Medical Analysis

Understanding Vitamin B10: Clinical Insights and Para-Aminobenzoic Acid (PABA) Diagnostics

Introduction to Vitamin B10 (PABA) and Clinical Relevance

Vitamin B10 is currently recognized in clinical practice as PABA, which stands for Para-Aminobenzoic Acid. It is important to note that PABA is not currently recognized as an essential human vitamin [3]. However, it plays a vital role in bacterial folate synthesis and has been utilized clinically for various purposes. Testing for PABA remains relatively rare in modern diagnostic settings. These tests are generally performed for research purposes or to assess the completeness of a 24-hour urine collection, often referred to as the “PABA test” [1, 2]. Beyond its diagnostic utility, PABA is widely known for its UV-absorbing properties, which are commonly utilized in the formulation of sunscreens. Furthermore, it functions in antioxidant roles [4, 5, 9] and is known to interact with sulfa drugs.

Dietary Sources and Nutritional Profile of Vitamin B10 (PABA)

Vitamin B10 (PABA) can be obtained from several dietary sources, as well as through internal physiological processes. The following table delineates these sources:

Functional Overview of Vitamin B10

Vitamin B10 (PABA) serves various biological functions that support overall wellness. These primary functions include:

• Skin Health Support: Assisting in maintaining skin integrity [4].

• Improving Hair Health: Playing a role in hair maintenance.

• Antioxidant Benefits: Acting as an antioxidant to mitigate oxidative stress [4, 5, 9].

• Strengthening Immune System: Contributing to immune support.

• Preventing Premature Graying: Helping to maintain natural hair pigmentation.

• Supporting Red Blood Cells: Aiding in the support of healthy red blood cells.

• Pigmentation Protection: Providing protection related to skin pigmentation.

Recommended Daily Allowances for Vitamin B10

PABA is not considered an essential nutrient for humans; therefore, standard daily allowances have not been established [3].

Clinical Indications for Testing Vitamin B10

Diagnostic testing for PABA is indicated for several clinical scenarios, including:

• Assessing exocrine pancreatic insufficiency [6, 8].

• Screening for chronic pancreatitis diagnosis [6, 8].

• Monitoring pancreatic enzyme replacement therapy [6].

• Investigating severe unexplained malabsorption [6].

• Evaluating photosensitivity.

• Confirming if 24-hour urine collection is complete [1, 2].

• Assessing anemia and low red blood cell counts.

Laboratory Methods of Estimation

Several analytical methods are employed for the estimation of PABA in clinical samples:

• Colorimetric method

• High-performance liquid chromatography (HPLC) [1, 2]

• Liquid chromatography-mass spectrometry (LC-MS/MS)

• Spectrophotometric method

Pre-Analytical Requirements and Sample Collection

Before sample collection, it is essential to follow specific protocols. This test is typically used to assess the completeness of a 24-hour urine collection or as part of a specific test for pancreatic function [1]. Patients should avoid alcohol, smoking, and strenuous exercise before the test. It is important to remain hydrated and fasting is often preferred. Patients must follow proper instructions for the 24-hour urine collection process. Ultimately, this test is used to assure whether the 24-hour urine collection is properly performed or not [1, 2].

The PABA Test: Clinical Procedure

The PABA test is a diagnostic procedure used to assess pancreatic exocrine function [6, 8]. During the test, PABA is given orally and then collected in the urine. The pancreatic enzyme chymotrypsin cleaves the PABA. Urine PABA levels are used to measure this enzyme activity. Low output suggests impaired pancreatic function. The test is relatively simple, non-invasive, and has historically been a low-cost screening method [1, 2].

NBT-PABA Test Protocol

In the NBT-PABA test, the patient orally ingests a specific dose of a PABA substrate, such as Bentiromide (chemically N-benzoyl-L-tyrosyl-p-aminobenzoic acid, often called BT-PABA or PABA-peptide) [1, 2]. Standard doses are often 333 mg tablets, with most protocols administering 1 gram of BT-PABA. Pancreatic enzyme chymotrypsin splits off the PABA, which is then absorbed by the small intestine. All urine is collected over a 6-hour or 24-hour period, and the total PABA excretion is measured. A normal range is typically over 70% PABA excretion. Low PABA output indicates poor pancreatic function, while high recovery confirms the complete 24-hour urine collection [1, 2].

Clinical Reference Ranges and Sample Requirements

Blood samples (plasma or serum) should be light-protected, for example, using an amber tube or wrapping the tube.

Clinical Applications and Monitoring

Vitamin B10 (PABA) status serves as a diagnostic marker for several clinical applications:

• It reflects pancreatic exocrine functional status [6, 8].

• It helps evaluate chronic pancreatitis and malabsorption [6, 8].

• It assesses response to pancreatic enzyme replacement therapy [6].

• It screens for exocrine insufficiency in cystic fibrosis [1].

• It helps differentiate pancreatic from intestinal malabsorption syndromes [6].

• It supports monitoring in post-pancreatic surgery patients.

For Non-Medicos: Understanding Vitamin B10 (PABA)

What is Vitamin B10?

You may hear it called Vitamin B10, but it is technically known as Para-Aminobenzoic Acid, or PABA. It is not a “true” vitamin that your body requires in the same way as others [3]. Instead, your body produces it using bacteria in your gut. While you might find it in some supplements, its main use today is in specific medical tests to see how well your pancreas is working. You might also recognize the name from sunscreen labels, as it is good at absorbing UV light.

What Does PABA Do in Your Body?

