Chap 7

V.

Chan, MS, RD

Classification & definitions of Vitamins

•

Essential, noncaloric, organic•

Role: help make other body processes occur to digest, absorb, metabolize nutrients, also help build body structures

•

Precursors/ Previtamins: compounds converted into active vitamins–

(Ex) Beta Carotene & Vitamin A

•

2 types of Vitamins

Classification of Vitamins

•

Fat Soluble–

Absorbed into the lymph

–

Travel in the blood with protein carriers–

Can be stored in the liver or fatty tissues

•

Water Soluble–

Absorbed into the blood stream

–

Travel freely in the blood system–

Excess excreted in urine

Fat Soluble Vitamins•

Sources: fats & oils of foods

•

Absorption: bile•

Storage: liver & fatty tissues until the body needs them–

Body can survive weeks w/o consuming

–

Beware of toxicity•

Excesses of Vit

A & D from supplements and highly fortified foods

•

Possible deficiency–

Fat malabsorption

(Ex: liver disease)

–

Mineral oil (used as a laxative) –

Extremely low fat diets

Vitamin A

•

Precursor•

3 forms of Vitamin A–

Retinol: (active form) stored in specialized liver cells

–

Retinal: (converted from Retinol), function in vision

–

Retinoic Acid: (converted from Retinol) function in growth & embryonic development

•

Food Sources–

Liver, fish oil, fortified foods, eggs, carrots, apricots, pumpkin, sweet potatoes, etc

Vitamin A Role: Protein Synthesis & Cell Differentiation

•

Synthesize protein through gene regulation–

Retinoic acid activate protein production

•

Cell differentiation allows immature cells cells to mature & perform specific functions

•

(Ex) Epithelial cells –

Epithelial tissues on the outside of the body form the skin–

Epithelial tissues on the inside of the body form the mucous membranes

Vitamin A Role: Reproduction & Growth

–

Sperm development in men–

Normal fetal development in women

–

Growth in children•

Remolding Bone Process:

–

Osteoclasts

are cells that destroy bone growth–

Osteoblasts

are cells that build bones–

Lysosomes

are sacs of degradative

enzymes that destroy bones

•

Failure to grow is one of the 1st

signs of poor vitamin A intake

Vitamin A Role: Immune Function

•

Keeps the immune system strong against infections

•

Maintains mucosal surfaces •

Deficiencies are associated with impaired immunity & increased risk of infections diseases

Vitamin A Role: Vision

•

Help to maintain the cornea–

Hard transparent membrane covering the outside of the eye

•

Light perception –

Conversion of light energy into nerve impulses at the retina

•

Rhodopsin•

Light-sensitive pigment of the retina that contains a protein called opsin

Vitamin A Deficiencies•

Infectious Diseases–

Impaired immunity correlates with vitamin A deficiency in children.

•

The goals of worldwide health organizations include vitamin A supplementation

•

Night Blindness –

First detectable sign of vitamin A deficiency

–

Inability to see in dim light or inability to recover sight after a flash of bright light

–

Prolonged deficiency can lead to chronic dry eye (xerosis) & build up of keratin debris in the corners of the eyes (kerantinization)

–

Which can lead to retinal corneal damage and lead to permanent blindness (xerophthalmia)

Vitamin A Deficiencies•

Blindness–

Xerophthalmia

is blindness due to vitamin A deficiency

–

Xerosis

is the first stage where the cornea becomes dry and hard

–

Keratomalacia

is the softening of the cornea

•

Keratinization–

Epithelial cells secrete a protein called keratin—the hard, inflexible protein of hair and nails

–

Changes in epithelial cells results in keratinization, rough, dry and scaly skin

Vitamin A Toxicity

•

Can occur with large amounts from fortified foods and/ or supplements

•

Consuming excessive amounts of beta carotene from supplements can also be harmful

