VITAMINSChapter 7

Learning Objectives Explain the roles vitamins play in growth

and good health List and describe the general functions

and food sources of fat-soluble vitamins and water-soluble vitamins

List nutrients of concern that many Americans lack in their diets and foods sources of these nutrients

Learning Objectives

Identify diseases caused by specific vitamin deficiencies

Give tips to ensure that vitamin intake is sufficient

Identify cooking techniques that promote retention of nutrients and those that cause nutrient loss from foods

Vitamins Essential for life and

health Needs are small

measured in milligrams (1/1000 of a gram) or micrograms (1/1000 of a milligram)

Do not provide energy

Must be obtained through food

Vitamins

All are organic compounds (contain carbon in their structure)

Each vitamin has specific biological functions

Absence of each vitamin causes a specific deficiency disease

Vitamins

13 are essential nutrients

Must come from food, not made in the body or the body does not make enough

Some foods contain precursors that can be converted in the body into vitamins

How the Body Uses Vitamins

Facilitate the processes by which other nutrients are: Digested Absorbed Metabolized Built into body structures

Absence of a vitamin may cause a nutrient deficiency (symptoms go away when vitamins are replenished through diet)

Dangers of Excess Vitamins

Regular intake of high-dose supplements can be dangerous, stressing liver and kidney

Amounts found in foods are safe

Fat-soluble vitamins are stored, toxicity possible

Supplements can interfere with meds/ alter lab tests

Two Types of Vitamins1.) Fat Soluble

A, D, E, K

2.) Water SolubleB vitamins -thiamin, riboflavin, niacin,

folate, B12, B6, Biotin, Pantothenic Acid

Vitamin C

Shortfall Nutrients – or Nutrients of ConcernMany people do not get adequate amounts of:

• Vitamin A• Vitamin C• Vitamin D*• Vitamin E• Vitamin K

• Calcium*• Magnesium• Potassium *• Sodium*

Vitamins Minerals

* Biggest nutrient gaps Most diets also lacking dietary fiber Most children and adults get too much sodium

FAT SOLUBLE VITAMINS

Fat Soluble Vitamins Must be absorbed with fat

Stored in body fat and liver

Can build up to toxic levels, especially as supplements in high doses

Vitamins A, D, E, K

Vitamin A

Antioxidant

Important roles in:VisionBone and tooth growthReproductionCell functionsImmune system

Vitamin A Retinol – active form

liver, egg yolks, dairy foods

Precursors include carotenoids – beta-carotene which can be changed to active form in intestine bright orange, yellow, green fruits and vegetables

Measured in retinol activity equivalents (RE) it takes 12 mcg of beta-carotene to convert to 1 mcg

retinol

Vitamin DSome made in body with sunlight

Those who do not have skin exposed to sunlight need more from diet

Acts like a hormone to help body absorb and regulate calcium and phosphorus for strong bones, teeth and muscle

Several forms: Calciferol D2 = ergocalciferol D3 = cholecalciferol

Vitamin DFood sourcesdairy and other fortified foods, egg yolks butter, salmon, shrimp, mushrooms100 IU in 1 cup milkDeficiency fragile bones (osteoporosis)soft bones (osteomalacia), rickets increased cancer riskdepression, dementiainfections, gum disease

Vitamin D Requirements Dietary Guidelines 2010

600 IU children, most adults 800 IU 70 and older 1000 IU common supplementation

recommendation Up to 10,000 IU recommended to

replenish for 1-2 weeks, then 1000 IU a day

Vitamin E - TocopherolAntioxidant in cell membranes especially lungs, brain, blood

SourcesSeeds, nuts, oils fortified cereals, spinach greens, pumpkin, red bell peppers

Vitamin K - Phylloquinone

Intestines make about half of daily need Antibiotics reduce production

Needed to make the proteins involved in blood clotting People who take meds to reduce blood clotting may

need to adjust intake of foods with vitamin K

Works with vitamin D to regulate blood calcium levels and form bone

Food sources: green leafy veg (kale, greens, spinach, broccoli)

WATER SOLUBLE VITAMINS

Water Soluble Vitamins Should be eaten daily

None or little stored

Excesses usually excreted through urine

Excess by supplements can cause increased need

The B Vitamins

B Vitamins- General Functions

Metabolize Energy as Coenzymes(catalysts)release calories from carbohydrates, protein and fats