Think of PABA as a support worker for your health. It is believed to help:

• Protect your skin and hair: It is often linked to supporting healthy skin and preventing hair from turning gray too early [4].

• Fight stress: It acts as an antioxidant, which helps protect your cells from damage [4, 5, 9].

• Support your immune system and blood: It helps keep your immune system strong and supports the health of your red blood cells.

Can I Get it from Food?

Yes, you can get PABA by eating a variety of healthy foods. Good sources include organ meats like liver and kidney, beef, pork, poultry, eggs, and dairy. If you prefer plant-based foods, you can find it in whole grains, wheat germ, bran, and dark green leafy vegetables. Brewer’s and baker’s yeast are also great sources [3].

Why Would a Doctor Order a “PABA Test”?

Doctors don’t usually test for PABA levels for general health. Instead, they use the “PABA test” to check your pancreas [6, 8]. If you are having trouble digesting food or have signs of chronic pancreatitis, this test helps doctors see if your pancreas is releasing enough enzymes to break down your meals. Sometimes, they also use it to double-check that a 24-hour urine collection (where you save all your pee for a full day) was done correctly [1, 2].

Preparing for a PABA Test

If your doctor orders this test, they will give you specific instructions. Generally, you should:

• Avoid alcohol, smoking, and heavy exercise before the test.

• Stay hydrated.

• Follow your doctor’s instructions strictly for collecting your urine over the full 24 hours.

• Remember that the goal of the test is to see how well your pancreas functions by measuring how much of the substance appears in your urine [1].

References:

1. Weizman, Z., Forstner, G. G., Gaskin, K. J., Kopelman, H., Wong, S., & Durie, P. R. (1985). Bentiromide test for assessing pancreatic dysfunction using analysis of para-aminobenzoic acid in plasma and urine. Studies in cystic fibrosis and Shwachman’s syndrome. Gastroenterology, 89(3), 596–604. https://doi.org/10.1016/0016-5085(85)90456-1 Cited by: 42

2. Miwa, M., Senoue, I., Watanabe, H., Nomiyama, T., Sakita, R., Suzuki, S., Harasawa, S., Tani, N., & Miwa, T. (1980). B.T. PABA test: a new absorption test. Tokai Journal of Experimental and Clinical Medicine, 5(1), 1–13. Cited by: 3

3. Perli, T., Wronska, A. K., Ortiz-Merino, R. A., Pronk, J. T., & Daran, J.-M. (2020). Vitamin requirements and biosynthesis in Saccharomyces cerevisiae. Yeast, 37(6), 283–304. https://doi.org/10.1002/yea.3461 Cited by: 172

4. Haroon, F., Farwa, U., Arif, M., Raza, M. A., Sandhu, Z. A., El Oirdi, M., Farhan, M., & Alhasawi, M. A. I. (2023). Novel Para-Aminobenzoic Acid Analogs and Their Potential Therapeutic Applications. Biomedicines, 11(10), 2686. https://doi.org/10.3390/biomedicines11102686 Cited by: 27

5. Chen, S. (n.d.). Molecular mechanisms and therapeutic prospects of 4-aminobenzoic acid in neuropsychiatric disorders: a comprehensive review of neurotransmitter modulation, anti-inflammatory pathways, and antioxidant defense. Exploration of Digestive Diseases. Cited by: 2

6. Capurso, G., Traini, M., Piciucchi, M., Signoretti, M., & Arcidiacono, P. G. (2019). Exocrine pancreatic insufficiency: prevalence, diagnosis, and management. Clinical and Experimental Gastroenterology, 12, 129–139. https://doi.org/10.2147/ceg.s168266 Cited by: 296

7. Matsuhashi, M., & Tsuno, N. H. (2018). Laboratory testing for the diagnosis of immune-mediated thrombocytopenia. Annals of Blood, 3, 41. https://doi.org/10.21037/aob.2018.09.02 Cited by: 10

8. Keller, J. (n.d.). Diagnosis of pancreatic exocrine insufficiency in chronic pancreatitis. Pancreapedia. Cited by: 16

9. Devliya, B. (n.d.). Design, synthesis, antimicrobial and antioxidant evaluation, cytotoxicity assessment, and molecular dynamics-based computational studies of novel PABA analogues as dual DHPS/DHFR inhibitors. RSC Advances. Cited by: 0

10. Miteva, M. T. (2026). Vitamin deficiencies and Alzheimer’s disease: evidence and implications for supplementation. Frontiers in Nutrition. Cited by: 1

FAQ’s:

• Is PABA an essential vitamin?
  No, PABA is currently not classified as an essential vitamin for humans.

• What is the PABA test?
  It is a screening method used to assess pancreatic exocrine function and urine collection completeness.

• How is PABA test performed?
  Patients ingest a PABA substrate, and total excretion is measured in collected urine samples.

• What does PABA test indicate?
  It reflects pancreatic exocrine function and helps evaluate conditions like chronic pancreatitis.

• What is a normal result?
  A normal result is typically characterized by over 70% PABA excretion in the urine.

• Does PABA benefit skin?
  Yes, it provides skin health support and offers protection against UV radiation.

• What are common dietary sources?
  Sources include liver, kidney, meat, eggs, whole grains, and dark green leafy vegetables.

• Can PABA prevent hair graying?
  It is associated with preventing premature graying and generally improving hair health.

• Who needs a PABA test?
  Patients with suspected pancreatic insufficiency, malabsorption, or those requiring monitoring after pancreatic surgery.

• Does PABA interact with drugs?
  Yes, PABA is known to interact with certain sulfa-based medications.

Related Tests

• 24-Hour Urine Collection

• Stool Fat Test