Vitamins-Essential organic compounds required in small amounts for normal metabolism and good health- not a source of energy

Water soluble - C and Bs-must be replenished everyday-Difficult to overdose

Fat soluble - A, D, E, K-does not need to be replenished everyday-can cause toxicity

Names and RolesVitamins

A retinol phototransduction

D cholecalciferol bone remodelingE tocopherols antioxidant

K phytylmenaquinonemultiprenylmenaquinone

coagulationbone remodeling

B1 thiamine carbohydrate metabolismB2 riboflavin redox, respirationB3

niacin redox

B6

pyridoxinepyridoxaminepyridoxal

aa metabolismglycogenolysis

B5 Pantothenic acid tca, fa and cholesterol

B7 Biotin gluconeogenesis, tca, fa, aa

B12 cobalamin 1C&H metabolismB9 Folic acid 1C metabolism

C ascorbic acid hydroxylation

Deficiencies and SourcesVitamins

A - night blindnesspreformed: liver, egg yolk, butter, milkb-carotene: dark green and yellow veggies

D - ricketts, osteomalaciamilk, fortified food, fish oils, egg yolks, liver

E - neurologic?, hemolytic anemia veggie oils, nuts

K - bleeding disorders green leafy veggies, fruits, dairy products, veggie oils, cereals, meats

B1 - beri-beri seeds, nuts, wheatgerms, legumes, lean meatB2 - pellagra meats, nuts, legumesB3 - pellagra meats, nuts, legumes

B6 - neurologic disease yeast, liver, wheatgerm, nuts, beans, bananas

B7 - widespread injury corn, soy, egg yolk, liver, kidney, tomatoes

B12 - pernicious anemia liver, kidney, egg, cheese

B9 - anemia yeast, liver, leafy veggies

C - scurvy citrus and soft fruits

B5 - none known yeast, grains, egg yolk, liver

Recommended Daily Allowances (RDA)

Vitamin Absorption and Storage

• All absorption takes place in the small intestine

• Fat-soluble vitamins – Are absorbed in the duodenum– Storage

• Vitamin A is mainly stored in the liver • Vitamins K and E are partially stored in the liver• Vitamin D is mainly stored in the fat and muscle tissue• Can build up in body to point of toxicity

Vitamin Absorption and Storage

• Water-soluble vitamins– Absorbed with water and enter directly into the

blood stream– Most absorbed in the duodenum and jejunum– Most are not stored in the body– Excess intake excreted through the urine– Important to consume adequate amounts daily– Dietary excesses can be harmful

Digesting and Absorbing Water-Soluble Vitamins

Figure 10.1

Water-Soluble Vitamins

Fat-SolubleVitamins

Absorbed in the Small Intestine Small IntestineHydrophobic or

Hydrophilic Hydrophilic Hydrophobic

Absorbed into the Blood Lymph

Stored in the body Not Generally Yes

Can build up and become toxic Not Generally Yes

Need to consume daily Yes No

Bioavailability

• Varies based on– Amount in food– Preparation– Efficiency of digestion and absorption of food– Individual nutritional status– Natural or synthetic

• Fat-soluble vitamins are generally less bioavailable than water-soluble vitamins

• Vitamins from animal foods are generally more bioavailable than those in plant foods

Fat Soluble Vitamins

- Many have precursors- Less vulnerable to cooking losses- Can cause toxicity- Transported like fat in chylomicrons, VLDL, LDL

16

vitamin A

• aka: retinol• Converted to active form• Regulates response of rod and cone cells in the retina to light • Regulates gene expression of development of epithelial tissue• Used to treat severe acne, wrinkled skin

24

vitamin D• A prohormone synthesized

from cholesterol

• Vitamin D3 = cholecalciferol

• Found in animal products

• Vitamin D2 = egocalciferol

• Found in plants and fortified foods

Vitamin D3 and D2

• Time spent outdoors

• Amount of skin exposed

• Skin color

• Clothing

• Body fat

• Latitude

• Season and time of day

What affects your vitamin D level?

Vitamin D Synthesis and LatitudeVitamin D Synthesis and Latitude

Childhood rickets

• Epidemic with industrialization in 19-20th centuries

• With discovery of vitamin D and fortification, rickets was almost entirely eliminated

• Until now…

London 1889

Idaho 1989

• 40-90% of US community dwelling elderly• 50% of premenopausal women• 50% of Hispanic and black adolescents• 48% of French preteens• 30-50 % of adults in Saudi Arabia and UAE• 73 % of pregnant women taking prenatal

vitamins …are DEFICIENT

How to get vitamin D...

