Aronia continues to increase in interest not only in research science, but also in the public due to the uniquely high values of nutrients it contains. For several phytochemicals, aronia has the highest or among the highest measured in plants. Oxygen Radical Absorbance Capacity (ORAC) is a laboratory test which was assessed to measure antioxidant capacity of many foods.
The ORAC value for Aronia is 16,062 umol TE/100g. Written out: the Oxygen Radical Absorbance Capacity assay for fresh aronia berries is 16,062 micromoles Trolox Equivalent per 100 g fresh berries. Now, we need to put this into a real world context, and also explain about Trolox Equivalents.
I will show a graph below of how Aronia fits into the scheme of other foods, but there is more to this story than 16,062 ORAC Units.
There is some interesting history behind the ORAC Database. It is likely that most of the population has no idea exactly what ORAC is/was, or what it was trying to assess.
It seemed that a food (or supplement) with a higher ORAC value would be more healthful than one with a lower value. However, this lab test was not only prone to misunderstanding by normal people, but also for misuse by the nefarious.
We did a quick summary article on ORAC here: What Is ORAC?
Let’s expand on this topic by starting with the essentials. What is an antioxidant and what in the world is Trolox?!
What is an Antioxidant?
Most everyone has at least heard of the word “antioxidant”. We could go on and on (and on) into the esoteric details of this, but for our purposes, we won’t need to do this. Essentially we just need to stir up a little bit of your high school science memories.
Remember that a molecule has a nucleus which is surrounded by electrons orbiting around it? If a molecule loses an electron (=oxidizes), it becomes a free radical. It will try to gain an electron by taking it from some other molecule. This other molecule might be a DNA molecule, or other cells, and so, can cause damage to these cells at the molecular level.
The free radical in the body comes from either:
- a result of normal chemical processes in the body, or
- materials that the body ingests or is otherwise exposed.
Some examples of exogenous sources of free radicals (“oxidants” or “reactive oxygen species”):
- smoke
- some processed foods
- ozone
- pesticides
- radiation
- pollutants
- ultraviolet light
- industrial chemicals.
Think of an antioxidant as a molecule that can donate electrons which will result in stabilizing the free radical. The body has a whole array of molecules/materials that oxidize, as well as molecules/materials that are antioxidants.
Examples of antioxidants which your body has/makes (=endogenous):
- Superoxide Dismutase
- Glutathione
- Bilirubin
- Ubiquinol
- Melatonin
- Ferritin
- Ceruloplasmin
Examples of antioxidants which can be ingested (=exogenous):
- Vitamin C (ascorbic acid)
- Vitamin E (tocopherols)
- Vitamin A (carotenoids-carotenes, lycopenes, lutein)
- polyphenols (anthocyanins, flavonoids, stilbenes, lignans, phenolic acids)
- Trace elements – such as selenium and zinc.
OK, so if I have a higher amount of free radicals, or take in a lot of exogenous free radicals (I smoke, or eat unhealthily, or are exposed to more harmful sources), I should then take in more antioxidants, and the higher the antioxidant value, the healthier, right?
It turns out that it is not necessarily that simple.
For example, we know that vitamin E is important- it is a very powerful antioxidant in the body, and low vitamin E causes problems. However, there have been several historical studies on giving supplements of vitamin E for certain health conditions which did not turn out to be helpful, and in some cases was more harmful… but, in some more recent studies, vitamin E indeed was helpful.
The USDA (United States Department of Agriculture) had noted that several medical conditions could be attributed in some manner to oxidative stress (= damage from free radicals). So, they worked to quantify antioxidant activity and published a database which quantified antioxidant activity.
The method they used to quantify antioxidant activity is a laboratory test called the Oxygen Radical Absorbance Capacity assay (ORAC).
What exactly is an ORAC, how does it measure antioxidant activity, and what is Trolox?
The ORAC laboratory assay was developed and published in 1993 (Cao, et al). The ORAC test compares how well a substance of interest (food, berry, etc) neutralizes an amount of free radical, using a control standard of an antioxidant: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid =Trolox.
Trolox is a molecule that is a derivative of Vitamin E. Since Vitamin E is a powerful antioxidant, think of Trolox as something that is good at neutralizing a free radical.
One “ORAC unit” is defined as the net antioxidant protection produced by 1 micromole/liter (µM) of trolox.
If you are interested in the scientific details of the test itself, here is the link for the original Cao article on ORAC: https://zenodo.org/record/1258621/files/article.pdf
For those interested in the chemistry, here are the chemical structures for Trolox and for Vitamin E. (Everyone else, skip ahead.)
TROLOX (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid)
VITAMIN E (There are 8 forms of Vitamin E. This is D-alpha-Tocopherol)
If you want to read up on Vitamin E, Here is a nice fact sheet (from National Institutes of Health, Office of Dietary Supplements). https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/
ORAC sounds like it is great! What was the problem?
ORAC numbers became used in ways they were not meant to represent:
questionable implications, misleading advertisements, and nefarious intent.
What is wrong with using ORAC?
ORAC became used by many companies and organizations to advertise their product’s health benefits. The implicit story went something like “{my product} has a higher ORAC than {other product}, therefore mine is superior, it works better, it could cure your {fill in the blank medical condition}” and on and on. Also, it was reported that companies added substances to their products to artificially increase their ORAC value during laboratory testing.
So, USDA withdrew their online ORAC database in 2012, citing 2 reasons:
- “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.” (Cunningham 2013)
- “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.” (Cunningham 2013).
