We all want strong, healthy nails. But when brittleness, dryness, and breakage come into the mix, acquiring them can be easier said than done. Brittle nails can be caused by various things, including age, poor diet, and even overdoing treatments at the nail salon. Sometimes, you know exactly what's led to your nail trauma (for example, if you're on your third gel manicure in a row, that's probably the culprit). Other times, the cause is more elusive. If that's the case for you, it could signal a nutrient deficiency. Read on to discover the nutrient you might be lacking that can lead to brittle nails. RELATED: If You See This on Your Nails, It Could Be a Tell-Tale Sign of Diabetes. Shutterstock One common medical cause of breakage-prone nails is iron deficiency anemia. This may occur if there is a lack of iron in someone's diet, an inability to absorb iron, blood loss, or even pregnancy. "Iron helps ...