The ORAC determination (Oxygen Radical Absorbance Capacity) is a method developed by the National Institutes of Health in Baltimore, USA to measure the antioxidant activity in certain foods, herbs and spices both physiologically and chemically.
Although not the only method, it is the most popular one for determining antioxidant values in vitro.
The correlation between high antioxidant activity in particularly beneficial fruits and vegetables and the impact on a diet high in them is the basis for the free radical theory in aging. However, there is no proof as yet of this theory which has its basis in controlled, laboratory experiments (in vitro). Consequently, the ORAC and similar methods cannot be applied to living organisms (in vivo).
What does this mean?
It means that currently, there exists no means to prove that what can be shown in lab testing is applicable to human biology. Theoretically, 1 gram of cinnamon powder which has an ORAC value of 2,675 units may have only a far smaller value for the body. Or it may not.
With the exception of Vitamins A, C and E, no particular food or compound has been proven in vivo with antioxidant ability.
In spite of all this, until science discovers a means to prove the effectiveness of antioxidant activity of certain foods and prove the free radical theory, the ORAC values should be used only as a guide to determine the potential antioxidant capacity of a particular food.
It is important to understand that while lab testing generally isolates one particular factor for study, nature is holistic. Seldom is one isolated food or ingredient more important than its combined synergetic interaction with other foods we ingest.
ORAC Method Limitations
While ORAC determines the antioxidant values, it does not identify the free radicals nor takes into consideration phytochemicals or their absorption on a cellular or blood level. Also, xanthones, minerals and fibre are highly beneficial components yet have no ORAC value.
Comparing ORAC Data
Care must be taken when comparing ORAC data that one understands the units involved – grams (ie 1 g or 100 g), dry weight, wet weight or units per serving. Lab data charts are per 100 grams, whereas home use, for example of turmeric would be per 1 gram unit.
Herbs and spices have a much higher ORAC value but are used in rather small units. Melons are high in water and may appear to have lower values and a fresh (juicy) berry may seem to be lower in value compared to a dried berry because of less water weight.
In conclusion, use the ORAC values as an informative and interesting guide, but not an all conclusive one when choosing your foods and supplementation. It’s not just the numbers but the complete benefits and properties of a particular food that should be considered.