Sometimes the blood clot lasts only a moment—not long enough to notice but still long enough to kill off a tiny portion of your brain. These so-called silent strokes can multiply and slowly reduce cognitive function until full-blown dementia develops.4 The goal is to reduce the risk of both the massive strokes that can kill you instantly and the ministrokes that kill you over the course of years. Just as with heart disease, a healthy diet can reduce stroke risk by reducing cholesterol and blood pressure while improving blood flow and antioxidant capacity.
Fibre! Fibre! Fibre!
In addition to its well-known effects on bowel health, high fibre intake appears to reduce the risk of cancers of the colon5 and breast,6 diabetes,7 heart disease,8 obesity,9 and premature death in general.10 A number of studies now show that high fibre intake may also help ward off stroke.11 Unfortunately, less than 3 percent of Americans meet the minimum daily recommendation for fibre.12 This means about 97 percent of Americans eat fibre-deficient diets. Fibre is naturally concentrated in only one place: whole plant foods. Processed foods have less, and animal-derived foods have no fibre at all. Animals have bones to hold them up; plants have fibre.
It apparently doesn’t take much fibre to cut stroke risk. Increasing fibre intake by just seven grams a day may be associated with a 7 percent risk reduction.13 Different strokes for different folks—depending, evidently, on how much fibre they ate. An additional seven grams of fibre is easy to add to your diet; it’s the equivalent of a bowl of oatmeal with berries or a serving of baked beans.
How does fibre protect the brain? We’re not exactly sure. We do know that fibre helps control your cholesterol14 and blood sugar levels,15 which can help reduce the amount of artery-clogging plaque in your brain’s blood vessels. High-fibre diets may also lower blood pressure,16 which reduces the risk of brain bleeds. But scientists don’t have to know the exact mechanism before you act on this knowledge. As the biblical passage goes: “A man scatters seed on the ground . . . the seed sprouts and grows, though he does not know how.” Had the farmer from scripture postponed his sowing until he understood the biology of seed germination, he wouldn’t have lasted very long. So why not go ahead and reap the benefits of eating fibre by eating more unprocessed plant foods?
It’s never too early to start eating healthier. Though stroke is considered an older person’s disease—only about 2 percent of stroke deaths occur before the age of forty-five17—the risk factors may begin accumulating in childhood. In a remarkable study published recently, hundreds of children were followed for a period of twenty-four years, from junior high school to adulthood. Researchers found that low fibre intake early on was associated with stiffening of the arteries leading up to the brain—a key risk factor for stroke. By the time these adolescents were only fourteen, clear differences in arterial health were found for those consuming different amounts of fibre in their daily diets.18
Again, it did not appear to take much. One more apple, an extra 40 grams of broccoli, or just two tablespoons of beans a day during childhood could translate into a meaningful effect on artery health later in life.19 If you really want to be proactive, the best available science20 suggests you can minimize stroke risk by eating a minimum of 25 grams a day of soluble fibre (fibre that dissolves in water, typically found in beans, oats, nuts, and berries) and 47 daily grams of insoluble fibre (fibre that does not dissolve in water, found primarily in whole grains, such as brown rice and whole wheat). Granted, you’d have to eat an extraordinarily healthy diet to attain this level of fibre intake, far beyond what is arbitrarily determined as adequate by most health authorities.21 Rather than patronizing you with what they think is “achievable”22 by the masses, though, I wish these authorities would just tell you what the science says and let you make up your own mind.
Potassium
Take a plant, any plant, and burn it to ash. Throw that ash in a pot of water, boil it, skim off the ashes, and eventually you’ll be left with a white residue known as potash (“pot ash”). Potash has been used for millennia for making everything from soap and glass to fertilizer and bleach. It wasn’t until 1807 that an English chemist figured out that this “vegetable alkali” contained an undiscovered element, which he called pot-ash-ium—that is, potassium.
