Vitamins

Vitamins

Recall from the first week:

Organic molecules (contain C, H, O, + other atoms) which regulate & assist with many metabolic reactions

Micronutrients: Needed in only small amounts

Found in all food groups

Vitamins:

Vitamins:

Vitamins in foods:Many vitamins lost during long-term storage cooking

Often enriched or fortified in foodsEnriched—replacing lost ingredientsFortified—adding extra nutrients to foods

May be obtained as “provitamins” – precursors which the body can convert to the active forms

Vitamins:

Two groups:

Fat-soluble

Water-soluble

Vitamins:

Two groups:

Fat-soluble: Vitamins A, D, E, K Absorbed with fat

into lymphatic system Stored in larger quantities Less vulnerable to

cooking losses

Vitamins:

Two groups:

Fat-soluble: Vitamins A, D, E, K Absorbed with fat

into lymphatic system Stored in larger quantities Less vulnerable to

cooking losses

Water-soluble: Eight B vitamins and vitamin CAbsorbed into bloodstreamStored in small amountsMore vulnerable to cooking losses

Vitamins:

Let’s discuss the thirteen different vitamins, focussing on - Functions of each vitamin - Sources of each vitamin - Results of too little or too much of the vitamin

Let’s start with Vitamin A

Vitamins:

Vitamin A:Group of related molecules:

Active forms (Retinoids)RetinolRetinalRetinoic Acid

Provitamins (Carotenoids) Alpha-carotene Beta-carotene Gamma-carotene

Stored in liver, released into blood as needed

Functions of vitamin A:1. Vision – both night vision and color vision

Vitamin A:

Retinoids are part of rhodopsin and iodopsin, the molecules which react to light in cells of the retina.

Vitamin A:

Helps regulate protein synthesis as cells divide & differentiate, particularly in the skeletal system and skin.

Functions of vitamin A:2. Cell growth and differentiation

Vitamin A:

Helps regulate the production and function of immune cells such as lymphocytes and macrophages.

Functions of vitamin A:3. Immune system

Vitamin A:Functions of vitamin A:

4. Reproductive system Helps regulates sperm

production and the function of uterus, Fallopian tubes,and vas deferens.

Required for normal development of embryo and fetus.

Vitamin A:Dietary sources of vitamin A:

Retinoids are only found in foods of animal origin: liver, eggs, milk

Carotenoids (can be converted to retinoids) found in yellow / orange vegetables, some leafy green vegetables

Both are often used to fortify cereals

Vitamin A:Dietary Recommendations:

“Vitamin A” is actually a group of related molecules which can be converted into other forms, and the recommended intakes are different for each.

Thus, Dietary Reference Intakes are expressed according to how active they are relative to the most common one, retinol.

For adults, the Recommended Dietary Allowance of vitamin A is between 700 and 900 ug of retinol or its equivalent per day.

Vitamin A:Dietary Recommendations:

Because vitamin A compounds are stored in the liver, excess dietary intake is not easily removed from the body and excess amounts can be toxic.

Its Tolerable Upper Intake Level is about 3,000 ug of retinol or its equivalent per day.

Vitamin A:

Deficiency:BlindnessDry, thick skinReduced immunity

Groups at riskElderlyPremature infantsAlcohol or liver diseaseAbsorption problems

Vitamin A:

Excess:Dry, itchy skinFingernail and hair damageBrittle bonesLiver damageMuscle damageAnemia

In pregnancy it is a teratogen – a substance which causes birth defects

Vitamin D:Next: Vitamin D

“Vitamin D” is also a group of related compounds.

Next: Vitamin D

“Vitamin D” is also a group of related compounds.

The two most common and important are ergocalciferol(also known as D2) and cholecalciferol (D3).These are converted in the liver and kidneys to the active form of the vitamin 25-hydroxyvitamin D [25(OH)D],also known as calcitriol.

Vitamin D:

Regulates blood calcium levels in three ways:

Function of vitamin D:

Vitamin D:



Vitamin D:



Vitamin D:

Dietary sources of vitamin D:Sun exposureOily fish (e.g. sardines, herring, salmon

Most of our intake is fromfortified foods such as milk and cereal

Vitamin D:

Dietary Recommendations:In the absence of sunlight exposure, the Adequate Intake of vitamin D is 5 to 10 ug/day.However, most people are exposed to enough sunlight for their skin to produce at least some of this: Light-skinned individuals: 8 to 30 minutes per week Dark-skinned individuals: 20 to 90 minutes per week

Vitamin D:

Dietary Recommendations:Like vitamin A, vitamin D is stored in the liver, so excess dietary intake is not easily removed from the body and excess amounts can be toxic.

