Is there such a thing as vitamin B10?: Unpacking the PABA Connection

January 13, 2026 •

4 min read

Despite its popular moniker, a true, recognized vitamin B10 does not exist in human nutrition. Instead, the term refers to para-aminobenzoic acid (PABA), a compound with a much more limited, and sometimes controversial, role in the body. This article answers: is there such a thing as vitamin B10?

Quick Summary

The term vitamin B10 is an older, inaccurate name for para-aminobenzoic acid (PABA), a compound not considered an essential human nutrient. PABA has limited, sometimes unproven, uses and is not part of the standard B-vitamin family.

Key Points

Outdated Name: The term "vitamin B10" is an old, medically inaccurate name for para-aminobenzoic acid (PABA).
Not an Essential Nutrient: PABA is not considered an essential human vitamin because the body can produce it and does not strictly require it from the diet.
Role in Folate Synthesis: PABA acts as a precursor for the production of folate (vitamin B9) in bacteria, including some gut bacteria, but not efficiently enough for human needs.
Historical Sunscreen Ingredient: PABA was once used in sunscreens for its UV-absorbing properties, but its use has been restricted due to safety concerns and allergic reactions.
Limited Supplemental Evidence: Limited research and mixed results exist for supplemental PABA's claimed benefits, such as darkening gray hair or treating certain skin conditions.
Potential Toxicity: High doses of PABA supplements can lead to serious side effects and liver problems, and can interfere with some antibiotics.

The Myth of Vitamin B10

When we think of B-vitamins, we typically recall the essential group ranging from B1 (thiamine) to B12 (cobalamin). Each plays a critical role in human metabolism, energy production, and overall health. However, the mention of "vitamin B10" often leads to confusion. The simple answer to the question "Is there such a thing as vitamin B10?" is no, at least not in the same sense as the others. The name is an historical label for a substance known as para-aminobenzoic acid, or PABA, which is no longer classified as a true vitamin for humans.

What is Para-Aminobenzoic Acid (PABA)?

PABA is an organic compound that is naturally found in certain foods and is also produced by bacteria. While it is chemically associated with the B-vitamin complex, it does not meet the criteria of an essential human nutrient. This is because the human body, unlike some microorganisms, does not rely on PABA for fundamental functions that cannot be fulfilled by other means. The compound gained attention in the mid-20th century, but its status has been re-evaluated over time.

PABA and Folate Production

One of the most significant roles of PABA is its function as an intermediate in the synthesis of folate (vitamin B9). Bacteria, including some that reside in the human gut, utilize PABA to produce folate. However, the amount of folate produced by these gut bacteria is insufficient to meet human nutritional needs, meaning we still must obtain the bulk of our folate from our diet. This distinction is why PABA is not considered a true vitamin like folate itself.

Historical Use in Sunscreens

PABA was famously used in sunscreens, starting in the 1940s, because of its ability to absorb ultraviolet B (UVB) rays, which are associated with sunburn and skin damage. However, its use has fallen out of favor due to two main reasons: the potential for allergic skin reactions in some individuals and concerns raised by animal and in vitro studies suggesting it might cause cellular damage under UV exposure. As of 2019, the FDA no longer recognizes PABA as a safe and effective ingredient for sunscreen use.

Limited Evidence for Other Benefits

Over the years, supplemental PABA has been marketed for a variety of health claims, but scientific evidence is limited or mixed.

Some of these claims include:

Darkening gray hair: Early studies suggested PABA could help re-pigment prematurely gray hair, but this effect has not been recently studied or substantiated, and hair was shown to gray again upon discontinuing the supplement.
Skin conditions: PABA has been investigated for its use in treating autoimmune disorders like scleroderma and Peyronie's disease, but results have been conflicting or inconclusive.
Fertility: Some sources have claimed PABA can assist with female infertility, but robust scientific evidence is lacking.
Antioxidant effects: PABA is cited as having antioxidant properties, which could help protect cells from damage by free radicals.

PABA vs. Essential B-Vitamins: A Comparison

To understand why PABA is not a true vitamin, it's helpful to compare it with an essential B-vitamin, such as Vitamin B9 (Folate).


Feature	PABA (HistoricaL "Vitamin B10")	Vitamin B9 (Folate)
Essential for Humans?	No, considered nonessential	Yes, essential for human health
Primary Function	Precursor for bacterial folate synthesis; UV absorber	DNA/RNA synthesis; red blood cell formation
Human Production	Synthesized by gut bacteria	Not synthesized by humans; must be obtained from diet
Dietary Requirement	No official recommended daily intake	Recommended daily intake established (e.g., 400 mcg DFE for adults)
Toxicity Risk (High Dose)	Possible liver and kidney issues	Generally low risk, but high intake can mask B12 deficiency

PABA Sources: Food and Supplements

While not essential, PABA can be obtained naturally from the following food sources:

Liver
Brewer's yeast
Mushrooms
Whole grains
Spinach
Molasses

PABA is also available in dietary supplements, often as part of a B-complex formula. However, it's crucial to consult a healthcare professional before taking PABA supplements, especially at high doses.

Safety and Side Effects of PABA

Although PABA is largely non-toxic in small amounts, high oral doses can be dangerous. Reported side effects of excessive intake include:

Nausea and vomiting
Diarrhea
Fever
Allergic skin reactions, such as rashes
Liver and kidney damage in extreme cases

Furthermore, PABA may interact negatively with certain antibiotics known as sulfonamides, reducing their effectiveness. It is also not advised for individuals with liver or kidney issues. The safety of PABA supplements for pregnant or breastfeeding women has not been established.

Conclusion: The Final Verdict on Vitamin B10

The existence of vitamin B10 is a medical myth rooted in an outdated name for a compound called PABA. While PABA has a chemical relationship with the B-vitamin complex, it is not an essential nutrient for human survival. It plays a role in bacterial folate synthesis and was historically used in sunscreens, but scientific evidence supporting many of its purported health benefits is limited or contradictory. Given the potential for side effects at higher supplemental doses and its interactions with certain medications, PABA is a compound that should be approached with caution and medical consultation. The most reliable way to obtain essential nutrients is through a balanced diet, without relying on supplements for a non-essential substance.

Visit the National Cancer Institute's definition of para-aminobenzoic acid (PABA) for authoritative information on this compound.

Frequently Asked Questions

No, there is no such thing as a true vitamin B10. The name is an outdated term for the chemical compound para-aminobenzoic acid (PABA).

PABA, or para-aminobenzoic acid, is an organic compound that is part of the B vitamin complex but is not considered an essential human vitamin.

PABA is not a true vitamin because the human body does not rely on dietary intake for it. Some gut bacteria produce PABA, and while humans require folate, which PABA helps synthesize in bacteria, we must still get sufficient folate from our diet.

Historically, PABA was used in sunscreens due to its UV-blocking properties. As a supplement, it has been anecdotally used for skin conditions, fertility, and darkening gray hair, though evidence is limited or mixed.

Yes, high oral doses of PABA can be potentially unsafe and may cause serious side effects, including liver and kidney damage. It can also interfere with sulfa-based antibiotics.

Some early studies suggested high doses of PABA might help darken gray hair, but this effect has not been widely or recently studied. The effect was also shown to be temporary.

PABA can be found in a variety of foods, including liver, brewer's yeast, mushrooms, spinach, whole grains, and molasses.

Yes, PABA was a common ingredient in sunscreens from the 1940s onward, valued for its ability to absorb UVB rays. However, it is no longer widely used for this purpose due to safety concerns and potential allergic reactions.