•

Bone Defects–

Increased activity of osteoclasts

causes

weakened bones and contributes to osteoporosis and fractures

Vitamin A DRI

•

Vitamin A recommendations is based on body weight

•

Men need average of 900 micrograms/ day•

Women need average of 700 micrograms/ day–

During lactation, needs will increase

–

Children needs decrease•

Regular balanced diet should supply more than adequate amounts–

With fruits & vegetables

Beta Carotene•

Precursor form of Vitamin A–

Type of carotenoid

(pigment)

•

Plant-based foods–

Dark leafy greens, orange and yellow fruits/ vegetables

•

Macular degeneration–

Common progressive loss of function in the retina

–

Leads to blindness•

Dietary antioxidant–

Help to reverse effects on oxidation in tissues

•

Measuring beta-carotene –

Retinol activity equivalents (RAE)

–

12 micrograms beta carotene= 1 microgram retinol–

IU (international units)

Too Much Beta Carotene….

•

Toxicity –

Can occur when beta carotene cannot be converted to retinol

Vitamin D

•

AKA Calciferol, Calcitrol, Cholecalciferol (D3), Ergocalciferol

(D2)

•

Nonessential, acts like a hormone in the body

•

Bone regulation•

Sunlight

•

The plant version: ergocalciferol

(D2)•

The animal version: cholecalciferol

(D3)

•

Once the vitamin enters the body it must become activated –

By the liver & kidneys

Vitamin D Role: Bone Growth

•

Help maintain blood levels of calcium and phosphorus

•

Work in combination with other nutrients and hormones–

Vitamin A, vitamin C, vitamin K

–

Parathormone

and calcitonin–

Collagen

–

Calcium, phosphorus, magnesium, and fluoride

More of Vitamin D Roles

•

Immune System–

Regulate immune system & cells

–

May help to prevent cancer

•

Brain & nervous system development

Vitamin D Deficiency Factors

•

Contributing factors to deficiencies–

Dark skin

–

Breastfeeding without supplementation–

Lack of sunlight

–

Use of nonfortified

milk

Vitamin D Deficiency: Rickets

•

Children: bowed legs–

Inadequate calcification of bones

–

Growth retardation–

Misshapen bones including bowing of the legs

–

Enlargement of the ends of long bones–

Deformities of ribs

•

Adults: Osteomalacia–

Bones become soft, flexible, brittle & deformed

–

Easily missed in elderly, often mistaken for arthritis–

Can further lead to osteoporosis

Vitamin D From The Sun•

Ultraviolet (UV) B light rays–

Converted into a vitamin D precursor (7-

dehyrocholesterol)–

Directly absorbed in the blood

•

Over the next 2 days, the liver & kidneys convert the precursor to the active form of vitamin D (calcitriol)

•

Sunlight does not cause Vitamin D toxicity–

Sun can break down excess vitamin D made in the skin

•

Over sun exposure causes premature skin wrinkles & skin cancers

•

SPF over 8 prevents vitamin D synthesis

Vitamin D DRI•

Infants, children, adolescent-

400 IU daily

–

Teens who drink soda instead of milk & live a sedentary lifestyle (indoors) fail to develop bone density needed later in life

•

Adults 19-

50: 5 micrograms daily•

Adults 51-

70: 10 micrograms daily

•

Adults over 70: 15 micrograms daily•

DRI UL: 50 micrograms daily–

Or 2,000 on supplement labels

Vitamin D Food Sources•

Cod liver oil

•

Salmon •

Mackerel

•

Sardines•

Fortified milk, soy milk, butter, margarine

•

Fortified cereals•

Egg

•

Liver•

Vegans may need supplementation if they do not get enough sun exposure

Vitamin E (Tocopherol)•

4 different tocopherol

compounds

–

alpha-tocopherol

is the active form in humans •

Deficiencies–

Rarely occur in healthy people

–

May occur in those who have fat malabsorption

or in premature infants

•

In premature infants, red blood cells rupture (erythrocyte hemolysis), thus becoming anemic

–

May occur in those with liver or pancreas disease–

Symptoms in adults include loss of muscle coordination & reflexes and impaired vision & speech

•

Toxicities–

Rare & least toxic of the fat soluble vitamins

Vitamin E (Tocopherol) Role

•

Antioxidant –

Stops the chain reaction of free radicals

•

Free radicals can cause inflammation which may lead to cancers, heart disease & other diseases

