L8 Vitamin Bioavailability and Niacin Quiz
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Questions and Answers

What is the primary role of provitamin A?

  • It is converted to retinol in the body. (correct)
  • It provides energy to the body.
  • It functions as a mineral for bone health.
  • It serves as a water-soluble vitamin.

Which factor does NOT influence bioavailability?

  • Age of the individual (correct)
  • Previous nutrient intake
  • Digestion efficiency
  • Preparation of the food

What is a misconception about the toxicity of vitamins?

  • All vitamins are safe in high doses. (correct)
  • Fat-soluble vitamins have a lower risk of toxicity.
  • Water-soluble vitamins can cause harm at high levels.
  • Excess vitamin intake can be harmful.

What are the two types of solubility concerning vitamins?

<p>Fat-soluble and water-soluble (C)</p> Signup and view all the answers

Which of the following statements about β-carotene is accurate?

<p>It is a precursor that is converted to retinol. (C)</p> Signup and view all the answers

What is the definition of bioavailability?

<p>The amount of a nutrient that is absorbed and utilized by the body. (B)</p> Signup and view all the answers

What effect does cooking have on the bioavailability of nutrients?

<p>Cooking can enhance or diminish nutrient absorption. (A)</p> Signup and view all the answers

Which statement about B vitamins is correct?

<p>They are primary sources of energy. (B)</p> Signup and view all the answers

What is a possible health benefit of large doses of nicotinic acid?

<p>Increased HDL cholesterol (D)</p> Signup and view all the answers

Which of the following statements regarding niacin toxicity is true?

<p>Niacin flush occurs at doses three to four times the RDA. (D)</p> Signup and view all the answers

Which food characteristic is noted about niacin in the content?

<p>More stable during food processing (B)</p> Signup and view all the answers

Which symptom is associated with niacin deficiency?

<p>Dermatitis of pellagra (D)</p> Signup and view all the answers

Which option best describes the cause of 'niacin flush'?

<p>Caused by high doses of nicotinic acid (A)</p> Signup and view all the answers

What is NOT a characteristic of naturally occurring niacin?

<p>It can cause toxicity. (C)</p> Signup and view all the answers

Which of the following reflects a misconception about niacin supplements?

<p>There are no side effects to niacin supplementation. (A)</p> Signup and view all the answers

What best describes the role of niacin in the body?

<p>Supports energy metabolism (B)</p> Signup and view all the answers

Which health effect may be a direct result of high doses of nicotinic acid?

<p>Skin flush (D)</p> Signup and view all the answers

What is the relationship between niacin and food preparation methods?

<p>Niacin is preserved during most cooking methods. (B)</p> Signup and view all the answers

What is the role of riboflavin (B2) in the body?

<p>It serves as a coenzyme in energy metabolism. (A)</p> Signup and view all the answers

Which symptom is associated with riboflavin deficiency?

<p>Inflammation of membranes (C)</p> Signup and view all the answers

What is the likely consequence of riboflavin being destroyed by ultraviolet light?

<p>Reduced stability and safety of food products. (D)</p> Signup and view all the answers

What is the primary form of niacin in the blood?

<p>Nicotinamide (A)</p> Signup and view all the answers

Which of the following accurately states the relationship between tryptophan and niacin?

<p>60 milligrams of tryptophan equals one milligram of niacin. (D)</p> Signup and view all the answers

Which disease is caused by niacin deficiency?

<p>Pellagra (A)</p> Signup and view all the answers

What is the relationship between vitamin toxicity and riboflavin?

<p>Riboflavin has a low chance of toxicity even at high doses. (D)</p> Signup and view all the answers

What is a commonly recognized source of riboflavin?

<p>Nutritional yeast (D)</p> Signup and view all the answers

Which of the following statements about niacin is true?

<p>Niacin plays a role in redox reactions. (C)</p> Signup and view all the answers

What are the symptoms of pellagra?

<p>Diarrhea, dermatitis, dementia, and death (A)</p> Signup and view all the answers

Which of the following is a primary function of Pantothenic Acid (B5)?

<p>Synthesis of essential compounds (D)</p> Signup and view all the answers

What is a consequence of excessive intake of Vitamin B6?

<p>Neurological damage (C)</p> Signup and view all the answers

What role does Biotin (B7) play in metabolism?

<p>Delivers carbon to pyruvate (C)</p> Signup and view all the answers

Which vitamin primarily acts as a coenzyme for the conversion of Vitamin B12?

<p>Folate (B)</p> Signup and view all the answers

Which statement accurately describes a characteristic of Vitamin B6?