Necessary to form red blood cells, heal wounds

Growth and development

Nerve functions

Proper digestion and appetite

B Vitamins Continued.. B vitamins found in most protein foods, leafy

green vegetables and grain (enriched) productsEnrichment- replaces thiamin, riboflavin,

niacin

Generally little stored in the body

Oversupply or deficiency of one B vitamin can effect need and use of others

Thiamin- B1

Critical role in energy metabolism

Necessary for nerve and heart function

Riboflavin- B2

Essential for metabolism of carbohydrates to produce energy

Milk, dairy and organ meats are rich in riboflavin.Light destroys riboflavin. Dairy should be in containers that block light

Niacin- B3

Essential for metabolism of carbohydrates to produce energy

Body can make niacin by converting tryptophan (essential amino acid)

Niacin- high doses can cause itching, flushing, liver damage, high blood sugar

Pantothenic Acid- B5 Coenzyme in metabolic processes Deficiencies Uncommon No toxicities reported

Pyridoxine- B6

Part of coenzyme necessary for metabolism of carbohydrates, fat and protein

Necessary for nervous and immune system

Needed to convert tryptophan to niacin Needed to make hemoglobin

Vitamin B12

Assists in bone-blood cell formation

Pernicious anemiaProtects nerve fibersCarbohydrate, protein, fat energy metabolismNeeds intrinsic factor for absorptionFound in animal foods, fortified in vegetarian. Vegans should B12 supplement

Folate

Part of coenzymes necessary to form DNA

Important for red blood cell formation

Helps the body use protein

Folate Food Sources: legumes, oranges, green leafy

vegetables, enriched grains, asparagus, beets

Some lost in cooking

Fortification- adds folacin to grain foods. Folacin- more stable form

Critical in early pregnancy to prevent birth defects Part of coenzymes necessary to form DNA Women of child bearing age need supplemented

folate

Vitamin C – Functions

Helps make collagen (protein that stabilizes cell walls)

Helps keep gums and other tissues healthy

Aids in the healing of cuts and wounds

Helps the body absorb iron

Necessary to form thyroxin (hormone that regulates metabolic rate)

Vitamin C

Shortfall nutrient because many Americans do not eat enough fruits and vegetables

More needed by: Pregnant and lactating women Smokers Infections, fevers or wound healing

Food Issues Related to Vitamin C

Least stable nutrient. Destroyed by: Heat Leaching into water while cooking Evaporation

Some juices and cereals fortified with Vitamin C

Supplements in high doses may cause gastrointestinal symptoms

Vitamin C - SourcesExcellent sources include: Red bell peppers Oranges Grapefruit Broccoli Strawberries Papaya Brussels sprouts Fortified cereal or juices Tomatoes

Bioavailability is Influenced By: Nutritional status - if you are deficient your

body will absorb more

Other nutrients at the same meal- compete for protein carriers needed for absorption

Nutrients in high dose supplements are not used as well as nutrients in foods

Binders such as oxylates and phytates

Nutrient Bioavailability Enhanced By:

The form of a nutrient; • vitamin D3 is absorbed better than D2

Fermentation processes• Ex. miso and tempeh, may improve iron

bioavailabilityFood preparation techniques

• soaking and sprouting beans, grains and seeds, leavening bread, can reduce binding of zinc by phytic acid and increase zinc bioavailability

Organic acids• Ex. citric acid can enhance zinc absorption

Nutrient Bioavailability is Reduced By:

Too much of one mineral can reduce the absorption of another

Polyphenols in regular and herbal teas, coffee and red wine bind some iron

Cooking softens cell walls of food so more nutrients released

Nutrient Retention – Purchase Forms

Canned: Canned foods are packed at their peak of freshness and due to the absence of oxygen during their storage period, canned fruits and vegetables have a longer shelf life and remain relatively stable up until opened.

Fresh: Fresh is best if consumed within a short time after purchasing.

Frozen: Frozen products are packed at their peak of nutrition and freshness. At least equal to fresh in nutrients.

Nutrient Retention – In the Kitchen To retain nutrients: keep fresh produce

chilled and covered Peel only when necessary. Peeling

removes nutrients and fiber of peel and under peel

Use pulp in citrus rather than straining it out

Purees and coulis increase nutrient availability by breaking cell walls

Serve cooked vegetables immediately after cooking – holding causes nutrient losses

Nutrient Retention – In the Kitchen

Reserve liquids from cooked vegetables and add to stocks, sauces, etc

Fry as little as possible. High heat destroys some nutrients and creates free-radicals

Drain and rinse canned beans to reduce sodium

Drain brines from capers, pickles and other foods packed in salted liquids

Chapter 7: Vitamins, Minerals and Phytochemicals

Discussion Questions and Answers Assignments