ORAC is the new oracle or ‘source of wise counsel’ in nutrition. Standing for oxygen radical absorbance capacity, it’s a way of measuring the antioxidant rating of different foods. Originally developed by the National Institute on Ageing in the US, it shows how well the antioxidants present in fruits and vegetables can mop up harmful free radicals, which are recognised as one of the main triggers of the ageing process.  

Although everyone knows they should eat at least five portions of fruit and vegetables per day (and ideally eight to ten), the average intake is only two and a half. Based on surveys in the US, scientists have calculated that the average person obtains around 5,700 ORAC units per day. Ideally, at least 7,000 per day are needed for health and those consuming an ideal nine servings of fruit and vegetables per day could obtain an optimum 20,000 units per day, or more.

The fruit and vegetables you select have a major impact on your ORAC score, however, as they contain different types and amounts of antioxidants of varying potency. And, in most cases, their potential is reduced by cooking.
If you select five average servings made up of blueberries, plums, red kidney beans, spinach and red peppers, you can rack up an astonishing 33,000 ORAC units in a single day. On the other hand, if your five servings comprise a kiwi, slice of watermelon, a mixed salad, cauliflower and carrots you would obtain less than 2,000 units - even though you have achieved your recommended five servings.

By balancing your intake of foods with high, medium and low ORAC scores, you can maximise the antioxidant potential of your diet on a daily basis. The higher a fruit or vegetable’s score, the higher its ability to neutralise free radicals - the molecular fragments that damage cells through a chemical process known as oxidation. Oxidation damages our genetic material and cell proteins, contributing to age-related problems such as skin mottling and wrinkling, hardening and furring up of the arteries, coronary heart disease, arthritis and Alzheimer’s. Free radicals are also associated with the development of uncontrolled growth in cancerous cells.

How the ORAC test works
Fruit and vegetables contain a variety of natural antioxidants, some of which work quickly and some of which work slowly but still provide important protection. The ORAC test (see box below) measures how well these antioxidants prevent the breakdown of a chemical (fluorescein) after it is mixed with a strongly oxidant substance (peroxyl radical). Fluorescein is used because it is luminescent and the intensity of light it emits decreases as it breaks down. This provides an easy way of measuring how much fluorescein remains intact at set intervals after the fruit or vegetable extract and the oxidant are added. If the food has a low ORAC value, it provides little protection and the mixture’s luminosity rapidly decreases. If the food has a high value, it protects the fluorescein from degradation and the sample remains luminescent for longer. By measuring the intensity of fluorescence in the mixture every 35 minutes after adding the oxidant, scientists develop graphs which are compared with the results from different concentrations of a standard antioxidant related to vitamin E (trolox). The final results are given as ‘trolox equivalents’ or TE.

As well as supplying antioxidants, fruit and vegetables provide other important phytochemicals and nutrients, including vitamins, minerals, trace elements and fibre. Because of that, the majority of the five to ten servings of fruit and vegetables you eat per day (e.g. 3 out of 5, or 7 out of 10) should be vegetables rather than fruit, even though vegetables tend to have a lower ORAC score. This is because vegetables tend to contain more fibre, less water (so are a more concentrated source of nutrients) and less sugar.
Although diet should always come first, if you have difficulty achieving an intake of at least five portions of fruit and vegetables daily (not to mention ten) a nutritional supplement can act as an insurance policy to help protect your antioxidant status. Look out for high potency antioxidant supplements such as pycnogenol, lycopene and green tea, or a multi-antioxidant blend.
Supplements containing fruit and veg extracts that provide a known ORAC value are also available.

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