Chapter 8 The Water-Soluble Vitamins. Copyright 2010, John Wiley & Sons, Inc. Which statement is...

Chapter 8The Water-Soluble Vitamins

Copyright 2010, John Wiley & Sons, Inc.

Which statement is true?

Vitamin deficiencies are rare in the United States.

Vitamins are necessary in many biochemical reactions in the body.

It generally takes longer to develop a deficiency of a fat-soluble vitamin than a deficiency of a water soluble vitamin.


The Vitamins (water and fat soluble)


Vitamin Talk

Vitamins are organic compounds essential in the diet to promote growth and health maintenance.

Water-soluble vitamins include the B vitamins and vitamin C.

Fat-soluble vitamins include A, D, E and K. B vitamins were originally thought to be one

chemical substance but are actually many different substances. That is the reason for B1, B2, B12, etc.


Which statement concerning vitamins is incorrect?

a) vitamins are organic compounds

b) If a vitamin is not provided by the diet, the body will synthesize it

c) vitamins are needed in small amounts than

macronutrients

d) vitamins are essential for growth, reproduction and health


Fortified and Enriched Foods Vitamins may be lost when food is processed. When these

vitamins are added back to the processed food at the same or higher level, the food is said to be?

a. Enhanced

b. Fortified

c. Enriched

d. Supplemented Fortification: process of adding nutrients to foods. The added

nutrients are generally not found in the food, ie) fortifying orange juice with calcium.

Enrichment: adding nutrients back to foods that have lost nutrients due to processing. Ie) addition of B vitamins to white rice.

Sometimes this process puts people above FDA guidelines. Ie, almost all breakfast cereals are fortified with iron and calcium, and many other vitamins not deficient in the U.S. diet.


Dietary Supplements Dietary supplements can be another source

of vitamins in the modern diet. Dietary supplements cannot replace the

benefits of a diet containing a wide variety of foods: epidemiological studies show that people who eat more fruits/veggies have a lower incidence of a host of chronic diseases.

These same benefits are not duplicated by taking supplements of nutrients found in these foods.

Dietary supplement production is not supervised by the FDA.


Absorption of Vitamins


Bioavailability of Vitamins Vitamins must be absorbed by the body in order to

perform their functions. Approximately 40-90% of vitamins are absorbed in

the small intestine. Fat-soluble vitamins require fat in the diet to be

absorbed and water-soluble vitamins may require transport molecules or specific molecules in the GI tract.

Some vitamins are absorbed in inactive provitamin or vitamin precursor forms that must be converted into active forms by the body.

The form in which a vitamin is presented can impact its absorption and utilization.


Which of the following terms is used to describe how much of a vitamin is absorbed and used by the body?

Absorption

Assimilation

Bioavailability

Functionality


Thiamin: B1 Thiamin was the first B vitamin to be identified

and is also called B1. The disease resulting from deficiency is beri-beri

and present in east Asia for over 1000 years. It came to western medical attention in colonial Asia in the 19th century. Why there?

Thiamin deficiency

Beri-beri: a disease of the muscles and nervous system characterized by

Depression and weakness (after just 10 days on thiamin free diet).

Neuromuscular symptoms such as paresthesia (spontaneous sensations, such as itching, burning, etc.) in-coordination … explained by lack of acetylcholine.

enlargement of the heart… the reason is not well understood.


B1 :Functions

Thiamin assists in energy production from glucose. carbohydrate metabolism and the production of

ribose (necessary for RNA) the health of the nervous system (synthesis of

acetylcholine, a neurotransmitter)


Thiamin Deficiency Deficiency is rare in the United States because

most foods are now vitamin enriched (previously common in places with predominantly a polished rice diet).

Today, beriberi occurs mostly in patients who abuse alcohol. Drinking heavily can lead to poor nutrition, and excess alcohol makes it harder for the body to absorb and store B1

Beriberi can occur in breast-fed infants when the mother's body is lacking in thiamin



Thiamine DeficiencyWernicke-Korsakoff syndrome

confusion, psychosis, confabulation, and impaired retentive memory. In severe cases the patient may slip into a coma.

(korsakoff syndrome refers to the retrograde amnesia)


Carl Wernicke

Alcohol: Toxicity is dose dependent



A primary function of thiamin in the body is to:

clot blood

regulate cell differentiation

increase uptake of iron by hemoglobin

facilitate production of energy from glucose


Thiamin


Riboflavin (B2)

Dairy products are a good source of riboflavin.

Why is milk often supplied in opaque containers?

Riboflavin is easily destroyed by heat and exposure to light.

Plant sources of riboflavin include mushrooms, broccoli, asparagus, whole grains and green, leafy vegetables. Animal sources include red meat, poultry and fish. Milk is the best source in the American diet.


Flavin adenine dinucleotide (FAD)


Riboflavin forms active coenzymes that do all the following except

help produce energy from carbohydrate, protein and fat.

function as electron carriers.

function in the citric acid cycle.

send messages between nerve cells.

B2 deficiency

• Deficiency leads to ariboflavinosis : injuries are slow to heal, inflammation of eyes, lips, mouth, tongue (tissues that grow most rapidly).

• Deficiency develops after ~ 2 months of B2 poor diet….



Riboflavin


Niacin (B3) Meat and fish are good sources. The emergence of deficiency states can be traced to the

cultivation of corn as the dietary staple. Today, Niacin is added to enriched flours in North America.

Carpenter found in 1951 that niacin in corn is biologically unavailable, and can be released only in very alkaline lime water of pH11.

Niacin can be synthesized in the body from the essential amino acid tryptophan if the diet is adequate in tryptophan (milk, eggs, etc).

