Welcome to Nutrition Facts. I’m your host, Dr. Michael Greger, and I’m here to ask you, what is the most important decision you’ll make today, is it how you’ll get to work, who you’ll set up a meeting with, what friend you’ll call for lunch? Well, as it turns out, probably the most important decision you’ll make today is what to eat. What we eat on a day-to-day basis is the number one determinant of our health and longevity—literally. Most premature deaths in the United States are preventable and related to nutrition. So, we’re going to explore some smart nutrition choices based, naturally, on facts. Here, we refer to the science, the research, the available data published in the peer-reviewed medical literature right now. That’s why I wrote my book, “How Not to Die”, and why I created my nonprofit site NutritionFacts.org and, now, this podcast.
Today, we’ll take a close look at the many benefits of antioxidant-rich foods. On average, plant foods contain 64 times the antioxidant power of animal products. This may be why those eating more plant-based diets, even for a short amount of time, tend to have higher antioxidant levels in their bloodstream. The meat industry has considered adding plant foods to meat in order to boost antioxidant levels, though ironically this may make processed meat even more carcinogenic.
To stay out of oxidative debt, we need to take in more antioxidants than we use up. Here’s how that shakes down.
“The postprandial state is a pro-oxidant state”, meaning that after each meal, free radicals are produced as our body assimilates the food. So, we can’t just have a bowl of berries in the morning to meet our minimum daily antioxidant needs, and call it a day. “Each and every meal” should contain high-antioxidant foods which, if you remember, means plants. “Antioxidant-rich foods originate from the plant kingdom.” This is due to the thousands of natural antioxidant compounds found naturally in plant foods.
So, for example, “consuming fruits,” which are high in phenolic phytonutrients, increases the antioxidant capacity of the blood and, when they are consumed with the Standard American Diet, high-fat, refined carbohydrate, “pro-oxidant, pro-inflammatory” meals, they may help counterbalance some of the negative effects. “Given the content and availability of fat and sugars in the Western diet, regular consumption of phenolic-rich foods, particularly in conjunction with meals, appears to be a prudent strategy to maintain oxidative balance and health.”
And of all fruits, berries may be the best. The spike in oxidation caused by a Mediterranean meal of pasta, tomato sauce, olive oil, and fried fish, obviously, not enough tomatoes. Add a glass of red wine, which contains berry phytonutrients from grapes, and we can bring down the level of oxidation, but not blunt it completely. So, the meal needs even more plants.
In this study, they gave people standard breakfast items, resulting in lots of oxidized cholesterol in their bloodstream one, two, three, four, five, six hours after the meal. But, all it took was a cup of strawberries with that same breakfast to at least keep the meal from contributing to further oxidation. Note, though, without the strawberries, where we’d be at lunchtime. Let’s say we ate a standard American diet at 6 am, then 7, 8, 9, 10, 11, you know, noon, if we didn’t eat that cup of strawberries with breakfast, by the time lunch rolls around, we’d already be starting out in a hyper-oxidized state and could just make things worse. “Since Western eating patterns include eating multiple meals a day, including snacks, one can only speculate on the level of biological unrest.”
But, at least if we had some berries for breakfast, we’d be starting out at baseline for lunch. “This acute protection is likely due to the antioxidant effects of the strawberry phytonutrients.”
Even better than baseline, how about our meal actually improving our antioxidant status? Eat a big bunch of red grapes with the meal, and the antioxidant level of our bloodstream goes up, such that our body is in a positive antioxidant balance for a few hours. Same thing after enough blueberries. And, imagine if these ensuing hours between our next meals, right, we were sipping green tea, or hibiscus, right, we’d have this nice antioxidant surplus all day long.
What, according to the researchers, are the practical implications? “These data provide an interesting perspective for advising individuals on food choices when consuming a moderate- to high-fat meal is unavoidable.” Unavoidable? So, if we’re like locked in a fast food joint, or something? Well, then they suggest chasing whatever we’re forced to eat with some berries. Reminds me of those studies on smokers I talked about, suggesting those who smoke should eat lots of kale and broccoli to reduce the oxidative damage to their DNA—or, they could just not smoke.
“In a single day, the systemic stress of all that fat in our blood and redox imbalance being in a mild pro-oxidant state after meals may seem trivial. Over time, however, these daily insults can lead to complicated atherosclerosis,” contributing to hundreds of thousands of deaths a year.
Those eating a more plant-based diet may naturally have an enhanced antioxidant defense system to counter the DNA damage caused by free radicals produced by high-intensity exercise. Here’s the research.
If oxidizing glucose to produce energy for our bodies is so messy, creating free radicals, the way cars burning their fuel produce combustion by-products out the exhaust, even if we’re just idling, living our day-to-day lives, what if we rev up our lives, and start exercising—really start burning fuel? Then, we create more free radicals, more oxidative stress, and so, need to eat even more antioxidant-rich foods.
Why do we care about oxidative stress? Well, it’s “implicated in virtually every known human disease and there is an increasing body of evidence linking free radical production to the process of aging.” Why? Because free radicals can damage DNA, our very genetic code. Well, if free radicals damage DNA, and exercise produces free radicals, “Does physical activity induce DNA damage” if we don’t have enough antioxidants in our system to douse the free radicals? Yes. In fact, ultra-marathoners show evidence of DNA damage in about 10% of their cells tested during a race, which may last for up to two weeks after a marathon. But, what about just short bouts of exercise? We didn’t know, until recently.
