Horizontal grooves (Beau’s lines): These indentations that run across the nail can indicate that the body experienced a period of intense stress. They may appear after a serious illness, high fever, major emotional strain, or be associated with long-term conditions such as diabetes or poor circulation.

Vertical ridges: Fine vertical lines are common as we age, but when ridges become deep, uneven, or suddenly more noticeable, they may suggest nutritional imbalances. Low levels of iron, vitamin B12, or other essential nutrients are often linked to these changes.

Dark lines or streaks: A dark stripe appearing on a nail—especially if it shows up suddenly, grows wider, or affects only one nail—should never be ignored. In some cases, it may be an early sign of melanoma, a serious form of skin cancer, and requires immediate medical evaluation.

White horizontal lines (Muehrcke’s lines): These pale lines can point to low protein levels in the blood and may be connected to liver or kidney disorders. Unlike other nail markings, they often do not move as the nail grows.

Takeaway: After the age of 40, noticeable changes in nail texture or color deserve attention. Nails can reflect internal health issues long before other symptoms develop. If you notice unusual lines, discoloration, or changes that persist, consulting a healthcare professional is an important step toward early detection and prevention.