Energy is supplied to the body through food, which is the only form of energy humans can utilize to maintain the structural and biochemical integrity of the body. This energy enables us to perform daily physical and intellectual activities. Numerous vitamins and minerals are involved in the process of cellular energy production. Among them, B-group vitamins function as coenzymes in the breakdown of carbohydrates, fats, and proteins to generate energy. All B-group vitamins, except folate (vitamin B9), are involved in at least one or more steps in energy metabolism. The body requires an adequate supply of B-group vitamins to maintain the normal functioning of energy production systems. However, a deficiency in any of these vitamins can hinder the energy production process, leading to severe metabolic and health consequences [1, 2].
Vitamin B1 (Thiamin) exists in the body as free thiamine and other phosphorylated forms, including thiamine pyrophosphate (TPP), which plays a critical role in energy metabolism by supporting glucose metabolism and the synthesis of RNA, DNA, and ATP. Vitamin B1 acts as a coenzyme in two types of reactions: oxidative decarboxylation and transketolation. These reactions are crucial for carbohydrate metabolism, particularly in the citric acid cycle and pentose phosphate pathways. Specifically, TPP participates in dehydrogenase reactions, facilitating the decarboxylation of pyruvate and branched-chain amino acids to form acetyl-CoA. In the citric acid cycle, TPP supports the decarboxylation of alpha-ketoglutarate to succinyl-CoA [2,3]. A deficiency in vitamin B1 can disrupt carbohydrate and amino acid metabolism, resulting in significant outcomes such as reduced acetylcholine, which affects nervous system functions [1-4].
Vitamin B2 (Riboflavin) is an essential structural component of the coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which serve as proton carriers in oxidation-reduction reactions critical for the metabolism of carbohydrates, fats, and proteins. FAD is involved in the production of acetyl-CoA from fatty acids through beta-oxidation, from glucose through the oxidative decarboxylation of pyruvate, and from the catabolism of branched-chain amino acids. FAD is necessary for steps in the citric acid cycle that generate succinyl-CoA from alpha-ketoglutarate and fumarate from succinate, while FADH2 serves as an electron donor in the electron transport chain [1,2]. Therefore, vitamin B2 is essential for growth and reproduction. It functions as part of the enzymatic group responsible for breaking down and utilizing carbohydrates, proteins, and fats. Additionally, vitamin B2 is critical for cellular respiration as it collaborates with enzymes to utilize oxygen [2,4].
Vitamin B3 (Niacin) refers to nicotinamide and its derivatives, which exhibit the biological activity of nicotinamide, serving as precursors for NAD and nicotinamide adenine dinucleotide phosphate (NADP). Niacin acts as a carrier or coenzyme for hydrogen ion transfer in hydrolytic enzymes, supporting the metabolism of glucose, fats, and proteins. NAD plays a role in intracellular respiration and participates in the oxidation of energy molecules like glyceraldehyde 3-phosphate, lactate, alcohol, 3-hydroxybutyrate, pyruvate, and α-ketoglutarate. Niacin serves as a coenzyme in over 200 enzymes catalyzing oxidation-reduction reactions. NAD and NADP act as electron acceptors or donors in these reactions. NAD is involved in the degradation of carbohydrates, fats, proteins, and alcohol, while NADP participates in biosynthetic reactions such as fatty acid and cholesterol synthesis [2,4,5].
Vitamin B5 (Pantothenic Acid) is a vital precursor in the biosynthesis of coenzyme A (CoA) and phosphopantetheine in living cells. Pantothenic acid functions as a key coenzyme in various chemical reactions essential for sustaining life, including energy production from food (fats, carbohydrates, and proteins), synthesis of cholesterol, steroid hormones, neurotransmitters, acetylcholine, melatonin, and heme in red blood cells. Acyl carrier proteins require the 4'-phosphopantetheine derivative of pantothenic acid to function as enzymes. Both CoA and acyl carrier proteins are needed for the synthesis of fatty acids, which are vital for normal physiological functions. Certain essential lipids like sphingolipids contribute to nerve myelin for enhancing nerve transmission, while phospholipids are part of cell membranes [2,4,5].
Vitamin B6 (Pyridoxine) exists in natural forms such as pyridoxine (PN), pyridoxal (PL), and pyridoxamine (PM), along with derivatives containing 5’-phosphates like PLP, PNP, and PMP. The primary forms in animal tissues are PLP and PMP, while plants mainly contain PN and PNP. Vitamin B6 plays a significant role in enzymes required for amino acid, glycogen, and sphingoid metabolism. Its derivatives act as cofactors for enzymes involved in amino acid metabolism, glycogen breakdown, gluconeogenesis, heme synthesis, niacin formation from tryptophan, and lipid metabolism [6]. Pyridoxal phosphate (PLP) serves as a cofactor for glycogen phosphorylase, releasing glucose-1-phosphate from glycogen to provide glucose during muscle activity [2, 6].
Vitamin B7 (Biotin) acts as a cofactor for several carboxylases that catalyze the incorporation of bicarbonate as a carboxyl group into substrates. These enzymes are essential for fatty acid synthesis, branched-chain amino acid catabolism, and gluconeogenesis, thereby playing a crucial role in cellular energy metabolism and storage. Biotin-dependent enzymes involved in energy metabolism include propionyl-CoA carboxylase, which catalyzes the incorporation of bicarbonate into propionyl-CoA to form methylmalonyl-CoA, which enters the citric acid cycle through conversion into succinyl-CoA, and pyruvate carboxylase, which catalyzes the carboxylation of pyruvate to form oxaloacetate, an intermediate in the citric acid cycle [2,4,5].
Vitamin B12 (Cobalamin) is distinct from other B-group vitamins as it is almost absent in plant-based foods. Animal-derived foods are the primary sources of vitamin B12. Methylcobalamin and 5-deoxyadenosylcobalamin are the metabolically active forms of vitamin B12 in the human body. Vitamin B12 is crucial for the growth, myelination, and functioning of the central nervous system, the formation of healthy red blood cells, and DNA synthesis. Vitamin B12 acts as a cofactor in the metabolism of L-methylmalonyl-CoA, a reaction vital for energy production from fats and proteins [2,4,5].
Figure: Involvement of vitamins in cellular energy production processes [1]
References
[1] Tardy AL, Pouteau E, Marquez D, Yilmaz C, Scholey A. Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients. 2020;12(1):228.
[2] https://www.tramnangluong.com/vi-sao-phuc-hop-vitamin-nhom-b-lai-giup-ho-tro-tao-nang-luong/
[3] Depeint F., Bruce W.R., Shangari N., Mehta R., O’Brien P.J. Mitochondrial function and toxicity: Role of the B vitamin family on mitochondrial energy metabolism. Chem. Biol. Interact. 2006;163:94–112.
[4] Viện Dinh dưỡng (2016), Nhu cầu dinh dưỡng khuyến nghị cho người Việt Nam, NXB Y học.
[5] https://openoregon.pressbooks.pub/nutritionscience/chapter/9e-energy-metabolism-vitamins-minerals/
[6] Mackey A., Davis S., Gregory J. Vitamin B6. In: Shils M., Shike M., Ross A., Caballero B., Cousins R., editors. Modern Nutrition in Health and Disease. Lippincott Williams and Wilkins; Baltimore, MD, USA: 2006. pp. 194–210.