<p>Involved in over 100 enzymatic reactions (B)</p> Signup and view all the answers

Which process does Biotin not participate in?

<p>Transamination of amino acids (D)</p> Signup and view all the answers

What is the consequence of freezing, canning, and refining foods on Pantothenic Acid content?

<p>Destroys the vitamin content (B)</p> Signup and view all the answers

What is the primary active form of Folate?

<p>Tetrahydrofolate (THF) (A)</p> Signup and view all the answers

Which of the following substances can cause a loss of Vitamin B6?

<p>Isoniazid medication (C)</p> Signup and view all the answers

Which of the following vitamins is known for not having an established upper limit for toxicity?

<p>Biotin (B7) (A)</p> Signup and view all the answers

What is a primary effect of folate deficiency during pregnancy?

<p>Neural tube defects (B)</p> Signup and view all the answers

What is the bioavailability of folate from food sources compared to supplements?

<p>50% from food and 100% from supplements on an empty stomach (D)</p> Signup and view all the answers

What is a potential consequence of high doses of synthetic folate?

<p>Obscuring a vitamin B12 deficiency (C)</p> Signup and view all the answers

Which of the following is not a source of folate?

<p>Dairy products (B)</p> Signup and view all the answers

What type of anemia is primarily associated with folate deficiency?

<p>Macrocytic or megaloblastic anemia (A)</p> Signup and view all the answers

What effect does heat and oxidation have on folate?

<p>Destroys folate (D)</p> Signup and view all the answers

What is the folate form that is more bioavailable?

<p>Synthetic monoglutamate from supplements (D)</p> Signup and view all the answers

Flashcards

Bioavailability of a nutrient

The amount of a nutrient that is absorbed and used by the body.

Factors influencing bioavailability

Digestion efficiency, previous nutrient intake, and food preparation methods.

Provitamin A

A form of vitamin A that needs conversion into a usable form.

Beta-carotene

A precursor to vitamin A.

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Solubility

Vitamins can either be fat-soluble or water-soluble.

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Toxicity of Vitamins

Excessive intake of vitamins can be harmful.

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Precursors

Inactive forms needing transformation into active vitamins.

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B Vitamins and energy

B Vitamins are essential for energy production in the body.

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Riboflavin (B2) function

Acts as a coenzyme in energy metabolism, using flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD).

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Riboflavin Deficiency Symptoms

Inflammation of membranes in the mouth, skin, eyes, and gastrointestinal tract.

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Niacin (B3) Forms

Exists as nicotinic acid and nicotinamide; nicotinamide is the primary form in the blood.

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Niacin Coenzyme roles

Key in metabolic reactions as NAD (nicotinamide adenine dinucleotide) and NADP (phosphate form), transporting hydrogen and electrons.

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Niacin Recommendations

Recommended daily allowance (RDA) is expressed in niacin equivalents (NE).

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Tryptophan & Niacin Conversion

Body converts the amino acid tryptophan to niacin, but ONLY after other protein needs are met.

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Pellagra Cause

Niacin deficiency leads to pellagra, characterized by symptoms like diarrhea, dermatitis, dementia, and potentially death (4 D's).

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Niacin Conversion Ratio

60 milligrams of tryptophan are equivalent to 1 milligram of niacin.

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Riboflavin Stability

Riboflavin is heat stable but is destroyed by ultraviolet (UV) light.

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Nutritional Yeast and Riboflavin

Nutritional yeast is a good source of riboflavin.

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Pellagra Symptoms

A skin condition (dermatitis) is a symptom of niacin deficiency.

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Niacin Deficiency

Results in a skin condition called pellagra.

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Niacin Toxicity Source

High doses of nicotinic acid from supplements, not naturally occurring niacin.

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Niacin Toxicity

Large doses of nicotinic acid from supplements can cause health problems.

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Niacin Flush

A reaction that occurs in doses of 3-4 times the recommended daily allowance (RDA).

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Niacin Source

Food sources are less likely to cause problems from excessive intake compared to supplements.

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HDL Cholesterol

Higher in blood due to large doses of nicotinic acid.

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Food Preparation Loss

Niacin is less vulnerable to loss because of how it is prepared, compared to other vitamins.

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Toxicity and Supplements

Supplement-based nicotinic acid consumption can induce toxicity.

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Naturally Occurring Niacin

Does not generally cause toxicity.

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Folate deficiency in pregnancy

A lack of folate during pregnancy can lead to neural tube defects in the developing baby. It is crucial to consume folate-rich foods or supplements before and during the first trimester.

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Folate's role in blood clot formation

Folate plays a crucial role in the formation of blood clots, which is important for wound healing and preventing excessive bleeding.

