WATER SOLUBLE VITAMINS

• Vitamins (Water Soluble):

  • B1: Thiamin
  • B2: Riboflavin
  • B3: Niacin
  • B5: Pantothenic acid
  • B6: Pyridoxine
  • B7: Biotin
  • B12: Cobalamin
  • Folate
  • Vitamin C
• Common characteristics of water-soluble vitamins:

  • In food: Bound to protein that must be cleaved prior to absorption, easily destroyed by cooking
  • Digestion mostly in small intestine
  • Absorption mostly in small intestine (some in stomach), simple diffusion (high intake) but active diffusion (low intake), many factors
  • Circulation via blood to liver
  • Functions as coenzymes, especially in energy metabolism
  • Minimal toxicity
• Thiamin (B1):

  • Thiamin contains a thiol (sulfur) group and an amine group
  • Present as thiamin pyrophosphate (TPP) with 2 phosphate groups and thiamin triphosphate (TTP) with 3 phosphate groups
• Dietary Sources and Regulation of Thiamin:

  • High vs. low intake relates to absorption
  • Antithiamin factors: raw fish, coffee, tea, alcohol, berries, and cabbage
  • Vitamin C can counteract antithiamin factors
  • Functions as coenzyme and noncoenzyme roles
  • Deficiency leads to Beriberi
• Riboflavin (B2):

  • Consists of a multiring structure attached to a simple sugar ribose
  • Found as coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
  • Important for energy metabolism
• Dietary Sources and Regulation of Riboflavin:

  • High in meat, cereals, and fortified products
  • Marginal in fruits and vegetables
  • Stable during cooking but easily destroyed by light
  • Bioavailability: Animal > plant
  • Alcohol can inhibit absorption
• Niacin (B3):

  • Nicotinic acid and nicotinamide used to make coenzymes NAD+ and NADP+
  • Required for energy metabolism
• Dietary Sources and Regulation of Niacin:

  • Converted from tryptophan
  • Bioavailability: Animal > grain products
  • Niacin in grains is bound to protein, difficult to absorb
  • Deficiency leads to pellagra
• Pantothenic Acid (B5):

  • Found in almost every plant and animal tissue
  • Functions as a component of coenzyme A (CoA) in metabolic reactions
• Dietary Sources and Regulation of Pantothenic Acid:

  • High vs. low intake relates to passive vs. active absorption
  • Functions in metabolism of glucose, amino acids, and fatty acids for energy production
• Vitamin B6:

  • Three forms: pyridoxine, pyridoxal, pyridoxamine
  • Involved in metabolism of proteins and amino acids, synthesis of neurotransmitters and hemoglobin, glycogenolysis, and regulation of steroid hormone function
• Vitamin B6:

  • Deficiency leads to microcytic hypochromic anemia
  • Inadequate heme production results in lower concentrations of hemoglobin in red blood cells
  • Decreased oxygen availability in tissues impairs ATP production via aerobic metabolism
  • Symptoms include cheilosis, glossitis, stomatitis, and fatigue
  • Excess stored vitamin B6 can cause neurological problems
  • Toxicity from supplement use can lead to difficulty walking and numbness in feet and hands
• Biotin (Vitamin B7):

  • Acts as a coenzyme for several enzymes involved in carboxylation reactions
  • Required for gluconeogenesis and the citric acid cycle for ATP production
  • Dietary sources include peanuts, almonds, mushrooms, egg yolk, tomatoes, and avocado
  • Deficiency is uncommon but can be caused by chronic intake of raw egg whites or conditions impairing intestinal absorption
  • Symptoms of deficiency include hallucination, skin irritations, infections, hair loss, poor muscle control, seizures, and developmental delay in infants
• Folate (Folic Acid):

  • Acts as a coenzyme for many reactions involving the transfer of single-carbon groups
  • Important for amino acid metabolism, purines and pyrimidines, and nerve tissue development in fetuses
  • Dietary sources include organ meats, legumes, okra, spinach, and green leafy vegetables
  • Deficiency symptoms range from fatigue and weakness to macrocytic anemia
  • Severe deficiency can lead to neural tube defects and spina bifida
• Vitamin B12 (Cobalamin):

  • Unique as it can only be produced by microorganisms like bacteria and fungi
  • Dietary sources include shellfish, beef liver, crab, salmon, and fortified breakfast cereals
  • Functions in energy metabolism and conversion of homocysteine to methionine
  • Deficiency can be seen in vegans, infants breastfed by deficient mothers, or autoimmune diseases affecting intrinsic factor production
  • Symptoms of deficiency include pernicious anemia and closely relate to folate deficiency
• Vitamin C:

  • Acts as an important antioxidant
  • Can be made by all plants and is technically referred to as ascorbic acid
  • Dietary sources include citrus fruits, guava, sweet red peppers, broccoli, strawberries, and kiwi
  • Functions include enhancing iron, copper, and chromium bioavailability, protecting from free radicals, and decreasing the risk of diseases like the common cold
  • Deficiency can lead to scurvy with symptoms like small red spots on the skin caused by internal bleeding
• Consider taking supplements when:

  • Food availability or variety is limited
  • Certain foods are not consumed
  • During rapid growth and development periods
  • Economic situations are difficult
  • Following a low-calorie diet for weight loss
  • In health conditions that increase nutrient requirements