After just five minutes of moderate or intense cycling, you can get an uptick in DNA damage. We think it’s the oxidative stress, but “regardless of the mechanisms of exercise-induced DNA damage, the fact that a very short bout of high-intensity exercise can cause an increase in damage to DNA is a cause for concern.”
But, we can block oxidative damage with antioxidant-rich foods. Of course, when drug and supplement companies hear antioxidant-rich foods they think, pills! You can’t make billions on broccoli, so “Pharmacological antioxidant vitamins have been investigated for a prophylactic effect against exercise-induced oxidative stress; however, large doses are often required and, in pill form, may, ironically, lead to a state of pro-oxidation, and even more oxidative damage.” For example, guys doing arm curls taking 500 milligrams of vitamin C appeared to have more muscle damage, inflammation, and oxidative stress.
So, instead of vitamin supplementation, how about supplementation with watercress, the badass of the broccoli family? What if, two hours before exercise, you eat a serving of raw watercress, and then get thrown on a treadmill whose slope gets cranked up higher and higher, until you basically collapse? In the control group, without the watercress preload, which I imagine would describe most athletes, here’s the amount of free radicals in their bloodstream at rest, and after exhaustive exercise—which is what you’d expect.
So, if you eat a super-healthy antioxidant-packed plant food, like watercress, before you exercise, can you blunt this effect? Even better! You end up better than you started! At rest, after the watercress, you may start out with fewer free radicals but, only when you stress your body to exhaustion can you see the watercress really flex its antioxidant muscle.
So, what happens to DNA damage? Well, in a test tube, if you take some human blood cells bathed in free radicals, you can reduce the DNA damages it causes by 70% within minutes of dripping some watercress on them. But, does that happen within the human body, if you just eat it? We didn’t know, until recently.
If you exercise without watercress in your system, DNA damage shoots up. But, if you’ve been eating a single serving a day for two months, your body’s so juiced up on green leafy goodness, no significant damage after punishing yourself on the treadmill. So, with a healthy diet, can you get all the benefits of strenuous exercise without the potential risks?
We know regular physical exercise is “a key component of a healthy lifestyle,” but it can elicit oxidative stress. To reduce that stress, some have suggested pills to improve one’s antioxidant defense system. But, those eating more plant-based diets may naturally have “an enhanced antioxidant defense system” without pills, to counter exercise-induced oxidative stress, due to the increased quantities of plants!
Remember, plant foods average 64 times more antioxidants than meat, fish, eggs, and dairy, and, on top of that, the animal protein itself can have a pro-oxidant effect. But, look, anyone eating sufficient quantities of whole healthy plant foods could plausibly reach an antioxidant status similar to those eating vegetarian. It’s not just about what you’re eating less of—saturated fat and cholesterol—but what you’re eating more of–the phytonutrients. Whether it’s about training longer or living longer, we’ve got to eat more plants.
How many antioxidant-rich foods do we need to eat every day just to stay out of oxidative debt? Let’s look at some answers.
Carbohydrate means, basically, hydrated carbon—carbon dioxide and water, which is what plants use to make carbs with, and all that’s left after we then burn them for energy to power our muscles and brain. But, this process of oxidizing carbs to make energy is messy and generates free radicals, such that if we chug down straight sugar water, the level of oxidation in our bloodstream goes up over the next few hours. Why would our bodies evolve to have a negative reaction to our primary fuel? Because over our millions of years of evolution, there was no such thing as sugar water—all sugars and starches came pre-packaged with what? With antioxidants. In nature, sugar always comes with phytonutrients.
If you drink the same amount of sugar in the form of orange juice, you don’t get that spike in oxidation. Why? Because the sugar in fruit comes prepackaged with antioxidants. Can’t we just drink vitamin C-enriched sugar water? No. It wasn’t the vitamin C in the OJ, but the citrus phytonutrients, like hesperidin and naringenin, that beat back the oxidation.
If we don’t eat phytonutrient-rich plant foods with every meal, like fruit, then, for hours after we eat, our bodies are tipped out of balance into a pro-oxidative state, which can set us up for oxidant-stress diseases. The free radicals in our body can oxidize the fats in our blood, for example, and set us up for heart disease.
If we don’t eat phytonutrient foods with our meals, our body has to dip into its backup supply of antioxidants and you can’t get away with that for long. So, while ideally we should stuff our faces with as many phytonutrient-rich foods as we can, in the very least, we should eat enough antioxidants to counter the oxidation of digestion. At the very least, we don’t want to slide backwards every day and end up with fewer antioxidants in our bodies than we woke up with.
Men in the U.S. average about 2,500 calories a day and so should be getting at least 11,000 micromoles a day. Women who eat about 1,800 calories, on average, so should get at least 8,000, just to stay solvent. The average American, doesn’t even get half the minimum! No wonder oxidant stress-related diseases abound. We’re getting so few antioxidants in our diet, we can’t even keep up with the free radicals created just digesting our meals. We are a nation in chronic oxidative debt.
In developed societies, we eat a lot of food, but not enough plants, which could result “in exaggerated and prolonged metabolic, oxidative, and immune imbalance, presenting opportunity for biological insult that over time could supersede biological defense and repair systems manifesting in cellular dysfunction, disease, and ultimately death.”
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Thanks for listening to Nutrition Facts. I’m Dr. Michael Greger.
This is an approximation of the audio content, contributed by Allyson Burnett.