W9: Vitamin B1, B2

Question 1

Thiamin deficiency is associated with which disease?
A. Pellagra
B. Beri beri
C. Rickets

Answer 1

B. Beriberi

Beriberi is a disease that results from severe thiamin deficiency. It affects the cardiovascular, nervous, muscular and gastrointestinal systems and can manifest in 3 different forms:

• Dry
• Wet
• Cerebral

depending on the systems affected by the deficiency in the individual.

Dry beriberi (paralytic or nervous form) manifests in peripheral neuropathy with burning feet (‘burning feet syndrome’), exaggerated or abnormal
reflexes, decreased sensation and weakness in the arms and legs, muscle pain and tenderness, difficulty rising from a squatting position and seizures.

Wet beriberi (cardiac) can manifest in rapid heart rate, edema and enlargement of the heart, difficulty breathing and eventually, Congestive Heart Failure.

Cerebral beriberi can lead to Wernicke encephalopathy and Korsakoff psychosis (especially in cases of alcohol abuse). Wernicke encephalopathy exhibits a triad of symptoms:

1. Abnormal eye movements
2. Abnormalities in stance and gait
3. Abnormalities in mental function (confused and may include apathetic state and a memory disorder (Korsakoff amnesia or Korsakoff psychosis))

Thiamin deficiency affecting the central nervous system without amnesia is Wernicke disease. When amnesia is present along with eye movement and gait disorders, it is known as Wernicke Korsakoff Syndrome (WKS).

Question 2

Thiamin is stored in:
A. liver
B. skeletal muscle
C. heart
D. kidneys
E. brain
F. A & B
G. All of the above

Answer 2

G. All of the above

In the body, thiamin exists in both free and phosphorylated forms.
The human body (adult) contains ~ 30 mg of thiamin

Question 3

TPP – Thiamin pyrophosphate (also thiamin diphosphate) is required as a coenzyme for which reactions?
A. Pyruvate dehydrogenase
B. 2-oxoglutarate dehydrogenase
C. Branched chain keto acid dehydrogenase
D. All of the above

Answer 3

D. All of the above

These reactions occur in the mitochondria and form Acetyl CoA, succinyl CoA and a derivative of Branched chain amino acids (which are all critical in the production of energy from food). If any of these reactions is inhibited, the synthesis of ATP and Acetyl CoA (required for the synthesis of fatty acids, cholesterol and other compounds) decreases or stops and lactate, pyruvate and alpha-ketoglutarate can accumulate.

Question 4

True or False. Thiamin is released with stimulation of the nervous system.

Answer 4

True.

Thiamin is though to be involved in transmitting nerve impulses via
the regulation of sodium channels and through the phosphorylation of proteins.

Question 5

Is thiamin present in animal or plant foods?

Answer 5

Both!

Plant foods have thiamin present in free (nonphosphorylated) form. In animal foods, 95% is phosphorylated (TPP) and ~5% is TMP and TTP. Phosphorylated forms require digestion (which occurs via intestinal phosphatases) in order to be absorbed.

Question 6

True or False. Raw fish can disrupt absorption of thiamin.

Answer 6

True.

Antithiamin factors (thiaminases) are present in raw fish (they are inactivated by cooking), in tannic, chlorogenic and caffeic acids (coffee, tea, tap water, blueberries, black currants, brussel sprouts and red cabbage).

Question 7

What minerals increase the destruction of thiamin by thiaminases?
A. Zinc
B. Magnesium
C. Calcium
D. B & C

Answer 7

D. B & C

Calcium and magnesium

Question 8

What vitamin helps prevents enzymatic destruction of thiamin?
A. Vitamin D
B. Vitamin E
C. Vitamin C

Answer 8

C. Vitamin C

Question 9

Where does absorption of thiamin occur?
A. Duodenum
B. Ileum
C. Jejunum
D. B & C

Answer 9

D. Absorption is in the small intestine (mainly in the jejunum and ileum (some in the duodenum)

Question 10

FUN FACT!!
Most free thiamin is taken up by the liver and phosphorylated to TPP.
Recall that 90% of thiamin in the blood is found within the blood cells as TPP.

Question 11

Thiamin excretion occurs mostly in:
A. Sweat
B. Stool
C. Urine

Answer 11

C. Urine

Question 12

Riboflavin (B2) absorption ________ with concurrent ingestion of calcium
A. decreased
B. increased
C. Unaffected

Answer 12

A. decreased

Question 13

True or False. Diuretics can lead to excess loss of thiamin.

Answer 13

True.

Diuretics (increase urinary flow may prevent reabsorption of thiamin by the kidneys and increase urinary excretion of the vitamin)

Question 14

True/False: A deficiency of riboflavin is associated with increased oxidative stress.