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Folate bioavailability

Bioavailability of folate refers to how much of the folate consumed is actually absorbed and utilized by the body. Synthetic folate is more bioavailable than naturally occurring folate.

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Folate deficiency anemia

A lack of folate can lead to a type of anemia characterized by abnormally large red blood cells (macrocytic or megaloblastic anemia).

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Folate's effect on atherosclerotic lesions

Studies suggest that folate may help reduce the risk of developing atherosclerotic lesions, which can lead to heart disease.

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Folate's absorption and activation

Different folate forms exist, and their bioavailability varies depending on the source. Monoglutamate folate from supplements is more readily absorbed than polyglutamate folate from food.

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Folate's role in preventing birth defects

Folate plays a crucial role in preventing neural tube defects in babies during pregnancy. It is essential to consume adequate folate before and during pregnancy.

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What is Niacin Flush?

A temporary reddening of the skin, often experienced after consuming large doses of nicotinic acid (niacin). It's a common side effect, but not experienced with nicotinamide.

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What does Coenzyme A do?

Coenzyme A (CoA) plays a crucial role in metabolism by transporting activated carbon units (acetyl groups) to various reactions. It's essential for energy production.

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Sources of Pantothenic Acid (B5)

Pantothenic acid (B5) is abundant in various foods, including meat, poultry, eggs, dairy products, and vegetables. It is also found in whole grains but is easily destroyed by processing.

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B6 and Amino Acid Metabolism

Vitamin B6 (pyridoxine) is a critical player in amino acid metabolism, enabling the transfer of amino groups for protein synthesis and the creation of non-essential amino acids.

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What makes up B6?

B6 exists in three forms: pyridoxal, pyridoxine, and pyridoxamine. All three can be converted into the active coenzyme form, pyridoxal phosphate (PLP).

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Where is B6 Stored?

Vitamin B6 is primarily stored in muscle tissue, with limited stores in other tissues. This means muscle cells have higher concentrations of B6 compared to other organs.

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How does B6 Deficiency Occur?

Alcohol consumption, certain medications like isoniazid, and some contraceptives are associated with B6 deficiency. These factors can interfere with B6 absorption or utilization.

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Biotin's Role in Energy Production

Biotin (B7) acts as a coenzyme in the citric acid cycle (TCA), a crucial step in energy production. It carries activated carbon dioxide for key reactions.

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Role of THF

Tetrahydrofolate (THF) is the active coenzyme form of folate (B9). It facilitates the transfer of single-carbon units during crucial metabolic processes.

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Key Functions of Folate (B9)

Folate is vital for DNA synthesis, the conversion of vitamin B12 into its active coenzyme, and the regeneration of methionine (an essential amino acid).

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Study Notes

Chapter 10: Water-Soluble Vitamins: B Vitamins and Vitamin C

  • This chapter details water-soluble vitamins, specifically B vitamins and Vitamin C
  • Vitamins are crucial for nutritional health
  • B vitamins differ from energy nutrients as they do not yield energy.
  • Dietary Reference Intake (DRI) values are set as goals for individuals or groups to ensure good nutrition and health. These include RDA, AI, UL, and EAR.
  • Bioavailability: The degree to which a nutrient is absorbed and used. This is affected by several factors.

The Vitamins - An Overview

  • Vitamins support nutritional health.
  • B1- Structure: individual units
  • B2- Function: no energy yielded
  • B3- Food contents
  • DRI (Dietary Reference Intake) established goals for individuals or groups for nutritious health: RDA, AI, UL, & EAR.

Bioavailability

  • Bioavailability is the rate at and the extent to which a nutrient is absorbed and used by the body
  • Factors influencing bioavailability:
    • Efficiency of digestion and time of transit through the GI tract
    • Previous nutrient intake and nutrition status
    • Method of food preparation (raw, cooked, processed)
    • Source of the nutrient (synthetic, fortified, natural)
    • Other foods consumed at the same time

Synthetic vs Organic Vitamins

  • Synthetic vitamins are produced in a lab from chemical compounds.
  • Organic vitamins are sourced from whole foods
  • Bioavailability of synthetic vitamins is often lower than organic vitamins.
  • This is often due to the body's inability to process synthetic compounds as easily.
  • High dosages of synthetic vitamins could cause health risks due to overdosing.

Precursors

  • Precursors are substances that precede other compounds that can be converted from inactive forms into active forms.
  • Provitamins. Often referred to as inactive forms that can be converted into active forms.
  • Example: Beta-carotene (Provitamin A) is about 1/6 the biological activity of retinol (vitamin A) and the body converts it using an enzyme.