Niacin plays an important role in the production of energy and in general metabolism.


Niacin Deficiency A niacin deficiency disease is pellagra which

causes progressive mental and physical deterioration.

Advanced pellagra’s symptoms include the 3 D’s: dermatitis, diarrhea and dementia.

Niacin toxicity from overuse of niacin supplements can result in flushing of the skin, elevated blood pressure, cardiac arrhythmia, nausea, vomiting, elevated blood sugar levels and impaired liver function.



Pellagra occurs when _____ is the staple grain in the diet and the diet does not provide adequate variety.

corn wheat rice barley


Niacin

Biotin Discovered when rats fed protein derived from raw egg

developed hair loss, dermatitis, and neuromuscular symptoms.

Avidin, a protein in raw eggs tightly binds biotin and prevents absorption.

Functions in energy production

form the citric acid cycle Deficiency is rare, but observed

in those receiving tube feeding

or those who are malnourished. Dose=200 mg qd

Pantothenic Acid (B5)

Panthethinc acid from greek pantothen (meaning ‘from everywhere’)

The wide distribution makes deficiency rare. Particularly high in meat, eggs, whole grains,

legumes. Part of acetyl-CoA (for energy production)



Pantothenic Acid


Pantothenic acid (B5) is abundant in:

meat

eggs

whole grains

All answer choices are correct.


Vitamin B6 Vitamin B6 is also called pyridoxine Vitamin B6’s role in amino acid metabolism

distinguishes it from the other B vitamins. (needed to synthesize nonessential a.a. by transamination).

B6 is easily lost via exposure to heat, light, processing. Not usually added back.

Vitamin B6 deficiency may result in anemia due to impaired hemoglobin synthesis (pyridozil phosphate)

Both B6 and B12 are needed to synthesize the myelin coat of nerve cells. And essential for normal nerve cell transmission.

Vitamin B 6 and cardiovascular risk Individuals with high homocysteine levels develop atherosclerosis at an early age

B6 helps in the breakdown of this amino acid Folate and B12 are also required in this

important pathway.



Vitamin B6 does not perform which of the

following roles?

a) It is vital in the formation of non-essential amino acids.

b) It is required for the synthesis of

hemoglobin.

c) It is necessary in collagen

formation.

d) Large doses can reduce high blood homocysteine levels which is a risk factor for cardiovascular disease.


Vitamin B6


Many B vitamins are essential for the metabolism of energy yielding nutrients. They perform this function by binding to and promoting the activity of enzymes. When B vitamins perform in this way, they are ____?

provitamins

transport proteins

coenzymes

hormones


Folate or Folic Acid

Folate coenzymes are needed for DNA synthesis and the metabolism of some amino acids.

Low folate intake in early pregnancy is associated with an increased risk of neural tube defects.

Low folate intake has been associated with an increased risk of heart disease related to the metabolism of the amino acid homocysteine.


Folate Deficiency and Neural Tube Defects


Macrocytic Anemia and Folate Deficiency


Folate deficiency symptoms are less of a problem recently because:

grain products have been fortified with folate

more people are taking supplements

more people are drinking low-fat milk

green tea is more popular


Folate or Folic Acid


Vitamin B12

Pernicious anemia is a form of anemia that does not respond to iron supplementation.

Vitamin B12 is necessary for the proper absorption of iron in the body.

Excessive intake of folic acid can mask B12 deficiencies.

Vitamin B12 is most readily absorbed from animal products.

Vegan diets need to be supplemented with readily-absorbable forms of B12.

Atrophic gastritis may lead to B12 deficiencies.


Absorption of Vitamin B12


Vitamin B12


Vitamin C Vitamin C is also known as ascorbic acid or

ascorbate. Functions include:

an antioxidant in the body helps maintain the immune system is important in the production of collagen and aids in iron absorption.

Vitamin C in foods can be destroyed by oxygen, light and heat, as well as contact with copper or iron cookware.


Deficiency Vit C leads to scurvy


Which group is at risk for developing vitamin C deficiency?

Sailors in the in the 1300s

infants fed cow's milk

alcoholics

elderly people consuming nutrient poor diets

Copyright 2010, John Wiley & Sons,

Inc.

Which is the best source of vitamin C?

a) green pepper

b) milk

c) eggs

d) beef


Vitamin C


How Antioxidants Work


Which lifestyle factor increases the requirement for vitamin C?

drinking alcohol

exercising frequently and intensely

smoking cigarettes

eating a diet high in fiber


Summary of Water-Soluble Vitamins and Choline



Benefits and Risks of Water-Soluble Vitamin Supplements


Beriberi is a disease caused by lack of _____________ in the diet.

riboflavin

thiamin

vitamin C

niacin


Which disease is caused by a niacin deficiency?

a) ariboflavinosis

b) beriberi

c) pellagra

d) scurvy


Which is the TRUE statement about niacin?

It can be synthesized in the body from the amino acid, tryptophan.

Eggs are a good source of preformed niacin.

Heat and light easily destroy it.

Corn has a protective effect against niacin deficiencies.


Another name for vitamin B6 is

a) pantothenic acid

b) pyridoxine

c) pyruvate

d) biotin


Finding Vitamins in Foods


Chapter 8

Copyright 2010 John Wiley & Sons, Inc.

All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein.

.

Date post:	02-Jan-2016
Category:	Documents
Upload:	melanie-mathews
View:	217 times
Download:	1 times

Chapter 8 The Water-Soluble Vitamins. Copyright 2010, John Wiley & Sons, Inc. Which statement is...

Documents