What Vitamin is PABA? Understanding Para-Aminobenzoic Acid

January 13, 2026 •

4 min read

Historically, PABA, or para-aminobenzoic acid, was once mistakenly called a B vitamin, often referred to as 'vitamin B10' or 'vitamin Bx'. Though it shares a close relationship with the B-complex, PABA is now classified as a nonessential nutrient, not a true vitamin, primarily because the body's gut bacteria can produce it.

Quick Summary

PABA is a nonessential nutrient that is a component of the folic acid molecule and is produced by intestinal bacteria. Once called 'vitamin B10', it is not considered a true vitamin but plays a role in metabolic processes and has been explored for hair and skin health applications.

Key Points

Not a True Vitamin: PABA is a nonessential nutrient, not a true vitamin, because the human body's intestinal bacteria can produce it.
Precursor to Folic Acid: Its primary biological role is serving as a precursor that gut microbes use to synthesize folic acid (vitamin B9).
Known as Vitamin Bx or B10: In the past, due to its link to the B-vitamin complex and folate production, it was often referred to as 'vitamin Bx' or 'vitamin B10'.
Historical Skincare Use: It was once a popular ingredient in sunscreens for its ability to absorb UVB rays, but its use has been discontinued due to allergic reactions and safety concerns.
Available from Diet: PABA can be found in common foods like liver, whole grains, eggs, milk, and certain vegetables like spinach and mushrooms.
High-Dose Risks: While generally safe in small amounts, high doses from supplements can cause side effects and have been linked to liver toxicity.

Is PABA a True Vitamin?

Para-aminobenzoic acid (PABA) is a chemical compound that, despite its historic association with the B-complex vitamins, is no longer considered a true vitamin. A substance is classified as a vitamin if it is an organic, essential nutrient that the body cannot produce and must obtain from an external source, such as food. PABA does not meet these criteria for humans because our intestinal bacteria can synthesize it. This means that for healthy individuals, PABA is not an essential dietary component.

The Historical Misclassification of PABA

In the past, PABA was dubbed "vitamin Bx" or "vitamin B10" due to its involvement with other B vitamins, specifically its role in the synthesis of folic acid (vitamin B9). This connection led to its inclusion in some B-complex supplements. However, modern scientific consensus recognizes that PABA's primary role in human health is as a precursor for folic acid production by gut flora, and we primarily get our folate from dietary sources.

PABA's Role and Function in the Body

Even though it is not a vitamin, PABA plays several important biological roles. Its most significant function is its contribution to the synthesis of folic acid, which is vital for cell growth, DNA synthesis, and red blood cell production.

List of PABA's Biological Functions:

Folic Acid Synthesis: As a crucial precursor, PABA is used by intestinal bacteria to produce folic acid.
Skin and Hair Health: It has been historically linked to maintaining skin health and promoting hair pigmentation, though evidence is limited and outdated.
Antioxidant Properties: PABA acts as an antioxidant, helping to neutralize harmful free radicals that contribute to cellular damage and aging.
Protein Metabolism: It assists in the metabolism of protein, which can support energy production.

PABA and Sunscreen: A Controversial History

PABA was once a ubiquitous ingredient in sunscreens due to its ability to absorb ultraviolet (UV) rays, particularly UVB radiation. It was an effective chemical UV filter used extensively from the 1940s onwards. However, its use has since been largely discontinued in modern sunscreen formulations due to a number of safety concerns.

Reasons for PABA's Decline in Skincare:

Allergic Reactions: A significant number of users developed allergic contact dermatitis, photosensitivity, and rashes from topical application.
Photosensitivity: PABA can increase sensitivity to sunlight in some individuals.
Staining: PABA has been known to stain clothing yellow.
Safety Concerns: More recent studies have raised concerns about potential endocrine disruption and the production of free radicals when PABA interacts with sunlight. This has led to the development and widespread adoption of safer, more stable alternatives like zinc oxide and titanium dioxide.

Sources of PABA: Dietary vs. Supplements

Most people get sufficient PABA from a healthy diet, as it is found in a variety of foods. The contribution from gut bacteria also helps maintain levels.

Foods Containing PABA:

Whole Grains: Wheat germ, rice, and whole-grain products.
Organ Meats: Liver and kidney contain significant amounts.
Dairy and Eggs: Milk, yogurt, and eggs are sources.
Vegetables: Spinach and mushrooms.
Brewer's Yeast and Molasses: These are particularly rich sources.

PABA Supplementation

For individuals with a healthy gut microbiome and balanced diet, PABA supplementation is generally not necessary. However, some supplements, particularly those marketed for hair and skin health, may contain PABA. High doses can carry risks, including potential liver toxicity, especially when exceeding 8 grams daily. It is crucial to consult a healthcare provider before taking high-dose PABA, as it can also interact with certain medications, including sulfa antibiotics.

PABA vs. Folic Acid


Feature	PABA (Para-aminobenzoic acid)	Folic Acid (Vitamin B9)
Classification	Not a vitamin; nonessential nutrient.	A true, essential B vitamin.
Source for humans	Produced by gut bacteria; found in some foods.	Must be obtained from dietary sources or supplements.
Role in the Body	Precursor for bacteria to synthesize folate.	Essential for numerous metabolic processes, including DNA synthesis and repair.
Use in supplements	Present in some B-complex and hair/skin health supplements.	Commonly included in multivitamins and prenatal vitamins.
Historical context	Previously labeled "vitamin B10" due to association.	Universally recognized as a vital nutrient.

Conclusion

In summary, PABA is not a vitamin but rather a compound that serves as a precursor for the synthesis of the true vitamin, folic acid, primarily by gut bacteria. Despite its history of being mistakenly classified as a B vitamin and its use in older sunscreen formulas, it is now understood as a nonessential nutrient for humans. While it plays a role in metabolic processes and was historically linked to skin and hair benefits, most healthy individuals obtain sufficient PABA through a balanced diet and internal production. The historical use of PABA in sunscreen has been phased out due to safety concerns, with more modern and safer alternatives now standard. When considering supplements containing PABA, it is always recommended to consult a healthcare professional due to potential side effects and interactions.

Frequently Asked Questions

PABA is not considered a true vitamin for humans because our intestinal bacteria are capable of producing it. A vitamin is, by definition, an essential nutrient that the body cannot synthesize on its own.

PABA is a component that intestinal bacteria use to create folic acid (vitamin B9). Folic acid, unlike PABA, is a true, essential vitamin that humans must obtain from their diet to support critical functions like cell growth and DNA synthesis.

Yes, PABA is naturally present in a variety of foods, including organ meats (like liver), whole grains, eggs, dairy, and leafy greens such as spinach. Brewer's yeast and molasses are also excellent sources.

Yes, PABA was a key ingredient in many sunscreens starting in the 1940s because it effectively blocked UVB rays. However, its use has been phased out due to reports of allergic reactions, photosensitivity, and clothing stains.

High doses of PABA supplements can be dangerous. Side effects can include nausea, allergic reactions, and, in rare cases, liver toxicity with very high doses. It can also interfere with certain medications like sulfa antibiotics.

Historically, PABA has been linked to potential benefits for skin and hair health, such as slowing hair graying and softening skin. However, modern scientific evidence supporting these claims is limited and largely based on older studies.

PABA deficiencies are extremely rare in healthy individuals who consume a balanced diet, as our intestinal bacteria can produce it. A deficiency is most likely to occur in cases of long-term antibiotic use that disrupts the gut microbiome.