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Total Antioxidant Capacity of the Diet, Age-Related Cataract and risk of myocardial infarction (2014-02-02)

The total antioxidant capacity (TAC) concept aims to measure the capacity from all antioxidants in the diet by also taking synergistic effects into account.

The objective of this study was to investigate the association between the TAC of the diet and the incidence of age-related cataract in a population-based prospective cohort of middle-aged and elderly women. JAMA Ophthalmol. Published online December 26, 2013. doi:10.1001/jamaophthalmol.2013.6241

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Researchers analized data from questionnaire-based nutrition survey within the prospective Swedish Mammography Cohort study, which included 30.607 women (aged 49-83 years) who were observed for age-related cataract incidence for a mean of 7.7 years.

The TAC of the diet was estimated using a database of foods analyzed with the oxygen radical absorbance capacity assay.
Information on incident age-related cataract diagnosis and extraction was collected through linkage to registers in the study area.

There were 4309 incident cases of age-related cataracts during the mean 7.7 years of follow-up (234.371 person-years). The multivariable rate ratio in the highest quintile of the TAC of the diet compared with the lowest was 0.87 (95% CI, 0.79-0.96; P for trend =.03).

The main contributors to dietary TAC in the study population were fruit and vegetables (44.3%), whole grains (17.0%), and coffee (15.1%).

Dietary TAC was inversely associated with the risk of age-related cataract. Future studies examining all antioxidants in the diet in relation to age-related cataract are needed to confirm or refute our findings.

Authors of the study are Susanne Rautiainen, PhD and Alicja Wolk, DMSc (Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden), Birgitta Ejdervik Lindblad, MD, PhD (Department of Ophthalmology, Örebro University Hospital, Örebro University, Örebro, Sweden) and Ralf Morgenstern, PhD (Division of Biochemical Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden).

In a previous study Alicja Wolk found that a diet rich in antioxidants, mainly from fruits and vegetables, can significantly reduce the risk of myocardial infarction. The study is published in the October 2012 issue of The American Journal of Medicine.

"Our study was the first to look at the effect of all dietary antioxidants in relation to myocardial infarction," says lead investigator Alicja Wolk, DrMedSci, Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden. "Total antioxidant capacity measures in a single value all antioxidants present in diet and the synergistic effects between them."

The study followed 32,561 Swedish women aged 49-83 from September 1997 through December 2007. The women completed a food-frequency questionnaire in which they were asked how often, on average, they consumed each type of food or beverage during the last year.
The investigators calculated estimates of total antioxidant capacity from a database that measures the oxygen radical absorption capacity (ORAC) of the most common foods in the United States (no equivalent database of Swedish foods exists). The women were categorized into five groups of total antioxidant capacity of diet.

During the study, 1,114 women suffered a myocardial infarction. Women in the group with the highest total antioxidant capacity had a 20% lower risk, and they consumed almost 7 servings per day of fruit and vegetables, which was nearly 3 times more than the women with the least antioxidant capacity, who on average consumed 2.4 servings.

Dr. Wolk notes that trials testing high doses of antioxidant supplements have failed to see any benefit on coronary heart disease and, in fact, in one study higher all-cause mortality was reported. "In contrast to supplements of single antioxidants, the dietary total antioxidant capacity reflects all present antioxidants, including thousands of compounds, all of them in doses present in our usual diet, and even takes into account their synergistic effects," she explains.

In a commentary accompanying the article, Pamela Powers Hannley, MPH, Managing Editor of The American Journal of Medicine, observes that with the industrialization of our food supply, Americans began to consume more total calories and more calories from processed food high in fat and sugar. As a result, obesity rates began to climb steadily.

For more information
Total Antioxidant Capacity of the Diet and Risk of Age-Related CataractA Population-Based Prospective Cohort of Women

Diet high in total antioxidants associated with lower risk of myocardial infarction in women
Elsevier

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