Your fingernails may reveal more about your health than you think. According to Dr. David Sinclair, they can reflect the state of your body and even hint at how quickly you’re aging. While many focus on major organs, nail growth shows how efficiently your body produces new, healthy cells—an important part of the aging process.

Dr. Sinclair pays close attention to his own nails as a way to track aging. Faster growth may suggest stronger cell regeneration and better protection against age-related decline. Research has shown that fingernail growth slows by about 0.5% each year after age 30, so quicker growth could indicate a younger biological age.

Nails can also signal potential health issues. Dark streaks may point to melanoma, while dents can be linked to skin conditions like psoriasis. Yellow nails might suggest lung disease or rheumatoid arthritis, and curved nails can be associated with heart, lung, or liver problems. Pale, white, or blue nails may indicate anemia, diabetes, liver disease, or low oxygen levels.

Not all changes are serious, though. Brittle or peeling nails can result from frequent exposure to water, nail products, or minor deficiencies. Improving diet or using moisturizers can often help. Still, noticeable or persistent changes in color, shape, or growth should be evaluated by a doctor to rule out underlying conditions.