NUTRITION: Chapter 8 - Vitamins & Phytochemicals

Define Vitamins

they are essential organic (carbon-containing) substances needed in small amounts for normal function, growth, and maintenance of the body

What is a megadose? Are there any negative consequences of consuming megadoses of vitamins?

Megadoses are larger than the usual vitamin/drug. It will cause GI distress to toxcity, organ damage, or in extreme cases, death.

What are the to broad classes based on solubility?

Fat-soluble vitamins: Vitamins A, D, E, and K
Water-soluble vitamins: Vitamins B (thiamin, riboflavin, niacin, pantothenic acid, biotin, B-6, folate, and B-12), and C

What are some notable exceptions to having a strict dietary need for vitamin?

Vitamin A: Synthesize from certain pigments in plants
VItamin D: Synthesized in the body if the skin is expose to adequate sunlight: niacin; from amino acid tryptophan
Vitamin K: biotin and others that are synthesized by bacteria in the intestinal tract

How were the vitamins discovered?

They were identified by scientist for deficiency related diseases such as scurvy (vitamin C) and rickets (vitamin D). The rest were discovered and name alphabetically.

What are fat-soluble vitamins

Vitamins A, D, E, and K

What are the differences between fat-soluble and water-soluble vitamins?

Fat-soluble absorbed with dietary fat. Anything interfering with fat absorption will impair fat-soluble absorption

Water-soluble absorbed primarily in small intestine, relatively high bioavailability. Transported to liver via portal vein and distributed to body tissues. Inside cells: Active coenzymes resynthesized

How can fat-soluble vitamins be toxic?

Vitamins A, D, E are not readily excreted from the body. Toxicity by vitamin A is most frequently observed

How can water-soluble vitamins be toxic?

Kidneys efficiently filter the excess from the blood and excrete these compounds in urine; exception are B-6 and B-12 stored in liver

What are some ways to preserve vitamin content when storing, preparing, or cooking foods?

Freezing, low heat cooking method, tightly sealed containers.

Enzymes in fruits and veggies begin to degrade vitamins once they are harvested - oxygen breaks down vitamins fastter

What is the affect of boiling vegetables?

Blanching destroys the enzymes that would degrade the vitamins over time.

Define Functional Foods

Food that are sources of the chemicals that provide health benefits beyond being essential dietary nutrients.
It can be placed into two categories: Zoochemicals and Phytochemicals

What are some examples of functional foods?

Oatmeal, contains soluble fiber that can lower cholesterol levels

Define Zoochemicals

Chemicals found in animal products that have health-protective actions

What are some phytochemical functions?

• Stimulate the immune system

• Reduce inflammation

• Prevent DNA damage and aid in DNA repair

• Reduce oxidative damage to cells

• Regulate intracellular signaling to hormones and gene expression

• Activate insulin receptors

• Inhibit the initiation and proliferation of cancer, and stimulate spontaneous cell death

• Alter the absorption, production, and metabolism of cholesterol

• Mimic or inhibit hormones and enzymes

• Decrease the formation of blood clots

What are some phytochemical recommendations?

They should be consumed as foods and eat wide variety of whole plant foods to obtain optimum amount of nutrients

Define antioxidants

substance that has the ability to preent or repair the damage caused by oxidation

Which disease can be lowered in risk with a dietary pattern in rich phytochemcials?

Cardiovascular disease, type 2 diabetes, and various cancers

What is a Vitamin A? Where are vitamin A stored?

Group of compounds known as retinoids

90% are stored in the liver; the remaining 10% is in the adipose tissue, kidneys, and the lungs

What is a Retinoid?

Chemical forms of preformed vitamin A found in animal products. There are 3 forms (preformed):
1 Retinol - Alcohol form of vitamin A
2 Retinal - Aldehyde form of vitamin A
3 Retinoic Acid - Acid form of vitamin A

What is the storage form of Vitamin A?

Retinyl

What are Carotenoids

They are plants contain pigments with health-promoting chemicals. Precursors of vitamin A have antioxidant properties

How are Carotenoids related to Vitamin A?

Carotenoids are provitamin A, they are plant-based precursor that the body converts into active vitamin A in the intestines and liver

Which carotenoids are provitamins (can be turned into vitamin A)?

• Beta-carotene

  • dark green, yellow-orange veggies and fruits

• Alpha-carotene

• Beta-cryptoxanthin

What other carotenoids have health benefits?

• Lycopene

• Zeaxanthin

  • Green leafy veggies, spinach, kale

• Lutein

What are the functions of Vitamin A in Epithelial Cells and Immune Systems?

