The Water-Soluble Vitamins: B Vitamins and Vitamin C

The Water-Soluble Vitamins: B Vitamins and Vitamin C

Chapter 10

The Vitamins – An Overview

• Vital to health, organic, and available in foods• Vitamins differ from macronutrients–Structure–Function–Food contents

• Both deficiency and excess of vitamins can affect health


•Bioavailability▫Quantity provided by food▫Amount absorbed and used by body▫Factors influencing bioavailability


•Precursors ▫AKA Provitamins

•Organic nature▫Can be destroyed during storage and in

cooking


• Solubility–Affects absorption, transport, and excretion–Water-soluble (B vit & vit C) VS Fat-soluble–Consumption frequency of vitamins


•Toxicity▫More is not necessarily better▫Excessive intakes

The B Vitamins – As Individuals

• Very active in the body, but do not provide the body with fuel for energy. –Several B vits form part of the coenzymes –Others participate in metabolism and cell

multiplication.• Recommendations for B vits come from

RDA, AI, and Tolerable Upper Intake Levels. –deficiencies, toxicities, and food sources

are unique for each

The B Vitamins – As Individuals

The B Vitamins – Thiamin

• Part of coenzyme thiamin pyrophosphate (TPP)–Energy metabolism–Nerve activity and muscle activity

• Recommendations:–RDA Men: 1.2 mg/day.–RDA Women: 1.1 mg/day.

The B Vitamins – Thiamin• Deficiency– Malnourished and alcoholics

• Deficiency symptoms:– Enlarged heart and possible cardiac failure.– Muscular weakness.– Apathy, poor short-term memory, confusion, and irritability.– Anorexia and weight loss.

• Wernicke-Korsakoff syndrome is a severe deficiency that develops in those who abuse alcohol.

• Deficiency results in the disease beriberi (dry & wet)

• Toxicity– None reported


• Food sources:–Whole-grain, fortified or enriched grain

products–Moderate amounts in all foods–Pork

• Other Information:– easily destroyed by heat)–Leaches into water–Steaming and microwaving

The B Vitamins – Riboflavin• Riboflavin (Vitamin B2):• Involved in energy metabolism. • Coenzyme forms:– Flavin mononucleotide (FMN) & flavin adenine

dinucleotide (FAD) • Recommendations– RDA Men: 1.3 mg/day; Women: 1.1 mg/day

• Deficiency– Inflammation of membranes– Deficiency symptoms– Deficiency disease is ariboflavinosis.

• Toxicity– No reported toxicities

The B Vitamins – Riboflavin

• Food sources–Milk and milk products, including yogurt

and cheese–Whole-grain, fortified, and enriched grain

products–Liver

• Destruction of riboflavin–Destroyed–Not destroyed by cooking

The B Vitamins – Riboflavin

The B Vitamins – Niacin(Vitamin B3) •Two chemical structures

▫Nicotinic acid▫Nicotinamide

•Two coenzyme forms – metabolic reactions▫Nicotinamide adenine dinucleotide (NAD)▫NADP (the phosphate form)

The B Vitamins – Niacin• Recommendations–Body manufacturers from tryptophan

• RDA is stated in niacin equivalents–RDA Men: 16 NE/day.–RDA Women: 14 NE/day.–Upper level of 35 mg/day for adults.

The B Vitamins – Niacin• Deficiency–Pellagra–Symptoms Deficiency symptoms:

• Toxicity–Supplements or drugs• Niacin flush

–Toxicity symptoms–Potential health benefits of large doses of

nicotinic acid:

The B Vitamins – Niacin• Food sources–Milk, eggs, meat, poultry, and fish–Whole-grain and enriched breads and cereals–Nuts and all protein-containing foods

• Other Information–Also called nicotinic acid, nicotinamide, and

niacinamide.–The amino acid tryptophan is the precursor.–The vitamin can be lost from foods when it

leaches into water.

The B Vitamins – Niacin

The B Vitamins – Biotin•As part of a coenzyme used in energy

metabolism•Coenzyme that carries activated carbon

dioxide▫Critical in TCA cycle▫Participates in gluconeogenesis and fatty

acid synthesis▫Participates in breakdown of fatty acids

and amino acids

The B Vitamins – Biotin

•Recommendations – AI Adults: 30 g/day.•Deficiency and Toxicity

▫Deficiencies are rare.▫Deficiency symptoms:

▫No reported toxicities.

The B Vitamins – Biotin•Biotin can be bound with an egg-white

protein called avidin.•Food Sources:

▫Widespread in foods.▫Organ meats, egg yolks, and fish.▫Soybeans.▫Whole grains.

•Biotin can also be synthesized by intestinal bacteria.

The B Vitamins – Pantothenic Acid•Part of chemical structure of coenzyme A,

used in E metabolism

•Recommendations▫AI: Adults 5mg/day

•Deficiency▫Rare▫Symptoms:

The B Vitamins – Pantothenic Acid•Toxicity

▫None reported

•Food sources (Widespread in foods):▫Chicken, beef, liver, and egg yolks. ▫Potatoes, tomatoes, and broccoli.▫Whole grains and oats.

•Can be destroyed by freezing, canning, and refining.

