Pantothenic acid (vitamin B5) is the water-soluble vitamin that is the sole precursor of coenzyme A (CoA) and of the acyl carrier protein (ACP) — the two essential cofactors that are required for all acyl group transfer reactions in the body, including the synthesis and the oxidation of fatty acids, the oxidation of pyruvate in the TCA cycle, the synthesis of cholesterol and steroid hormones, the acetylation of proteins and neurotransmitters, and the detoxification of drugs and xenobiotics by the cytochrome P450 system. Pantothenic acid is converted to CoA in a five-step pathway that requires ATP, cysteine, and magnesium as cofactors, and it is the CoA that is the metabolically active form of pantothenic acid. CoA is present in every cell in the body at concentrations of approximately 0.5-1mM, and it is the cofactor that is required for the function of over 100 enzymes that catalyse acyl group transfer reactions. Without adequate pantothenic acid, CoA synthesis is impaired, and every metabolic pathway that depends on CoA is compromised — producing the fatigue, the gastrointestinal symptoms, the dermatological manifestations, and the neurological dysfunction that are the hallmark of the pantothenic acid deficiency.
Coenzyme A and the Central Metabolic Pathways
Coenzyme A is the cofactor that is required for the function of the acyltransferases and the dehydrogenases of the central metabolic pathways — including the pyruvate dehydrogenase complex (which converts pyruvate to acetyl-CoA, linking glycolysis to the TCA cycle), the alpha-ketoglutarate dehydrogenase complex (which converts alpha-ketoglutarate to succinyl-CoA in the TCA cycle), the fatty acid synthase complex (which uses malonyl-CoA to extend the growing fatty acid chain by two carbons at a time), the carnitine palmitoyltransferase system (which uses CoA to form the acylcarnitine esters that are the transport form of fatty acids into the mitochondrial matrix), and the acyl-CoA synthetases (which activate fatty acids for oxidation by attaching them to CoA). Without CoA, none of these central metabolic pathways can function, and the cell cannot generate ATP from glucose or from fatty acids. This pantothenic acid-dependent vulnerability of acyl group metabolism is the foundation of the clinical syndrome of pantothenic acid deficiency — which includes the reversible dermatitis, the gastrointestinal symptoms, the fatigue, and the neuropsychiatric symptoms that are the hallmark of this deficiency.
The clinical importance of pantothenic acid for CoA synthesis is underscored by the observation that the pantothenic acid deficiency produces a characteristic reduction in the CoA content of all tissues and a corresponding impairment of all CoA-dependent metabolic pathways. The pantothenic acid deficiency is rare in the general population (because pantothenic acid is present in a wide variety of foods, including whole grains, eggs, meat, and vegetables), but it can occur in people with the severe malnutrition, with the chronic alcoholism, and with the genetic disorders of the CoA synthesis pathway. The treatment of the pantothenic acid deficiency involves the supplementation with 10-50mg of pantothenic acid daily, which rapidly restores the CoA levels and reverses the clinical manifestations of the deficiency.
Pantothenic Acid and the Skin Health
Pantothenic acid is also essential for the health of the skin and for the wound healing process. The mechanism by which pantothenic acid supports skin health involves its role as a component of CoA, which is required for the synthesis of the fatty acids and of the sterols that are incorporated into the skin lipids, for the proliferation of fibroblasts and keratinocytes, and for the synthesis of the collagen and elastin fibres that are the structural components of the dermis. Pantothenic acid has been studied for its effects on wound healing — topical preparations containing dexpanthenol (the alcohol analogue of pantothenic acid, which is converted to pantothenic acid in the skin) have been shown to improve wound healing and to reduce the risk of wound dehiscence (the reopening of surgical wounds) after abdominal surgery. The mechanism of this wound healing effect is thought to involve the pantothenic acid-induced stimulation of fibroblast proliferation and of collagen synthesis.
Practical Application
For general pantothenic acid supplementation, the evidence-based dose is 5-10mg of pantothenic acid daily (as calcium pantothenate or pantethine, the two most common supplemental forms), which is approximately the RDA of 5mg daily for adults. Most people achieve adequate pantothenic acid from a varied diet — pantothenic acid is found in egg yolks, liver, nuts, seeds, salmon, avocado, and sweet potatoes. For the treatment of skin conditions and for wound healing support, higher doses of 100-500mg daily may be used, with good evidence for their use in the management of acne, of the dermatological manifestations of biotin deficiency, and of the wound healing process. Pantothenic acid is generally well-tolerated with no significant adverse effects at doses up to 10g daily, though very high doses (above 10g daily) can produce diarrhoea. For comprehensive metabolic and skin health support, pantothenic acid pairs well with the other B-complex vitamins (which are required for the function of the CoA-dependent enzymes and for the metabolism of the central metabolic pathways), with vitamin D (which supports skin health and immune function), with zinc (which is required for collagen synthesis and for wound healing), and with the omega-3 fatty acids (which have anti-inflammatory effects in the skin and which support the integrity of the skin lipid barrier).
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