Antioxidants

What is reduction

process of atoms gaining electrons

Oxidation

process of atoms losing electrons

Free radical

When electrons are lost, and that same electron does not re pair, it becomes highly reactive (one can create more)

Oxidative stress:

when the production of free radical exceeds the body’s ability to defend against them

Antioxidants:

mitigate the effect of free radicals by donating one of their own electrons

What are the fat soluble and water soluble vitamins?

fat: a, d, e, k

Water: c, b

Characteristics of water soluble vitamins

Cannot be stored extensively, easily absorbed into the bloodstream & excesses excreted in urine

Characteristcis of fat soluble

May be toxic in excess, requrie bile for absorption

What are the 3 active forms of vitamin A?

• retinol: alcohol form of vitamin a

• retinal: aldehyde form of vitamin a

• retinoic acid: acid form of vitamin a

What are carotenoids?

Plant derived products

What are the jobs of carotenoids? (2)

it is an antioxidant, and it is a vitamin a precursor (compound that can be converted into active vitamins)

What is beta carotine?

This is split to form retinol in the intestine (absorption and conversion is less efficient that retinoids

What is the digestion of vitamin A?

• absorbed through the lymph system along side fat

• vitamin a circulates to the liver where it can be stored

• retinol-binding protein (rbp) transports vitamin a from the liver through the blood to the rest of the body’s cells that need it

• cells that use vitamin a have special protein receptors for rbp, its action will depend on the cell’s receptor (i.e., retinoic acid stimulates cell growth in skin but inhibits cell growth in tumours)

What are the functions of vitamin A?

• Vision

• Protein synthesis and cell differentiation

• Support reproduction and regulating growth

What is rhodopsin:

light sensitive pigment in retina made up of protein (opsin) and contains retinal, form of vitamin a

What is the special units for vitamin A and why are they special?

since vitamin A is derived from retinoids and cartenoids, recommendations are expressed as retinol activity equivalents (rae)

What is the recommended amount of vitamin A?

• men: 900 ug rae/day

• women 700 ug rae/day

hypovitaminosis a:

vitamin A deficiency (symptoms only start showing after 2 years)

Symptoms of hypovitaminosis A

Poor immunity, night blindness

WHat is xerophthalmia

blindness from a lack of vitamin A in the front of the A

xerosis

• drying and hardening of the cornea because of inadequate mucus production

keratomalacia

progression from xuerosis, softening of the cornea that leads to irreversible blindness

keritinization

• accumulation of keratin (hard, inflexible protein)

Hypervitaminosis A

vitamin A toxicity (leads to bone defects, birth defects and acne)

Beta carotene toxicity

does not convert enough to retinol (turning skin bright yellow/orange)

Functions for vitamin E

• prevents oxidation of pufas, thus as pufa intake increases need for vitamin e increases

• also protects other lipids and compounds (e.g. vitamin a) from being oxidized

• special antioxidant effect in lungs and red blood cells

• defends against heart disease by protecting low-density lipoproteins against oxidation and reducing inflammation

Tocopherol

• chemically related compounds, one of which has vitamin e activity

Alpha-tocopherol:

active vitamin E compound

Recommendation for vitamin E

• rda adults: 15mg/day

• ul: 1000mg/day

Erythrocyte hemolysis:

breaking open of red blood cells due to vitamin E deficiency

What is the result of vitamin E deficiency?

• prolonged deficiency → neuromuscular dysfunction → loss of muscle coordination/reflexes, and impaired vision and speech

What is ascorbic acid?

Vitamin C

Functions of Vitamin C

• antioxidant

• Cofactor in collagen formation

• Cofactor in carnitine formation

• Assists in hormon production

• Stress

• Immunity and the common cold

What is carnitine?

Transports fatty acids across the inner membrane of the mitochondria

Recommendations for Vitamin C

• rda

  • men: 90mg/day

  • women: 75mg/day

  • need increased in smoking individuals

• ul: 2000mg/day

Early signs of vitamin C deficiency

• Scorbutic gums: bleeding of the gums

• Pinpoint hemorrhgages: bleeding under the skin, appears like small red dots

Long term vitamin C deficiency

Scurvy:

• wounds will stop healing, bones rebuilding will falter

• loss of appetite, tenderness to skin, weakness, anemia, infections

• psychological signs → hysteria and depression

• eventually can result in sudden death caused by internal bleeding

Selenium functions

• antioxidant

• Plays a role in activating thyroid regulation

Recommendations for selenium

• rda adults: 55 ug/day 

  • ul: 400ug/day 

Deficiency of selenium is associated with…

Keshan Disease