Guajava - Guajava demonstrates antifungal, antibacterial, anti-inflammatory, laxative, and analgesic properties. It is used to treat herpes ulcers, ringworm, dermatitis, and urinary tract infections. Guajava is related to cassia and senna, and contains anthraquinones found in those other species as well.
Vitamins B, particularly biotin (vitamin B7) and B12 are important to keep healthy nails. If your nutrition lacks in vitamins B, nails will be dry and brittle. Vitamin C deficiency is associated to brittle nails and may cause infections of nail tissues.
Vitamin B-12 of the B vitamin complex strengthens nail growth; therefore, a deficiency in B vitamins may cause fingernail ridges. Iron deficiency causes ridges in the fingernails usually accompanied with white spots; Koilonychia is a condition associated with iron deficiency.