Nutrition Quiz: Vitamins B1, B2, and B3

Water-Soluble Vitamins: B Vitamins and Vitamin C

• Water-soluble vitamins are organic, essential nutrients needed in small amounts for optimal health.
• Examples include B vitamins and vitamin C.
• The first vitamins discovered contained nitrogen.

Chapter Outline

• An overview of vitamins, roles, deficiency symptoms, and food sources will be covered for each of the B vitamins and vitamin C.

Vitamins - An Overview

• Vitamins are organic nutrients.
• Vitamins are needed in small amounts to prevent deficiencies and support optimal health.
• They differ from carbohydrates, fats, and proteins because they are not linked in chains and do not produce energy directly when metabolized.
• Daily intake is measured in micrograms or milligrams, not grams.
• Vitamins are essential, organic, and available from food.

How Vitamins Differ from Other Macronutrients

• Vitamins are individual units, not linked like molecules of glucose or amino acids.
• Many vitamins assist enzymes involved in releasing energy.

Classification of Vitamins

• Vitamins are categorized as either water-soluble or fat-soluble.
• Water-soluble vitamins include the B vitamins and vitamin C, and these are absorbed directly into the bloodstream.
• Fat-soluble vitamins include vitamins A,D,E, and K; they require protein carriers to pass into the lymph and then into the bloodstream. These are stored in fat-tissue.

Water-Soluble Vitamins - Handling and Requirements

• Absorption: Travel directly into the bloodstream.
• Transportation: Travel freely in water-filled portions of the body.
• Storage: Circulates freely throughout the body. Excess is excreted by the kidneys in urine.
• Toxicity: Can reach toxic levels if consumed in large quantities from supplements.
• Requirements: Needed frequently (e.g., 1-3 days).

The B Vitamins

• Choline, thiamine, riboflavin, niacin, biotin, pantothenic acid and vitamin B6.
• Vitamin B12 and folate are also considered B vitamins.
• The B vitamins have different functions within the body, all relating to energy metabolism. Specific functions are detailed in the slides discussing each individual vitamin.

Several B Vitamins

• Thiamine, riboflavin, niacin, pantothenic acid, and biotin are part of the coenzymes which assist enzymes for energy release from carbohydrates, fats, and protein.

The B Vitamin Reactions for Energy Release

• Coenzymes accept and transfer electrons and groups of atoms.
• Compounds are attracted to their sites on enzymes during the reactions that enable the release of energy.

Simplified Overview of Energy-Yielding Pathways

• All energy-producing nutrients (protein, carbohydrates, and fat) are broken down to Acetyl CoA.
• Acetyl CoA enters the TCA cycle, and hydrogen atoms with electrons are released to carry to the transport chain which enables synthesis of ATP.
• Hydrogen atoms react with oxygen to produce water.

Chemical Intermediates in Metabolic Pathways

• Che mical intermediates help with interlinking between different metabolic pathways for energy production and specific vitamin use in many reactions.

Thiamin (Vitamin B1)

• Active form is Thiamin pyrophosphate (TPP).
• TPP is involved in energy metabolism and occupies a specific site on nerve cell membranes.
• TPP helps to produce energy by converting pyruvate to Acetyl CoA.

Thiamine's Food Sources and Recommendations

• Found in whole-grain, fortified, or enriched grain products in moderate amounts in nutritious foods.
• Recommended daily intake for men is 1.2 mg/day, while for women it is 1.1 mg/day.

Thiamin Deficiency

• People relying on empty-calorie foods or beverages risk thiamin deficiency.
• Prolonged deficiency leads to beriberi, a disease exhibiting dry or wet symptoms.

Riboflavin (Vitamin B2)

• Active forms: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD).
• Involved in energy-releasing reactions.
• Function as coenzymes.

Riboflavin Roles In The Body

• It plays many roles in metabolic reactions, most notably in energy metabolism.

Niacin (Nicotinic Acid; Vitamin B3)

• Active forms: nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+).
• Important in energy-transfer reactions.
• Converts glucose and fat into energy.
• Protects against some neurodegenerative illnesses.

Niacin Food Sources and Recommendations

• Found in milk, eggs, meat, poultry, fish: whole grains, fortified and enriched-grain products; nuts.
• Converts amino acid tryptophan to niacin.
• Recommended intakes are expressed as Niacin Equivalents (NE), including the amount of niacin present in food. (Tryptophan intake is often considered as well to assess the amount of NE obtained).

Niacin Deficiency and Toxicity

• Deficiency can lead to pellagra.
• High doses from supplements can result in "niacin flush".