Another item of concern regarding ORAC values is that the ORAC valuation for any food is dependent on what form the food was in. A common example is that of a grape and a raisin. Each have the same antioxidant property (a raisin is a dried grape, after all). But, in terms of an amount “per 100g”, the raisin will look like it has a higher ORAC value since the water weight was removed. The same is for spices. There is an amazingly high ORAC number for spices—but again, these are given per 100 grams.
Here is a visual example: The highest ORAC values in the USDA database include ground cloves (314,446), ground cinnamon (267,536), and dried oregano (265,700). Pretty high, right?
Here is an example of the small stubby typical container that spices are commonly sold at your grocery store:
This container will hold:
- 0.9oz (ground cloves) = 25.5 grams
- 1oz (ground cinnamon) = 28.3 grams
- 0.75oz (ground oregano) = 21.3 grams
So, 100g would be like eating at one time: ~4 containers of ground cloves or ground cinnamon, or ~5 containers of ground oregano.
So, listing spices and herbs or touting a superiority by their “per 100g” trolox equivalent is not specifically helpful or accurate.
Similarly, foods have been concentrated into powder and some have used the powdered value as a marker for superiority, with some companies comparing their powder ORAC values against whole foods- most commonly with raw berries or juices.
Using acai as an example (since acai powder is noted in the ORAC database): Acai has a considerable ORAC value in berry/pulp form. But, like any powdered spices/herb, Acai in powder form has a very high ORAC value, listed as 102,700 per 100 grams.
Using Acai commercial sources: 100 grams of Acai powder is approximately 3.5 ounces.
So, in order to get 102,700 ORAC units of Acai in this form, you need to ingest 3.5 spice containers of powder.
So, when researching foods and supplements for yourself, one important thing to remember is to to check the labels so that you are comparing items accurately.
ORAC Graph
This includes the highest ORAC value foods in the USDA ORAC Database and includes some other moderately high ORAC foods that were interesting to add for comparison.
(There are 326 food items in the database.)
Again, these are of foods, as defined as 100g of something you could eat raw or mashed into a pulp and eat.
Not included are spices, herbs, or other artificially concentrated substances such as foods concentrated into powders.
In order to have comparable forms, 2 items were not included in the USDA database, so these were obtained from other sources. These values are found to be in general agreement with other sources.
Not assessed in this chart is any relative difficulty in locating a supply of a food, unless you are in a geographically favorable location.
For example, it can be difficult to locate raw black raspberries unless you are in Oregon, USA. It is impossible to acquire fresh Acai outside of South America due to rancidity problems with Acai occurring rapidly after picking, so exportable forms include pulps, powders, or juices.
So, is ORAC Bad or Good?
It is both and neither. It is a tool. It might guide researchers in antioxidant studies (i.e. which high antioxidant foods to investigate). Don’t just look at the number to do your own assessments. That being said, it seems that antioxidant studies had stimulated considerable interest and have led to advancement in several other molecules related to antioxidant content.
It turns out that these foods with high antioxidant valuations tend to have complicated compounds of naturally occurring polyphenols (flavonoids including anthocyanins, phenolic acids, stilbenes, and lignans). These are antioxidants, thus positively contribute to their ORAC valuation.
There is an increasing current body of research on the potential benefits of high polyphenol foods particularly in Aronia which has high values, not only in ORAC, but also in various polyphenols.
More Info
Since ORAC assessment is not sufficient, what else should I be looking for?
As discussed, the other complex biomolecules which contribute to ORAC may be the key, not only as to why the antioxidant content is high, but also may be the source of health benefits include polyphenols (anthocyanins, flavonols, isoflavones, phenolic acids). USDA has compiled a database for the flavonoid content of selected foods here:
USDA Database for the Flavonoid Content of Selected Foods
How should I best look up information on ORAC and other substances?
- Identify good sources. It may be that a company that sells a product will have good information, but remember that is what they are selling, so a more neutral source such as USDA, NIH, PubMed, or a University study would be better, generally speaking.
- Don’t just use laboratory numbers to make your decisions. Look up research articles which actually use your product in a clinical manner, so you can assess for yourself. PubMed and American Chemical Society can be good sources for peer reviewed scientific articles and abstracts.
Sources
Cao, G, Alessio, HM, and Cutler, RG. 1993. “Oxygen-Radical Absorbance Capacity Assay for Antioxidants” Free Radical Biology & Medicine. 14. 303-311, 1993.
Cunningham, E. 2013. “What Has Happened to the ORAC Database?” Journal of the Academy of Nutrition and Dietetics. p740. https://jandonline.org/article/S2212-2672(13)00242-6/pdf. . Refers to: Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 (2010). US Department of Agriculture website. http:// www.ars.usda.gov/services/docs.htm? docid15866. Accessed February 26, 2013. Original USDA article no longer available.
Haytowitz, DB, and Bhagwat, S. (Preparers). 2010. “USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2”. USDA Agricultural Research Service. http://www.orac-info-portal.de/download/ORAC_R2.pdf
Jennings, K. 2017. “5 Impressive Health Benefits of Acai Berries” 5/31/2017. https://www.healthline.com/nutrition/benefits-of-acai-berries (accessed 4/26/2020).
Schauss, AG. 2012. “Should We Ditch the ORAC Antioxidant Test?” Nutritional Outlook. Accessed 2/12/2020. https://www.nutritionaloutlook.com/science/should-we-ditch-orac-antioxidant-test.
“Acai Berries, ORAC, Omegas and Anthocyanins” https://www.powersupplements.com/acai/acai-orac.html, (Accessed 4/26/2020).
Daya, S. “Facts and Myths about Acai Berry” https://www.victoriahealth.com/editorial/facts-and-myths-about-acai-berry (Accessed: 4/26/2020)