Retinoic acid is required for immature epithelial cells to develop into mature, functional epithelial cells. (Maintain structure throughout the body).
Also supports the activity of certain immune system cells, specifically the T-lymphocytes (T-cells).

What are the names of two carotenoids known to have antioxidant functions?

Lycopene and Beta-carotene

What are the results in 3 main problems of Vitamin A deficiency?

Impaired vision, weakened immune function, and stunted growth. Deficiency contributes to death

What is Xerophthalmia?

A disease that hardens the cornea, loses the ability to produce mucus and cause drying of the surface of the eye where dirt particles scratch the dry surface of the eye - can result in blindness.

What is hyperkeratosis?

A condition in which patches of skin become thicker, rougher, or drier than usual; a possible consequence of vitamin A deficiency

How does Vitamin A deficiency affect blindness?

Causes:
Night Blindness

• loss of the ability to see under low-light conditions

Maternal Night Blindness

• An issue in developing nations

• Leads to pregnancy-related deaths, malnutrition, anemia, infant mortality

Screen and supplementing is effective in treating and preventing

What is a macula? What is Age-Related macular degeneration?

The macula (yellow spot) controls central vision (straight-ahead)

Age-Related macular degeneration: Changes in this macular area of the retina. Leading cause of blindness among older adults in the U.S

Which veggie is rich in Lutein and Zeaxanthin?

Broccoli, Brussels sprouts, Kale, Peas, Romain Lettuce, Spinach, and Zucchini

How does carotenoids impact our vision?

Higher intakes help prevent or slow the progression of age-related macular degeneration. Also decrease risk of cataracts in the eyes.

Functions: Cardiovascular Disease Prevention

• Carotenoids may inhibit oxidation of low-density lipoproteins (LDLs)

• Consume a total of at least 5 servings of a combinations of fruits and veggies per day as part of an overall effort to reduce the risk of cardiovascular disease

Functions: Growth, Development, and Reproduction

Bind to receptors in DNA to increase the synthesis of a variety of proteins (Required for growth).

Differentiation and maturation of cells that form tissues and organs

Breakdown and formation of healthy bone tissue

Aids in sperm production (epithelial role) and normal in reproductive cycle for adult females

Function: Cancer Prevention

Role in cellular differentiation and embryonic development

Diets rich in provitamin A carotenoids associated with lower risk of skin, lung, bladder, and breast cancers

• Lycopene is the red pigments found in tomatoes, watermelon, guava, and pink grapefruit and seems to protect against prostate cancer,

Toxicity risk in megadose of vitamin A through supplement use

Which food sources contain preformed vitamin A?

Liver, fish, fish oils, fortified milk, butter, yogurt, eggs, margarine, and spreads

What is the retinol activity equivalents (RAE)?

Adult Male - 900 mcg per day
Adult Female - 700 mcg per day
DV - 900 mcg per day
Reserves stored in liver

How much vitamin A should we avoid taking?

• UL: 300 micrograms RAE

• Intakes in excess of the UL for vitamin A

• Liver toxicity increase risk of hip fracture

• Birth defects

  • Fetal malformations and spontaneous abortions

  • Women of childbearing age should limit overall intake of preformed vitamin A from diet and supplements to no more than of Daily Value

What is Hypercarotenemia?

Too many carrots or beta-carotene supplements cause skin to turn yellow-range (palms or soles). Revertable.

What is Vitamin D?

• fat-soluble (essential) vitamin,

• also a hormone

• produced in the skin when exposed to uv light.

• cholesterol is vitamin D precursor

• activation occurs in liver and kidneys

What are forms of Vitamin D?

• Vitamin D₂ (ergocalciferol)

  • Synthetic product derived from irradiation of plant sterols (ergosterol)

  • Used in some supplements

• Vitamin D₃ (cholecalciferol)

  • More commonly used in supplements and to fortify foods

What are some synthesis of Vitamin D?

• 7-dehydrocholesterol: precursor found in skin

  • Converted to D₃ by sunlight exposure

• Vitamin D₂ and D₃

  • Travel to liver, concerted to 25-hydroxyvitamin D₃ (calcidiol), main form of vitamin D found in blood

• Calicidiol

  • Chemically converted in kidneys 1, 25-dihydroxyvitamin D₃ (calcitriol), the biologically active form of vitamin D

What is the function of Vitamin D?

