Sandra M. Grant P.Dt. - Registered Clinical Nutritionist
My Blog

Antioxidants and disease prevention

Hello everyone and welcome to my blog!

I thought I would start with a topic that I find quite fascinating...antioxidants. We have all been told since we were knee high to a grasshopper to eat our fruits and vegetables, but has anyone ever explained why we need to eat so many? Perhaps you've heard that they're low in calories and will help keep you slim. Maybe it's because their fibre content helps you feel full sooner so you actually eat less. Or perhaps its the fact that they contain a lot of water, and we all know how good water is for us! These are all valid points, but new research is focusing on other compounds they contain called antioxidants. Antioxidants are compounds that may help protect against oxidative damage which in turn can lead to premature aging and disease. 

To understand how they work, we need a little chemistry 101. You might want to get comfortable and prop yourself up with a pillow so you don't bump your head as you nod off, but I'll try to simplify it and keep it short. Oxidative damage can be caused by external factors such as exposure to radiation, cigarette smoke, air pollution or industrial chemicals, but it can also be caused by oxygen. SInce oxygen is vital to life, any effort to avoid it would be futile to say the least. Oxygen is a negatively charged ion and as it travels through the body it tries to neutralize itself by removing ions from cells in the body. This results in formation of what we call "free radicals". Antioxidants can replace the ions taken away by oxygen and prevent the damage. The best way to see this in action is to cut an apple in half, sprinkle only one half of the apple with lemon juice, and leave both halves exposed to the air. In a few minutes the half of the apple without lemon juice will turn brown. This is the effect of the oxygen working on the flesh of the apple. The other half remains white as the vitamin C (a rich antioxidant found in citrus fruit) prevents damage to the fruit. The same thing happens in the body. Fruit and vegetables can protect us from oxydative damage whether it's due to external toxins or simply breathing! Damaged cells result in free radicals and free radicals are associated with pre-mature aging and a number of diseases including atherosclerosis, Alzheimer's disease, cancer, and rheumatoid arthritis.

Two things are important to remember. 

1: Our exposure to free radicals is occurring constantly thoughout the day. Antioxidants only stay in our system for a few hours. Sooooo we need to eat fruit and/or vegetables OFTEN. Ideally we should be having some type of fruit with breakfast and again between meals, as well as LOTS of vegetables at lunch AND supper. 5 to 6 times a day for good protection. 

2. Research does not show the same result with antioxidants in supplement form. It appears to be the synergy of all the compounds together (vitamins, minerals, fiber, antioxidants and other phytochemicals) within the plant that may protect us from premature aging and disease.

Additionally some supplements can be detrimental. For example Beta-carotene supplementation might increase the risk of smoking-related cancers and should be avoided by tobacco users. Rich antioxidant supplements can interfere with some chemotherapy medications and should be avoided during chemo treatment. 

So there you have it. Now you understand why we keep on pushing for more and more plant foods in the diet. They are currently our greatest protection against many diseases. Different plants provide different compounds which work at different levels of disease prevention so variety is important!

I hope you're still awake and have found this as fascinating as I do...but if you don't then I hope at least you've learned something and you'll consider adding a few extra sprigs of broccoli or maybe fresh herbs to dinner tonight. 


Ref: Res Pharm Sci. 2010 Jan-Jun; 5(1): 1–8.,
       R.Beliveau, Ph.D., D. Gingras, Ph.D., Foods that fight Cancer, 2005

7 Comments to Antioxidants and disease prevention:

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Lisa Keyser on September-03-13 8:24 PM
Actually i find this fascinating! I am so used to eating fruits and vegetables at breakfast and dinner only, but will step it up to all day long now. I would like to know your thoughts on fish oil supplements. I have been taking this for years, am I wasting my money? thanks
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Sandra on September-07-13 2:12 PM
Hello Lisa, and thank you for your comment. Glad to hear you enjoyed my post! As for your question on fish oil supplements, it's a great question, but there are several things to consider. Omega 3s (ɷ3s) are often used as a dietary supplement for depression, to lower cholesterol, reduce the risk of heart attack, prevent cancer etc. However much of the research available is contradictory or inconclusive. For instance although individuals with depression have marked depletion of ɷ3fa, ɷ3fa supplementation does not relieve the depression. Additionally their antiinflammatory effect may help patients with ulcerative colitis, but is ineffective for treatment of Crohn's disease. Studies do indicate that they may reduce the risk of colon cancer and reduce pain associated with rheumatoid arthritis. SO the first thing to consider is...why you are taking them. The second thing to consider is that ɷ3s come in several forms. EPA, DHA and ALA. ALA is the plant based ɷ3 and is not as effective as EPA and DHA. So unless you are vegetarian, your supplement should be mainly EPA/DHA and should be from a small source such as sardines, anchovies or krill, to reduce the amount of PCB and toxins in the oil. The recommendations for adults without coronary heart disease are 2 servings of oily fish per week or, if you do not want to eat fish, then 1g of ɷ3 supplement daily. However, compared to the supplement, fish also provide beneficial proteins, vitamins and selenium and is considered the optimal method to obtain ɷ3s. One final word...There is currently no regulation on supplements meaning that what is written on the label is not always necessarily in the product. Whenever possible look for a supplement with a DIN or a NHP #. This will minimize the chance that you are completely wasting your money. I hope that answers your question or at least confirms that you're taking the right supplement for the right reason! Have a great week! Ref: Br J Nutr. 2008 Feb; 99(2) 421-31 Rheumatology (Oxford) 2008 May; 47(5) 665-9

Luke on October-21-13 6:30 PM
What's confusing to me, and to many others, is the amount of information available from a variety of sources. Although I believe what your saying and it follows what I've been reading, it also goes against what others are saying. It can be interpreted differently and it also depends on who's writing it and their goals. How can we make sense of the massive amount of information or misinformation? Thank you
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Sandra on October-22-13 9:11 PM
Hello Luke, If I understand your question correctly, you are asking why there is so much conflicting information. Well unfortunately this isn't going to be short...but I'll try. First and foremost, nutrition is not something where one mold fits everyone. It should be personalized to the individual. Our lifestyle, height, weight, age, medical history, activity level and even the types of activities we engage in all make a difference in our nutritional requirements. So what might be recommended for one individual might be completely contraindicated for another. Unfortunately there are a lot of people out there who feel they are experts on the topic of nutrition because they read alot. But they need to have the knowledge of the human body, specifically the endocrine and digestive systems to be able to determine whether what they are reading makes sense or not. They also need to assess whether the source they are reading is a credible source, which many people do not do, or do not know how to do. So as you can see it can get very complicated and confusing. Your best source of information is a registered dietitian. The person will have the letters RD or PDt or DtP after their name, depending on which province they are working in. This assures you that they have completed a University degree AND have done an internship working with medical doctors.
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Elizabeth on October-27-13 9:02 PM
Well written and easily understood! good work!
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Sandra on February-01-14 3:23 PM
Thank you!
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Habib on March-05-15 2:11 AM
Hi Sandra, your post is very important and actually we never thought about antioxidants and preventing diseases. Many times, we think after getting diseases and finding doctors and it's too late. I am going to take spinach tonight :)
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