I mention this simply to emphasize the primary source of potassium in your diet—namely, plants. Every cell in your body requires potassium to function, and you need to get it from your diet. For much of human history, we ate so many plants that we got upward of 10,000 mg of potassium every day.23 Nowadays, less than 2 percent of Americans even reach the recommended daily intake of 4,700 mg.24
The major reason is simple: We don’t eat enough unprocessed plant foods.25 What does potassium have to do with stroke? A review of all the best studies on the relationship between potassium and our top-two killers, heart disease and stroke, determined that a 1,640 mg increase per day in potassium intake was associated with a 21 percent reduction in stroke risk.26 That isn’t enough to bring the average American’s potassium levels to where they should be, but it’s still enough to substantially reduce the risk of stroke. Imagine how much lower your risk would be if you doubled or tripled your intake of whole plant foods.
Bananas, although they’ve been marketed for their potassium content, aren’t actually particularly rich in the mineral. According to the current U.S. Department of Agriculture database, bananas don’t even make the list of the top-thousand foods with the highest levels of potassium; in fact, they come in at number 1,611, right after Reese’s Pieces.27 You’d have to eat a dozen bananas a day just to get the bare minimum recommended amount of potassium.
What are some of the truly potassium-rich foods? The healthiest common whole-food sources are probably greens, beans, and sweet potatoes.28
Citrus
Good news for all you orange lovers: Citrus fruit intake has been associated with reduced stroke risk—even more so than apples.29 Say I can’t compare them? I just did! The key may lie with a citrus phytonutrient called hesperidin, which appears to increase blood flow throughout the body, including the brain. Using a machine known as a doppler fluximeter, scientists can measure blood flow through the skin using a laser beam. If we hook people up to this machine and give them a solution containing the amount of hesperidin found in two cups of orange juice, blood pressure decreases and overall blood flow increases. When subjects drank straight orange juice instead of the hesperidin solution, their blood flow was even better. In other words, the stroke-reducing effects of oranges extend beyond just the hesperidin.30 When it comes to food, the whole is often greater than the sum of its parts.
The positive effects of citrus fruits on blood flow don’t require a machine to measure them. In one study, scientists recruited women who suffered from sensitivity to cold weather due to poor blood flow—women with chronically cold hands, feet, and toes—and placed them in a highly air-conditioned room. The women in the experimental group drank a solution containing actual citrus phytonutrients, while another (control) group drank a placebo (an artificially flavored orange drink). The placebo drinkers got colder and colder. Because of decreased blood flow, the temperature of their fingertips dropped nearly 9 degrees Fahrenheit during the course of the study. The fingertips of the women who drank real citrus, meanwhile, cooled less than half as fast, because their blood flow remained steadier. (The researchers also had both groups of women plunge their hands into icy water and saw the citrus drinkers recover about 50 percent faster than the control group.)31
So eating a few oranges before snowboarding may help keep your fingers and toes from getting as chilly. But while warm digits are nice, the reduced stroke risk associated with higher citrus intake is even nicer.
Optimal Sleep Duration and Stroke
Lack of sleep, or even too much of it, is associated with increased stroke risk.32 But how much sleep may be too little? How much too much?
Scientists in Japan were the first to take a major stab at this question. They followed nearly 100,
000 middle-aged men and women for fourteen years. Compared with people who slept an average of seven hours per night, subjects who got four hours of sleep or less, or ten hours or more, had roughly a 50 percent greater likelihood of dying from a stroke.33
A recent study of 150,000 Americans was able to examine the issue more thoroughly. Higher stroke rates were found among individuals sleeping six hours or less, or nine hours or more. Those at lowest risk got around seven or eight hours of sleep a night.34 Large studies in Europe,35 China,36 and elsewhere37 have confirmed that seven or eight hours appears to be associated with the lowest risk. We’re not sure if the relationship is cause and effect, but until we know more, why not aim for that range? Sleep well!
Antioxidants and Stroke
Awarded the National Medal of Science, the highest honor for scientific achievement in this country, revered biochemist Earl Stadtman was quoted as saying, “Aging is a disease. The human lifespan simply reflects the level of free radical damage that accumulates in cells. When enough damage accumulates, cells can’t survive properly anymore and they just give up.”38
First proposed in 1972,39 this concept—now called the mitochondrial theory of aging—suggests that free radical damage to your cells’ power source, known as mitochondria, leads to a loss of cellular energy and function over time. This process may be a little like charging your iPod battery over and over—each time, its capacity gets less and less.
But what exactly are free radicals, and what can we do about them?
