appearance of dark streaks may signal melanoma, a serious skin cancer, and require immediate medical attention.

White lines (Muehrcke’s lines): These may be linked to liver or kidney problems, or low protein levels.

Bottom line: After age 40, changes in your nails—especially unusual lines—should not be ignored. They can be an early warning from your body, so it’s important to consult a healthcare provider if you notice anything unusual. Your nails might be revealing health issues before other symptoms appear.