Tolerable Upper Intake Level for most people: 50 ug/day

Vitamin D:

Deficiency results in insufficient blood calcium levels

Rickets in children Osteomalacia and osteoporosis in adults

Vitamin D:

Deficiency results in insufficient blood calcium levels

Rickets in children Osteomalacia and osteoporosis in adults

Vitamin D:

Excess: Hypercalcemia leading to: Failure of nerve conduction Muscle weakness / fatigue Digestive / absorption problems Kidney stones / tissue calcification Excessive thirst and urination Confusion / lethargy Severe: heart and breathing stop

Vitamin E:Next: Let’s move on to Vitamin E

“Vitamin E” is also a group of related compounds: - alpha-tocopherol - beta-tocopherol - gamma-tocopherol - delta-tocopherol - alpha-tocotrienol - beta-tocotrienol - gamma-tocotrienol - delta-tocotrienol

Vitamin E:Next: Let’s move on to Vitamin E

“Vitamin E” is also a group of related compounds: - alpha-tocopherol - beta-tocopherol - gamma-tocopherol - delta-tocopherol - alpha-tocotrienol - beta-tocotrienol - gamma-tocotrienol - delta-tocotrienol

All are active and have similar effects. but alpha-tocopherol is the most common

Vitamin E:Function of vitamin E:

All forms of the vitamin are antioxidants:

They react with, and thus neutralize, highly reactive products of metabolism called oxygen free radicals in cell membranes of the heart, lungs, nerves, eyes, and other tissues.

They also appear to protect against DNA mutations and to help regulate cellular growth and differentiation.

Vitamin E:Dietary sources of vitamin E:

Nuts Seeds CornAvocadosTomatosLeafy vegetablesVegetable oilsWheat germ oil

Most of our intake is from fortified foods such as cereal and milk

Dietary Recommendations:Recommended Dietary Allowance = 15 mg/dayTolerable Upper Intake Level = 800 to 1000 mg/day

Vitamin E:

Deficiency: Very rare, take years to develop Nervous disorders: - Motor weakness - Sensory problems - Speech problems - Cataracts Slow growth Slow healing

Vitamin E:

Excess: Very rare Abnormal blood clotting Abnormal immune function

Vitamin E:

Vitamin K:The last of the fat-soluble vitamins: Vitamin K

Just like vitamins A, D, and E, “Vitamin K” is a group of related compounds rather than a single molecule.These are the phylloquinones and menaquinones.

Vitamin K:Function of vitamin K:

Vitamin K regulates the reactions of blood clotting It helps regulate bone growth

Vitamin K:Dietary sources of vitamin K:

Leafy vegetablesBlueberries and blackberriesLegumes (beans, peas, etc.)

Bacteria in the large intestinesynthesize and release Vitamin K, which can then be absorbed

Vitamin K:Dietary Recommendations:

Adequate intake = 90 ug/day for women = 120 ug/day for men

Because the liver easily breaks down vitamin K, no Tolerable Upper Intake Level has been established

Vitamin K:Deficiency:

Rare except in people with malabsorption syndromes or taking antibiotics which kill intestinal bacteria Infants often given supplemental vitamin K

Abnormal clotting, internal bleeding

Excess: Very rare No symptoms defined

Vitamin K:

Vitamins A, D, E, and K were “fat soluble”, stored in the liver or fat cells.

Vitamin C and the eight B vitamins are “water soluble”, distributed through the fluids of the body and eliminated by the kidneys.

Vitamins:

Let’s start discussing the water-soluble vitamins with Vitamin C

Also called “ascorbate” or “ascorbic acid”

Vitamin C:

Function of vitamin C:

Vitamin C:

It is an antioxidant which reacts with, and thus neutralizes, highly reactive products of metabolism called oxygen free radicals in the cells of many tissues and organs.

Cells also need vitamin C to produce the protein collagen which holds them together and forms many of the body’s connective tissues.

