Chapter 37
Which Foods Have the Most Antioxidants?
Plants seemingly produce impressive amounts of antioxidants out of thin air to defend their structure against free radicals in the firestorm of photosynthesis. There’s a reason plants can stand in the sun all day without getting sunburned (which in us is an inflammatory reaction to the DNA damage caused by the free radicals generated by UV rays). The human body has to defend itself against the same kinds of pro-oxidants, so we, too, have developed a whole array of amazingly effective antioxidant enzymes—but they’re not infallible. Free radicals can, in fact, break through our defenses and cause cumulative DNA damage with age. And this is where plants come in.
Plants generate antioxidants so we don’t have to. Because antioxidant-rich foods traditionally made up such a large part of our ancestors’ diets, we didn’t have to develop such a robust antioxidant system. We simply let the plants we ate do the work for us—for example, supplying us with vitamin C—so we could save ourselves the trouble of making it ourselves. Using plants as a crutch may have taken the pressure off us to continue developing our own defenses over the course of evolution. That made us dependent on consuming enormous quantities of plant foods, otherwise we may suffer negative consequences for our health.
At what point in our evolutionary history did we stop eating enough antioxidant-rich plants? During the Stone Age, that wasn’t a problem. Only recently have we turned away from whole plant foods. These days, Paleo and low-carb adherents may eat more vegetables than people who follow the Western standard diet. Great! The problem isn’t that people want to lower their carbohydrate intake by swapping junk food for vegetables. What’s concerning is that they shift toward foods of animal origin. According to Marion Nestle, emerita professor of nutrition at New York University, an important conclusion can be drawn from the anthropological study of prehistoric diets—namely that “diets mainly composed of plant foods promote health and longevity …”.
Which Foods Have the Most Antioxidants?
In many ways, our prehistoric ancestors got more antioxidants than we do, but needed them less. In modern life, we’re surrounded by new oxidation-promoting stressors—from air pollution and cigarette smoke to alcohol and junk food to pesticides and industrial chemicals. That makes it even more important to bolster our innate defenses with antioxidants from the right foods. Today we have the advantage of being able to obtain seasonal produce such as frozen berries from around the world year-round, which makes it much easier to supply ourselves steadily with antioxidants through our diet.
Given that the overall antioxidant capacity of our diet is associated with a lower risk of developing cancer and dying from it and from all causes combined, scientists have made it their mission to identify the foods with the most antioxidants. 16 researchers from around the world published a database of the antioxidant power of more than 3000 different foods, beverages, supplements, herbs, and spices. They tested everything from Cap’n Crunch breakfast cereal to the crushed, dried leaves of the African baobab tree to see what had the most antioxidants. They even looked at dozens of beer brands. (Samichlaus beer from the Austrian brewery Schloss Eggenberg was the brew with the most antioxidants.) In America, beer is actually the fourth-largest dietary source of antioxidants. Check out the table at see.nf/antioxidantlist to find out where your favorite foods and drinks rank.
No need to hang the entire 138-page table on your refrigerator. Just remember this simple rule: On average, plants contain 64 times more antioxidants than foods of animal origin. As the researchers noted, “antioxidant-rich foods originate from the plant kingdom, whereas meat, fish, and other foods from the animal kingdom have a low antioxidant content.” Even iceberg lettuce, which is 96 percent water and is the least healthy plant food I can think of, contains 17 units (micromoles per decagram according to a modified FRAP test) of active antioxidants. To put that in perspective: Some berries have more than 1000 units, making iceberg lettuce look pale by comparison. But compare iceberg lettuce’s 17 units with some common animal products. Fresh salmon has only three units of antioxidant power, chicken meat only five, and skim milk and a hard-boiled egg just four each. “A diet based primarily on animal products therefore has a low antioxidant content,” the research team concluded, “whereas a plant-based diet is rich in antioxidants because of the thousands of bioactive, antioxidant phytochemicals in plants that are retained in many foods and beverages.”
Among plant foods, berries average ten times more antioxidant power than other fruits and vegetables, and they’re only outdone by herbs and spices. Cherries may have up to 714 units, but there’s no need to cherry-pick individual foods to increase antioxidant intake. Just try to eat lots of fruit, vegetables, and salt-free seasonings at every meal. That way you can supply your body steadily and abundantly with antioxidants to ward off age-related diseases.
Boosters for Your Blood
Just as in foods and beverages, the amount of antioxidants can also be measured in the blood. Compared with most foods in the produce aisle, their level in the body is quite modest. Like meat, we don’t even reach the level of iceberg lettuce! On the other hand, we’re made of meat, so that’s probably no surprise.
Better than measuring a food’s antioxidants in a test tube, you can confirm that antioxidants are actually absorbed into our system by looking at the change in antioxidant performance in the blood after eating. Antioxidant supplements do little in that regard and also do not reduce oxidative DNA damage, but fruits and vegetables do both. And the higher the antioxidant status in our blood, the longer we’re likely to live.
Antioxidant capacity in the blood may just be a marker of healthier eating in general, but at least one study found that its benefit for lower mortality was independent of fiber intake. That shows we don’t live longer merely because we generally eat more whole plant foods, although tea could skew the statistics. Tea, in fact, has no fiber and stands unchallenged at the top of the list of foods supplying Americans with antioxidants. Tea consumption is associated with longer life expectancy, so it would be interesting to see whether the protective association of antioxidants against early death holds up when examined more closely.
Antioxidant-Rich Foods at Every Meal
Every meal is an opportunity to tilt the balance for or against oxidation. Any meal without antioxidants can plunge us for hours into an oxidation-promoting state and make the antioxidants in our blood drop steeply, while the body’s reserves are slowly depleted. (For details, see see.nf/antioxidantmeals.) But we don’t want to backslide every day and end the day with fewer antioxidants in the body than we had when we woke up. This is especially important if we’re under increased oxidative stress due to illness, secondhand smoke, air pollution, or sleep deprivation.
The Journal of Biomedical Optics published a remarkable study that reported in detail on a novel experiment. In it, German researchers noninvasively monitored patients’ antioxidant status by measuring fluctuating antioxidant levels in their skin with an argon laser. The most important result was that antioxidant levels can crash two hours after an upsetting experience, and it can take up to three days to return to normal values. Gone within hours, but only back after days—so healthier eating is especially important when we already suspect we’ll be stressed, sick, or tired. Ideally, we should consume antioxidant-rich foods with every meal and every snack.