September 2008 Issue

Making Sense of Antioxidants
By Lindsey Getz
Today’s Dietitian
Vol. 10 No. 9 P. 50

Despite the mysteries surrounding these elusive substances, your clients can benefit by keeping some simple advice in mind.

The research on antioxidants is, well, nothing short of confusing. There are new findings published daily that appear to conflict with one another, and the media are constantly reporting on new disease-fighting foods. How many stories have you read about green tea, chocolate, red wine, or even coffee? While there are no conclusive answers, understanding the antioxidant basics can help you guide your patients in the direction of a fulfilling diet.

In simple terms, an antioxidant is a chemical compound that protects cells against the effects of free radicals (molecules produced when the body breaks down food or is exposed to pollutants such as tobacco smoke or radiation). Free radicals can damage cells and may play a role in heart disease, cancer, and other medical conditions; hence, researchers are interested in determining exactly which antioxidants are effective against them. But the truth is those answers have been elusive—unsurprising, considering scientists have yet to discover all forms of antioxidants. To date, there are more than 4,000 known flavonoids—and that’s just one class of antioxidant.

“There are so many different antioxidants, ones the public hasn’t even heard of yet,” says D. Milton Stokes, MPH, RD, CDN, owner of One Source Nutrition, LLC, a nutrition counseling and consulting firm in southern Connecticut. “We hear a lot about research on five or six antioxidants that we know well, but that isn’t even the tip of the iceberg.”

“I think the jury will be out until the end of time on this issue,” adds Laura Shane-McWhorter, PharmD, BCPS, FASCP, CDE, BC-ADM, a professor in the pharmacotherapy department at the University of Utah. “There are no clear answers.”

This means doing the best you can to decipher the current evidence and making decisions based on each client’s needs. Focusing too much on the available studies can become confusing, since many of them contradict one another, but that doesn’t mean you shouldn’t stay informed.

The Real Thing
While some may debate how many supplements clients should take or what doses are safe, there’s practically no debate that it’s always better to get antioxidants from whole food sources. “I don’t know of anyone who would say, ‘Don’t eat food, just take supplements,’” says Jeffrey Blumberg, PhD, FACN, CNS, director of the Antioxidants Research Laboratory and a professor at the Friedman School of Nutrition Science and Policy at Tufts University. “And I also think there’s a general consensus that there is a perfectly good reason to take dietary supplements. They are called supplements for a reason; they’re not called dietary substitutes.”

There are many reasons to consider a supplement routine. About 90% of Americans don’t meet their recommended daily allowance for vitamin E, notes Blumberg. “It seems reasonable, since there are shortfalls, that clients would want to consider supplements such as a multivitamin,” he continues. “People should both eat healthy and take a supplement if they still aren’t meeting their needs.”

But getting the majority of your antioxidants directly from food sources is smart both for nutritional reasons and practical ones. While clients may not always remember to take their supplements, they will always remember to eat. “Although data from the National Health and Nutrition Examination Survey show that 50% of U.S. adults report taking a dietary supplement, I have had my clients report that they forget to take it, lose interest, or fail to replenish their supply,” says Jenna A. Bell-Wilson, PhD, RD, CSSD, a nutrition consultant in Boston. “So I always recommend that people try to eat their antioxidants first.”

“Food is the best source of antioxidants,” says Joanne Larsen, MS, RD, LD, of “Fruits and vegetables can help reduce the oxidative stress through the antioxidant effect of phytochemicals such as flavonoids. Adults should have three servings of fruit and three servings of vegetables per day.”

Bell-Wilson adds that foods rich in antioxidants are also typically nutritious in a variety of other ways. “They often contain fiber, have vitamins and minerals that are not necessarily antioxidants, and have naturally occurring phytochemicals unique to foods,” she explains.

Encouraging your clients to get their antioxidants from food is a great idea, but don’t get hung up on any particular antioxidant or even a certain food. Research often singles out specific antioxidants, which can be confusing when clients hear one day that blueberries will ward off disease and the next that broccoli is the way to go. “I really do think that a lot of the marketing [of these foods] is way ahead of the actual science,” says Stokes. “I’m not trying to discredit eating these foods, but it causes confusion when we’re constantly seeing different information mentioned in studies. Red wine is a good example because I’ve had clients ask me, ‘How much should I drink? I heard I should start having a glass.’ And I tell them, ‘If you don’t drink now, there’s no reason to start. There are so many other sources to get antioxidants from.’”

Chocolate is another food that’s gotten a lot of attention. “I’m a big chocolate fan,” continues Stokes. “But I think if you enjoy chocolate, you should eat it for the taste and the flavor. Making it into a health or nutrition decision should not be the priority. It’s already been under debate what in chocolate makes it so healthy. It’s good to know it has health benefits, but let’s not get so caught up on it. No single food is a wonder cure.”

The best way for your clients to get a diet rich in antioxidants is to eat a healthy diet that includes a lot of fruits, vegetables, and whole grains. Variety is key; there’s no reason to focus on one food. Stokes is a fan of the Dietary Approaches to Stop Hypertension diet, which focuses on limiting sodium and consuming a lot of nuts, whole grains, fish, poultry, fruits, and vegetables. “If you’re following that pattern of eating, you have nothing to worry about,” he says. “You’ll get vitamins, minerals, fiber, water, and every antioxidant under the sun.”

Disease Prevention
Of course, the main reason people are so interested in antioxidants is their potential role in preventing disease. Researchers have conducted many studies on the subject but are still a long way from realizing all of the answers. “No matter how much searching you do, you’ll never find a single study that tells health professionals that a particular antioxidant is conclusively going to help cure or prevent something,” says Stokes. “The study will always say, ‘More research is needed.’”

