Fat Soluble vitamins (A, D, E, K)

How may a deficiency occur?

(1) fat malabsorption (2) long-term use of antibiotics (killing the intestinal bacteria) results in: VKDB=failure to form normal blood clots

Two different ways of measuring vitamin A

(1) international unit (2) RAE=retinol activity equivalent 1 RAE=12 mcg beta-carotene and 1mcg retinol

three populations at risk if vit. D deficiency

(1) people living in cloudy or cold climates (2) people with dark skin (3) the elderly -supplements should be taken by these people, as well as those with liver or kidney disease or fat malabsorption issues

Two types of vitamin A deficiencies

(1) primary=inadequate intake of the vitamin itself (2) secondary=due to other problems that interfere with the absorption/conversion of vitamin A compounds

Forms of vitamin A: retinoids

*retinoids*=preformed -comes in three compounds (1) retinol=reproduction (2) retinal=vision (3) retinotic acid=regulates growth -found in animal products -function directly as vitamin A

phytochemicals

-*non pro vitamin A carotenoids* -cannot be converted to vitamin A -lycopene, astaxianthin, lutein, zeaxanthin

Vitamin E RDA, upper intake level, and what population needs more?

-15mg/day for both men and women -upper limit is 1000mg and there can be toxicity with supplements -can interfere with vit. A and cause excessive bleeding -smokers require more

What are fat soluble vitamins associated with?

-NOT found in the water regions of tissues, but with lipids -handled differently in the body

Deficiency in vitamin E?

-RARE -premature infants at risk

Vitamin E and Cancer?

-antioxidants protect DNA from free radicals -diets high in vitamin E are associated with decreased cancer risks -have found that there is no benefits when clinical trials were preformed

Where do we get vit. K

-approx. 50% is produced by bacteria in our intestines -food: leafy veggies, veggie oils, carrots, liver, kiwi, broccoli

beta-carotene

-can be used to make vitamin A & acts as a weak antioxidant -good at protecting lipids from oxidation -may be beneficial, no RDA or DRI

What occurs without any vitamin A?

-cells deteriorate ex. xerophthalmia (blindess) & follicular hyperkeratosis (dry bumpy skin)

Metabolism and storage of vit. D

-excess is stored in liver and fat tissue -individual variation in levels and activation -excreted mainly via bile

Food sources of vit. D

-fatty fish (salmon, herring)/ oils -fortified milk -fortified cereal -liver, beef, eggs

Night blindness

-from not enough amounts of retinal to reform rhodopsin -in order to get night vision, you need opsin and vitamin cis-retinal

Sources of beta-carotene

-fruits and veggies that are *colorful*! -not harmed but cooking

Hypercarotenemia

-high amounts of carotenoids in blood -too much carrots, squash, or beta supplements -skin turn yellow in color, but NOT harmful, can be reversed

What can excess vit. D cause?

-high concentrations of calcium in blood and urine -can then cause meneralization in soft tissues=bad -affects nervous system -promotes bone loss

Infant Vit. K Injections

-infants are born with low stores and are sterile so do NOT have the vitamin K producing bacteria -breast milk has low levels ...therefore, babies are given injections at birth so they do not bleed to death

Blood clotting process and fibrin

-is a muti-step process that involves many proteins -*fibrin* is the final protein threads that form the webbing of a blood clot

Vit. D deficiency symptoms

-less calcium is absorbed and the bones cannot mineralize properly=soft bones children=rickets (bone deformities) adults=osteomalcia

Vitamin A and the immune system

-maintains protective barriers (mucous) -plays a role in differentiating cells of the IS (lymphocytes and antibodies)

Vitamin D

-nonessential nutrient that acts like a hormone in the body -derived from cholesterol -made from sun exposure, if not enough exposure it acts as a *vitamin* -activated by enzymes in the *liver and kidneys* (hydroxylation steps can also happen in other cells as well)

Vitamin K

-part of the family of molecules called *quinones* -essential for production of the blood clotting protein *prothrombin* -involved in bone mineralization/bone strength -needed for the function of 2 proteins made by osteoblasts (low intake associated with increased risk of hip fractures) -possible relationship to osteoporosis risk

Vitamin D and Cancer?

