Antioxidants...What are they?


It seems like everywhere you look these days there is something advertised with antioxidants.  If they are all over the place, it is probably a good idea to know exactly what they are.  For many people this term means something that protects against cancer or protects the body in some way, and this is correct, but it is much more complicated than that.

ANTIOXIDANT- compounds that protect our cells from damage caused by oxidation.

OXIDATION- A chemical reaction in which molecules are broken down and atoms lose electrons.

Sounds like a boring chemistry lesson, doesn't it.  While the process itself may seem complex, the concept can be explained in simple terms.  I am sure you have heard the term FREE RADICAL.  I once did a presentation on antioxidants and they were designated with a picture of a policeman, the free radicals were dressed like prisoners and put behind bars (can't take all the credit, my friend and fellow RD Christa came up with that one).  It really helps to get the message across.  Antioxidants are the good guys, free radicals are the bad guys and the antioxidants will need to "catch" them.

FREE RADICAL- A highly unstable atom missing an electron in it's outer shell

Ok, away from the boring science lesson and back to the simplicity of the law enforcement analogy.  So if oxidation means an atom loses an electron, then the end result of this reaction is the formation of free radicals.  Think of this reaction as the law being broken (oxidation is the crime) and the result is the bad guy, or free radical, on the loose inside your body.

So how does oxidation occur: smoking, pollution, sun exposure, toxic substance exposure, radiation, and well, just plan old living can do this to the body.  Our natural process of metabolism within the body can result in the formation of a free radical.  Once that free radical is formed and "on the run" it is free to roam about the body and "steal" an electron from other stable atoms within the body, making those unstable.  The free radical is very powerful and will always want to become stable.  The only way to do this is to "steal" an electron from somewhere else.  The problem with this is that in the ongoing process of "stealing" electrons and making atoms unstable, the cell structure is damage, sometimes beyond repair.

Free radical damage in the body is linked with:

  • cancer

  • heart disease

  • kidney disease

  • diabetes

  • arthritis

  • Alzheimer's

  • Parkinson's
Basically it can cause the usual suspects...

Enter the good guys, the antioxidants.  There are tons out there, vitamins, minerals, phytochemicals, and so on, but I don't want to get too crazy with all the details.  Today I am going to stick with a few common ones that can be obtained on a daily basis from foods you are probably already eating.  The idea is that you do not need to go out and supplement your diet with extra nutrients to get the benefit and protection from free radicals, but that you are making a conscious choice when choosing foods to select those that are of benefit to your body, and taste good too.

THE GOOD GUYS:
-Vitamin E
-Vitamin C
-Beta-Carotene (provitamin for vitamin A)
-Vitamin A
-Selenium

Let's start of with vitamin E:
Obviosuly it protects the cells from oxidation damage, but what else does this do.  Protects polyunsaturated fatty acids from oxidation, protects vitamin A from oxidation and prtects white blood cells.  The RDA for vitamin E is 15 mg alpha-tocopherol.  This can be found in great food sources including sunflower seeds, almonds, some fortified cereals, and sunflower oil.  While those are your highest sources, it can be found in other foods as well, including broccoli.  Vitamin E is a fat soluble vitamin, meaning it can be dissolved (or absorbed into) fat molecules.  This is why you may find it in skin products.  We rub the vitamin E on our skin which contains fat molecules as part of the membrane, and anything fat soluble can be absorbed right in.  Well, since this is fat soluble, we also run the risk for toxicity, or too much in our bodies.  Often times toxicity will occur from supplements since these fat soluble vitamins can build up in the organs and fat deposits in the body.  Some toxicity effects include decreased ability for blood clotting, increased risk for hemorrhagic stroke (bleeding oout in the brain due to the inability for blood to clot), and maybe some GI upset.  My fave place to get my vitamin E is from almonds.

On to vitamin C:
I am sure most of you, if not all, have heard that vitamin C is a strong antioxidant.  Well, it's true.  Vitamin C can regenerate oxidized vitamin E, reduce formation of nitrosamines (which can cause cancer) in the stomach, helps with collagen formation, enhances immune function and enhances the absorption of iron, among a few others.  Overall this is a great protect of the body.  Too bad it is water soluble and unstable and will readily leave the body.  That is why recommendations are to consume a vitamin C rich food daily.  Some good sources include (in order of amount per 1 cup or 8 fl oz serving) sweet red peppers, sweet green peppers, OJ, broccoli, strawberries, kiwi fruit (pictured at top!), grapefruit juice and an orange.  The deficiency disease is known as scurcy, but this is not too much of a public health concern in our country.  Toxicity is rare as this is water soluble and can easily leave the body in urine, but if it does occur, symptoms may include GI upset, nosebleeds and an increase in kidney stone formation.  Oh, and you might have heard that if you feel a cold coming on, take some vitamin C.  Well, scientifically this has not been proven.  Since this protects immune function it is thought to load up if you are getting sick.  The idea really is not to become deficient in the first place to allow your immune system to get down.  What I am really saying is consume your vitamin C rich foods daily, if you wish to take a supplement that is probably ok (the only one you will ever hear me support the use of for everyone), but once the cold has established onset, it is too late to boost the immune system with vitamin C.  Now, if you find it helps, this is possible, maybe it does, or maybe it is the placebo effect (which is what they found in researching this).  If you are a smoker you need more as smoking causes free radical damage, so it may make sense to increase intake of the good guys.  The RDA for men is 90 mg, women 75 mg, and if you are a smoker you need 35 mg more per day than the RDA.

