ORAC and Antioxidants: Realizing the Potential

The idea of antioxidants and the abundance of antioxidant products on the market have become more widely accepted by consumers. People understand “the good guys vs. the bad guys”, so antioxidants vs. free radicals is a match-up they can tune in to. People also agree the jam-packed, average modern lifestyle has created a food culture of nutritional deficiencies and quick fixes. They realize their diet and genetic make-up is not sufficiently armed to deal with the increase in free radicals such lifestyles have created. Thus, they are willing, even eager, to supplement with antioxidants.

Little do they know, the world of antioxidants and oxidation is quite complex, and the marketplace for antioxidant supplements is riddled with misleading, inconsistent or inaccurate marketing and labeling. Sure, marketers’ hands are somewhat tied by federal regulations on what they can say about the benefits of dietary supplements and functional foods; but, consumers looking for results show no mercy when a product fails to deliver what they perceive should be the benefits.

To summarize this complex category: antioxidants can act generally and/or specifically, and the marketing of antioxidants using Oxygen Radical Absorbance Capacity (ORAC) and similar test scores is largely about potential.

In the mid-1990s, Ronald Prior, Ph.D., at USDA's Human Nutrition Research Center on Aging at Tufts University, Boston, joined forces with the team that first published the ORAC assay principles—physician and chemist Guohua Cao, M.D., Ph.D., and his colleagues at the National Institute on Aging (NIA), Bethesda, Md.—to apply the test to food evaluation. The test pits an antioxidant sample—an extract, for example—against free radicals in a test tube. The amount of oxidative stress/damage and inhibition of this oxidation is measured relative to a fluorescent tube, yielding a score that represents the antioxidant capacity of the sample.

To understand what ORAC scores really mean to human health and the diet, it is important to first grasp the differences between various antioxidant compounds and their mechanisms of action. “Consumers are not fully aware of the existence of both water-soluble antioxidants (vitamin C) and fat-soluble antioxidants (vitamin E),” said W.H. Leong, vice president of Carotech Inc. “Each category of antioxidants works best in different parts of cells, and they work synergistically to confer the optimum antioxidant protection.”

This is key because the original ORAC test was water-based; thus, a water-soluble antioxidant, such as vitamin C, would generate a higher ORAC score than a fat-soluble antioxidant, like vitamin E. This does not mean vitamin E is less worthy an antioxidant.

“What is important to understand is that each antioxidant has its own unique properties and works best in different parts of cells,” Leong stressed. “Vitamin C may be most effective in the cytosol of a cell (aqueous part), whereas vitamin E is most effective in the membrane bilayer and mitochondria (fat part) of a cell.”

Brunswick Labs, which has long worked with Prior on improving the ORAC test, has recently expanded the ORAC test to be suitable for both water- and fat-soluble antioxidants; however, the test still only measures activity against peroxyl radicals and hydroxyl radicals. There are at least four other harmful reactive oxygen species (ROS)—hydrogen peroxide, superoxide anion, singlet oxygen and peryoxynitrite—that cause oxidative problems to human lipids, proteins and DNA. However, Brunswick has recently developed versions of ORAC to test for peryoxynitrite (NORAC test) and hydroxyl radicals (HORAC). Also, it is currently developing an assay for singlet oxygen, under a recent federal grant. But until these new assays make their mark, the limitations of the main ORAC test permeate the market.

“Antioxidants such as carotenoids (which do not have high ORAC values) are excellent against singlet oxygen, but do not work well against peroxyl radicals, hence the low ORAC score,” noted Charles DePrince, president of Fuji Health Sciences. “A high ORAC value, by itself, only indicates part of the protection; Unfortunately, ORAC, from a marketing view, tends to simplify the otherwise complex biological antioxidant system needed for good human health.”

People like simple, but not misleading. What, then, is the simple value of ORAC to consumers? Susanne Mertens-Talcott, Ph.D., a researcher in the Nutrition and Food Science Dept., Texas A&M University, College Station, said ORAC is currently used to characterize and compare a multitude of antioxidant fruit- and vegetable-based products.