It helps synthesize a number of different hormones and neurotransmitters and helps regulate the immune system.

Dietary sources of vitamin C:

Vitamin C:

Dietary Recommendations:

Vitamin C:

Recommended Dietary Allowance = 90 mg/day for men = 75 mg/day for women (more if pregnant or breastfeeding)

Tolerable Upper Intake Level = 1,800 to 2,000 mg/day

Deficiency: Scurvy: Bone and joint deterioration Connective tissues weaken Gums bleed Skin hemorrhages Open wounds Can be fatal

Vitamin C:

Excess: Removed through the urine, but megadoses can cause Abdominal cramping & diarrhea Kidney stones Liver damage

Vitamin C:

When the B vitamins were first discovered, they were thought to be just a single compound which acted as a “coenzyme” – a molecule which binds to enzymes and is necessary for them to function.

B Vitamins:

When the B vitamins were first discovered, they were thought to be just a single compound which acted as a “coenzyme” – a molecule which binds to enzymes and is necessary for them to function.

Fairly soon, however, eight different molecules were identified with specific functions. These were identified by adding numbers to the “B” designation.

B Vitamins:

B1 = ThiaminB2 = RiboflavinB3 = NiacinB5 = Pantothenic acidB6 = PyridoxineB7 = Biotin B9 = Folic acid B12 = Cobalamin

B Vitamins:

B1 = ThiaminB2 = RiboflavinB3 = NiacinB5 = Pantothenic acid

B6 = Pyridoxine

B7 = Biotin B9 = Folic acid

B12 = Cobalamin

B Vitamins:

However, some of them are now commonly known only by thier names and others are commonly known only by their numbers.

This is how you should know them.

B1 = ThiaminB2 = RiboflavinB3 = NiacinB5 = Pantothenic acid

B6 = Pyridoxine

B7 = Biotin B9 = Folic acid

B12 = Cobalamin

B Vitamins:

However, some of them are now commonly known only by thier names and others are commonly known only by their numbers.

This is how you should know them.

In some foods and supplements, all of these B vitamins are present together, referred to as the vitamin B complex

Function of thiamin:Like all of the B vitamins, it is a coenzyme which binds to enzymes to make them active.

For thiamin, these are enzymes involved in - the breakdown sugars to release energy - synthesis of DNA and RNA - production of neurotransmitters

First: Thiamin (vitamin B1 )

Sources of thiamin:

B Vitamins: Thiamin (vitamin B1 )

Meats and fishLegumesGrainsNuts and seedsDairy productsFruits

Commonly used to fortify cereals, juices, and other foods.

Dietary recommendations:


Recommended Dietary Allowance = 1.2 mg/day for men = 1.1 mg/day for women (more if pregnant or breastfeeding)

No Tolerable Upper Intake Level set

Deficiency:


Beriberi – muscle loss / weakness inability to stand or walk nerve damage edema heart damage

Excess:No known symptomsKidneys quickly clear excess into urine

Function of riboflavin:Like all of the B vitamins, it is a coenzyme which binds to enzymesto make them active. It is also part of flavin adenine dinucleotide, a molecule the body uses to help extract energy by metabolizing glucose or other fuel molecules.

Next: Riboflavin (vitamin B2 )

Sources of riboflavin:Milk & dairy productsEggsLiver & meatSpinach

Commonly used to fortify cereals, juices, and other drinks

B Vitamins: Riboflavin (vitamin B2 )

Dietary recommendations:Recommended Dietary Allowance = 1.3 mg/day for men = 1.1 mg/day for women (more if pregnant or breastfeeding)

No Tolerable Upper Intake Level set


Deficiency:Rare except in vulnerable populations: elderly, ill, eating disorders alcoholic.Oral lesions, dry skin, anemia



Function of niacin:

Like all of the B vitamins, it is a coenzyme which binds toenzymes to make them active.It is also part of nicotinamide adenine dinucleotide, a molecule the body uses to help extract energy by metabolizing glucose or other fuel molecules.