Here’s my best attempt to simplify the quantum biology of oxidative phosphorylation: Plants get their energy from the sun. You take a plant and place it in the sun, and through a process called photosynthesis, the chlorophyll in the leaves harnesses the sun’s energy and transfers it to tiny building blocks of matter called electrons.
The plant starts out with low-energy electrons and, using the energy of the sun, charges them up into high-energy electrons. In this way, plants store the sun’s energy. When you then eat the plant (or the animals who ate the plant), these electrons (in the form of carbohydrates, protein, and fat) are delivered to all your cells. Then your mitochondria take the plant’s power-packed electrons and use them as an energy source—that is, as fuel—and slowly release their energy. Mind you, this process has to occur in a precise, tightly controlled manner, because these electrons are packed with energy and are therefore volatile, like petrol.
In fact, petrol, petroleum, oil, and charcoal aren’t called fossil fuels for nothing. The tanks of our SUVs are filled with mostly prehistoric plant matter that stored the energy of the sun that shone millions of years ago as high-energy electrons.
And just as it would be dangerous to toss a match into a can of petrol and release all its energy at once, your body has to be cautious. That’s why your cells take these same high-energy electrons from the plants you eat and release their energy in a controlled manner, like a gas cooker—just a little at a time until the energy is used up. Your body then passes these used-up electrons to an all-important molecule you may have heard of: oxygen. In fact, the way poisons like cyanide kill you is by preventing your body from giving up these spent electrons to oxygen.
Fortunately, oxygen loves electrons, although maybe a little too much. While your body is taking its sweet time, slowly releasing the electrons’ energy, the oxygen is waiting impatiently at the end of the line. Oxygen would love to get its grubby little hands on one of those high-energy electrons, but your body says, “Hold on. We’ve got to do this slowly, so wait your turn and let it cool off first. We’ll give you your electron, but only after we’ve removed the energy so it’s safe to play with.”
Then the oxygen molecule gets all huffy and exclaims, “I could handle one of them souped-up electrons any day!” Pouting, it spies a stray high-energy electron sitting out in the open. Oxygen looks left, looks right, and then pounces on it. Your body isn’t perfect; it can’t keep an eye on oxygen all the time. About 1–2 percent40 of all high-energy electrons that pass through your cells leak out where oxygen can grab them.
When oxygen gets its hands on a high-energy electron, it basically turns into the Hulk, changing from lowly oxygen into what’s called superoxide, a type of free radical. A free radical is what it sounds like—a molecule that can be unstable, out of control, and violently reactive. The superoxide is just pumped up with energy and can start smashing around the cell, knocking stuff over and tripping over your DNA.
When superoxide comes in contact with DNA, it can damage your genes, which, if not repaired, can cause mutations in your chromosomes that may lead to cancer.41 Thankfully, the body calls in its defense squad, known as antioxidants. They arrive at the scene and say, “Drop that electron!”
The superoxide fights back. “You want a piece of me, Mr. Vitamin C? Bring it!”
So the antioxidants proceed to jump the superoxide and wrestle the supercharged electron away from it, leaving behind poor little oxygen and its ripped jeans.
In scientific circles, the phenomenon by which oxygen molecules grab stray electrons and go crazy is called oxidant, or oxidative, stress. According to the theory, the resulting cellular damage is what essentially causes aging. Aging and disease have been thought of as the oxidation of the body. Those brown age spots on the back of your hands? They’re just oxidized fat under the skin. Oxidant stress is thought to be why we all get wrinkles, why we lose some of our memory, why our organ systems break down as we get older. Basically, the theory goes, we’re rusting.
You can slow down this oxidant process by eating foods containing lots of antioxidants. You can tell whether a food is rich in antioxidants by slicing it open, exposing it to air (oxygen), and then seeing what happens. If it turns brown, it’s oxidizing. Think about our two most popular fruits: apples and bananas. They turn brown quickly, which means there aren’t a lot of antioxidants inside them. (Most of the antioxidants in apples are in the peels.) Cut open a mango and what happens? Nothing happens, because there are lots of antioxidants in there. How do you keep fruit salad from turning brown? By adding lemon juice, which contains the antioxidant vitamin C. Antioxidants can keep your food from oxidizing, and they may do the same inside your body.
