Video Interview: Researchers on Antioxidants & Eating Smart
Since current research on antioxidants has moved beyond the simple messages we see in so many articles and books discussing nutrition, what do researchers actively working in the field say about healthy eating choices?
In this series on antioxidants featuring video interviews with respected researchers Navindra Seeram, PhD and Alan Crozier, PhD, we’ve noted that most of the plant compounds hailed as antioxidants based on laboratory tests are actually poorly absorbed out of the digestive tract. They are broken down to other compounds, however, that can be absorbed. Animal and human studies suggest that consuming polyphenol-rich foods and drinks offers potential to protect our health through a variety of mechanisms that extend far beyond antioxidant effects. Here, in our final interview segment, Dr. Seeram and Dr. Crozier share what excites them about today’s research, and what it means for healthy eating choices.
Following the video, read on for practical take-home tips to amp up the healthfulness of your eating.
(Email subscribers, click here to go to my Smart Bytes® blog to view the video.)
Reductionism vs. Seeking Synergy
In this portion of our interviews, Dr. Crozier and Dr. Seeram both refer to the problems of a ‘reductionist view’ of antioxidant plant compounds. When it comes to nutrition, reductionism refers to former ways of trying to look at health effects of nutrients and phytochemicals (compounds like carotenoids or flavonoids that occur naturally in plant foods) independently of one another.
In fact, a growing field of research looks at how compounds in our food work together synergistically to protect health; together they are more effective than would be expected from adding up the effects of each on its own. Although controlled laboratory studies need to look at compounds in isolation to answer certain questions, they don’t represent what goes on when compounds are consumed as part of a whole diet.
♦ Tomato and broccoli together showed stronger anti-cancer effects in laboratory research than either could alone.
♦ Isothiocyanates, the breakdown products from glucosinolates in cruciferous vegetables such as broccoli may work independently, and also synergistically with selenium influencing pathways involved in cancer development.
♦ Piperine, a phytochemical in black pepper, may increase the “bioavailability” of curcumin, the compound in turmeric that’s been linked in laboratory research with a variety of anti-cancer effects.
We can give up searching for the single ‘best’ or ‘highest-antioxidant’ food. When it comes to healthy eating choices, no matter how exciting the potential for protective benefits from a nutrient or food, since phytochemicals in our food can all work in slightly different places or metabolic pathways, we’ll do best with an overall healthy eating pattern that includes a variety of nutritious foods.
3-Part Strategy for a New Approach
Vegetables, fruits, whole grains, beans, nuts and seeds offer dietary fiber, vitamins, minerals and a wide range of phytochemicals (natural plant compounds). When you’re thinking about how you might eat more healthfully, consider variety, amount and distribution of nutrient-rich plant foods through your day.
Variety is the key to getting the wide-ranging nutrients and protective phytochemicals plant foods offer. Do you regularly include healthy choices like these?
- Berries are consistently found among fruits highest in polyphenol compounds. Since specific polyphenols in each type vary, and each shows potential for health benefits, include blueberries, raspberries (red and black), strawberries, blackberries, cranberries and whatever other choices suit your fancy. Cloudberries? Gooseberries? Currants? Enjoy exploring them.
- Cruciferous vegetables contain compounds that may play unique cancer-protective roles. So find ways to love including broccoli, Brussels sprouts, cabbage, bok choy, cauliflower and others often.
- Garlic and other onion-family vegetables, including leeks and scallions, don’t just make healthy food taste great, they add a special class of protective phytochemicals.
- Citrus fruits, such as oranges, grapefruit and others supply vitamin C and special flavonoids.
- Dark green leafy vegetables, such as spinach, kale, and collard and other greens are great sources of beta-carotene and other carotenoids, polyphenols, as well as vitamins like folate and C. Many also supply magnesium, potassium or other minerals. Those that are members of the cruciferous vegetable family such as arugula and watercress also supply those unique glucosinolate-derived compounds under study for apparent cancer-protective effects.
- Legumes – dry beans, peas and lentils are super sources of fiber and nutrients, and contain phytochemicals not as concentrated in other plant foods.
- Tomatoes are by far Americans’ top source of lycopene, and also provide other carotenoids and nutrients. In one small study, tomatoes reduced the oxidative stress and signs of inflammatory response that otherwise occurred following a meal, which highlights an interesting area for further study.
- Whole grains supply much more than dietary fiber; they are higher than refined grains in several nutrients, and can be an important source of polyphenol compounds that are lost when grains are refined.
Don’t stop there! Apples, deep orange vegetables and fruits (such as winter squash, carrots, cantaloupe and apricots), nuts and seeds all supply nutrients and phytochemicals that we now see offering potential heart-protective and anti-cancer effects going far beyond the antioxidant power that initially drew attention. Once-overlooked vegetables (including mushrooms, artichokes, celery, eggplant and many more); beverages like green tea, black tea and coffee; and even dark chocolate and unprocessed cocoa also contain unique phytochemicals that may add to the synergistic benefits of a plant-based diet.
