Transcript Water-Soluble Vitamins - 35-206-202

WATER-SOLUBLE VITAMINS
CHAPTER 13
LEARNING OUTCOMES
• Identify the water-soluble vitamins
• List important food sources for each water-soluble
vitamin
• Describe how each water-soluble vitamin is
absorbed, transported, stored and excreted
• List the major functions of and deficiency symptoms
for each water-soluble vitamin
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LEARNING OUTCOMES
• Describe the toxicity symptoms from the excess
consumption of certain water-soluble vitamins
• Distinguish between vitamins and non-vitamins,
such as carnitine and taurine
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OVERVIEW OF WATER-SOLUBLE
VITAMINS
• Storage in body
tissues is minimal
• Risk of toxicity less
than fat-soluble
• Many of the B
vitamins act as
coenzymes, which
are important for
energy metabolism
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PRESERVING NUTRITION IN WATER
SOLUBLE VITAMINS
T or F: Most fruits and vegetables will last
longer if you refrigerate them.
T or F: You should trim, cut, and peel fruits
and vegetables shortly after buying them to
keep them from spoiling.
T or F: The best way to cook vegetables is to
boil them.
T or F: Organic fruits and vegetables have
more nutrition than non-organic.
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THIAMIN (B1)
• Foods
• Pork, sunflower seeds and legumes
• Bread and cereals (enriched grains)
• Needs and upper level
• RDA 1.2 mg/day men, 1.1 mg/day women
• Fairly uncommon deficiency in US
• No UL
• Absorption in small intestine
• Transported by RBC as TPP
• Storage and excretion- little stored, excess
excreted
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THIAMIN (B1)
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THIAMIN (B1)
Functions
• Thiamin helps the body's cells convert carbohydrates into
energy. It is also essential for the functioning of the heart,
muscles, and nervous system.
• Co-enzyme-thiamin pyrophosphate (TPP)
• Decarboxylation reactions: energy metabolism, amino
acid metabolism
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THIAMIN (B1)
• Functions
• Coenzyme for transketolase
• Converts glucose to pentose
(used to make DNA and RNA)
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THIAMIN (B1)
• Deficiency
• Beriberi
• Peripheral neuropathy (dry)
• Congestive heart failure
(wet)
• Who?
•
•
•
•
•
14 days with no thiamin
White rice staple food
Parental nutrition
Severe vomiting and diarrhea
Weight loss surgery
• Wernicke-Korsakoff (Alcohol
use)
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RIBOFLAVIN (B2)
• Foods
• Milk, enriched grains, eggs and meat
• Needs and upper level
• RDA 1.3 mg/day men and 1.1 mg/day women
• Uncommon deficiency in US
• No UL
• Absorption (needs HCl, absorbed in SI)
• Transport by protein carriers
• Storage and excretion-mostly excreted in
urine
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RIBOFLAVIN (B2)
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RIBOFLAVIN (B2)
• Functions
• Co-enzymes: flavin mononucleotide (FMN) and flavin
adenine dinucleotide (FAD)
• Energy metabolism
• Citric Acid Cycle
• Beta oxidation
• Shuttles H atoms to the electron transport system
• Other B vitamin functions (niacin, B6, and folate)
• Antioxidant function
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RIBOFLAVIN (B2)
• Deficiency
– Ariboflavinosis after 2
months
– Most often seen in
alcoholics, elderly, and
adolescent girls
– Light sensitive (milk
containers are now
plastic and cardboard to
preserve riboflavin)
– Use of some types of
medications can increase
riboflavin breakdown
(drug used for sleeping
and seizures)
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NIACIN (B3)
• Foods
• Available as niacin or synthesized from
tryptophan
• Preformed niacin: Poultry, meat, fish, and
enriched grains, some in coffee and tea
• RDA expressed as niacin equivalents
• 60 mg tryptophan =1 mg niacin
• 1 gr of protein = 10 mg tryptophan
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NIACIN (B3)
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NIACIN (B3)
• Needs and upper level
• RDA 16 mg/day men and 14 mg/day women
• U.S. intake exceeds RDA
• UL 35 mg/day applies only to supplements and
fortification
• Absorption- passive diffusion
• Transport-to liver
• Stored in liver or excreted
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NIACIN (B3)
• Functions
+
• Co-enzymes NAD and NADPH
• Required for catabolism of carbohydrate,
fat and protein
• Required in at least 200 reactions
• Pharmacological use
• Nicotinic Acid-lower LDL, increase HDL
• 1-2 g (60x the RDA)
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NIACIN (B3)
• Deficiency
•
•
•
•
Pellagra
Corn based diets
Casal’s necklace
Once a significant
problem in the US
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NIACIN (B3) IS USED IN ALMOST EVERY
