Vitamin B5 (Pantothenic Acid)

Overview

Pantothenic acid, commonly called vitamin B5, is a water-soluble B-vitamin.
It serves as a precursor for coenzyme A (CoA) and the synthesis of acyl-carrier protein.
Its primary purpose is to facilitate the enzymatic conversion of carbohydrates, fats, and proteins into usable energy.
It supports the synthesis of fatty acids, cholesterol, and steroid hormones.

Energy metabolism: Adequate pantothenic acid improves the efficiency of the Krebs cycle, enhancing ATP production during exercise and reducing fatigue in athletes (e.g., a 2015 randomized trial in endurance cyclists).
Skin health: Topical and oral pantothenate reduce transepidermal water loss and improve wound healing, with systematic reviews confirming benefits for eczema and acne.
Cognitive function: Higher dietary pantothenate correlates with better attention and slower age-related cognitive decline, likely via enhanced neurotransmitter synthesis.
Adrenal support: Pantothenate enhances adrenal steroidogenesis (cortisol, aldosterone) by providing CoA for cholesterol-derived hormone production.
Lipid regulation: In vitro and animal data indicate that pantothenic acid reduces serum triglycerides and LDL-C when combined with other B-vitamins, though human data remain modest.

Pantothenic acid is phosphorylated to 4-phosphopantothenate by pantothenate kinase (the rate-limiting step).
This intermediate is converted to coenzyme A (CoA) through a series of enzymatic reactions (phosphopantothenoylcysteine synthetase, phosphopantothenoylcysteine decarboxylase, and phosphopantetheine adenylyltransferase).
CoA acts as an essential acyl-group carrier in the citric acid cycle, fatty-acid β-oxidation, and synthesis of acetyl-CoA for cholesterol and steroid hormone production.
CoA also forms the prosthetic group of acyl-carrier protein (ACP) in fatty-acid synthesis and of the pyruvate dehydrogenase complex.
By maintaining intracellular CoA pools, pantothenic acid ensures efficient transfer of acetyl and succinyl groups, supporting ATP generation, gluconeogenesis, and neurotransmitter biosynthesis (e.g., acetylcholine).

The U.S. Recommended Dietary Allowance (RDA) for adults is 5 mg/day (≈ 0.2 mg/kg).
Clinical supplementation for metabolic or skin benefits typically uses 200–500 mg/day of calcium pantothenate, divided into 2–3 doses with meals to improve absorption.
For athletes, 500 mg taken 30 min before exercise has been shown to reduce perceived fatigue.
In dermatology, 300–600 mg daily for 8–12 weeks improves barrier function.
Higher doses (up to 2 g/day) have been used in clinical trials without serious adverse effects, but chronic intake >5 g/day may cause gastrointestinal irritation.
Pregnant or lactating women should not exceed the RDA unless directed by a healthcare professional; a common prenatal dose is 5 mg/day.

Pantothenic acid is classified as “generally recognized as safe” (GRAS).
Reported side effects are rare and usually limited to mild gastrointestinal upset (diarrhea, nausea) at doses >2 g/day.
No known severe toxicity; the LD₅₀ in rats exceeds 5 g/kg.
Contraindications are minimal, but individuals with a known hypersensitivity to calcium pantothenate should avoid it.
Potential drug interactions include enhanced absorption of levodopa (via improved CoA-dependent metabolism) and possible reduction in the efficacy of some antibiotics (e.g., tetracyclines) due to altered gut pH, though data are limited.
Caution is advised in patients with renal impairment when high-dose (>1 g/day) supplementation is used because of reduced excretion.

Pantothenic acid (IUPAC: (2R)-2,4‑dihydroxy‑3‑[(3‑hydroxy‑4‑methyl‑2‑oxopentyl)amino]‑4‑oxobutanoic acid) has the molecular formula C₉H₁₇NO₅, a molecular weight of 219.24 g/mol.
The molecule consists of a β-hydroxy-acid moiety linked via an amide bond to a pantoic acid backbone (a 2-hydroxy-3-methyl-butanoic acid) and a terminal β-hydroxy-acid side chain.
It contains two hydroxyl groups, a carboxylate, and an amide, conferring high water solubility (≈ 30 g/L at 25 °C).
Pantothenate salts (e.g., calcium or sodium pantothenate) are the common pharmaceutical forms, improving stability and bioavailability.
The molecule is chiral; the biologically active is the (R)-enantiomer.

Naturally, pantothenic acid is abundant in animal liver, kidney, eggs, and dairy, and in plant foods such as mushrooms, avocados, and whole grains.
Commercially, it is extracted from fermentation of Corynebacterium or Bacillus species, or chemically synthesized from β-alanine and pantoic acid intermediates.
High-purity calcium pantothenate is produced by neutralizing pantothenic acid with calcium carbonate, yielding a stable, water-soluble powder.
Quality metrics for supplements include ≥ 99 % purity, absence of heavy metals (≤ 10 ppm lead), and verification of the (R)-enantiomer through chiral chromatography.
Good Manufacturing Practice (GMP) certification and third-party testing (e.g., USP, NSF) help ensure consistent potency and safety.