ORAC : ORAC (acronym for Oxygen Radical Absorbance Capacity, meaning in French: oxygen radical absorption capacity) is a method of measuring the capacities antioxidant in biological samples. A wide variety offoodstuffs have been tested using this methodology, with some spices, berries et vegetables getting high scores. The correlation between the high antioxidant capacity of fruits et vegetables, and the positive impact of a diet rich in fruits and vegetables, is believed to play an important role in the theory of free radicals of ageing.
A controversial index: In 2012, the Nutrient Data Laboratory (NDL) of the'USDA removed the USDA ORAC database from the website of NDL due to growing evidence that the values of capacitance antioxidant are not relevant to human health for the effects of specific bioactive compounds, including polyphenols.
A number of bioactive compounds are theorized to play a role in the prevention or amelioration of various chronic diseases such as cancer, coronary vascular disease, Alzheimer's disease and diabetes. However, the associated metabolic pathways are not completely understood and non-antioxidant, as yet undefined mechanisms may be responsible. Dietary supplement and supplement manufacturing companies food commonly misuse ORAC values to promote their products and that consumers guide their food and supplement choices food.
A number of chemical techniques, including oxygen radical absorbance capacity (ORAC), have been developed in an attempt to measure the antioxidant potency of foodstuffs. The ORAC test measures the degree of inhibition of the oxidation induced by a peroxy radical by the compounds of interest in a chemical medium. It measures the value in Trolox equivalents and includes both the inhibition time and the degree of oxidation inhibition. Some more recent versions of the ORAC test use other substrates and the results obtained with the different ORAC tests are not comparable. Besides the ORAC test, other measures of antioxidant capacity include potency antioxidant ferric ion reducer (FRAP) and the trolox equivalence antioxidant capacity assay (TEAC). These tests are based on discrete underlying mechanisms that use different radical or oxidant sources and therefore generate distinct values and cannot be directly compared.
There is no evidence that the beneficial effects of foodstuffs rich in polyphenols can be attributed to the properties antioxidant of these foods. Data concerning the antioxidant capacity of foodstuffs generated by in vitro (test tube) methods cannot be extrapolated to in vivo (human) effects and clinical trials designed to test the benefits ofantioxidants food gave mixed results. We now know that the molecules ofantioxidant about foodstuffs perform a wide range of functions, many of which are unrelated to the ability to absorb free radicals.
A few random excerpts from the long list of plants compiled by theUSDA :
ORAC antioxidant activity of various plants, according to USDA | |||
Part consumed | Plant (botanical name) | Medium ORAC (μmol TE/100g) |
|
---|---|---|---|
Chaga mushroom (use medicinal) | Inonotus oblique | 345 858 | |
sumac | rhu typhina | 312 400 | |
Nuts | Juglans regal | 13 541 | |
haskap | Lonicera caerulea | 13 400 | |
Cranberry | Vaccinium Oxycoccos | 9 500 | |
Artichoke, background raw | Cynara scolymus | 6 552 | |
Plums fresh | Prunus domestica | 6 100 | |
Red wine de Cabernet Sauvignon | Vitis vinifera | 4 523 | |
Grenade, fresh | Punica granatum | 4 479 | |
Strawberry fresh | Fragaria × ananassa | 4 302 | |
Granny smith apple, freshWith the skin | Malus pumila | 3 898 | |
Red cabbage, boiled | Brassica oleracea var. capita f. rubra | 3 145 | |
Green tea, leaves infused | Camellia sinensis | 1 253 |