You have opportunities all day long to make simple choices that add potentially beneficial compounds as you make it taste great with olive oil, also a source of polyphenols when you choose the extra virgin type that retains polyphenols removed when it is refined to light oil, and herbs and spices.
♦ Although it might seem that one super-nutritious meal can make up for low-nutrient eating-on-the-run all day, the reality is that although it’s surely better than none, it can’t give you the same nutrient, fiber and phytochemical total that you can accumulate with a variety of delicious plant foods all day.
♦ Peak blood levels of the compounds that form from polyphenol phytochemicals in our food tend to occur between one and six hours after eating, and they are almost completely broken down or excreted within a day. Emerging research is looking at how the metabolic environment in the body in the hours right after a meal may have important health effects. If “post prandial” effects are important, then providing your body with protective compounds more than once a day may provide more benefits beyond the daily total you reach.
♦ Although this Smart Bytes® series has focused on antioxidants in foods, when our healthy eating habits include vegetables, fruits, whole grains and beans throughout the day, we are also promoting health in another way. These foods – as long as we don’t load them up with fat and sugar – are low in calorie density, allowing us to satisfy hunger without eating more calories than we can burn.
Phytochemicals in our food seem likely to play a protective role in fighting the inflammation that’s linked to cancer and heart disease. Yet inflammation also stems from excess body fat, which secretes inflammation-promoting proteins called cytokines.
♦ In order for vegetables, fruits and other foods low in calorie density and rich in protective compounds to help with weight control, make sure you are choosing them as substitutes for less healthful foods, not simply adding them to eating habits that already supply plenty of calories.
♦ Portions matter. Two bites of a nutritious vegetable are better than none; still better, find ways to prepare them that you enjoy so much, you’ll give them a major portion on your plate. On the other hand, there is such a thing as too big a portion. A glass of juice may be loaded with polyphenols, but it’s also a concentrated source of calories. Many people who drink several tall glasses of juice each day are shocked to find out how many calories they’re getting, and how they may be contributing to rather than fighting inflammation with their waistline fat.
The Bottom Line: We’ve moved from thinking we could identify “best” food choices with simple lab tests of antioxidant capacity, to understanding that “antioxidant” compounds are broken down in our body to produce other compounds that likely protect our health in a variety of ways, like reducing inflammation. Finding how to accurately test and measure these effects is a challenge. While we wait for clearer answers, the best research-grounded strategy is to focus eating habits around a wide variety of vegetables, fruits, whole grains, beans, nuts, seeds and polyphenol-rich drinks and flavorings, and to enjoy them in appropriate portions throughout the day.
Let’s Talk: Please scroll down and comment below, sharing one or two steps you plan to try to expand the variety of protective plant foods in your eating habits.
Jacobs DR et al. Food synergy: an operational concept for understanding nutrition. Amer J Clin Nutr. 2009; 89:1543S.
Barrera LN, et al. Epigenetic and antioxidant effects of dietary isothiocyanates and selenium: potential implications for cancer chemoprevention. Proc Nutr Soc. 2012; 71(2):237-45.
Burton-Freeman B and Reimers K. Tomato Consumption and Health. American Journal of Lifestyle Medicine, 2011. 5(2): p. 182-191.
Burton-Freeman B et al. Protective activity of processed tomato products on postprandial oxidation and inflammation: a clinical trial in healthy weight men and women. Mol Nutr Food Res. 2012; 56(4):622-31.
Moreno-Luna R et al. Olive oil polyphenols decrease blood pressure and improve endothelial function in young women with mild hypertension. Am J Hypertens. 2012; 25(12):1299-304.
Habauzit V and Morand C. Evidence for a protective effect of polyphenols-containing foods on cardiovascular health: an update for clinicians. Ther Adv Chronic Dis. 2012; 3(2):87-106.
Hollman PC, et al. The biological relevance of direct antioxidant effects of polyphenols for cardiovascular health in humans is not established. J Nutr. 2011 May;141(5):989S-1009S.
Del Rio D et al. Dietary (Poly)phenolics in Human Health: Structures, Bioavailability, and Evidence of Protective Effects Against Chronic Diseases. Antioxid Redox Signal. 2013 May 10; 18(14): 1818–1892.
McCullough ML et al. Flavonoid intake and cardiovascular disease mortality in a prospective cohort of US adults. Am J Clin Nutr. 2012; 95(2): 454-464.
Dauchet L et al. Fruit and vegetable consumption and risk of coronary heart disease: a meta-analysis of cohort studies. J Nutr. 2006;136(10):2588-93.