Sources: PABA is found in liver, brewer’s yeast, wheat germ, whole grains such as rice, eggs, and molasses. It is stored in body tissues and is also synthesized by the natural bacteria flora in our intestines.

Functions: Para-aminobenzoic acid, as part of the coenzyme tetrahydrofolic acid, aids in the metabolism and utilization of amino acids and is also supportive of blood cells, particularly the red blood cells. PABA supports folic acid production by the intestinal bacteria. PABA is important to skin, hair pigment, and intestinal health. Used as a sunscreen, it also can protect against the development of sunburn and skin cancer from excess ultraviolet light exposure.

Uses: Although PABA has been much used in attempts to stimulate hair growth and to turn gray hair back to its natural color, it has not had wide success in such uses. It may work in some cases that are related to a PABA deficiency. If graying of hair is caused by vitamin deficiency, it is likely a deficiency of a combination of vitamins, mostly the various Bs. PABA is usually used along with biotin, pantothenic acid, and folic acid in the restoration of hair, often with vitamin E as well. PABA is also used to reduce aging of the skin and lessen wrinkles. Vitiligo, a skin depigmenting condition, which could result from deficient hydrochloric acid, vitamin C, or pantothenic acid, may be helped somewhat by PABA, both orally and as a cream. PABA ointment is used commonly to prevent and treat sunburns and, with vitamin E, is often applied to other burns.

Deficiency and toxicity: It is possible that high doses of PABA can be somewhat irritating to the liver; in addition, nausea and vomiting have occurred, as have anorexia, fever, skin rash, and even vitiligo. Deficiency problems are not very common; they occur more frequently with the use of sulfa or other antibiotics that alter the functioning of intestinal bacteria and, therefore, the production of PABA. General fatigue, irritability, depression, nervousness, graying hair, headache, and constipation or other digestive symptoms may occur. Several patients have told me that they are "sensitive" to PABA in vitamin formulae and, thus, cannot take them (most vitamin combinations contain PABA). I do not know what this reaction is unless it is some allergy to the para-amino-benzoic acid molecule.

Requirements:No RDA is listed for PABA. It is available in supplements of 50–1,000 mg. Up to 1,000 mg. are used therapeutically in a time-released capsule, although the common treatment amount is usually about 50–100 mg. three times daily. If we take antibiotics, we might increase our intake of PABA for a while, although PABA taken with sulfa antibiotics may reduce their effectiveness. A therapeutic approach used by some authorities to attempt to restore normal hair color is 1,000 mg., time-released, daily for six days a week, taken with 400 mcg. of folic acid.