On to beta carotene and vitamin A:
Beta carotene is a precursor for vitamin A.  Some functions include protecting cell membranes, protecting the skin from UV radiation, and protects the eyes from oxidative damage.  There is no RDA set at this time.  The only known toxic side effect is a yellowing of the skin, so if you notice this, cut back on the high beta carotene/vit A foods!  Vitamin A, which is also a fat soluble vitamin, is needed for good eye sight as it protects our color vision and helps the eyes adjust to changes in light.  Taking vitamin A supplements instead of getting it all from foods may cause some problems, since it is fat soluble and can be stored in the body.  Some toxicity effects include spontaneous abortion if pregnant, blurry vision, loss of hair, and liver damage.  Taking supplements will not improve you eye sight unless you are actually suffering from a vitamin A deficiency.  Again, the idea is to eat a variety of foods daily to ensure adequate intakes of these nutrients.  The RDA for vitamin A for women is 700 micrograms and for men is 900 micrograms.  Dietary sources of beta carotene include (in order from highest per 1 cup portion) pumpkin, sweet potato, spinach, collard greens and kale.  I know many of you gets this in on a regular basis.  Vitamin A rich foods are similar.  They include beef liver (hey it's a fat soluble vitamin, so if something has a liver it is bound to be concentrated with many nutrients, especially fat soluble ones), pumpkin, carrots, sweet potato and collards.  I should also mention that the use of vitamin A as an antioxidant is still being studied, as we know all about it's precursor beta carotene, less is known on vitamin A.

Ok, we have made it to out last good guy for the day...selenium:
This is an antioxidant I feel strongly about because it has a very narrow margin for safety.  Believe it or not, you can develop toxic levels of this, and quickly.  Selenium does do many good things in the body as an antioxidant, including sparing vitamin E from oxidation, maintains immune function, and is part of an antioxidant enzyme.  The RDA is 55 micrograms for men and women.  The safe upper limit is 400 micrograms, however you should probably not go over 200 mg.  This can have very serious effects, very quickly.  An acute, or one time, overdose can result in death.  consuming selenium in foods does not really pose the threat for this, but supplementation does.  Selenium in found in the following foods: brazil nuts, mixed nuts, halibut, shrimp, tuna, beef liver, and couscous.  Selenium content of meats can vary depending on the content in the soil where they were raised.

So I think what I am really trying to get at here is a good reminder to eat a variety of foods every day and choose produce that is brightly colored.  Each of the colors results from the nutrients in them, so a variety of colors will give you a variety of nutrients.  You may see a lot of foods labeled as antioxidant containing or special formulation.  I just want to remind you that sometimes these foods may come with a higehr price tag for the label it bears, or that they may just be advertising something that was already naturally occuring in that product, which is OK as that serves as education for the public, I am just saying it doesn't make a product special when they are naturally occuring in other places.  You do not need to search out products that say contains antioxidants (although it is helpful to alert you to a product with these and helps with education on sources of antioxidants), it is  as easy as getting your fruits and veggies in, some nuts, and overall a variety of foods.  The goal is to make those good guys catch those bad guys and prevent damage to our already delicate bodies.

QUESTION: Did you learn something new from this post today?  What did you find most interesting?

Thanks for taking the time to read my oh so long post today, but I wanted to get the information out there.  Have a good Wednesday!

Reference: Thompson, J., Manore, M. (2006). Nutrition: An applied approach. Pearson Education: CA.

8 comments:

Anonymous said...

Great reminder to eat a variety of foods! I think it's sometimes easy for me to get "stuck" eating the same foods over and over and over. This post was a great reminder to "mix it up" a bit! Thanks! :)

Gina said...

FANTASTIC way to explain this concept!! Seriously, sometimes I even get confused myself when explaining it, or trying to remember it all. I am seriously going to use your jail/robbery analogy! Very helpful.

Melissa said...

I learned a lot from the post! And I like how you explained things in simple terms. Oxidation is a crime! :)

Very helpful and useful!

Melissa said...

Great post. I learned quite a bit. I'll make my food choices brightly colored. Thanks!

Chow and Chatter said...

awesome post well written will tweet it and link to chow and chatter facebook page

Love Rebecca

Anonymous said...

Great post! I've never known so much about selenium before! :D

Thanks for your comment yesterday on my blog - maybe I should have gone to the glucose tabs first?

Julie said...

great post :) i think i'm getting my fair share of antioxidants from beta caroten says my orange hands

Anonymous said...

Thanks for the review. Sometimes this stuff starts to get a big hazy after a while. I love the analogy. That is a simple way to put it!

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