The Water-Soluble Vitamins: B Vitamins !The Vitamins - An Overview • Vitamins – organic, essential nutrients required in small amounts by the body for health; vitamins regulate body processes that support growth and maintain life • Vita - “Vital to life” • Amine – containing nitrogen •Some of the first vitamins discovered contain nitrogen • Similarities to energy-yielding nutrients • Vital to life • Organic (contain carbon) • Available in foods • Beneficial in appropriate amounts, harmful in excess !Vitamins • Individual units • Do not yield energy • Assist in the release of energy from macronutrients (can’t get these energies from macronutrients without vitamins) • Small amounts needed • Measured in milligrams (mg) or micrograms (mcg) or (μg) !Macronutrients • Linked together (strings of glucose, amino acids, fatty acids) • Yield energy • Needed in larger amounts • Measured in grams (g) !The Vitamins – An Overview • Bioavailability–rate at which and extent to which a nutrient is absorbed and used • More simply: Quantity provided by food and the amount absorbed and used by body • Factors influencing bioavailability • Efficiency of digestion (people who are not consuming enough nutrients and energy (aka anorexia, where GI tract breaks down and becomes less efficient, also elderly, reduced absorption due to reduced stomach size- gastric bypass patients) • Nutrition status - if deficient in certain vitamins and minerals in general, body better at knowing we need to absorb some of those. body knows what to absorb more of if there is any competition • Method of food preparation - microwaving destroys some and is better option for others • Source of nutrient- greater amount of fiber breaking down bioavailability of a nutrient • Other foods consumed at same time- Vitamin C increases absorption of iron • Precursors • Substances that precede others• Provitamins (inactive form) - can be converted into active vitamins • Stability • Organic - can be destroyed during storage and in cooking (in comparison to minerals which are not organic and not susceptible to this destruction during cooking) • Heat, light, oxygen can destroy nutrients How to minimize nutrient loss: -refrigerate fruits and vegetables (to slow degradation) -store items cut in airtight wrappers to minimize oxidation of vitamins -prevent vitamin losses during washing: rinse fruits and veggies before cutting (not after) - minimize vitamin losses during cooking, use a microwave oven or steam vegetables in a small amount of water. Add vegetables after water has come to a boil use the cooking water in mixed dishes such as casseroles and soups. avoid high temperatures and long cooking times. !**(Table 10-2: study this)** !The B Vitamins • Vitamins do not provide the body with fuel for energy (help release energy) • Part of coenzymes • Assist enzymes with release of energy • Without coenzyme, an enzyme cannot function • Without B vitamins, coenzyme cannot be formed —> lack of energy (with a lack of B vitamins) !B Vitamin Sources • Different B vitamins are found in a variety of foods in all of the foods groups •B12 is only found in animal products (deficiency in vegans who do not eat any animal products) !Interactions among the B Vitamins • Deficiencies • Single B-vitamin deficiencies rare – usually multiple deficiencies •Poverty, illness, alcoholism (decrease intake of food in general, decreased nutrition) •Tongue is sensitive (beginning of GI Tract, so represents the rest of it) !The B Vitamins - In Concert • Toxicities • For most, excess eliminated through urine excretion • More is not necessarily better • Levels higher than UL a concern for: niacin, B6, & folate • Food sources should be first choice rather than supplements because of that concern • First choice should be foods rather than supplements !Review • Keep or remove the following prefixes? • Vitamins are (in)organic and (non)essential. • Vitamins support growth and maintenance of life. •Define precursor and name another word that can be used that is relevant to vitamins. •substance that precede others; provitamin •Define bioavailability = rate at and extent to which the nutrients are absorbed and used by body •Some of the B vitamins form part of coenzymes, which are complex organic molecules that assist enzymes in the enzymes’ activity. Specifically, B vitamins assist in the release of energy from carbohydrates, protein, and fat. If B vitamins are deficient, these coenzymes are produced in insufficient amounts and can lead to a lack of energy. • Which of the B vitamins have toxicity concerns? = Niacin, B6 and Folate • How can nutrient loss be minimized for B vitamins? = Refrigerate, reduce exposure to heat and water when boiling, wash before cutting, microwaving and steaming better !Thiamin • Part of coenzyme thiamin pyrophosphate (TPP) • Energy metabolism • Conversion of pyruvate to acetyl CoA (macronutrients need Thiamin to do this) • TCA cycle •Nerve activity and muscle activity !The B Vitamins - Thiamin •Recommendations can be met with food •Deficiency • Malnourished • Alcoholics - ↓ intake ↑ excretion • Deficiency —> Beriberi • Dry – damage to nervous system • Wet – damage to cardiovascular system $• Toxicity - no adverse effects—> No UL !• Food sources • Pork, grains; small amount in many foods • Prolonged cooking destroys thiamin • Leaches into water when boiling or blanching foods • Cooking with little or no water conserves thiamin • Steaming, microwaving, grilling (to maintain the thiamin in foods) !The B Vitamins- Riboflavin • Serves as coenzyme in energy metabolism • Both coenzyme forms accept and donate H to TCA cycle (hydrogens help convert ADP to ATP - need riboflavin to help us do that)• Flavin mononucleotide (FMN) • Flavin adenine dinucleotide (FAD) • Recommendations – met or exceeded with normal dietary intake • Deficiency • Inflammation of membranes of mouth, skin, eyes, GI tract • Toxicity – no harm in excess • No UL • Food sources • Milk and milk products - better for milk to be in opaque container • Grains; dark, leafy greens • Destruction of riboflavin
View Full Document
Unlocking...