Nutrition 709:255:02 Nutrition and Health Fall 2024 Professor Miller: Exam 3

Sources of Thiamin

sifh, dairy, lean meats, fortified bread and cereal

Cofactor of thiamin

TPP - Thiamin pyrophosphate

What is TPP

thiamin plus two phosphate groups

Where do the phosphate groups in TPP come from

2 ATP molecules1

What vitamin increases or faciliates absorption of thiamin

Vitamin C

What decreases absoprtion of thiman

Alcohol and Oxdiants

Functions of B1

ATP production, DNA synthesis, NADPH synthesis, nerve function

Deficiency of B1 causes what...

Beri Beri

4 types of Beri beri

Dry, Wet, Infantile, Cerebral

Dry beri beri

Muscle wasting, cramps, tenderness, tingling

Wet Beri beri

edema, increase of heart size, heart failure

Infantile Beri Beri

heart failure

Cerebral Beri beri

Confusion, Poor Coordination, eye Paralysis, short term memory loss

What are some aspects of thiamin global deficiency

Monotnous diet, low in animal product, foods with thiamine antagonist, conflict

B1 Toxicity

none

Riboflavin(B2) Sources

Meat, dairy, Leafy vegetables, nuts

What is a Cofactor

a substance (other than the substrate) whose presence is essential for the activity of an enzyme.

B2 cofactors

FMN & FAD

B2 Fucntion

Redox Reactions, ATP, Activation of other vitamins, Neurotransmitter Metabolism

B2 deficiency

Very Rare

Muscle weakness, lip sores, inflamed tongue, Can occur secondary to alcoholism and thyroid disease

What is the effect of B2 on people with MTHFR(blood pressure raiser gene) polymorphism

Significantly lowers it, ONLY on people with that genetic abnormality.

Conditions Associated with B2 Deficiency

Monotonous diets, low in animal source foods(meats, eggs, milk), Gastrointestinal infections

B2 Toxicity

none

Niacin(B3) Sources

Dairy, Meat, Eggs, Nuts

B3 Cofactors

NAD & NADP

NAD form

2 phospahte groups plus extrra stuff

NADP form

NAD plus a third phosphate group

What does the body use to sysntehsize B3

L-Tryptophan

Even though it can, why does the body not synthesize Niacin

It is incredibly inefficient

60mg of L-tryptophan is needed for 1mg of Niacin

B2 Site of absoprtion

duodenum and jejenum

B3 Site of absoprtion

duodenum and jejunum

B3 bioavailability

Animal sources more bioavailable than grains

Niacin in grains bound by proteins reduces bioavailability

Treating grains with alkaline (basic) substances such as lime water orbaking soda releases the niacin and makes it more bioavailable

What does B2 contribute in the ATP production cycle

FADH

What does B3 Contribute int he ATP production cycle

NADH

B3 Function

Redox reactions

ATP production

Synthesis and Metabolism of Many Compounds

Cholesterol Metabolism( Lowers LDL and raises HDL)

B3 positive health effects

Significantly lowers triglycerides and cholesterols levels reducing chance of heart issues.

B3 deficiency

Pellagra - Once was very common in the Southern U.S. due to corn being the primary source of protein (corn is low in both niacin and tryptophan)

The 4 "D's"- Dermatitis, Diarrhea, Dementia, Death

Conditions Associated with B3 Deficiency

Monotonous, maize-based diets

Drought, Conflict, Displacement

B3 Toxicity

Increased plasma glucose

Liver damage

Flushing, redness of the face

Sources fo Pantothenic Acid(B5)

Pretty much everything

site of absoprtion for b5

jejunum

functions for b5

atp,

deficiency b5

unlikely.

could cause burning feet, tingling, weakness, diarreah

toxicity b5

none

adequate intake b5

5mg

Sources Biotin(B7)

everything

Biotin Cycle

holocarboxylase is produced to perform protein catabolism, fatty acid synthesis, and gluconeogenesis.

absorption b7

duodenum, jejunum. Gut bacteria is a major source of biotin.

Bioavailability B7

Biotin is typically bound to protein in food; usually does not affect bioavailability much

Exception: avidin (found in egg whites)

\Very strong binding to biotin, inhibits absorption

Only a problem when eggs are eaten raw (uncooked)

Functions B7

Carboxylation Reactions:

Gluconeogenesis

Protein catabolism

fatty acid synthesis

ATP Production

B7 deficiency

Not common

but: Depression, hallucinations, skin irritation, infections, hair loss, poor muscle control, seizures, developmental delays

Biotin Toxicity

none

AI b7

30 µg/day

What is the active form of vitamin B6(Pyridoxine)?

a. Pyridoxine

b. Pyridoxal

c. Pyridoxal 5'-phosphate

d. Pyridoxic acid

C

In order for pyridoxal 5'-phosphate (PLP)to cross a membrane, a phosphate group must be added to the molecule.

a. True

b. False

B

Bulky molecules pass membranes easier

a. True

b. False

B

How does B6 enter the cell

A phosphate group is removed to make the molecule less bulky, and is re attatched back in the cell

What enzyme attaches the phosphate group to molecules

Kinase

(Note: notice the -ase ending which typically means cut.)

What molecule removes the phosphate group form molecules so that it can cross a membrane

phosphatase

(Note: notice the -ase ending which typically means cut.)

Vitamin B6 is not that important

a. True

b. False

B

How many reactions is B6 used for

100+

In severe vitamin B6 deficiency, the synthesis of heme is inhibited. This leads to what clinical manifestation of vitamin B6 deficiency?

a. Convulsions and EEG abnormalities

b. Hyperhomocysteinemia

c. Inflammation

d. Microcytic anemia

D

B6 deficiency symptoms

Convulsions and EEG abnormalities

Hyperhomocysteinemia

Inflammation

Microcytic anemia

What do cells look like with microcytic anemia

They are smaller and have less color due to low amounts of hemoglobin

As Inflammation increaes, the amount of B6 . . .

