According to Naturopathy Digest, para-aminobenzoic acid is present in such natural foods as liver, wheat germ, some grains and other items. They also consider it to be a water soluble vitamin with a slightly acidic nature, so it could cause some irritation to the stomach.
This compound also used to be used as a main ingredient of sunscreens. It absorbs UV light and so it was used for blocking those parts of sunlight. However, it is not used much for that anymore.
In terms of nutrition, this is just a scam -- most medical people do not consider it to be necessary for human beings.
This is an organic compound often used to treat Irritable Bowel Syndrome (IBS) and certain skin problems, such as eczema, and as far as a "certain" role goes, the medical community seems to agree it is effective for those two health issues. But others will claim it is useful to treat depression, exhaustion and anxiety disorders. These claims are unproven, however.
PABA - para amino benzoic acid, is not a vitamin, but it is a component of folic acid, supporting the production of folic acid and erythrocytes (they are carrying oxygen through the body).
PABA participates in metabolic processes but it has no nutritional value for human.
The lack of PABA include symptoms as depression, nervousness, skin problems, headaches, prematurely grey hair and wrinkled skin, digestive disorders.
The natural sources of PABA are : rice, spinach, whole egg, liver.