Your fingernails may reveal more about your health than you think. According to Dr. David Sinclair, “your fingernails can say a lot about the state of your health,” even hinting at how fast you’re aging. While most people focus on major organs like the heart or lungs, he explains that nail growth reflects how quickly your body produces new, healthy cells—an important factor in aging.

Dr. Sinclair regularly checks his nails to track aging. He notes that faster nail growth suggests better cell regeneration and stronger protection against age-related decline. In fact, research from 1979 showed that “fingernail growth rate slowed down by 0.5% annually from the age of 30 onwards.” If your nails grow faster than expected, it could mean your biological age is lower than your actual age.

Beyond aging, nails can also signal health problems. A dark streak might point to melanoma, while dents could suggest psoriasis or atopic dermatitis. Yellow nails may indicate rheumatoid arthritis or lung disease, and curved or “clubbed” nails can be linked to issues with the heart, lungs, or liver. Pale nails may signal anemia, white nails could relate to diabetes or liver disease, and blue nails might mean low oxygen levels.

However, not all nail changes are serious. Brittle nails can result from frequent wetting and drying, or conditions like iron deficiency or hypothyroidism. Peeling nails may simply come from nail polish removal or long exposure to water. Sometimes, improving diet or using specific lotions can help restore nail health.

In the end, your nails can act as a simple health indicator. As Dr. Sinclair suggests, tracking changes may reveal how your body is aging. While not every change is serious, noticeable differences in color, shape, or growth should be checked by a doctor to rule out underlying issues and maintain overall health.