Menu Close

What are ORAC Units?

The ORAC (Oxygen Radical Absorbance Capacity) unit, ORAC value, or “ORAC score” is a method of measuring the in vitro antioxidant capacity of different foods and supplements.

More than two decades in the making, it was originally developed by scientists working at the National Institutes of Health (NIH) and USDA. Measuring in vivo (meaning inside the human body) is not possible and for that reason, the exact relationship between the ORAC value of a food/supplement and any suspected health benefit it may have as a result is unproven.

Many scientists theorize that foods higher on the ORAC scale may be more effective at neutralizing free radicals. Although unproven, according to the free-radical theory of aging, this may slow the oxidative processes and free radical damage that can contribute to age-related degeneration and disease.

The antioxidant test combines a measure of both the time an antioxidant took to react and also its antioxidant capacity in a given sample. The ORAC unit then combines them into one measure, making it the first in vitro assay method for measuring total antioxidant potential. It is easily expressed as ORAC Units per 100 grams of sample.

There are a number of bioactive compounds which are theorized to have a role in preventing or ameliorating various chronic diseases such as cancer, coronary vascular disease, Alzheimer’s, and diabetes.  However, the associated metabolic pathways are not completely understood and non-antioxidant mechanisms, still undefined, may be responsible.


Please take note:

ORAC values are routinely misused by food and dietary supplement manufacturing companies to promote their products and by consumers to guide their food and dietary supplement choices.

A number of chemical techniques, of which Oxygen Radical Absorbance Capacity (ORAC) is, one, were developed in an attempt to measure the antioxidant capacity of foods. The ORAC assay measures the degree of inhibition of peroxy-radical-induced oxidation by the compounds of interest in a chemical milieu. It measures the value as Trolox equivalents and includes both inhibition time and the extent of inhibition of oxidation.  Some newer versions of the ORAC assay use other substrates and results among the various ORAC assays are not comparable.

In addition to the ORAC assay, other measures of antioxidant capacity include ferric ion reducing antioxidant power (FRAP) and trolox equivalent antioxidant capacity (TEAC) assays. These assays are based on discrete underlying mechanisms that use different radical or oxidant sources and therefore generate distinct values and cannot be compared directly.

There is no evidence that the beneficial effects of polyphenol-rich foods can be attributed to the antioxidant properties of these foods. The data for antioxidant capacity of foods generated by in vitro (test-tube) methods cannot be extrapolated to in vivo (human) effects and the clinical trials to test benefits of dietary antioxidants have produced mixed results. We know now that antioxidant molecules in food have a wide range of functions, many of which are unrelated to the ability to absorb free radicals.

That is why these charts is to be used as a broad reference only for awareness purposes as to what foods are high in antioxidants

Recommended Daily Dosage

The recommended daily antioxidant dose should add up to around 20,000 – 30 000 ORAC units each day.

Most people take in about 1200 ORAC units daily primarily from an average consumption of three servings of fruits and vegetables per day very far short from the absolute minimum of 11000.

The estimated minimum antioxidant need of 8,000-11,000 units does not take into account the added amounts needed if other oxidant stressors, such as illness, cigarette smoke, meat consumption, air pollution, sleep deprivation, are present. If we had to deal with these stressors we’d need to consume more fruits and veggies just to stay out of the red.

According to Andrew Weil, MD – While healthy foods tend to have high ORAC scores, simply having high scores in a lab does not necessarily indicate high antioxidant activity in the body, and he thinks you can avoid the math and get the same health benefits by sticking to his top choices of foods and eating them often.


These include:

Green vegetables (which contain lutein and zeaxanthin, carotenoid antioxidants that can protect aging eyes from developing cataracts and macular degeneration):


Cruciferous vegetables (contain antioxidants and other phytonutrients that reduce cancer risk):
Brussels sprouts


Orange/yellow fruits and vegetables (rich in carotenoids that protect the immune system):
sweet potatoes


Red pigmented fruits (contain lycopene, a powerful antioxidant that helps fight heart disease and some types of cancer, particularly prostate cancer):
pink grapefruit


Blue/purple fruits and vegetables (these hues come from anthocyanins, phytochemicals that protect against carcinogens and may help prevent heart disease):

red cabbage


Fruits and Vegetables
Berries are high on the ORAC scale; blueberries have an ORAC value of 4,669, raspberries have a value of 5,065 and the ORAC value of strawberries is 4,322.