–

Protection of polyunsaturated fatty acids and vitamin A

–

Protects the oxidation of LDLs

Vitamin E (Tocopherol)•

DRI Vitamin E–

Adults: 15 micrograms daily

–

Adults UL: 1000 micrograms daily•

Food Sources–

Vegetable oils

•

And products made from them (margarine, salad dressings, etc)

–

Wheat germ oil •

Whole grain products

•

Animal fat have little to none–

Leafy green vegetables

–

Liver & eggs–

Nuts & seeds

–

Easily destroyed by heat & O2

Vitamin K•

Unique in that ½

of human needs are from our

intestinal bacteria•

Essential in blood clotting

•

Bone protein synthesis that regulate blood calcium–

Can lead to low bone mineral density without Vitamin K

•

Deficiency can cause uncontrolled bleeding•

Deficiencies can occur in newborn infants and people taking antibiotics

•

Warfarin

is used to thin blood (by preventing blood clots)–

Rx for irregular heartbeats, those suffered from heart attacks, those with prosthetic heart values, thrombosis, pulmonary embolism

Vitamin K Deficiencies

•

Cause hemorrhages (profuse bleeding from ruptured blood vessels)

•

Secondary deficiencies may occur with use of antibiotics

•

Newborn infants receive a single dose of vitamin K at birth because of a sterile intestinal tract–

Takes weeks to establish vitamin K producing bacteria

Vitamin K Toxicity

•

Rare•

Infants & pregnant women may experience toxicity from over intake of Vitamin K supplements

•

Jaundice–

Increase of red blood cells breakdown

–

Bilirubin, byproduct of old red blood cells –

Jaundice can also occur due to liver damage

Vitamin K DRI•

Men: 120 micrograms daily

•

Women: 90 micrograms daily•

Vitamin K Sources–

Bacterial synthesis in the digestive tract

–

Significant Food Sources•

Leafy green vegetables & cabbage type vegetables

–

Kale, spinach•

Soybeans

•

Canola oil•

Liver

•

Fortified foods

Water Soluble Vitamins

•

Storage: None•

Toxicities: possible with supplement use

•

Types:–

Vitamin C

–

B Vitamins•

Thiamin

-B6 •

Riboflavin

-B12 (cyanocobalamin)•

Niacin

-Biotin•

Folate

-Pantothenic

Acid

Vitamin C•

As an antioxidant–

Defends against free radicals

–

Protects tissues from oxidative stress•

As a cofactor in collagen formation–

Collagen is used for bones and teeth, scar tissue, and artery walls

–

Works with iron to form hydroxiproline

which is needed in collagen formation

•

As a Cofactor in Other Reactions–

Converts tryptophan

to neurotransmitters

–

Makes hormones

Vitamin C

•

Needs increase during body stress–

(Ex): infections, burns, smoking

•

Cure for common cold–

Provides some relief of symptoms

–

Deactivates histamine (antihistamine) •

Disease prevention is still being researched–

As a Cure for the Common Cold

Vitamin C Deficiency•

Scurvy–

Breakdown of collagen

–

Loss of appetite–

Bleeding gums & loosen teeth

–

Bone fragility & joint pain–

Poor wound healing & frequent

infections–

Rough skin & blotchy bruises

–

Anemia

•

Those at risk:–

Smokers

–

Alcoholics–

Infants who only drink cow’s milk & receive no vitamin C

Vitamin C Toxicity

•

Symptoms can include:–

Nausea, abdominal cramps, diarrhea, headache, fatigue and insomnia

–

Hot flashes and rashes–

Interference with medical tests, creating a false positive or a false negative

–

Aggravation of gout symptoms, urinary tract infections, and kidney stones

Vitamin C DRI

•

Men: 90 mg/ day•

Women: 75 mg/ day

•

Smokers:+ 35mg/ day•

Adults UL: 2,000 mg/ day

Vitamin C Food Sources

•

Citrus fruits, cantaloupe, strawberries, papayas and mangoes

•

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

•

Other Relevant Information–

Also called ascorbic acid

–

Easily destroyed by heat and oxygen

Vitamin B:

•

8 types–

Function in unison

•

Coenzymes–

Metabolism & cell multiplication

•

There are deficiencies, toxicities and food sources that are unique for each vitamin

Thiamin (Vitamin B1)

•

Energy metabolism of all cells•

Deficiencies–

Wernicke-Korsakoff

syndrome

•

Brain damage due to inability to absorb thiamin•

Common in those with alcohol abuse

–

Beriberi•

Wet beriberi presents with edema, affects cardiovascular system

•

Dry beriberi presents with muscle wasting, affects the nervous system

Thiamin (Vitamin B1)•

DRI–

Men: 1.2 mg/day

–

Women: 1.1 mg/day•

Food Sources–

Pork

–

Organ meats–

Fortified/ enriched food products

–

Whole grains–

Nuts/ seeds

•

Easily destroyed by heat

Riboflavin (Vitamin B2)

•

Energy metabolism of all cells•

Deficiency symptoms–

Inflamed eyelids, sensitivity to light, and reddening of the cornea

–

Sore throat and cracks and redness at the corners of the mouth

–

Painful, smooth and purplish red tongue–

Skin rashes

Riboflavin (Vitamin B2)•

DRI–

Men: 1.3 mg/day

–

Women: 1.1 mg/day•

Food Sources–

Milk products, including yogurt and cheese

–

Enriched/ fortified and whole grains–

Liver

•

Destruction of vitamin–

UV light

•

Milk–

Irradiation

–

However, is heat stable (not destroyed by cooking)

Niacin (Vitamin B3)•

Involved in the metabolism of glucose, fat & alcohol

•

Deficiency –

Pellagra•

Diarrhea•

Dermatitis–

“flakey paint”–

Rash occurs in sunlight•

Dementia•

Death

•

Toxicity–

Niacin flush•

Physicians may give a large dose of niacin to help improve blood lipids due to CVD

•

When taken in large doses, niacin can dilate the capillaries & may be painful

Niacin (Vitamin B3)•

DRI–

Precursor: tryptophan

(60 mg of tryptophan

= 1 mg niacin); therefore niacin intake is measured in niacin equivalents (NE)

–

Men: 16 NE/day–

Women: 14 NE/day•

Food sources–

Milk–

Eggs, meat, poultry and fish–

Whole-grain & enriched/ fortified breads and cereals–

Nuts and all protein-containing foods•

Resistant to heat

Folate•

Involved in the synthesis of DNA and the formation of new cells

•

Require B12

to function properly•

Deficiencies–

Macrocytic

anemia

–

Diminished Immunity –

Abnormal digestive function

•

Most vulnerable of all the vitamins to interactions with medications–

Anticancer drugs

–

Antacids and aspirin

Folate

& Birth Defects

•

Neural tube defects, include spina

bifida and anencephaly (baby born w/o a part of brain & skull)

•

Recommended for women of childbearing age eat folate-rich foods and folate-fortified foods and take folate

supplements containing 0.4 mg

(400 microgram) of folate

daily.–

Pregnant women should take folate

supplements

Folate•

Toxicities–

Masks vitamin B12

deficiency symptoms•

DRI–

Adults: 400 micrograms/ day–

UL: 1,000 micrograms/ day•

Food Sources–

Beef liver–

Leafy green vegetables–

Fortified/ enriched grain products–

Legumes & seeds•

Easily destroyed by heat & O2

Vitamin B12

(Cobalamin)

•

Closely related to folate•

Involved in the synthesis of new cells, maintains nerve cells, reforms folate

coenzymes and helps

break down some fatty acids and amino acids•

Deficiencies–

May be masked by folic acid intake

–

Pernicious anemia•

Vitamin B12

absorption–

Intrinsic factor, compound aid in absorption

Vitamin B12

(Cobalamin)

•

DRI–

Adults: 2.4 micrograms /day

•

Food Sources–

Meat, fish, poultry, and shellfish

–

Milk, cheese and eggs–

Fortified/ enriched cereals

•

Easily destroyed by microwave cooking

Vitamin B6 (Pyridoxin)