Answer 14

True

Question 15

\_\_\_\_\_\_\_\_\_\_ is the term given to a clinical deficiency of riboflavin
A. Ariboflavinosis
B. Riboflavonesis
C. Ribocytosis
D. None of the above

Answer 15

A. ariboflavinosis

Question 16

Certain individuals who might be in need of increased requirements for thiamin include:
A. Strenuous exercise
B. Fever
C. Pregnancy
D. Breast feeding
E. Growth (adolescent)
F. HIV infected
G. Alcohol abuse (impairs intestinal absorption and utilization of thiamin)
H. A-E
I. All of the above

Answer 16

I. All of the above

Question 17

FUN FACT!! Rare case reports of megaloblastic anemias that respond to high doses of thiamin and Maple Syrup Urine Disease (MSUD) and pyruvate dehydrogenase deficiency can respond to high dose thiamin.

Question 18

True or False. Those who consume over over 100mg/day of thiamin can experience toxicity.

Answer 18

False.

There is no Tolerable Upper Limit for thiamin because there are no well established toxic effects from excess thiamin consumption in the
diet/supplementally (up to 200 mg/d).

Question 19

Signs of Riboflavin (B2) Deficiency include:

Answer 19

• Sore throat
• Redness and swelling of the mucosa in the mouth and throat
• Cheilosis (cracks and sores on the outside of the lips
• Angular stomatitis (cracks, sores at the corners of the mouth
• Glossitis (inflammation and redness of the tongue)
• Seborrheic dermatitis (moist, scaly skin rash/inflammation)

Question 20

Out of all the thiamin rich foods, it is most present in \_\_\_\_\_\_.
A. Beef
B. Pork
C. Legumes
D. Nuts/seeds

Answer 20

B. Pork

Thiamin is found in a wide variety of foods. Meat (especially pork) is rich in thiamin. It is also present in beef, beef liver, salmon, legumes, grains
(whole, fortified/enriched), yeast, wheat germ and soy milk

Question 21

Foods containing Riboflavin include:
A. Strawberries, rhubarb, pork, coffee
B. Cereal, milk, cheddar, egg, almonds
C. Coconut products, hemp seeds, salmon

Answer 21

B. Cereal, milk, cheddar cheese, egg, almonds

B2 is also rich in organ meats

Question 22

True/False: Glutathione reductase activity is considered a/the most sensitive measure for riboflavin. An activity coefficient is used to measure glutathione reductase activity and the levels below are used to determine riboflavin status:

Answer 22

Activity coefficient: How the activity coefficient is determined: it is the ratio of enzyme activity with FAD (added in vitro) to enzyme activity without FAD.

Question 23

The RDA for thiamin for adults 19 yo and older is _______ for males and _______ for females.
A. 1.2mg, 1.1mg/day
B. 1.4mg, 1.6mg/day
C. 2.0mg, 2.2mg/day

Answer 23

A. 1.2mg males, 1.1mg females

Question 24

Recommended Dietary Allowance of Riboflavin is:
A. 0.3-0.5mg
B. 1.1-1.3mg
C. 3.5-5mg
D. 10-12mg

Answer 24

B. 1.1-1.3mg

Question 25

___________ is required to convert thiamin into its active form.
A. Calcium
B. Magnesium
C. Vitamin D

Answer 25

B. Magnesium

Magnesium is required to convert thiamin to TPP (active form of the vitamin). Thus, if deficient in thiamin and magnesium, thiamin deficiency may not respond to thiamin supplementation in the absence of magnesium.

Question 26

This vitamin is an essential component of two major coenzymes, flavin mononucleotide (FMN; also known as riboflavin-5’-phosphate) and \_\_\_\_\_\_\_\_\_\_. These coenzymes play major roles in energy production; cellular function, growth, and development; and metabolism of fats, drugs, and steroids
A. FAD
B. NAD
C. NAD+
D. None of the above

Answer 26

A. FAD - flavin adenine dinucleotide

Question 27

___________ can be more toxic with thiamin deficiency. Thus it is advised to administer thiamin before supplementing with it.

A. Niacin
B. Calcium
C. Alpha lipoic acid (ALA)

Answer 27

C. Alpha lipoic acid (ALA)

Question 28

True/ False: Most riboflavin is absorbed in the proximal small intestine

Answer 28

True!

Question 29

True or False. Higher thiamin intakes decrease the likelihood of cataracts.

Answer 29

True.

Question 30

Anemia and cataracts can develop if riboflavin _______is severe and prolonged
A. deficiency
B. toxicity

Answer 30

A. deficiency

Question 31

True/False: Riboflavin does not have an establish TUL

Answer 31

True! Intakes of riboflavin from food that are many times the RDA have no observable toxicity, possibly because riboflavin’s solubility and capacity to be absorbed in the gastrointestinal tract are limited. Because adverse effects from high riboflavin intakes from foods or supplements (400 mg/day for at least 3 months) have not been reported, the FNB did not establish ULs for riboflavin. The limited data available on riboflavin’s adverse effects do not mean, however, that high intakes have no adverse effects.

Question 32

The RDA for thiamin of children ages ranging 1-13 is?
A. 0.2-0.6mg/day
B. 0.5-0.9mg/day
C. 0.6-1.2mg/day

Answer 32

B. 0.5-0.9mg/day