Despite the uncertainty, several recent studies have led people to question the effectiveness of antioxidants in treating disease and perhaps even raised concern about the safety of taking supplements. One meta-analysis reviewed 67 randomized studies and concluded that supplemental antioxidants do not reduce mortality rates. In fact, it also claimed that some antioxidants, including vitamin A, beta-carotene, and vitamin E, may actually increase mortality rates. But some say this study is no cause for concern.

“The meta-analysis looked at a variety of other studies and utilized patients who were already postdisease,” says Richard S. Bruno, PhD, RD, an assistant professor in the department of nutritional sciences at the University of Connecticut, who has long studied vitamin E. “The study author discovered, based on his statistical approach, that people taking extremely high levels of vitamin E were at some risk. While he took into consideration the dose, he did not consider the type of vitamin E, nor take into consideration other pharmaceutical drugs these patients could have been taking. And, on top of that, these patients were already sick. Based on current evidence, I see no reason why people should be worried about taking vitamin E.”

Blumberg adds that this particular analysis only examined studies with a death involved and did not disclose the cause of death. “Since it involved all-cause mortality, the subjects could have died from heart disease, cancer, or maybe an automobile accident,” he says. “How can you conclude that it was from taking antioxidants?”

As long as your clients maintain a healthy diet, they may not even need supplemental antioxidants. “I would recommend dietitians take an individual approach with each patient in recommending antioxidant supplements based on the evidence available for specific medical diagnoses as part of their nutrition intervention,” says Larsen.

“I’ve never met someone who was sick because of a mostly vegetarian diet,” adds Stokes regarding the questions raised about the safety of antioxidants in supplement form. “If it’s a concern, just get your antioxidants from food. Encourage your clients to eat lots of whole grains, fruits, and vegetables.”

There will also be those clients who seem to believe antioxidant supplements are cure-alls or some sort of magic potions. “I have patients who will come in with a whole bag full of different supplements, but their cholesterol isn’t under control or maybe their diabetes is out of control,” says Shane-McWhorter. “They’ve decided they don’t want to take medication, but they want to take all these supplements. But that isn’t keeping their medical conditions in order.”

Help your clients understand that supplements and a healthy diet still aren’t necessarily a substitute for important medications.

Making Sense of It All
Part of why the answers may be unclear is that scientists are still trying to gain a firm understanding of exactly how antioxidants function. Food is complex and so is the way our bodies process it; therefore, the research on food conducted in laboratories might not always lead to conclusive answers. “Many studies are done in labs with test tubes where a single nutrient is isolated,” says Stokes. “I don’t think we can apply that very well to what we eat and drink in daily life. We don’t consume single nutrients. It may not be that one single chemical that has a positive effect but rather a combination of how they all work together.”

Stokes adds that with so many antioxidants (known and unknown), a true understanding of exactly how or whether they prevent disease would be the result of a large investment of time and money—or perhaps the answers won’t ever be fully understood. “It would just take so much to get to an end point,” he says. “I’d rather just see people eating more fruits and vegetables instead of focusing so much on these different studies. In my opinion, I think it’s more practical to put all that money toward giving people free fruits and vegetables rather than putting it all into the lab. Then it’s a guaranteed return on your investment.”

It’s certainly true that the research is inconclusive and contradicting. A brief search at press time revealed there are currently 298 studies underway involving antioxidants. Although an absolute understanding may be a long shot, Blumberg concludes that professionals should be informed about what science has shown so far and know the evidence at least appears overwhelming that antioxidants, especially from whole foods, are beneficial. In what capacity, or even understanding exactly how or why they work, simply can’t be answered.

“There’s been no clear consensus; however, that doesn’t mean it’s not promising,” Blumberg notes. “While I can’t tell you that taking 400 IU [international units] of vitamin X will reduce your risk of disease Y, we do know that antioxidants play critical roles in reducing inflammation, and I am convinced they would have some benefit [in fighting disease]. Research can’t tell us which doses and which combinations have the best benefits, but I’m happy to say, in a very simplified way, that antioxidants are good for you. Get as many as you can through a healthful diet, and take a rational choice of supplements for those you aren’t getting enough of.”

— Lindsey Getz is a freelance writer based in Royersford, Pa.

A Handy Guide to Antioxidants

Found in: Orange and yellow fruits and vegetables such as carrots and cantaloupe; dark leafy greens such as spinach and kale

Benefits: Beta-carotene was long believed to help prevent cataracts, although today the research appears to be more conflicted, and scientists say more research is needed.

Found in: Leafy greens such as spinach; corn, carrots, and squash

Benefits: Research indicates that lutein may help lower the risk of developing cataracts and macular degeneration.

Found in: Red, fleshy fruits and vegetables such as watermelon and tomatoes

Benefits: Diets rich in lycopene may help protect against heart disease.

Found in: Seafood, lean meats, and whole grains

Benefits: Research often suggests that selenium may have a preventive effect against cancer.

Vitamin A
Found in: Animal sources such as eggs, meat, and dairy

Benefits: Research indicates that vitamin A promotes clear and healthy vision. It also helps form and maintain healthy teeth, skeletal and soft tissue, and skin.

Vitamin C
Found in: Citrus fruits such as oranges and grapefruit; bell peppers and broccoli

Benefits: Among its many functions, vitamin C can aid tissue growth and repair, adrenal gland function, and wound repair. It may also help cure or prevent colds by boosting the immune system.

Vitamin E
Found in: Wheat germ, nuts (eg, almonds, walnuts, hazelnuts), and monounsaturated oils (eg, sunflower oil)

Benefits: Preliminary research has led to a widely held belief that vitamin E may help prevent or delay coronary heart disease.

— LG