Decreases

B6 Toxicity

Neurological issues and damage

Sources of Folate(B9)

A lot

What is the syntehtic form of folate

Folic Acid

Structure of folic acid

pteridine, PABA, glutamic acid

Which of the following is NOT a natural,reduced form of folate?

a. Tetrahydrofolate

b. N5-Methyltetrahydrofolate

c. N5,N10-Methylenetetrahydrofolate

d. N5-Formyltetrahydrofolate

e. 10-Methyl-4-Aminotetrahydrofolate

E

What has to be removed from folates in foods in order for the folates to be absorbed in the small intestine?

a. All but one glutamate

b. PABA

c. The pterin ring structure

d. Hydrogens

A

What enzyme cuts the multiple glutamates from folate

GCP II

Reduced folates in foods are equallybioavailable as folic acid in supplementpills.

a. True

b. False

B

What is DFE(Dietary Folate Equivalent)

It shows that the bioavailability of folate changes when you consume folate from food, folic acid from food, and folic acid as a supplement.

Folate Functions

One-Carbon Metabolism

DNA and RNA synthesis: thymidine (T), adenine (A), guanine (G)

Methionine recycling: conversion of homocysteine to methionine

S-adenosylmethionine (SAM) synthesis: methylation reactions

Which of the following is a possible outcome of folate deficiency?

a. Macrocytic anemia

b. Hyperhomocysteinemia

c. Neural tube defects

d. All of the above

e. A and B, but not C

D

What does macrocytic anemia look like

Larger than normal red blood cells, and icnreased lobes in PMNs

Folate effect on pregnancy

It is recommnede for pregnant women to consume folate/folic acid to prevent Neural Tube Defects

Note: Increased folate consumption effect on pregnancy studies have shown to decrease NTDs

Folic Acid Government Intervention

CDC recommends folate to prevent NTDs and FDA has fortified many cereal grains with Folic Acid to make sure everyone reaches that level.

Toxicity Folic Acid

Not really but may mask b12 definciency.

Sources of B12(Cobalamin)

animal products

Supplement/Syntehtic form of B12

cyanocobalamin

What is the important feature of Cyanocobalamin

CN(cyanide) R-Group. Other countries use different R Groups for supplement From

Which of the following is an active form ofvitamin B12?

a. Methylcobalamin

b. Adenosylcobalamin

c. Cyanocobalamin

d. All of the above

e. A and B, but not C

E

Forms of B12

CN (cyanocobalamin, vitamin B12) Supplement form (used in U.S.)

OH (hydroxocobalamin) Supplement form (used in Europe)

CH3 (methylcobalamin) Cofactor form

Deoxyadenosyl (adenosylcobalamin) Cofactor form

What is required for B12 absorption

Haptocorrin (HC), Saliva

Intrinsic Factor (IF), Parietal cells of the stomach

Transcobalamin (TC), Intestinal cells

Also requires stomach acid (HCl), Parietal cells of the stomach.

Process of B12 Absoprtion

HC binds to B12 in the mouth and IF binds to both of them in the stomach. HC drops off in small intestine since ph rises. IF-B12 enters intestinal cells where IF breaks of and B12 is converted and used. TC attaches to B12 to exit cell and be transported. If you consume high amounts of supplement B12, it can directly pass through intestinal cells.

Which of the following are caused by deficiencies of either folate or vitamin B12?

a. Macrocytic anemia

b. Hyperhomocysteinemia

c. Degeneration of the spinal cord

d. All of the above

e. A and B, but not C

E

B12 Functions

One-carbon metabolism ( DNA and RNA synthesis: thymidine (T), adenine (A), guanine (G), Methionine recycling: conversion of homocysteine to methionine, S-adenosylmethionine (SAM) synthesis: methylation reactions)

Fatty Acid Metabolism - Conversion of methyl malonyl CoA to Succinyl CoA

Definciency B12

Macrocytic Anemia, Hyperhomocysteinemia, Neurological Disease.

Which of the following are possiblecauses of vitamin B12 deficiency?

a. Lack of vitamin B12 in the diet

b. Pernicious anemia

c. Atrophic gastritis

d. All of the above

e. A and B, but not C

D

Causes of B12 deficiency

Low b12 in diet, malabsorption(Pernicious anemia and atrophic gastritis)

Vegetarian/vegan affect on B12 in Diet

Since B12 comes from animal sources, especially vegans will not have a natural source of B12. It is reccomeneded they take supplements

Pernicious Anemia

Autoimmune disorder which results in a loss of IF. B12 can not be absorbed and can be fatal

Atrophic Gastritis

Loss of stomach acid. B12 can not be absorbed but results in mild definciency.

b12 toxicity

None

Effect of B Vitamin Supplements on Brain Atrophy

Lowers homocysteine levels and slows brain degneration

Sources of Vitamin A(Retinol)

Direct Vitamin A is found in animal products. Precursor to vitamin A(Beta-Cerotene) is found in vegetables.

When determining total dietary intake of vitamin A, we use "retinol activity equivalents"or "RAEs". Why do we do this?

a. Because the synthesis of beta-carotene from vitamin A is not 100% efficient

b. Because the synthesis of vitamin A from beta-carotene is not 100% efficient

c. Because the synthesis of vitamin A from beta-carotene is 100% efficient

d. Because nutritionists want to make it hard fornutrition students

B