|
DESCRIPTION
PABA (Para-aminobenzoic acid) is classified as a
vitamin-like substance. In its para-aminobenzoil moiety it is a factor in the
vitamin B-complex vitamins and a component of folacin. Bacteria are able to
synthesize folic acid from PABA; therefore, for these organisms, it is
considered a vitamin. Humans, however, cannot use aminobenzoic acid to
synthesize folacin. PABA does perform certain metabolic functions in some
animals.
METHOD OF ACTION
PABA is a component of many biological systems and
participates in many metabolic processes. It appears to function as a coenzyme
in the conversion of certain chemical intermediates to purines. It has also
been suggested that PABA has an antifibrosis activity, increasing oxygen uptake
at the tissues. This increase in oxygen may enhance monoamine oxidase activity;
furthermore, it is believed that too little monoamine oxidase activity is a
contributing factor to fibrosis. These effects are, at present, still
considered speculative.
PABA has no nutritional value for humans.
It has been reported that folacin and vitamin C assist
the absorption of PABA; ethanol, coffee, sulfa drugs, and cola drinks prevent
absorption.
PROPERTIES AND USES
PABA is used as a topical sunscreen, absorbing
ultraviolet light of wave lengths between 190 and 270 nanometers. However, it
does not absorb in the near ultraviolet range, 350 to 400 nanometers, and
therefore does not prevent drug-related photosensitivity and phototoxicity.
PABA is also used in combination with
salicylates in the treatment of rheumatic fever.
CONSEQUENCES OF DEFICIENCY
There is no consequence of deficiency
related to PABA.
TOXICITY FACTORS
There is no toxicity related to PABA.
RECOMMENDED DIETARY ALLOWANCES
RDA for adults: 400 mcg
RDA for children 200 - 300 mcg
RDA for infants 50 mcg
RDA for pregnancy 800 mcg
RDA for lactation 600 mcg
FOOD SOURCES
· Beef liver
· Bran flakes
· Brewer's yeast
· Chicken liver
· Egg (whole)
· Lamb liver
· Molasses
· Rice
· Turkey liver
· Veal liver
· Wheat germ
· Whole wheat |