The B Vitamins – B6

•Three forms: Pyridoxal, pyridoxine, and pyridoxamine

•Recent research claiming influence on cognitive performance, immune funx, steroid hormone activity.

•Stored exclusively in muscle tissue


•Recommendations▫Adults (19-50yrs): 1.3mg/day

•Deficiency▫Symptoms:

▫Alcohol destroys the vitamin.

▫Isoniazid (INH) drug used for tuberculosis acts as an antagonist.


•Toxicity

•Upper level for adults: 100 mg/day.

•Food sources Meats, fish, poultry, and liver Legumes and soy products Non-citrus fruits Fortified cereals, potatoes and other starchy

vegetables.

The B Vitamins – Folate

•Known as folacin or folic acid

•Primary coenzyme form – THF (tetrahydrofolate)

▫Transfers single-carbon compounds during metabolism

The B Vitamins – Folate•Recommendations

▫RDA Adults: 400 g/day.Dietary Folate Equivalents (DFE)

▫Higher recommendations for pregnant women. Folate and Neural Tube Defects

▫Pregnant women should take folate supplements.


•Folate and Heart Disease▫High levels of homocysteine and low levels

of folate increase risk of heart disease.▫Folate breaks down homocysteine.

•Folate may help to prevent cancer, but may also promote cancer growth once cancer has developed.

The B Vitamins – Folate•Deficiency

▫Elevated homocysteine levels.

•Most vulnerable of all the vitamins to interactions with medications.

•Toxicity▫Masks vitamin B12 deficiency symptoms.


•Toxicity:▫Upper level for adults: 1000 g/day.

•Food Sources▫Fortified grains▫Leafy green vegetables▫Legumes and seeds▫Liver

•Easily destroyed by heat and oxygen.

The B Vitamins – Vitamin B12

•Cobalamin – ▫Methylcobalamine and

deoxyadenosylcobalamin are the coenzyme forms.

•Recommendations▫RDA Adults: 2.4 g/day.


•Deficiency symptoms▫Anemia ▫Fatigue and degeneration of peripheral

nerves progressing to paralysis.▫Sore tongue, loss of appetite, and

constipation.

•Deficiency disease is called pernicious anemia.


•No known toxicities•Food Sources.

▫Meat, fish, poultry, and shellfish.▫Milk, cheese, and eggs.▫Fortified cereals.

•Other Information▫Binds with intrinsic factor▫Easily destroyed by microwave cooking.

The B Vitamins – In Concert

•Each B vitamin coenzyme is involved in energy metabolism▫Directly▫Indirectly

•Deficiencies▫Single B-vitamin deficiencies seldom show

up in isolation

The B Vitamins – In Concert•The B Vitamins are interdependent

•Presence of one may affect the absorption, metabolism, and excretion of another.

•A deficiency of one may affect the functioning or deficiency of another.

•A variety of foods from each food group will provide an adequate supply of all the B vitamins.

The B Vitamins – In Concert• B Vitamin Roles

▫ Coenzymes involved directly or indirectly with energy metabolism.

▫ Facilitate energy-releasing reactions.▫ Build new cells to deliver oxygen and nutrients for energy

reactions.

• B Vitamin Deficiencies▫ Deficiencies rarely occur singly except for beriberi and

pellagra.▫ Can be primary or secondary causes.▫ Glossitis and cheilosis are two symptoms common to B

vitamin deficiencies.▫ Symptoms that individuals experience are not necessarily

related to a vitamin deficiency.

The B Vitamins – In Concert•B vitamin toxicities can occur with

supplements.

•B Vitamin Food Sources▫Grains group provides thiamin, riboflavin,

niacin and folate.▫Fruits and vegetables provide folate.▫Meat group provides thiamin, niacin, vitamin

B6, and vitamin B12.

▫Milk group provides riboflavin and vitamin B12.

The B Vitamins – In Concert

Vitamin C – Roles •Antiscorbutic factor is the original

name•Roles

▫Serves as a cofactor to facilitate the action of an enzyme

▫Antioxidant▫As a Cofactor in Collagen Formation

Vitamin C▫As a Cofactor in Other Reactions

Hydroxylation of carnitine Converts tryptophan to neurotransmitters Makes hormones

•Needs increase during body stress, i.e. infections, burns, extremely high or low

temperatures, heavy metal intakes, certain medications, and smoking

Vitamin C▫In the Prevention and Treatment of the

Common Cold▫Role in disease prevention is still being

researched•Vitamin C Recommendations

▫RDA Men: 90 mg/day; Women: 75 mg/day▫Smokers: +35 mg/day

•Deficiency▫Disease is called scurvy▫Deficiency symptoms

Vitamin C – Deficiency

Vitamin C•Toxicity

▫Upper level for adults: 2000 mg/day•Food Sources

▫Citrus fruits, cantaloupe, strawberries, papayas, and mangoes

▫Cabbage-type vegetables, dark green vegetables like red peppers and broccoli, lettuce, tomatoes, and potatoes

•Other information▫Also called ascorbic acid▫Easily destroyed by heat and oxygen

Vitamin C – Food Sources

The Water-Soluble Vitamins: B Vitamins and Vitamin C

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