PABA stands for para-aminobenzoic acid and is best known as the ingredient in sunscreen that protects the skin against ultra-violet radiation. PABA has been found to reduce the onset of wrinkles, keep skin smooth, and even restore graying hair to its original color. PABA also improves the protein used in the body, aids red-blood-cell formation, and assists the manufacture of folic acid in the intestines. PABA deficiency leads to fatigue, irritability, nervousness, depression, and constipation.