NHM 101 Lecture Notes - Lecture 13: Dietary Reference Intake, Thiamine, B Vitamins
2 May 2018
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Ch 10 - Vitamins
VITA(life) + AMIN(nitrogen-containing group) = VITAMIN
How do vitamins differ from macronutrients?
STRUCTURE
● Vitamins have a single structure (vs. a chain of units)
FUNCTIONS
● Vitamins do NOT yield ENERGY; they assist with the process
FOOD CONTENTS
● Foods contain less vitamins than they contain macronutrients
● Our bodies need less amounts of vitamins- milligrams & micrograms (vs. grams)
How are vitamins similar to macronutrients?
● Vital to life
● Organic (contain carbon)
● Can be obtained from foods
Bioavailability- the rate and extent that a nutrient is used or absorbed
● Depends on:
○ Efficiency of digestion and transit time in the GI tract
○ Prior nutrient intake and nutrition status
○ Method of food preparation
○ Source of the nutrient
○ Other foods consumed at the same time
Toxicity of Vitamins
Tolerable Upper Intake Level (
UL
)- highest amount of a nutrient that can be consumed
without causing harm to most healthy people
● Risk symptoms of toxicity increase as one goes over the UL
● More = Better is FALSE with vitamins
Water-Soluble Vitamins
B & C
● Hydrophilic
● Most travel freely in the body
● Go directly to bloodstream when
absorbed
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● Circulate in water-filled
compartments
● Kidneys identify excess and
removes it through urine
B Vitamins
● Serve important roles in metabolism
○ By making up a portion of multiple coenzymes (work with an enzyme to
facilitate the enzyme’s activity)
Thiamin (B1)
Functions
Part of coenzyme
thiamine
pyrophosphate
(TPP)
- Assists with energy metabolism
- Participates in conversion of pyruvate
to Acetyl CoA
Occupies a special site on neuron membranes.
Food Sources & Cooking
● Grains
● Pork
Heat (prolonged cooking) can destroy thiamin.
- Steaming/microwaving helps retain
thiamin.
Recommendations
RDA *most americans meet or exceed the RDA
Men: 1.2 mg/day
Women: 1.1 mg/day
UL
---
Deficiency
Alcohol impairs thiamin absorption and
enhances thiamin excretion in urine.
Beriberi- damage to nervous system & heart
(Symptoms include loss of appetite, weakness,
pain in the limbs, shortness of breath, and
swollen feet or leg)
Riboflavin (B2)
Functions
Part of coenzymes
flavin mononucleotide
(FMN) and
flavin adenine dinucleotide
(FAD)
- Assists with energy metabolism
- Both can accept and donate 2 hydrogen
Food Sources & Cooking
● Milk products
● Grains
● Green leafy vegetables
UV light and irradiation destroys riboflavin.
- Milk sold in opaque plastic or cardboard
containers.
Recommendations
RDA *most americans meet or exceed the RDA
Men: 1.3 mg/day
Deficiency
Causes inflammation of:
● Mouth
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Vitamins have a single structure (vs. a chain of units) Vitamins do not yield energy; they assist with the process. Foods contain less vitamins than they contain macronutrients. Our bodies need less amounts of vitamins- milligrams & micrograms (vs. grams) Bioavailability- the rate and extent that a nutrient is used or absorbed. Efficiency of digestion and transit time in the gi tract. Other foods consumed at the same time. Tolerable upper intake level (ul)- highest amount of a nutrient that can be consumed without causing harm to most healthy people. Risk symptoms of toxicity increase as one goes over the ul. (cid:781)more = better(cid:782) is false with vitamins. Kidneys identify excess and removes it through urine. By making up a portion of multiple coenzymes (work with an enzyme to facilitate the enzyme"s activity) Heat (prolonged cooking) can destroy thiamin. to acetyl coa. Occupies a special site on neuron membranes. thiamin. Alcohol impairs thiamin absorption and enhances thiamin excretion in urine.