Two related forms: Nicotinic acid and nicotinamide

Next: Niacin (vitamin B3 )

Sources of niacin:Liver, meat, fish, nuts

Commonly used to fortify cereals, juices, and other drinks

Your body can make niacin from the amino acid tryptophan, although this decreases in age and disease

B Vitamins: Niacin (vitamin B3 )

Dietary recommendations:Recommended Dietary Allowance = 16 mg/day for men = 14 mg/day for women (more if pregnant or breastfeeding)

Often prescribed to help lower cholesterol and triglycerides in the blood

Tolerable Upper Intake Level: ~35 mg/day


Deficiency:Pelagra – rough, dry, red skin sensitivity to sunlight nervous disorders

Excess:Liver damageAbdominal pain & diarrheaSkin itching


Function of pantothenic acid:

Like all of the B vitamins, it is a coenzyme which binds toenzymes to make them active.It is also part of coenzyme A, a molecule the body uses to help extract energy by metabolizing glucose or other fuel molecules.

Next: Pantothenic Acid (vitamin B5 )

Sources of pantothenic acidLiverGrainsMushroomsSunflower seedsYogurt

Commonly used to fortify cereals

B Vitamins: Pantothenic Acid (vitamin B5 )

Dietary recommendations:Adequate intake = 5 mg/day

No tolerable Upper Intake Level set


Deficiency:Very rare: fatigue, muscle cramps, insomnia

Excess:No symptoms identified


Function of vitamin B6:

Like all of the B vitamins, it is a coenzyme which binds to enzyme to make them active.Necessary for normal white bloodcell formation and immunity, and for formation of some neurotransmitters.

Six related molecules in diet, converted to active form during digestion

Next: B6 (Pyridoxine )

Sources of vitamin B6:Liver, meat, fishWhole grainsPotatoesBeansBananas


B Vitamins: B6 (Pyridoxine )

Dietary recommendations:Recommended Dietary Allowance = 1.3 mg/day for both men & women More needed as you get older

Tolerable Upper Intake Level = 80 to 100 mg/day


Deficiency:Rare except in individuals with very poor diets. Anemia Skin rashes Nervous disorders

Excess:FatiguePain, numbness in extremitiesNerve damageInsomnia


Function of biotin:

Like all of the B vitamins, it is a coenzyme which binds to enzymesto make them active.

Next: Biotin (vitamin B7 )

Sources of biotin:TomatoesLettuceCarrotsEggsNutsDairy products


B Vitamins: Biotin (vitamin B7 )

Dietary recommendations:Adequate Intake= 30 ug/day for both men and women

No Tolerable Upper Intake Level


Deficiency:Rare. Hair loss Skin problems Lack of muscle tone, cramps

Excess:No symptoms known


Function of folic acid:

Like all of the B vitamins, it is a coenzyme which binds to enzyme to make them active.Necessary for normal formationof erythrocytes. Requires anothervitamin, B12, to be converted to active form

Next: Folic Acid or Folate (vitamin B9 )

Sources of folic acid:LiverSpinach, lettuceAsparagusLegumes

Commonly used to fortify cereals, bread, rice.

B Vitamins: Folic Acid (vitamin B9 )

In fact, since 1996, the U.S. Food and Drug Administration has required breads, cereals, flours, pastas, rice, and othergrain products to be fortified with folic acid.

Dietary recommendations:Recommended Dietary Allowance = 400 ug/day for both men and women Higher in pregnancy and breastfeeding

Tolerable Upper Intake Level = 800 to 1000 ug/day


Deficiency:AnemiaWeaknessAtherosclerosisWeight lossEmbryo: Neural tube defects



Function of vitamin B12:

Like all of the B vitamins, it is a coenzyme which binds to enzyme to make them active.Necessary for folic acid (vitamin B9) activation and formyelination of neuron axons.

Last: Vitamin B12 (Cobalamin)

Sources of vitamin B12 :Liver, meat, fish, seafoodsDairy products butCan only be synthesized by bacteria and algae: animals (including humans) absorb and concentrate the vitamin

Commonly used to fortify cereals, bread, rice

B Vitamins: B12 (cobalamin)

Dietary recommendations:Recommended Dietary Allowance = 2.4 ug/day for both men and women More required as you get older

Absorption in the intestine requires binding to a glycoprotein called “intrinsic factor” which is produced in the stomach

No Tolerable Upper Intake Level has been established


Deficiency:Almost always due to lack of absorption, or may occur in people whose diet contains inadequate animal-origin foods. Anemia Brain and nerve damage

Excess:Few symptoms, may include thrombosis pulmonary edema


Next: We’ll move on to water &

minerals

Vitamins

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