U01.01.067 Vitamin B5

Vitamin B5, also known as pantothenic acid, is a water-soluble vitamin crucial for various biochemical processes. Its name, derived from the Greek word “pantos” (meaning “everywhere”), reflects its widespread presence in both foods and the human body.

Functions of Vitamin B5

Vitamin B5 serves as an essential component of two key molecules:

Molecule	Role
Coenzyme A (CoA)	Facilitates acyl-group transfers in metabolic pathways like the Krebs cycle.
Fatty Acid Synthase	Essential for the synthesis of fatty acids.

Mnemonic: B5 is “pento”thenic acid, emphasizing its “five” roles in metabolic pathways.

Vitamin B5 Deficiency

Symptoms

Deficiency in Vitamin B5 is rare but can result in:

Dermatitis – Skin inflammation.
Enteritis – Inflammation of the intestines, leading to digestive discomfort.
Alopecia – Hair loss.
Adrenal Insufficiency – Impaired production of adrenal hormones.

Risk Factors for Deficiency

Poor dietary intake (e.g., severe malnutrition).
Chronic illnesses (e.g., malabsorption syndromes).
Prolonged use of certain medications.

Points to Remember for USMLE Step 1

Vitamin B5 is vital for energy metabolism, linking the Krebs cycle and fatty acid metabolism.
Coenzyme A deficiency disrupts energy production, leading to systemic symptoms like adrenal insufficiency.
Clinical correlations: Know how B5 deficiency might present in cases of malnutrition or chronic illness.

Quick Reference Table

Vitamin	Function	Deficiency Symptoms
B5 (Pantothenic Acid)	Component of CoA and fatty acid synthase	Dermatitis, enteritis, alopecia, adrenal insufficiency

USMLE Step 1 Review Series

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