Week 8 – Antioxidants
October 24 , 2012
What Are Antioxidants?
- Chemicals that prevent oxidation
- Molecules are a physical unit of an element; they consist of atoms; all atoms are unique; all atoms have a nucleus
(positively charged) and it is surrounded by electrons (negatively charged); the opposite attractions keep them together.
- During metabolism (the process by which our bodies break down and build up molecules), atoms may lose electrons; this
loss is called oxidation because it is usually fueled by oxygen; atoms can also gain electrons during this (called reduction);
the loss and exchange of electrons usually results in an equal exchange (exchange reaction)
- It happens because we use hydrogen and oxygen to generate energy (ATP)
*Results in the formation of free radicals
Superoxide (0 -2 Hydroxyl Radicals (OH) Nitric oxide (NO)
- Can be caused from environmental exposure:
o Exposure to toxic substances: tobacco, asbestos, pollution
o Sun exposure
o Radiation exposure
- They are dangerous because they are “luring” paired electrons away from their stable atoms; creating more free radicals.
- They form within the lipid layer of the cell membrane; when the lipid molecules are destroyed, they do not repel water and
they cannot regulate fluids in ad out of the cell
- Can also damage LDL’s, proteins and DNA.
Can cause: cancer, heart disease, diabetes, arthritis, cataracts, kidney disease, Alzheimer’s, Parkinson’s
Antioxidants: chemicals that decrease the adverse effects of free radicals by:
- Donate their electrons without creating more free radicals.
- Have complex enzyme systems that convert free radicals into less harmful substances.
Vitamin E Vitamin C Vitamin A Selenium
- minerals that are essential for us to eat (our bodies can’t make them)
- Can be fat or water soluble.
- fat saleable vitamin (non polar); absorb it better when you eat it raw
- absorbed in the intestines with fat in micelles
- transport in the blood via lipoproteins
- your body stores vitamin e in the adipose tissue (body fat)
- an antioxidant
- works in lipid environments; donates free radicals
Some fatty acids are oxidated more easily than others; poly unsaturated fats.
This is why: saturated fat/trans have a longer shelf life; old fish smells bad, frying in oil with high heat can smell bad.
The more pufa you eat the more vitamin e you need to eat; lucky foods that contain pufa also contain vitamin E; oils, avocado, nuts,
seeds, soy products. Vitamin E is destroyed by light; exposure to oxygen, metals, ultraviolet light and high temperatures; heating veggies destroys the
Uncommon and only happens with supplements; not with food; doses would have to be huge, over 800 mg according to RDA);
would cause nausea, and upset stomach.
Acute deficiency is rare because our bodies store vitamin E; puts people at risk for cardio vascular disease; causes erythrocyte
hemolysis – rupturing of blood cells; impaired vision, speech, movement and leg cramp.
27-41% of Americans have low vitamin E levels.
Water soluble vitamins are: polar molecules
Molecules are oxidized when they steal electrons? False; their molecules are stolen.
Vitamin E is an antioxidant in: cell membranes, lipoproteins.
3 food sources of vitamin E: avocado, soy, nuts and seeds, vegetable oils (margarine, salad dressing), green leafy vegetables
Ascorbic acid: a water soluble vitamin; can be carried freely in the blood; not stored in the body; should be eaten regularly.
- Most animals make their own vitamin c out of glucose; except monkeys, apes, guinea pigs and fruit bats and humans.
- We don’t have the right enzymes to do It.; explains why animals do not need to eat fruits and vegetables.
- It is a major water soluble water antioxidant (works in watery areas of our body or extracellular fluid).
- Donates its electrons to free radicals
- It recharges vitamin E by giving it electrons; can be recycled.