“The ORAC value tells us that a given amount of the tested product has the same radical scavenging capacity as a known amount of a water-soluble form of vitamin E, to which the assay is standardized,” she explained. “Because this assay is standardized to vitamin E, it enables us to compare among different products, and makes it a valuable indicator for its potential to promote wellness and prevention of disease.”

Charlene Lee, executive vice president and general manager for Cyvex Nutrition, further simplified ORAC’s value. “ORAC is a viable manner of assessing initial potency, in vitro, of an antioxidant,” she stated.

The key words here are “initial potency” and “in vitro”, as ORAC is conducted outside of the body, in lab cultures, and does not necessarily represent antioxidant power in the body (in vivo). “ORAC values are an excellent way to determine, in vitro, the antioxidant power of food and enable us to make comparisons, but essentially that is all this value does,” agreed Manuel Pavon, general manager of Chrysantis. “[ORAC scores] are a function of the antioxidants present in the food and the form of the food (as water content is important), and we know that different antioxidants do different things in the body.” He concluded while ORAC scores indicate potential, they are not absolute predictors of in vivo activity.

For example, Pavon noted, açaí fruit has one of highest ORAC values tested, but it is not the antioxidant of choice for age-related macular degeneration (AMD). According to substantial research, spinach and kale best the exotic fruit in this health condition, even though the ORAC scores for these vegetables is substantially lower than for açaí. Pavon noted the lutein and zeaxanthin in these two vegetables are the key antioxidants found beneficial to AMD. Hence, just using the ORAC scores could potentially mislead consumers to the wrong product for their specific health needs.

Measuring the ORAC of individual antioxidants might also bypass a synergistic combination that would be better suited for a particular consumer. In the case of lutein and zeaxanthin, many of their fellow carotenoids (lycopene, beta-carotene and astaxanthin) have better ORAC scores, but the highest score is not always the best. “Antioxidant activity in vivo depends on factors like the tissue involved, the nature of the oxidation challenge and the nature of other antioxidants present,” Pavon stressed. “This is why the only sure thing one can say about ORAC is that high-ORAC foods are better for our health, period.”

Frank Schönlau, Ph.D., director of scientific communication for Natural Health Science, agreed ORAC results are only one piece of a bigger puzzle and present special challenges to botanicals and phenols. “This may sound trivial, but the absorption, particularly of plant material and their extracts, is everything else than trivial,” he quipped, noting there is considerable debate over which of the many antioxidant flavonoid compounds are sufficiently bioavailable to offer objective health benefits. He pointed to the complete pharmacokinetic profile of French maritime pine bark extract to show the complexity of flavonoid bioavailability. In one study, researchers drew blood at regular intervals from subjects who had taken the pine bark extract, identifying “appearing molecules.” They found only a small number of the extract’s flavonoids appeared unaltered in the blood stream. Instead, 10 new molecules were discovered, apparently created when the extract was metabolized in the body. In an ORAC test, the score would reflect the parent flavonoids, while this in vivo study showed it is the metabolites created after absorption that are highly bioavailable for antioxidant activities.

Still, there are other limitations of ORAC. “Dried fruits will always score higher than the same fresh fruit—the more water removed the higher ORAC score,” noted Wayne G. Geilman, Ph.D., senior research scientist for Pure Fruit Technologies. “ORAC inflation can result from removing water from the sample.” He added changing sample size of the product can also affect the ORAC score, as larger serving sizes can generate higher scores.

“Without having a uniform standard, ORAC values can be reported as the grams (or units) of dry weight, grams of wet weight, or even the value per serving,” reasoned Ron Udell, president of Soft Gel Technologies. “Harvest times and growing conditions—season, temperature, soil conditions, ripeness, etc.—dramatically affect the antioxidant capacity of fruits, vegetables, and herbs.”

Based on these examples, it is important for responsible manufacturers and marketers to consider the different characteristics between the tested compounds when comparing scores. “We encourage formulators to compare apples-to-apples when working with ORAC scores, so they can formulate from a consistent foundation of application,” Lee said.