Minimizing Nutrient Losses

  • Slow the degradation of vitamins by refrigerating fruits and vegetables.
  • Minimize oxidation by storing cut fruits/veggies in airtight wrappers and refrigerate opened containers.
  • Rinse produce before cutting (or not after), to prevent contamination
  • Use microwave or steaming to minimize losses when cooking, add vegetables when the water is boiling. Use cooking water in casseroles/soups. Avoid high temperatures and long cooking times.

Dose Levels and Effects

  • As you increase intake in one direction, the effect improves, then no further increase yields further benefit
  • The most ideal effect occurs at an intermediate dose.
  • For most nutrients, too much intake can be just as detrimental as too little.

Water-Soluble and Fat-Soluble Vitamins Compared

  • Absorption, Transport, Storage, Excretion, Toxicity, Requirements

Solubility and Precursors

  • Match the following:
  • Precursors (Inactive vitamin forms that can be converted to active vitamins)
  • Solubility (Different types like fat and water soluble)
  • Organic (Vitamins obtained from whole foods)
  • Toxicity (Adverse effects of high dose)

The B Vitamins

  • B vitamins are essential for energy release although they are not themselves energy.
  • They assist enzymes with energy release. Many enzymes need a co-enzyme to function.

The B Vitamins (CONTINUED)

  • Without B vitamins, the body lacks energy
  • B vitamins help the body use macronutrients for fuel
  • Coenzymes assist enzymes with releasing energy.

Thiamin (B1)

  • Part of coenzyme thiamin pyrophosphate (TPP) used in energy metabolism
  • Assists in energy metabolism
  • Converts pyruvate to acetyl-CoA for use in the TCA cycle
  • Important in nerve and muscle activity

Riboflavin (B2)

  • Part of coenzymes FMN and FAD used in energy metabolism
  • Important for the functioning of membranes throughout the body including the mouth, skin, eyes, and digestive tract.
  • A deficiency in riboflavin is called Ariboflavinosis.

Niacin (B3)

  • Two chemical structures: Nicotinic acid and Nicotinamide. Nicotinic Acid is the major form of Niacin in the blood
  • Two coenzyme forms (NAD and NADP): used in metabolic reactions and carry hydrogen and electrons.
  • Significant deficiency in Niacin is called Pellagra (4 D's - Dermatitis, Dementia, Diarrhea, and Death)

Pantothenic Acid (B5)

  • Part of coenzyme A - Acetyl CoA
  • Critical for Metabolism and synthesis of essential compounds.
  • Widespread in foods
  • Easily destroyed by processing.
  • Rare deficiency.

Vitamin B6 (Pyridoxine)

  • Part of coenzymes PLP (pyridoxal phosphate) and PMP (pyridoxamine phosphate).
  • Used in amino acid and fatty acid metabolism, tryptophan conversion to niacin and serotonin, as well as red blood cell formation.
  • Essential for the functioning of proteins and enzymes in the human body
  • Stored exclusively in muscle tissue.

Biotin (B7)

  • Coenzyme in metabolism. It is involved in energy metabolism and the synthesis of fatty acids, glucose, and amino acids in the human body.
  • Critical in the TCA cycle, delivers carbon to pyruvate to form oxaloacetate.
  • Widespread in food sources.

Folate (B9)

  • Primary coenzyme form- THF (tetrahydrofolate)
  • Transfers 1-carbon compounds during several metabolic processes.
  • Needed for the formation of new cells.
  • Converts vitamin B12 to coenzyme form.
  • Regenerates methionine (amino acid) from homocysteine (amino acid), which is also an amino acid
  • Widespread in many different foods
  • Easily destroyed by heat and oxygen
  • Deficiency symptoms include anemia (macrocytic) as well as mouth and body issues such as fatigue, glossitis, mental confusion, shortness of breath and weakness
  • Folate is critical during pregnancy for the prevention of neural tube defects.

Vitamin B12 (Cobalamin)

  • Part of coenzymes methylcobalamin and deoxyadenosylcobalamin that are important in cell synthesis
  • It helps maintain nerve cells and break down fatty acids and amino acids.
  • Essential for cell function and nerve function.

Vitamin C

  • Antioxidants neutralize substances by donating electrons (two words)
  • Vitamin C can be reactivated as a process called recycling.
  • Vitamin C enhances iron absorption by preventing its oxidation
  • Structural protein of connective tissue called collagen
  • Essential for bone and teeth formation.
  • High doses can be harmful to some people.

Additional Notes

  • Supplements and fortified foods are more bioavailable than naturally occurring vitamins.
  • Vitamins have many roles throughout the human body like acting as co-factors in chemical reactions and overall health.

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