Biotin, a B vitamin closely linked to nail strength, also becomes more important after forty. Lower biotin levels are associated with brittle nails, and absorption may decline with age. Foods such as egg yolks, nuts, oats, mushrooms, and sweet potatoes help reinforce nail structure gradually at the cellular level.
Iron supports oxygen delivery to the nail matrix, where growth begins. Low iron levels can result in pale, thin, or fragile nails. Iron-rich foods like leafy greens, legumes, seeds, and moderate amounts of red meat, paired with vitamin C sources, improve absorption and nail resilience.