One of the diseases antioxidant-rich foods may help prevent is stroke. Swedish researchers followed more than thirty thousand older women over a period of a dozen years and found that those who ate the most antioxidant-rich foods had the lowest stroke risk.42 Similar findings were reported in a younger cohort of men and women in Italy.43 As with lung disease,44 antioxidant supplements don’t appear to help.45 Mother Nature’s powers cannot be stuffed into a pill.
Knowing this, scientists set out to find the most antioxidant-rich foods. Sixteen researchers spanning the globe published a database of the antioxidant power of more than a whopping three thousand foods, beverages, herbs, spices, and supplements. They tested everything from Cap’n Crunch cereal to the crushed dried leaves of the African baobab tree. They tested dozens of brands of beer to see which has the most antioxidants. (Santa Claus beer from Eggenberg, Austria, tied for first place.)46 Sadly, beer represents Americans’ fourth-largest source of dietary antioxidants.47 You can check out the list to see where your favorite foods and beverages rank at this link: http://bit.ly/antioxidantfoods.
No need to post the 138-page chart on your fridge, though. Here’s the simple rule: On average, plant foods contain sixty-four times more antioxidants than animal foods. As the researchers put it, “[A]ntioxidant rich foods originate from the plant kingdom while meat, fish and other foods from the animal kingdom are low in antioxidants.”48 Even the least healthy plant food I can think of, good old American iceberg lettuce (which is 96 percent water!49), contains 17 units (daμmol using a modified FRAP assay) of antioxidant power. Some berries have more than 1,000 units, to give you some perspective, making iceberg look pretty pathetic. But compare iceberg lettuce’s 17 units to fresh salmon, which has only 3 units. Chicken? As few as 5 units of antioxidant power. Skimmed milk o
r a hard-boiled egg? Just 4 units, and Egg Beaters has a big old goose egg—0 units. “Diets comprised mainly of animal-based foods are thus low in antioxidant content,” concluded the research team, “while diets based mainly on a variety of plant-based foods are antioxidant rich, due to the thousands of bioactive antioxidant phytochemicals found in plants which are conserved in many foods and beverages.”50
There is no need to necessarily cherry-pick individual foods to boost your antioxidant intake (though cherries do have up to 714!); you can simply strive to include a variety of fruits, vegetables, herbs, and spices at every meal. This way, you can continuously flood your body with antioxidants to help ward off stroke and other age-related diseases.
Antioxidants, in a Pinch
The food category that averages the most antioxidants is herbs and spices.
Let’s say you prepare a nice healthy bowl of whole-wheat pasta with marinara sauce. Together, they may achieve a score of about 80 units of antioxidant power (approximately 20 units from the pasta and 60 from the sauce). Add in a handful of steamed broccoli florets, and you may end up with a delicious 150-unit meal. Not bad. Now sprinkle on a single teaspoonful of dried oregano or marjoram, oregano’s sweeter and milder twin. That alone could double your meal’s antioxidant power, up to more than 300 units.51
How about a bowl of oatmeal for breakfast? By adding just half a teaspoon of cinnamon, you could bring the antioxidant power of your meal from 20 units to 120 units. And if you can stand the punch, adding even a pinch of cloves could bring your unassuming breakfast up to an antioxidant score of 160 units.
Plant-based meals tend to be rich in antioxidants on their own, but taking a moment to spice up your life may make your meal even healthier.
Antioxidant-rich diets appear to protect against stroke by preventing the circulation of oxidized fats in the bloodstream that can damage the sensitive walls of small blood vessels in the brain.52 They can also help decrease artery stiffness,53 prevent blood clots from forming,54 and lower blood pressure55 and inflammation. Free radicals can disfigure proteins in our bodies to the extent they become unrecognizable by our immune systems.56 The inflammatory response this triggers can be prevented by saturating our bodies with sufficient antioxidants. Whereas all whole plant foods may have anti-inflammatory effects,57 some plants are better than others. High-antioxidant fruits and vegetables, such as berries and greens, have been found to douse systemic inflammation significantly better than the same number of servings of more common low-antioxidant fruits and veggies, such as bananas and lettuce.58
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