-primary effect on bone health (calcification) -has been shown to have some effect on cancer risks -increased exposure to sun associated with less cancers (excluding skin cancer) -higher circulating calcidiol correlates with lower prostate and lung caners

Other major role of vit. D

-regulate gene expression and differentiation -almost all cells are affected by vit. D activation

Absorption of fat soluble vitamins (A) -retinoids vs. carotenoids

-required to be accompanied by *fat* (need bile, digestive enzymes, and packaged into micells and chylomicrons) -preformed retenoids are easily absorbed(90%), proformed carotenoids are not (10-50%)

How stable are the quinones? -where is it stored

-resistant to loses by cooking at high heats -stored in the liver and therefore deficiencies are very rare

Vitamin E and Heart disease?

-slows rate of plaque formation -there was many clinical trials preformed and they shows no benefit of vitamin E for heart attack or stroke, ACTUALLY saw an *increase* risk of heart failure and death

Vit. D and calcium homeostasis

-starts with low blood [calcium] -causes increased vit. D activation in the kidneys (1) increased cal. absorption in the SI (2) decreased cal. excretion by the kidneys (3) increased cal. resorption in bones

How can the different retenoids be transformed within the body?

-through OXIDATION reactions

Vitamin A (Carotenoids) & cancer -supplements?

-unless there is a deficiency already, they have no benefits (better to get from foods themselves) -diets rich in vitamin A have been associated with lower risk of some types of cancers *caret study*-long term high-dose actually increased incidence of lung and colorectal cancer

Carotenoids=proformed

-used to make vitamin A -comes in three compounds (1) beta-carotene [antioxidant role] (2) alpha-carotene (3) beta-crypoxanthin -need to be modified before they are useful -found in plant tissues -some carotenoids do NOT have the ability to be modified to vitamin A

How does vit. D affect individual cells?

-vit. D moves into nucleus -it has a receptor that then binds to DNA and regulates the expression of genes coding for specific proteins

Vitamin A functions

-wide range of functions, best known for sight -part of the visual pigment *rhodopsin* -growth/differentiation of cells/immune system -gene expression -maintenance of epithelial tissue *number one deficiency in the world*

1 mcg vitamin D=

40 IU vitamin D -naturally you cannot have toxicity from too much sun exposure, only can happen through supplementation (takes up calcium)

Vitamin E

aka: tocopherol -first identified as essential for reproduction -antioxidant in cell membranes -found in plant-based oils(margerine, salad dressing), dark green veggies, whole grains, nuts/seeds, eggs, fatty meats -easily destroyed by high heat and oxidation

Vit. D is important in the growth of...

bone! -helps maintain blood levels of calcium(regulates activation) and phosphorus

Sources of vitamin A (proformed) Beta...

dark veggies, yellow and orange veggies/fruits -pumpkin, carrots, squash

Retinoic acid

influences how epithelial cells differentiate and mature

Where is dietary D3 absorbed and transported?

it is absorbed in the SI and transported via chylomicrons

Sources of vitamin A (preformed)

liver (main storage), fish oils, milk, eggs, dairy products

Mega-doses of one antioxidant?

mega-dose of one may interfere with the action of another

In eye functioning, what does retinal bind to?

opsin protein!

Vitamin D in the skin, liver and kidneys

skin=7-dehydrocholesterol that is actually made in the liver -sun turns it into vit. D3 liver=hydroxylation occurs and turns it into 25-hydroxy vit. D3, which is the most abundant inactive form in the body kindeys=hydroxylated again and becomes fully active as 1,25=dihydroxy vit. D3

Which vitamin has the ability to act as a transcription factor?

vitamin A -binds to DNA to turn on/off genes, usually early on in development

VADD

vitamin A deficiency disorder -very common in poorer countries -leading cause of blindness around the world -*use of biotechnology may be turning point (golden rice)*