• 100 IU/d raises level by about 1 ng/mL

• Sunlight 3000 IU/10 minutes• Oily fish 300 IU/3 oz

– Salmon, sardines, mackerel, tuna• Mushrooms 100 IU/3 oz• Fortified drinks 100 IU/8 oz

– Milk, orange juice, yogurt, cereals

Endocrine, paracrine and intracrine functions of Vitamin D

• Role in Cancer Prevention– Low intake of vitamin D and calcium has been associated

with an increased risk of non-Hodgkin lymphomas, colon, ovarian, breast, prostate, and other cancers.

– The anti-cancer activity of vitamin D is thought to

result from its role as a nuclear transcription factor that regulates cell growth, differentiation, apoptosis and a wide range of cellular mechanisms central to the development of cancer. These effects may be mediated through vitamin D receptors expressed in cancer cells.

– Vitamin D is not currently recommended for reducing cancer risk

• Role in Cardiovascular Diseases– Vitamin D deficiency activates the renin-

angiotensin-aldosterone system and can predispose to hypertension and left ventricular hypertrophy.

– Additionally, vitamin D deficiency causes an increase in parathyroid hormone, which increases insulin resistance secondary to down regulation of insulin receptors and is associated with diabetes, hypertension, inflammation, and increased cardiovascular risk.

Updated Recommendations In Process

• Studies suggest that the daily vitamin D intakes should be much higher than 400 IU/d.

• Daily intakes in the range of 800 to 1000 IU/d should be strongly considered.

• Although there are concerns regarding vitamin D toxicity, side effects at intakes exceeding the current upper limit of 2000 IU/d have not been reported to date.

• Assessment of vitamin D status with serum measurements of 25(OH) vitamin D levels for a broader range of patients should be encouraged.

Key clinical recommendation

• Daily vitamin D supplementation of 800 to 1,000 IU is a reasonable dose for adults. Levels of 25-OH vitamin D should be maintained > 32 ng per mL (80 nmol per L) to maximize bone health.

• In patients with severe vitamin D deficiency, 50,000 IU of vitamin D should be given daily for one to three weeks, followed by weekly doses of 50,000 IU.

Vitamin E

• There are four different tocopherol compounds, but only the alpha-tocopherol has vitamin E activity in human beings.

• Vitamin E as an Antioxidant– Stops the chain reaction of free radicals

– Protection of polyunsaturated fatty acids and vitamin A

– Protects the oxidation of LDLs

Vitamin E• Easily destroyed by heat and

oxygen• Deficiency symptoms

–Red blood cell breakage–Nerve damage

• Toxicity symptoms–Augments the effects of

anticlotting medication

Vitamin E Deficiency

– Primary deficiency due to inadequate intake is rare

– Erythrocyte hemolysis• Occurs in premature infants• Hemolytic anemia can be treated with vitamin E.

Vitamin E Toxicity

– Rare and the least toxic of the fat-soluble vitamins– Upper level for adults: 1000 mg/day– May augment the effects of anticlotting

medication

Vitamin E• Other name: alpha-tocopherol• 2000 RDA

– Adults: 15 mg/day

• Upper level for adults:1000 mg/day

• Chief function in the body– Antioxidant (stabilization of cell

membranes, regulation of oxidation reactions, protection of polyunsaturated fatty acids and vitamin A)

Antioxidant Nutrients In Disease Prevention

Vitamin E• Significant sources

–Polyunsaturated plant oils (margarine, salad dressings, shortenings)

–Leafy green vegetables, wheat germ, whole grains, liver, egg yolks, nuts, seeds

Vitamin K• Also known as phylloquinone, menaquinone, menadione, and

naphthoquinone

• Vitamin K is unique in that half of human needs are met through the action of intestinal bacteria.

• Vitamin K is essential in blood clotting.

• deficiency can cause uncontrolled bleeding.

• Deficiencies can occur in newborn infants and people taking antibiotics.

Vitamin K

• Vitamin K Deficiency– Symptoms include hemorrhaging– 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.

Vitamin K• Other names

–Phylloquinone–Menaquinone–Menadione–Naphthoquinone

• 2001 AI–Men: 120 g/day–Women: 90 g/day

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vitamin K

– Blood clotting cofactor– Prothrombin formation is blocked by warfarin– Deficiency is rare

Vitamin K• Chief functions in the body

–Synthesis of blood-clotting proteins and bone proteins that regulate blood calcium

Vitamin K• Significant

sources–Bacterial

synthesis in the digestive tract

–Liver–Leafy green

vegetables, cabbage-type vegetables

–Milk

Vitamin K

• Deficiency symptoms–Hemorrhaging

• Toxicity symptoms–None known