METABOLIC PATHWAY
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PANTOTHENIC ACID (B5)
• Foods
• Meat, milk and many vegetables
• Needs and upper level
• AI 5 mg
• Deficiency uncommon in US
• No UL
• Functions
• Co-enzyme A needed to form acetyl CoA and
acyl carrier protein to build fatty acids
Deficiencies are RARE
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BIOTIN (B7)
• Food sources
• Whole grains, eggs, nuts
and legumes
• Needs and upper level
• AI 30 micrograms
• Deficiency uncommon in
US
• No UL
• Absorption in small
intestine
• Storage in muscle, liver
and brain or excreted
in urine or bile
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BIOTIN (B7)
• Functions
• Co-enzyme that adds CO2 to compounds
• Required for metabolism of carbohydrates, fats and
proteins
• Deficiency
• Biotinase enzyme deficiency
• Skin rash, hair loss, convulsions, impaired growth)
• Excessive consumption (>12) of raw eggs (avidin)
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VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE, PYRIDOXAMINE)
• Foods
• Meat, fish, poultry,
fortified cereals, potatoes
• Needs and upper level
• RDA 1.3 mg/day women
1.7 mg/day men
• Deficiency uncommon in
US
• UL 100 mg day
• Permanent nerve damage
• Absorption via passive
diffusion
• Transport to liver,
phosphorylated
• Storage in liver or
excreted
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WHOLE GRAINS BETTER THAN
ENRICHED
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VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE,
PYRIDOXAMINE)
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VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE,
PYRIDOXAMINE)
• Functions
• Metabolism
• PLP coenzyme involved in more than 100 enzymatic
reactions, all involving nitrogen (ie needed for amino acid
metabolism)
• Synthesis of compounds
• Heme, neurotransmitters, vitamins (niacin)
• Deficiency
• Very poor diet, alcoholism, medications
(Parkinson’s)
• Anemia, convulsions, confusion, depression
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TRANSAMINATION USES B6
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VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE,
PYRIDOXAMINE)
• Pharmacological use
• Carpal tunnel syndrome
• PMS (no significant benefit)
• Nausea during pregnancy
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FOLATE (B9)
• Folic Acid
• Synthetic sources of folate
• Foods
• Liver, legumes and leafy green vegetables
• Now fortified grains
• Needs and upper level
• RDA 400 micrograms/daily
• Dietary Folate Equivalents (DFE)
• UL 1 mg
• May mask B-12 deficiency
• Concern is with synthetic sources
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FOLATE (B9)
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FOLATE (B9)
• Absorption via passive diffusion
• Transported to liver, travels in blood or bile
• Excreted in urine or feces
• Functions
• Central co-enzyme form: tetrahydrofolic acid
(THFA)
• DNA synthesis
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FOLATE DEFICIENCY
• Megaloblastic anemia
• Neural Tube defects
• Maternal deficiency of folate plus genetic
predisposition
• All women capable of getting pregnant urged to
take in 400 micrograms of folic acid
• Current fortification yields about 200 micrograms
of folic acid daily
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MEGALOBLASTIC ANEMIA
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VITAMIN B-12 VITAMIN B-12
(COBALAMIN)
• Foods
• Animal products
• Needs and upper
level
• RDA 2.4 micrograms
daily
• Average intake 2-3
times RDA
• No UL
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VITAMIN B-12 (COBALAMIN)
• Absorption, transport,
storage and
excretion
• Stomach:
• B12 freed from foods by
HCl
• Free vitamin binds to Rprotein
• SI
• Pancreatic lipases frees
B12 from R-protein
• Free vitamin binds with
intrinsic factor to
enhance absorption
• B12-intrinsic factor
complex travels to liver
where it can be stored
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VITAMIN B-12 (COBALAMIN)
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VITAMIN B-12 (COBALAMIN)
• Functions
• Required for enzymatic reactions
• Formation of THFA, needed for nucleic acid
synthesis
• Formation of methionine from homocysteine,
needed to metabolize homocysteine and
make methyl groups
Methylated Folate
B12
THFA
Methylated-B12
Methionine (methyl
groups)
Homocysteine
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VITAMIN B-12 (COBALAMIN)
• Deficiency
• Pernicious Anemia
• Macrocytic/Megaloblastic Anemia
• Neurological changes
• Homocysteine
• At risk for deficiencies: Atropic gastritis (elderly) and
malabsorption, vegetarians
• Treatment
• Monthly injection
• Nasal gel
• Oral doses (1-2 mg)
• Passive diffusion
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WHO WOULD BE AT MOST RISK FOR
VITAMIN B12 DEFICIENCY?