Cranberries are particularly high, with a value of 9,090 and blackberries have a value of 5,905. Other fruits with a high ORAC value, ranging from about 1,000 to 3,000, include apples, pears, citrus fruits, gooseberries and figs.

Grapes and grape juice are also high in antioxidants, with a value around 1,000 – but is very high in fructose so beware of those.

Vegetables are rich in antioxidants, and some examples of vegetables with an ORAC value of at around 1,000 include onions, broccoli, artichokes, eggplant and asparagus.

Along with their range of antioxidants, some of the essential nutrients in fruits and vegetables are potassium, vitamin C, vitamin A and dietary fiber.

Herbs and Spices
Many herbs and spices have a high ORAC value for their weight. Garlic, peppermint, thyme, oregano and basil have a high antioxidant capacity, with values as high as more than 10,000 in 100 grams, although you’d rarely eat that much. Other spices, with values around 20,000, include black pepper, ginger, cinnamon, curry powder, cumin and paprika.

Dried spices have considerably higher ORAC values than fresh due to their concentrated amounts. For example, fresh basil has an ORAC of 4,805 and dried basil has an ORAC of 61,063.

Starches, Nuts and Peanuts
Potatoes and sweet potatoes are other starchy foods with a high ORAC value of around 1,000 to 2,000, and they are also rich in fiber, potassium and vitamin A or vitamin C. The ORAC value of peanuts and nuts, including almonds, pecans, walnuts and pistachios, is around 3,000 to 5,000, and lentils, beans and peas are low-fat, high-protein sources of antioxidants, with values around 7,000 per 100 grams.

Other Foods
Black and green tea score high on the ORAC scale, and unsweetened dark chocolate is another high-antioxidant food, with a value near 5,000 per 100 grams. Olives, olive oil and avocados are good sources of antioxidants, with values around 1,000, and of heart-healthy monounsaturated fats, but they are also high in calories.

Sources of charts

The following tables are presented for reference only. Values are not absolute and will be influenced by growing conditions, harvest timing, processing and storage conditions and methods used to measure ORAC Values of the individual foods.

ORAC Values: Antioxidant Values of Foods & Beverages Online chart (This is been updated regularly that’s why it’s online)

For more information on what foods have High ORAC Values, read Dr. Mariza Snyder and Dr. Lauren Clum’s The Antioxidant Counter: A Pocket Guide to the Revolutionary ORAC Scale for Choosing Healthy Foods.

For a free searchable database that uses USDA figures, check out this useful, press on ORAC Values

Measuring Up: How to Calculate the Quality and Quantity of Antioxidant-Rich Foods

By Worker Bee

One method of measuring antioxidant capacity is the Oxygen Radical Absorbance Capacity (ORAC). Developed by the Baltimore-based National Institute of Aging, the calculation specifically measures the oxidative degradation of fluorescein (the stuff that the hotties on C.S.I. spray to detect the presence of blood, though not in this case) as it reacts with an agent called peroxyl radical (a free radical).

The reaction between the antioxidant and the free radical is then measured at 35 minute intervals to create a graphic curve that is then used as the basis for trolox equivalents (TE), or, in non-geek terms, the measure of a compounds potential for absorbing free radicals.

In 2004, the U.S. Department of Agriculture published a list of ORAC values for more than 100 common foods. Earning top billing on the ORAC list—meaning the items that contained the highest antioxidant value per serving—were small red beans, wild blueberries, red kidney beans, pinto beans, blueberries and cranberries.

The list has since been updated to include 277 food items. (Here is the PDF report.)

While these calculations are certainly scientific, this method does have some caveats. For example, the ORAC value of a particular food can vary significantly depending on whether the food is measured based on units per gram dry weight or units per gram wet weight.

When comparing grapes and raisins, for instance, raisins will clock in as having a higher antioxidant potential, simply because they are smaller than grapes and therefore more raisins are included in the calculation than would be if you were measuring for grapes.

Despite this nuance ORAC still reigns supreme as the vitamin-industry standard and as the one of the easiest ways to convey the antioxidant power of foods and supplements.

If you’re looking for a simpler solution – there is none.

Researchers determined that while creating a uniform unit of measurement was necessary, there was no consensus on which of the approximately 100 different methods used to measure them was best. They did, however, agree to disagree and drafted a multi-disciplinary team consisting of scientists from the industry, academia and the government to develop and test new methods for measuring the value of antioxidants.

Although more than three years later we’re, still waiting for those recommendations, the one thing the researchers at the meeting can agree upon is just to eat your fruits and veggies.


Did You See This?