Had my second exam this morning, I think it went pretty well; three more to go! In a weird way, I kindof like being in finals; studying all day (with the exception of a few climbing breaks here and there :p)- It makes me feel very productive and good about myself lol. I told this to my roommate… she openly told me that that made her hate me just a little bit :p lol. Either way, cannot wait until Christmas break! I’ve got some cute ideas for decorating our place (post exams as a reward lol), I’ll definitely share some pictures of the finished product!

Here’s a picture of me taken at devil’s glen in Ontario – photo cred to my friend Jess, awesome shot!

Anyyyywayyyss….

Everyone wants to get more antioxidants in their diet, what’s all the fuss about? So many people come to the nutrition store I work at asking for antioxidant supplements, stuck on the idea that these supplements will make them healthier. With all the interest, this post will be on antioxidants, with emphasis on beta-carotene, and the differences between dietary and supplemental forms.

So what do antioxidants do? Antioxidants work to quench free radicals and prevent the buildup of reactive oxygen species; this may reduce our risks for cancer and other chronic diseases. There are both enzymatic antioxidants, which scavenge hydrogen peroxide and superoxides and can be regulated based on our body’s requirements, as well as dietary antioxidants. Dietary antioxidants (non-enzymatic) include vitamin A, E and C as well as beta carotene and other nutrients. They are ‘chain breaking’ antioxidants and aid enzymatic antioxidants in reducing reactive oxygen species and reactive nitrogen species.

So before I move onto the question of whether supplementing with antioxidants are a good idea, I’ll discuss one dietary antioxidant followed by the results of this antioxidants supplementation. The antioxidant I’ll discuss is b-carotene…

Diets that are higher in carotenoids are thought to be protective through antioxidant activity; with beta-carotene in mind, lower levels are correlated to a higher incidence of heart disease and cancer. In 1981, beta-carotene was suggested to be the active carotenoid in vegetables that contribute to these healthy effects. This idea spawned from the fact that beta-carotene is the most abundant carotenoid in vegetables.

In 1996, the famous CARET study came around and changed the game in terms of beta-carotene. Smokers were given beta-carotene supplementation; the expected result was an improvement in cancer risk. Unfortunately, participants who were given beta-carotene had a 28% increase in lung cancer incidence and a 17% increase in death along with an increased rate of heart disease. The trial had to stop due to these adverse effects on participants.  A similar trial to the CAROT study used alcohol users as subjects. Beta-carotene was also observed to increase their risks of cancer. These studies confused a lot of people since beta-carotene has been long thought to be an antioxidant.

So what went wrong? Beta-carotene can have pro-oxidant effects at increasing oxygen tensions (from e.g. smoking) as well as increased beta-carotene concentration. This is an effect that we are only beginning to understand.  Breakdown products of carotenoids are formed when they interact with free radicals; these breakdown products present a risk for ’genotoxicity’. Since supplements have a much higher concentration of beta-carotene, they pose a risk firstly from their high concentration and secondly, if they are exposed to something that will cause oxidative stress (which is very common given modern lifestyles).

Something else to keep in mind, supplements do not have the same phytochemicals (‘plant chemicals’) that are present in actual vegetables- phytochemicals also decrease cancer rates, but through different pathways (e.g. toxin metabolism).In normal beta-carotene intakes (seen through the diet), it would be extremely hard to get adverse effects from the antioxidants present for a number of reasons including the lower amounts of antioxidants and higher amounts of phytochemicals. Take home points- dietary antioxidants=good idea, supplements=maybe not.

Something else to add is that, although fruits have a higher amount of antioxidants than vegetables, vegetables actually are more effective at reducing risks for cancer. What can we take away from that fact? Phytochemical content is very important for risk reduction (but I will get to them in a future post!), likely more so than antioxidants. Furthermore, the food matrix is very important for preventing risks associated with antioxidant breakdown products.

So to wrap things up, antioxidants and phytochemicals through our diet helps keep us healthy; we need to be cautious when we move out of a food matrix and into a neutraceutical. Research on antioxidants is both complex and hard to follow; e.g. one day it’s good, next day it causes cancer. Personally, I think the best way to eat for your health is through a proper diet with lots of vegetables (and fruits).

Anyways, gotta start studying for my next exam (on Friday); hope you all have a good day!

Jen

Alija, A., Bresgen, N., Sommerburg, O., Langhans, C., Siems, W., and Eckl, P.(2005) Cyto- and genotoxic potential of beta-carotene and cleavage products under oxidative stress. Biofactors 24(1-4):159-63.

Leo, M. and Lieber, C. (1999). Alcohol, vitamin A, and b-carotene: adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr. 69(6):1071-85.

Omenn, G., Goodman, G., Thornquist, M., Balmes, J., Glass, A., Keogh, J., Meyskens, F., Valanis, B., Williams, J., Barnhart, S., Cherniack, M., Brodkin, C., and Hammar, S. (1996)Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial.J Natl Cancer Inst. 6;88(21):1550-9.

Peto, R., et al. Can dietary beta-carotene materially reduce human cancer rates? Nature, Vol. 290, March 19, 1981, pp. 201-08.

Singh, P., Chandra, A., Mahdi, F., Roy, A., and Sharma, P. (2010) Reconvene and reconnect the antioxidant hypothesis in human health and disease. Indian J Clin Biochem. 25(3):225-43.