Maintains calcium and phosphorus levels in blood. Controls growth of parathyroid gland. May decrease certain types of cancer risk.
involved in:

• Gene expression

• Cell growth regulation

• Neuromuscular and immune function

• Reduction of inflammation

How does Vitamin D regulate calcium?

Regulates absorption of calcium and phosphorus from small intestine. Through bone remodeling, Calcium excretion via kidney:

• Causes the kidneys to reduce calcium excretion in the urine

• Releases calcium from bone by stimulating osteoclast activity

What is the association between vitamin D and sun exposure?

UV exposure is the primary method of boosting serum vitamin D levels
Amount of sun exposure needed to activate vitamin D is affected by:

• skin color

• age

• time of day

• latitude and strength of UV light

• exposure time

• season

Who are at risk with Vitamin D deficiency?

• dark-skinned people

• exclusively breastfed infants

• elderly

• insufficient sun exposure

• diet without fortified foods and low vitamin d diet

What are some disorders with low levels of Vitamin D?

• Osteomalacia: soft bones in adults (rickets)

• Intestinal calcium absorption diseases

• Rickets: softens and weakens bones in children, low calcium

RDA recommendation for Vitamin D intake?

• 15 micrograms (600 IU) for 1-70 year olds; 25 microgram for 70+ with limited sun exposure

• 20 micrograms (800 IU) for age 71+

What are some rich food sources of Vitamin D?

Mushrooms, salmon, sardines, fortified dairy, breaskfast cereals.

Can Vitamin D be toxic?

Yes, UL is 100 micrograms (4000 IU) per day. High intake results in increased blood calcium. Does not result from excessive sun exposure.

Symptoms: weakness, loss of appetite, diarrhea, vomiting, mental confusion, and increase urine ouput

What is Vitamine E? What are the functions?

A compound named tocopherol. identified as essential for rat fertility, 1920s but has no effect in humans.

Functions: Development of muscles and central nervous system, antioxidant, maintains nervous tissue and immune function

Where is Vitamin E found in the human body?

Vitamin E is primarily found in adipose tissue and in lipid bilayers of cell membranes. Lipids are polyunsaturated fatty acids, which is susceptible to oxidative attack by free radicals

What is a free radical?

An unstable atom with an unpaired electron in the outermost shell; also called reactive oxygen species

How does vitamin E work to prevent oxidative damage?

Vitamin E donate electrons or hydrogen to free radicals to make cell more stable. They’re important in areas exposed to high levels of oxygen (red blood cells and the lungs)

Vitamin E Deficiency

• Preterm infants can be deficient in vitamin E because its transfer from mother to fetus occurs late in pregnancy

• Individuals who use tobacco products are high risk of deficiency. smoking readily destroy vitamin E in the lungs

What are some rich food sources of Vitamin E

Only synthesized by plants - plant are best sources (plant oils for unsat. fats from oxidation)
Animal products (meat, dairy, and eggs) and fish oils
Depends on how its harvested, stored, processed, and cooked

RDA of vitamin E

Adults: 15 mg per day of alpha-tocopherol

Avoiding too much Vitamin E

• UL for vitamin E is 1000 mg per day of supplemental alpha-tocopherol

• Excess intake of vitamin E can interfere with vitamin K’s role in clotting mechanism, leading to hemorrhage

  • Can produce nausea, gastrointestinal distress, and diarrhea

Functions of Vitamin K (Quinone)

Fat-soluble nutrient essential for blood clotting (binds to calcium) and build strong bones

• Produce prothrombin, a protein essential for blood blotting

• Leading to conversion of soluble fibrinogen in to insoluble fibrin (protein that forms blood clots)

• Important to bone health

Where is vitamin K found?

In plants, plant oils, fish oils, and some animal products
Synthesized by gut bacteria - fulfills about 10%
3 forms:

1. Phylloquinone - abundant form; synthesized by green plants

2. Menaquinone - synthesized by gut bacteria

3. Menadione - synthetic form found in supplements

Vitamin K Deficiency

Rare but its consequences can be dangerous. - Body doesn’t store enough

• can lead to excessive bleeding - hemorrhage

• Newborn infants are at highest risk of deficiency bleeding because of low stores of vitamin K when born

• Poor bone development in children and osteoporosis in older adults

• Development of cardiovascular disease

What are food sources of vitamin K?

Phylloquinone: green leafy veggies, broccoli, asparagus, and peas
Menaquinone: neats, eggs, and dairy products
Pomegranates

Why is it important for people who take Coumadin to monitor their dietary intake of vitamin K?

To keep their blood clotting times stable