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•
•
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Someone on the Atkins diet
Someone who never eats fruits and vegetables
Someone who takes large doses of antacids
Someone who drinks alcohol heavily
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CHOLINE (AN ESSENTIAL NUTRIENT
ALTHOUGH NOT A B VITAMIN
• Foods-in the form of lecithin (naturally occurring
and added)
• Milk, liver, eggs and peanuts
• Needs and upper level
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•
•
•
AI 550 mg/daily men 425 mg/daily women
Can be synthesized by the body
Deficiency is rare
UL 3.5 grams (fishy smell, low blood pressure, vomiting,
GI upset)
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CHOLINE
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CHOLINE
Absorption in small intestine, then to liver
Transport in blood
Storage in all tissues
Excreted in urine or converted to betaine or
methyl groups
• Functions
•
•
•
•
• Phospholipids, lipoproteins, cell membranes and a precursor to acetylcholine (neurotransmitter)
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VITAMIN C
• Foods
• Citrus fruits, peppers and green vegetables
• Needs and upper level
• RDA 90 mg/day men 75 mg/day women
• Smokers need an additional 35 mg/day
• UL 2 grams/day (GI upset)
• Absorption efficiency changes with
consumption
• Storage in glands, WBC, eyes, and brain
and excreted in urine
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VITAMIN C
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VITAMIN C
• Functions
• Collagen synthesis
• Synthesis of other vital compounds (amino
acids, hormones, carnitine, neurotransmitters)
• Antioxidant activity (eyes, cancer)
• Iron absorption
• Immune function (WBC)
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VITAMIN C
• Deficiency
• Scurvy
• Cancer, heart
disease
• Colds
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COLLAGEN SYNTHESIS REQUIRES
VITAMIN C
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VITAMINS AND CANCER
• Cancer is caused by changes (mutations) to the
DNA within cells. The DNA inside a cell contains a
set of instructions telling the cell how to grow and
divide. Errors in the instructions may allow a cell to
become cancerous.
• What do gene mutations do?
A gene mutation can instruct a healthy cell to:
• Allow rapid growth of mutated genes
• Fail to stop uncontrolled cell growth
• Make mistakes when repairing DNA errors
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VITAMINS AND CANCER
• Role of vitamins
• Prevent DNA damage
• Control gene expression
• Play a role in DNA synthesis
• What foods?
• Will more of these foods (i.e. supplements)
protect you further?
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ROLE OF VITAMINS
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VITAMIN-LIKE COMPOUNDS
• Needed for normal metabolism
• Synthesized by the body and found in
foods
• Increased need during rapid growth and
some disease states
• Often found in infant formulas
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CARNITINE
• Carnitine
• Made from lysine and methionine and
found in meat and dairy
• Transports fatty acids from cytosol to
mitochondria for energy metabolism
• Used as weight loss aid or exercise aid
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TAURINE
• Taurine
• Made from methionine and cysteine and
found in foods of animal origin
• Functions as antioxidant, helps with insulin
action, and needed for cell differentiation
and growth
• Used in kids with cystic fibrosis and preterm
infants
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TABLE 13_03A
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NUTRITION AND PUBLIC HEALTH
•Two most common
serious birth defects
of the spine and
brain are spina
bifida and
anencephaly
•Incomplete
closure/formation of
the neural tube
•300,000 infants
yearly worldwide
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IN 1992, THE U.S. PUBLIC HEALTH
SERVICE
FOLIC ACID RECOMMENDATION
• All women capable of
becoming
• pregnant should
consume 400 micrograms
folic acid daily
• 400 mg is the quantity in
most multivitamin
supplements that has
been associated with a
reduced risk in the large
observational studies
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USE AND KNOWLEDGE OF FOLIC ACID IN WOMEN
OF CHILDBEARING AGE IN 1995
• Heard of folic acid
52%
• Knew folic acid can prevent birth defects
9%
• Knew folic acid should be taken before pregnancy
2%
• Took folic acid daily
28%
March of Dimes Birth Defects Foundation, Gallup Polls 1995
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FOLIC ACID FORTIFICATION
• The FDA issued a regulation to go into effect by
January 1998 mandating that all enriched cereal
grain products (flour, rice, bread, pasta, corn grits,
corn meal, farina, macaroni and noodle products)
be added with 140 g folic acid/100 g of the cereal
grain product.
• This program was designed to increase average
folate intake by ~100 µg/d, although reports have
indicated it may be closer to 200 µg/d.
EFFECT OF FORTIFICATION IN THE US
ON PREVALENCE OF NTDS
Study
Results
Honein et al. 2001
19% decrease in NTD rates
Williams et al. 2004
26% decrease in NTD rates
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WHY MIGHT INCREASED SYNTHETIC FOLIC ACID
INTAKE BE ASSOCIATED WITH ADVERSE EFFECTS?
•Folic acid is the synthetic version of the
vitamin.
•The safe upper limit (UL) for adults is 1 mg of
folic acid.
– Masking a B12 deficiency.
•High folate intakes can increase the
progression of cancer in those who
already have cancer.
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