What Is the Difference Between Antioxidant Capacity (Orac) and Antioxidant Bioavailability?

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What is the difference between antioxidant capacity (ORAC) and antioxidant bioavailability? Antioxidant capacity (ORAC ranking) and antioxidant bioavailability sound similar but they are two very different things! In simple terms, one is measured outside the human body, and the second one is measured inside the human body. What do we mean by that? As you’ve seen in Module 8, ORAC refers to the overall “antioxidant capacity” of a plant food. The oxygen radical absorbance capacity is a way to measure the ability of the antioxidant compounds in plant foods to absorb free radicals. This is tested in vitro (rather than inside the human body). On the other hand, you need to think of “antioxidant bioavailability” as your body’s capacity to assimilate and absorb the antioxidant compounds of a plant food into your system. In other words, how many of its antioxidants actually make it into your bloodstream and then into your cells? Now, before you even consume the food item, its ORAC ranking can be changed by different cooking methods. Boiling and frying “oxidise” the antioxidants in the food – in other words, we’re losing the antioxidants! Why? Because they are already busy absorbing and neutralising the free radicals from cooking (in the case of frying) or leaching into the water (in the case of boiling). Steaming and microwaving tend to retain more of the antioxidants than frying and boiling. The ORAC may go down a notch when steaming and microwaving, as you’ve seen in the raw vs. steamed spinach example (Module 8, slide 23), where the raw spinach has a higher ORAC. Now, even if a food has a higher ORAC (e.g. raw spinach), it doesn’t mean that your body will be able to absorb and assimilate 100% of the antioxidants in it! Here’s where the concept of antioxidant bioavailability comes in. Although steamed spinach has a slightly lower ORAC, your body will be able

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