So, if ORAC is only one factor—with a limited ability to determine total antioxidant capacity—what else is there? Other tests considered for standardization in the measurement of antioxidant capacity of foods include the Total Radical-trapping Antioxidant Parameter (TRAP) assay, the Total Oxidant Scavenging Capacity (TOSC) assay, the Folin-Ciocalteu assay (which is used in the determination of total phenolic content) and the Trolox Equivalent Antioxidant Capacity (TEAC) assay.

Mertens-Talcott noted the Folin-Ciocalteu assay measures the metal-reducing activity of a food (total phenolic content), offering specific scores for the food’s amino acids, ascorbic acid, reducing sugars, sulfites. Therefore, results do not truly represent the content of antioxidant compounds for all foods. On the other hand, the TEAC assay is useful in determining the radical scavenging activity of a food, however it uses a free radical source that does not occur in the human body.

Another test measures antioxidants with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. However, Eric Anderson, brands manager at PL Thomas, noted there are substantial inconsistencies between tests, such as the case with ORAC vs. DPPH. “These two different tests will give dramatically different results for the same ingredient, as in the case with cranberry,” he said.

The bottom line? “All assays have their advantages and limitations, though the ORAC test has virtues because of high versatility and convenient data analysis,” Schönlau contended. He referenced a 2005 review of antioxidant assays by Andrew Collins, a nutrition professor in the School of Medicine at University of Oslo, Norway, which noted assays for antioxidant status and oxidative damage are many and varied. “The simplest ones are purely chemical in vitro reactions or tests in cell cultures,” Collins wrote. “They can yield useful information about mechanisms of action, but extrapolation to effects of dietary antioxidants in vivo is dangerous, because uptake from the gastrointestinal tract and metabolism are not considered.”

The best way to measure the strength of an antioxidant is to look at it in a series of different comparative tests against other antioxidants, according to Bob Capelli, director of marketing for Cyanotech Corp. “You can see extreme differences in antioxidant strength when you look at different models of testing,” he noted.

In fact, two different studies found wildly different levels of antioxidant activity for vitamin E. One reported vitamin E was second to astaxanthin, while another study reported vitamin E was 550 times less active than astaxanthin in singlet oxygen quenching. “This shows how slanted it can be to look at only one test of antioxidant strength, such as ORAC, and draw conclusions,” Capelli said.

“Although ORAC value is a standard industry method for measuring antioxidant capacity, the best evaluations should look at studies that actually measure a product’s effectiveness in promoting good health,” reasoned Massood Moshrefi, Ph.D., vice president of operations and technical services for InterHealth Nutraceuticals. “These measures include the product’s bioavailability and, in the case of many products containing berry extracts, its anti-angiogenesis properties.” He conceded studies of this type require more resources, but offer so much more useful data about the actual health benefits of a given antioxidant product.

Vladimir Badmaev, M.D., Ph.D., vice president of scientific and medical affairs at Sabinsa, agreed serious conversations on antioxidants must focus on advanced studies. “We need to start talking more about clinical effectiveness of antioxidants, rather than their wished-for efficacy based on in vitro established antioxidant potency,” he argued. “Can a specific antioxidant prevent, alleviate or treat a specific health problem or problems in real life or in clinical condition? This is the type of question that should be more often asked now that we have available on the nutritional supplement market such a variety of natural and synthetic antioxidants.” For comparison, he offered curcumin, which has demonstrated its antioxidant and health benefits via in vitro, in vivo and clinical studies. “Putting a compound to real-life test should take priority,” he punctuated.

While positive clinical results on health conditions certainly catapult compounds beyond preliminary in vitro victories, such as with a high ORAC score alone, newer ingredients on the scene—like the currently hot exotic fruits—can get a foot in the door with good potency scores. Geilman noted ORAC scores of various fruits can be used to help formulators select fruits and food components that have the ability to deliver polyphenols. “Now there is a rush to identify healthful compounds and their mechanisms of action,” he said. “ORAC scores are a valuable tool in helping identify fruits and vegetables with the highest potential to impact human health.” However, he agreed antioxidants have other useful non-oxidative-related functions in the body, and there is a point of diminishing returns when it comes to high ORAC scores. “Currently, consumption of a diet that provides a combined ORAC score of 3,000 to 5,000 units is suggested,” he advised. “Increasing consumption over this level has not demonstrated any increase in health benefits.”

