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PABA (Para-Amino benzoic Acid):

By VRP Staff

PABA is a naturally-occurring, water-soluble compound which is found in many foods as a cofactor of the vitamin B complex (associated with folate). It first became popular due to the writings of pioneer nutritionists like Gaylord Hauser, Lelord Kordell, and Adelle Davis. Several decades later, life extension scientists Durk Pearson and Sandy Shaw extolled the potential virtues of PABA in their best-seller, Life Extension-A Practical Scientific Approach. Pearson and Shaw described PABA as an antioxidant B vitamin which could: (1) slow cross-linking; (2) enhance flexibility; (3) promote membrane fluidity; (4) provide protection against ozone, secondhand smoke and other air pollutants; (5) alleviate the inflammation of arthritis; and (6) restore the original color of hair in perhaps 10-25% of cases. Pearson and Shaw reported they consumed as much as three grams of PABA per day.

Is PABA a Vitamin?

By definition, a vitamin is a biologically active organic compound that is essential for an organisms normal health and growth, a deficiency of which results in a deficiency disease or disorder. Though PABA has many vitamin-like qualities, it fails to meet the strict definition. Early animal studies did, however, demonstrate that PABA increased lactation in rodents and increased the weight of chicks that were fed a diet with low levels of folate. These early studies suggested that PABA was essential, and it was given the preliminary designation vitamin Bx. Since then, it has erroneously been described as a B vitamin by many nutritionists and health educators in dozens of books. In fact, what was occurring in these folate-deficient animals was that PABA was being converted into folate (PABA is actually a structural part of folic acid) by intestinal bacteria. PABA is a vitamin for many bacterial species (bacterial vitamin H1) but not for humans or other large animals. Furthermore, animals lack the enzymes of the folate synthetic pathway, so it is impossible for them to incorporate PABA into folate. Though PABA is not technically a vitamin, it does appear to have a number of interesting and potentially valuable uses.

The Anti-Gray Hair Vitamin

One very interesting application for this versatile substance is its potential to restore hair to its natural color. In 1941, Sieve reported that administration of 200 mg of PABA per day for two months resulted in marked darkening of the hair in 30 patients who presented with achromotrichia (gray hair). In an attempt to replicate this study, Brandaleone and colleagues (1944) muddied the waters by administering 200 mg of PABA with 100 mg of calcium pantothenate (vitamin B5) and 50 grams (approx. 2 ounces) of brewers yeast for eight months to patients with gray hair. He found that only 2 of 33 individuals had significant hair color change. Dr. Chris Zarafonetis (1964) of Temple University followed these investigations with a report that described 5 cases of dramatic hair color change and hair regrowth in 20 patients who presented with markedly gray hair, who were taking 6-24 grams of PABA per day for other conditions. The hair color changes were serendipitous results of this therapy. Zarafonetis concluded that consumption of 6-24 grams of PABA per day for at least 6 weeks restored the natural hair color of 25% of people with markedly gray hair. He did not speculate on the mechanism for hair color restoration and pointed out that the effects were highly variable and might require extended periods of administration. Zvak (1986) confirmed that forty years ago, large doses of PABA were clearly shown to darken grey hair; the regained color was lost within 3-4 weeks of stopping the treatment. While it is clear that the hair color restoration effects of PABA were less than universal, any therapy which results in 10-25% reversal of what is generally considered to be an irreversible condition (like hair grayness) must certainly be considered significant.

PABA as an Antioxidant

It has been well established that PABA is a potent neutralizer of singlet molecular oxygen, a potent free radical, which is a common by-product of normal metabolism. In theory, use of antioxidants protects cellular membranes and mitochondrial DNA from free radical attack. The mitochondria are the energy-producers of the cells. Mitochondrial degradation results in reduced cellular energy production which causes numerous undesirable physiological conditions, which may include fatigue and the aging process itself. As an antioxidant, PABA also provides protection against ozone, smoking, and other air pollutants which damage other cell structures and membranes through oxidative stress. PABA promotes cell membrane fluidity by preventing such oxidant damage.

PABA as an Anti-Crosslinking Agent

The cross-linkage theory of aging was proposed by Professor Johan Bjorksten in 1974. Bjorksten believed that the aging process was due to cross-links—undesirable bonds induced by excess free radicals that formed between molecules, progressively impairing the function of the body, resulting in aging. PABA appears to slow and in some cases even reverse cross-linking in the protein structures of connective tissues such as collagen. Collagen cross-linking, in addition to resulting in the loss of flexibility with age, and perhaps the aging process itself, also is the primary process in a number of fibrotic diseases, including: Peyronies disease (formation of fibrotic plaques of the penis, usually in men over 50, resulting in painful, crooked erections, rendering intercourse difficult or impossible); Dupuytrens contracture (wherein the flexor tendons of the fingers of the hands become fibrotic and contract, rendering the fingers useless); and scleroderma (a rare condition characterized by heavily cross-linked skin and tissues, with disabling systemic results). Zarafonetis (1964) found PABA to have a marked therapeutic effect in these conditions, in doses of 12 grams per day. Zarafonetis also used PABA to treat dermatitis herpetiformis (200 mg, 4-5 times daily), and vitiligo (a depigmenting disease). By slowing cross linking, PABA may promote greater body flexibility in normally aging individuals. Williams (1973) reported dramatic life span increases in animal longevity studies performed with PABA at Texas University School of Medicine.

Potential Side Effects and Cautions

High-dose PABA is generally well-tolerated, with its most significant adverse side effects being diarrhea and nausea, which resolved with cessation of use, or lowering of the dose. As PABA is water soluble, it is rapidly excreted in the urine, and must therefore be administered in divided doses throughout the day. High-dose PABA should be discontinued when taking sulfa antibiotics (like Bactrim or Septra). We recommend that no more than 2-3 grams of PABA be consumed per day without the supervision of a physician.


Allen, J.M. Rapid Reaction of Singlet Molecular Oxygen (1O2) With P -Aminobenzoic Acid (PABA) in Aqueous Solution Biochemical and Biophysical Research Communications, July, 1995

Brandaleone, H., Maine, E., and Steele, J.M. The effect of calcium panthothenate and para-aminobenzoic acid on gray hair in man. Am J Medical Science, 1944, 206: 315.

Bjorksten, J. Crosslinkage and the aging process, in: Theoretical Aspects of Aging, by Morris Rockstein (ed), Academic Press, NY, 1974.

Pearson, D., and Shaw, S. Life Extension A Practical, Scientific Approach, 1982, Warner Books, New York.

Sieve, B.F. Clinical achromotrichia. Science, 1941, 94: 257.

Williams, R. Nutrition Against Disease, 1973.

Zarafonetis, C. Darkening of gray hair during para-amino-benzoic acid therapy. J Investigative Dermatology, 399-401.

Zarafonetis, C. Antifibrotic Therapy with POTABA. American Journal of Medical Sciences, 1964, 248:550-561.

Zvak, C. The Science of Hair Care, 1986, Marcel Dekker, Inc., New York, p. 450.