Biotin

• Acts as a coenzyme, carrying activated carbon dioxide in metabolic processes.
• Involved in gluconeogenesis, fatty acid synthesis, and certain fatty acid and amino acid breakdowns.

Biotin in Food Sources and Recommendations

• Biotin is widespread in foods including egg yolks, liver, fish, and whole grains.
• Recommended daily intake for adults is 30 µg/day.

Pantothenic Acid (Vitamin B5)

• Part of coenzyme A (CoA) which forms acetyl-CoA, a key compound in various metabolic pathways (including the TCA cycle).
• Involved in lipid, neurotransmitter, and hemoglobin synthesis.

Pantothenic Acid Food Sources, Recommendations, and Deficiency Symptoms

• Found in beef, poultry, whole grains, potatoes, tomatoes, and broccoli.
• Recommended intake for adults is 5 mg/day.
• Deficiency symptoms are rare.

Vitamin B6

• Occurs in three forms: pyridoxal, pyridoxine, and pyridoxamine.
• All can be converted to the coenzyme PLP or pyridoxal phosphate.
• PLP is involved in over 100 reactions, including carbohydrate and amino acid metabolism.
• Converts tryptophan to niacin and to the neurotransmitter serotonin.
• Plays a role in the synthesis of heme, nucleic acids, and lecithin.

Vitamin B6 Recommendations and Food Sources

• Found in meats, fish, poultry, potatoes, legumes, fortified cereals, and liver.
• Recommended daily intake for adults is 1.3 mg.
• Large doses can cause neurological damage.

Folate (Folacin / Folic Acid)

• Converted to tetrahydrofolate (THF).
• THF receives one-carbon fragments and transfers in amino acid synthesis and other important metabolic reactions.
• Activated folate coenzyme is involved in synthesis of DNA, RNA.

Folate in foods and recommendations

• Folate is widespread in fortified grains, leafy green vegetables, legumes, seeds, and liver.
• Daily recommendation of 400 µg.
• A high upper limit (UL) intake is 1000 ug.

Folate and Neural Tube Defects

• Folate requirements are especially crucial during pregnancy.
• Folate supplements can prevent neural tube defects in developing fetuses, reducing associated disorders and death.

Vitamin B12 (Cobalamin)

• Physiologic coenzyme forms: 5'-deoxyadenosylcobalamin and methylcobalamin.
• Vitamin B12 conversion to coenzyme form needs activation. Vitamin B12 depends on the conversion of folate and vice versa.
• Needed for DNA synthesis and amino acid metabolism.
• Involved in converting homocysteine to methionine and thus maintaining amino acid homoeostasis.

Vitamin B12 Digestion and Absorption

• Digestion involves several steps to absorb vitamin B12.
• Diet -> Stomach (parietal cells and R-protein that carries B12) -> Intestine -> Absorption into mucosal cells -> Blood.

Vitamin B12 and Folate Interactions

• Both vitamin B12 and folate depend on each other for activation (especially regarding folate conversion).

Vitamin B12 in the body

• The regeneration of the amino acid methionine and synthesis of both DNA and RNA depends on both folate and vitamin B12.
• Vitamin B12 maintains the sheath surrounding nerve fibers, promoting their normal growth and activity.
• Bone cell activity and metabolism depend on vitamin B12.

Vitamin B12 Food Sources and Recommendations

• Primarily derived from animals. (Meats, fish, poultry, dairy products)
• Adults require 2.4 µg daily.

Choline

• Although not a vitamin, it's grouped with the B vitamins.
• Essential nutrient involved in the synthesis of the neurotransmitter acetylcholine and the phospholipid lecithin.

Choline Food Sources, Recommendations, and Comments

• Sources include milk, liver, eggs, and peanuts
• AI: Men 550 mg/d and women 425 mg/d. UL:Adults 3500 mg/d.
• Liver damage can result from a deficiency. Low blood pressure and reduced growth rate may result from a high intake.

Vitamin C (Ascorbic Acid)

• Main function is as a reducing agent in multiple metabolic reactions.
• It protects against oxidative damage.
• Facilitates collagen formation, important for tissue structure and wound healing.
• Strengthens the body's resistance to infection.
• Aids in iron absorption.

Vitamin C Food Sources and Recommendations

• Citrus fruits, dark green vegetables, strawberries, tomatoes, and mangoes.
• Adults require 90 mg/d for men and 75 mg/d for women. Smokers need 35 mg more than non-smokers.
• UL: 2000 mg/d for adults.

Test your knowledge on essential vitamins, specifically Thiamin (B1), Riboflavin (B2), and Niacin (B3). The quiz covers their roles, sources, recommended daily allowances, and deficiency symptoms. Perfect for students in nutrition or health sciences!