What are vitamins?
organic compounds needed in small quantities in the body, but not synthesized in adequate amounts by humans or not at all.
What are the biological roles of vitamins?
essential cofactors for enzymatic reactions, components for energy carriers, precursors, biological regulatory molecules, antioxidant
Name the characteristics of fat-soluble vitamins
1.Insoluble 2. Bound to carrier protein/part of lipoprotein particles 3.40-90% absorbed 4. Can be stores in body fat depots except Vitamin K
Name the characteristics of water-soluble vitamins?
1. Soluble 2. Free form in circulation 3. not effectively stored in the body 4. Regular intake is important
Where does Vitamin C play a role a essential cofactor?
Hydroxylation of Proline and Lysine residues of collagen -> helps with crosslinking of collagen fibers
What is RDA ?
Estimated requirement of a vitamin/mineral to prevent deficiencies in population of healthy individuals, then increase by an amount sufficient to meet needs of nearly all (98%) members of that group
What is the population targeted by RDA?
healthy individuals, men and women, different age groups, pregnant and lactating women included
What is Reference Daily Intake?
highest RDA level across groups and usually referred as % Daily value
When and why were RDA first established?
WWII. To provide nutritional recommendations for armed forces and civilians during times of food rationing
What is the Dietary Reference Index? When has it been established?
In 1994, new set of dietary standards in the US
How is DRI different from RDA?
Include 1. Adequate Intake (AI) 2. Tolerable Upper Intake Level (UL) 3. Estimated Energy Requirements (EER).
What is Adequate Intake?
AI is established based on the levels of a given nutrient that are consumed by healthy people.
When are Adequate Intake values used instead of DRIs?
Insufficient experimental evidence and in infants
What is Tolerable Upper Intake Level?
Highest level of nutrient likely to pose no risks to adverse health effects
What are Estimated Energy Requirements?
Dietary energy intake needed to maintain energy balance in a healthy adult of a given age, gender, height, and level of physical activity
For which individuals DRIs is not valid?
individuals that are ill, under stress from surgery, alcoholics or on medications
What is the role of Vitamin E?
1.Free radical scavenger in cell membrane and lipid stores 2. frequently advertised as supplement to prevent related to aging
What do recent clinical trials tell about Vitamin E ?
No significance in health benefit. High doses (>200UI/day)might even increase risk of stroke, prostate cancer, and other causes of death
What is the role of Vitamin K?
1.Metabolic Cofactor for gamma carboxylase.2. Essential for blood coagulation cascade 3. Regulation of bone formation and other cellular processes
Which group of population is affected by dietary deficiency of Vitamin E?
Premature infants. Adults with defective lipid absorption or transport
Why is γ-carboxylation of glutamic acid?
post translational modification of precursors of clotting factors 2, 7, 9, 10
What is the action of Warfarin?
Anticoagulant. Acts on the enzyme responsible for the regeneration of the active form of vitamin K
What is the role of Vitamin A?
1. Regulatory Vitamin in vision, reproduction, embryonic development, immune function, differentiation and maintenance of epithelial tissues
Where are Vitamin K-dependent carboxylated proteins found?
blood coagulation cascade, osteoblasts (bone reformation), chondrocytes, and smooth muscle cells
What does the isomerization of trans- to cis- retinol trigger?
In rod cells of the eye, triggers the signaling pathway that allows us to detect light
What are retinoic acids?
Transcriptional regulators linked to cellular differentiation and cancer biology
What are the mode of action of retinoic acids (RA)?
Treatment of skin disorders (acne, psoriasis) and certain types of cancers
What disorders result in hypervitaminosis A?
Toxic syndrome, skin, liver and nervous system abnormalities, congenital malformations. Can increase tumor growth
What is the adequate Intake in infants based on?
levels of nutrients in breast milk of healthy mothers
What are minerals?
Inorganic elements or compounds required as structural components of enzymes, electrolytes, signaling molecules etc..
Which enzymes are highly dependent on copper?
Ceruloplasmin, cytochrome C, superoxide dismutase, tyrosinase
Does lack of ceruloplasmin result in copper deficiency? yes/no? why?
No. b/c presence of other copper containing proteins that overt the symptoms
What are the consequences of ceruloplasmin deficiency?
Deficiency of iron metabolism. Accumulation of iron in the pancreas, retina and brain-> diabetes, blindness and neurological symptoms.
Describe Wilson's disease.
AR disease. Defect in Cu transporter required for biliary excretion (but not Cu uptake). Low serum ceruloplasmin, high urinary copper excretion and high hepatic copper content. Accumulation of Cu in liver, brain and kidney.
Describe Menkel's syndrome
Rare X linked disease. Defect in a distinct Cu transporter that transports Cu to the fetus or through the intestine after birth ->Cu deficiency.
Low Cu levels in serum and most tissues. Very High Cu levels in intestine and kidney.
What is the action of penicillamine?
chelating agent. Solubilizes copper and promotes its urinary excretion and dietary zinc, which inhibits copper absorption.
What are the symptoms in Menkel's syndrome?
Infancy: slow growth, mental degeneration (irreversible), kinky white hair. Most individuals die within the first few years of life
When do vitamin/mineral supplementation have significant health benefits?
If health conditions limit absorption, transport/metabolism of vitamins or minerals. Calcium for teens and young adults
Describe protein requirements in rapidly growing infants
high protein need, low endogeneous rate of cysteine synthesis. Cysteine is essential
Which aa are considered essential in pre-term infants?
tyrosine, glutamine, arginine, proline, and glycine
What is the role of essential FA?
1. maintaining function and integrity of membranes 2. precursors for the synthesis of eicosanoids 3.Critical signaling molecules in inflammatory responses, blood clotting, etc..
When do symptoms associated with essential FA deficiency manifest? Why>
Months to manifest b/c large endogenous stores of essential FA
What is the difference between omega and delta system?
Delta system counts carbon from the carboxyl end. Omega system counts from the methyl end. For omega, only the position of the double bond most proximal the methyl end is given. Any additional double bonds always separated by 3 carbons like for linoleic acid
What is the nomenclature for FA?
1st number is the total number of C atoms. the second number is the number of double bonds.
Why FA essentials? Name their characteristics
1. Humans lack the enzyme req. to insert a double bond 3 or 6 carbons from the omega end. 2. very low quantity is needed but required 3. deficiencies are rare in general population 4. Essential diet component for enteral/parenteral nutrition
What role do non essential dietary components play in our health?
Dietary supplement can influence positively or negatively individuals health. Can be produced by humans in sufficient quantities
What is a dietary fiber?
Plant-derived carbs and lignins that are not digested in human stomach or small intestine
Why are dietary fibers beneficial for our health?
Decrease intestinal transit time and increase ease of elimination of feces, reducing risk for development of diverticulitis, hemorrhoids, and colon cancer
What role do high fiber food play in our diet?
Aid weight control by increasing appetite satiety w/o yielding much energy and slowing carbohydrate absorption
What are soluble fibers?
Dissolved/swell in water. Digested by bacteria in large intestine into short chain FA and gases.
What are the health benefits of lycopene?
Anti-oxidant for free radicals. Reduce risk for cancers, cvd, osteoporosis, diabetes, macular degeneration. Not FDA approved
What are semi-essential nutrients?
Nutrients that can be synthesized by humans, but under certain circumstances could be limiting