•

The coenzyme forms of vitamin B6

are involved in amino and fatty acid metabolism, the conversion of tryptophan

to niacin or serotonin

and the production of red blood cells•

Vitamin B6

Deficiency/ Toxicity–

Anemia

–

In adults, affects the peripheral nerves, skin, mucous membranes and the circulator system

–

In children, the central nervous system (CNS) is also affected

Vitamin B6 (Pyridoxin)

•

DRI–

Adults 19-50 years: 1.3 mg/day

–

UL: 100 mg/ day•

Food Sources–

Meats, fish, poultry and liver

–

Legumes and soy products–

Non-citrus fruits

–

Fortified/ enriched cereals•

Easily destroyed by alcohol

Biotin•

As part of a coenzyme used in energy metabolism, biotin assists in glycogen synthesis, fat synthesis, and amino acid metabolism

•

Deficiency–

Rare

–

Symptoms•

Depression, lethargy, and hallucinations•

Numb or tingling sensation in the arms and legs•

Red, scaly rash around the eyes, nose and mouth•

Hair loss–

Biotin can be bound with raw egg-white protein (avidin)

Biotin

•

DRI–

AI: Adults: 30 μg/day

–

No UL•

Food Sources–

Widespread in foods

–

Organ meats, egg yolks and fish–

Soybeans

–

Whole grains–

Can also be made by intestinal bacteria

Pantothenic

Acid

•

Involved in energy metabolism as a key enzyme

•

Deficiency–

Rare

–

Symptoms•

Vomiting, nausea, and stomach cramps

•

Insomnia and fatigue•

Depression, irritability, restlessness, and apathy

•

Hypoglycemia and increased sensitivity to insulin

Pantothenic

Acid•

DRI–

AI Adults: 5 mg/day

–

No UL•

Food Sources–

Widespread in foods

–

Organ meats–

Mushrooms, avocados, and broccoli

–

Whole grains•

Can be destroyed by freezing, canning, and refining

Non B-

Vitamin: Choline•

Conditionally essential nutrient, but not a vitamin

•

Involved in the synthesis of acetylcholine (neurotransmitter in the nervous system) and lecithin

•

Important role in fetal development•

Deficiency/ Toxicity–

Deficiencies are rare

–

Deficiency symptom is liver damage–

Toxicity Symptoms

•

Body odor and sweating•

Salivation

•

Reduced growth rate•

Low blood pressure

•

Liver damage

Non B-

Vitamin: Choline

•

DRI–

AI Men: 550 mg/day

–

AI Women: 425 mg/day–

UL: 3,500 mg/day

•

Food Sources–

Milk

–

Liver–

Eggs

–

Peanuts

Non B-

Vitamins: Inositol, Carnitine

& Lipoic

Acid

•

Nonvitamins–

Not essential nutrients for humans

•

Inositol

is made from glucose and is part of the cell membrane structure

•

Carnitine

is made from lysine and transports long-chain fatty acids to be oxidized

•

Alpha Lipoic

acid is used in the body to break down carbohydrates and to make energy for the other organs in the body

•

Be wary of supplements

Summary of B Vitamins

•

The B Vitamins are interdependent. The 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

Summary of B Vitamins

•

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

Summary of B Vitamins

•

B Vitamin Deficiencies–

Deficiencies rarely occur singly except for beriberi and pellagra

–

Can be primary or secondary causes–

Tongue inflammation and dry, cracked lips are two symptoms common to B vitamin deficiencies

•

B vitamin toxicities can occur with supplements

Summary of B Vitamins

•

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

Did You Know That…•

Vitamins can be destroyed by exposure to light, oxidation, cooking, and storage

•

Methods used to minimize nutrient lose–

Refrigerate fruits and vegetables–

Store cut fruits and vegetables in airtight wrappers or closed containers and refrigerate

–

Clean fruits and vegetables before they are cut–

Use a microwave, steam, or simmer in small amounts of water–

Save cooking water for other uses–

Avoid high temperatures and long cooking times