If ORAC has some merit and usefulness in early evaluation of antioxidants, then why is there intense debate over its scores? As far back as the Pepsi Challenge, marketers love to show their product is better than another. Schönlau explained all the knowledge about the pros and cons of ORAC does not satisfy marketing’s desire for quick and inexpensive demonstration of the antioxidant superiority of their product. “The ORAC assay is popularly abused,” he affirmed. “Impressive ORAC values are often presented in hopes consumers won’t question the bioavailability, safety and clinical research in support of their product.” More likely than not, he added, ORAC is the only testing the product has ever gone through, especially in cases when there is nothing else to talk about relative to efficacy.

Along the same line, Anderson asked, “Does a larger ORAC number guarantee a consumer is going to realize the promised benefits?” He contends the answer to this is never provided, because there is no proven correlation between ORAC score and clinical efficacy. “For now, ORAC is simply a marketing device.”

From the academic standpoint, Mertens-Talcott agreed there is still ground to gain in evaluating antioxidants. “The scientific field determining health benefits of antioxidant foods is far behind in determining efficacy and dosing recommendations for antioxidant foods in promotion of health and wellness,” she stated. Still, she reaffirmed ORAC does a good job of characterizing the antioxidant capacity of a product relative to other products, while also implying a potential promotion of health and wellness.

“I believe ORAC is helpful because consumers need something they can wrap their heads around and a bar chart makes it so simple for them to get it quick,” said Jeremy Black, global brand manager for Sambazon. “So ORAC tests help educate, but it’s ‘buyer beware’, because it is possible fake or spike an ORAC by adding extracts like grape seed.” Black reported Sambazon’s açaí has generated ORAC scores between 5,000 and 12,000. “Keep in mind this is our finished product in the freezer at a local health food store—not the value you’d get from fresh açaí off the tree and tested immediately, which we’ve seen much higher,” he cautioned. “But if you can’t deliver that tested product into someone’s hands, you shouldn’t market it with those kind of [ORAC] values.”

One of the early proponents of using ORAC for antioxidant phytonutrients, John Maher, a licensed chiropractor and vice president of education for Biopharma Scientific, echoed sentiments that ORAC is not the end-all and be-all, but he praised the test for being simple and having a lot of good science behind it. Among the issues with ORAC in the marketplace, according to Maher, some companies are using old ORAC data, as opposed to the improved newer ORAC data. He further warned, in addition to removing water from samples, some companies spike ORAC values by adding green tea or another high-ORAC compound. “It is also important for companies to report ORAC on a per-serving basis,” he advised. “And while ORAC values can help approximate the number of fruit and vegetable servings required to reach a similar score, there is a lot of faulty math out there.”

Maher suggested testing bioavailability by measuring serum antioxidants after ingestion of an antioxidant product. This proves especially productive for plant-based antioxidants, which contain some poorly absorbed phytonutrients. To address the dilemma presented when a lipophilic phytonutrient has a good ORAC score but is poorly bioavailable, Maher suggested nanotechnology. Creating a liposome that encapsulates both hydrophilic and hydrophobic phytonutrients for improved absorption, without significantly negating the original antioxidant potential.

The take-home message is that ORAC is expanding to cover more types of antioxidants and the radicals they scavenge. However, it is useful only in comparing the potential of a certain dose of one antioxidant compound to a certain dose of another antioxidant compound. Demonstrating potential is a benefit of ORAC, but this test alone does not prove a particular antioxidant will be absorbed in the body and lead to either general or specific health benefits. All antioxidants are not created equal, and many botanical and vitamin ingredients have strong health benefits beyond or in addition to their antioxidant activities.

In the end, ORAC is one starting point among many other touted tests. Whether it becomes the standard beacon of antioxidant potential in the natural products industry or among consumers, the most complete picture of an ingredient’s healthfulness is the totality of research, both in vitro and in vivo, on not just antioxidant potential and activities against certain radicals, but also its targeted mechanisms in certain health conditions, as proven by ongoing clinical and epidemiological studies.