Chapter 9. Micronutrients for Energy
Chapter Review
IMPORTANT: Key Takeaways
- Coenzymes and cofactors catalyze reactions as they assist in converting a substrate to an end product.
- Thiamin (B1) acts as a cofactor for enzymes that break down glucose to produce energy. Thiamin is required for the formation of pyruvate dehydrogenase, for the metabolism of branched chained amino acids, and for the synthesis of neurotransmitters.
- Thiamin deficiency, beriberi, can cause symptoms of fatigue, confusion, movement impairment, pain, swelling, and heart failure.
- The thiamin deficiency, Wernicke-Korsakoff syndrome, can cause similar symptoms as beriberi but is specific to alcoholics.
- Riboflavin (B2) aids in the transfer of electrons in the ETC, forms complexes and coenzymes involved in the Krebs cycle, and helps fight oxidate damage.
- Riboflavin deficiency, ariboflavinosis, is most common in those that suffer from alcoholism and is accompanied by other dietary deficiencies (ie. protein and other B vitamins).
- Niacin (B3) plays a role in DNA replication, repair, and cell differentiation, along with the production of hydrochloric acid. It is also a component of the coenzymes, NADH and NADPH, which play an important role in energy production. NADH transfers electrons to the ETC and NADPH is required for the fatty acid and cholesterol-synthesis anabolic pathways.
- Niacin deficiency, pellagra, is characterized by gastrointestinal changes that result in decreased hydrochloric acid production and absorption of nutrients.
- Niacin overconsumption from supplementation can cause toxicity, which results in burning and itching sensations. Large doses taken over an extended period can cause liver damage, glucose intolerance, blurred vision, and edema.
- Pantothenic acid (B5) forms coenzyme A, which carries the carbons of glucose, fatty acids, and amino acids into the citric acid cycle as Acetyl-CoA.
- Pyridoxine (B6) is a coenzyme for the synthesis of hemoglobin (which carries oxygen) and it plays a role in the synthesis of glycogen phosphorylase, nitrogen transfer between amino acids, and gluconeogenesis.
- Large supplemental doses of pyridoxine can cause severe nerve impairment.
- Biotin (B7) is required as a coenzyme in fatty acid synthesis, gluconeogenesis, and carbohydrate, lipid, and protein metabolism. It also plays a role in the synthesis of some nonessential amino acids.
- Iodine plays a role in body temperature regulation, reproduction, basal metabolism, and development.
- Excess iodine consumption can result in swelling of the thyroid gland, resulting in goiter and even hyperthyroidism.
Practice Questions
- Why is the lack of inclusivity in the existing micronutritional guidelines problematic?
- What are the effects of thiamin deficiency on the cardiovascular and nervous systems?
- How does riboflavin assist in the energy production process?
- What is the role of food packaging in preventing ariboflavinosis?
- How do diets high in tryptophan influence niacin synthesis? What role, if any, do these diets play in preventing niacin deficiency?
- What are the potential risks associated with niacin supplementation?
- Although a pantothenic acid deficiency is exceptionally rare, how might this deficiency disrupt the metabolism of lipids, carbohydrates, and proteins?
- Explain how vitamin B6 deficiency leads to anemia. How is this type of anemia different from those caused by deficiencies in folate, cobalamin, or iron?
- How does geographic location influence the iodine content in foods?
- How do low iodine levels affect growth and development?
- How did residential school nutrition experiments contribute to vitamin deficiencies?
