Food Fax

July 2002

The Mystique of Anti-oxidants
By Carol T. Culhane, P.H.Ec. MBA

'Wasn't Long Ago...
The November 1994 Editorial of JAMA (Journal of the American Medical Association) entitled "All that Glitters is not Beta Carotene" drew readers' attention to a number of newly discovered carotenoid anti-oxidants such as lutein (source: spinach; physiological association: macular degeneration) and lycopene (source: tomatoes; physiological association: prostate tumors), extolling their role in the maintenance of specific physiological functions.

Back in the mid-'90s these now-familiar anti-oxidants were overshadowed by B-carotene, the then best known carotenoid anti-oxidant due to its potential vitamin A activity. Further, the anti-oxidant spotlight shone mostly on Vitamin A, Vitamin C and the mineral selenium, all major components of the human body's "anti-oxidant system". Advice put forth in the Editorial seems elementary and ludicrous in light of the advanced clinical trials and subsequent anti-oxidant knowledge of the 21st century, such as:

"[...] Therefore, a null finding for one antioxidant on disease risk does not mean that other antioxidants could not be effective."

"Since dietary sources of carotenoids tend to overlap, levels and intake of other carotenoids should be controlled for when assessing specific carotenoids either in plasma or in the diet."

"Investigators should evaluate specific foods, nutrients, and vitamin supplements."

Has progress occurred?
Soon thereafter began a 5-year clinical study, the findings of which were published in this month's issue of The Lancet. 20,000+ UK adults suffering from coronary disease or diabetes were treated a daily regime of anti-oxidants Vitamin E, Vitamin C and B-carotene, or, matching placebos. The end result: no significant difference in outcomes such as all-cause mortality, coronary death, cancer incidence, and hospitalization -- despite substantially increased plasma vitamin concentrations in the treatment group. Predictably, the conclusion has generated less than favourable press coverage with headlines such as "MANY VITAMINS USELESS, STUDY SAYS: C, E AND BETA-CAROTENE: 'I'M GOING TO HAVE TO CHANGE MY STORY, ' SAYS VITAMIN ADVOCATE" in Canada's National Postª.

The Complexity of Anti-oxidants
Anti-oxidants are a mixed category of substances that protect the body from free radical activity, the damaging effect of cell oxidation. It is believed that the body's anti-oxidant system, which regulates the levels of anti-oxidants and free radicals, begins to de-generate with aging and exposure to contaminants such as cigarette smoke. Anti-oxidants are present in substantial concentrations in human plasma; most identified to date come from the plant kingdom. Examples include the phenol catechin found in tea, the mineral selenium, vitamins C and E, the pigment anthocyanin found in blueberries, the carotenoids lutein and lycopene. Each has a unique structure and specific biological property, which likely influences each one's ability to prevent a specific disease. Due to the natural inclination and professional curiosity of medical researchers, clinical trials will probably continue until each anti-oxidant is correctly associated with the protection and treatment of a particular physiological function. And not likely to be completed in our lifetime. FF

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