Shop for the reddest of strawberries, the blackest of blackberries, the most scarlet tomato, the darkest green broccoli you can find. The colors are the antiaging, anticancer antioxidants.
Antioxidant content is one of the reasons I’ve singled out berries for special treatment. They are second only to herbs and spices as the most antioxidant-packed food category. As a group, they average nearly ten times more antioxidants than other fruits and vegetables (and exceed fifty times more than animal-based foods).5
The Antioxidant Power of Berries
As with other green-light foods, the healthiest variety is the one you’ll eat most often, but if you have no particular preference, why not put the berry with the most antioxidants in your morning oatmeal? Thanks to a study that compared more than a hundred different berries and berry products, we now know which one that is.6
America’s favorite fruits are apples and bananas, with antioxidant power of about 60 units and 40 units, respectively. Mangos, the preferred fruit around the world outside of the United States, have even more antioxidant punch at around 110 units. (It makes sense when you consider how much more colorful they are on the inside.) But none of these fruits are a match for berries. Strawberries weigh in at about 310 units per 120 grams, cranberries at 330, raspberries at 350, blueberries at 380 (though wild blueberries may have twice as much7), and blackberries at a whopping 650 units. Above even those are exotic types you can pick wild in the Arctic tundra, like red whortleberries. (They sound like something from a Dr. Seuss book!) But in terms of what you can find readily in the shops, it’s blackberries for the win. (I share my whole-fruit cocktail recipe for using one of the runners-up, cranberries, here.) I’m happy as long as you’re eating a serving of any type of berry every day, but in terms of antioxidant content, choosing blackberries over strawberries appears to give you twice the bang for your berry.8
What About All the Sugar in Fruit?
There are a few popular diets out there that urge people to stop eating fruits because their natural sugars (fructose) are thought to contribute to weight gain. The truth is, only fructose from added sugars appears to be associated with declining liver function,9 high blood pressure, and weight gain.10 How could the fructose in sugar be bad but the same fructose in fruit be harmless? Think about the difference between a sugar cube and a sugar beet. (Beets are the primary source of sugar in the United States.11) In nature, fructose comes prepackaged with the fibre, antioxidants, and phytonutrients that appear to nullify adverse fructose effects.12
Studies show that if you drink a glass of water with three tablespoons of sugar (similar to what would be in a can of fizzy drink), you’ll have a big spike in your blood sugar levels within the first hour. That causes your body to release so much insulin to mop up the excess sugar that you actually overshoot and become hypoglycemic by the second hour, meaning that your blood sugar drops even lower than it would if you were fasting. Your body detects this low blood sugar, thinks you might be in some sort of famine situation, and responds by dumping fat into your bloodstream as an energy source to keep you alive.13 This excess fat in the blood can then go on to cause further problems. (See chapter 6.)
But what if you eat 120 grams of blended berries in addition to the sugar? The berries, of course, have sugars of their own—an additional tablespoon’s worth—so the blood sugar spike should be even worse, right? Actually, no. Study participants who ate berries with their glass of sugar water showed no additional blood sugar spike and no hypoglycemic dip afterward; their blood sugar levels merely went up and down, and there was no surge of fat into the blood.14
Consuming sugar in fruit form is not only harmless but actually helpful. Eating berries can blunt the insulin spike from high-glycemic foods like white bread, for example.15 This may be because the fibre in fruit has a gelling effect in your stomach and small intestine that slows the release of sugars16 or because of certain phytonutrients in fruit that appear to block the absorption of sugar through the gut wall and into your bloodstream.17 So eating fructose the way nature intended carries benefits rather than risks.
Low-dose fructose may actually benefit blood sugar control. Eating a piece of fruit with each meal could be expected to lower, rather than raise, the blood sugar response.18 What about people with type 2 diabetes? Diabetics randomized into a group restricted to no more than two daily pieces of fruit had no better blood sugar control than those randomized into a group told to eat a minimum of two pieces of fruit per day. The researchers concluded that “the intake of fruit should not be restricted in patients with type 2 diabetes.”19
Surely there must be some level of fructose consumption that’s harmful even when served in Mother Nature’s green-light form, right? Apparently not.
Seventeen people were asked to eat twenty servings of fruit per day for months. Despite the extraordinarily high fructose content of this fruit-based diet—the sugar equivalent of about eight cans of fizzy drinks a day—the investigators reported beneficial outcomes with no overall adverse effects for body weight, blood pressure,20 insulin, cholesterol, and triglyceride levels.21 More recently, the research group who invented the glycemic index found that feeding subjects a fruit-, vegetable-, and nut-based diet that included about twenty servings of fruit per day for a couple of weeks had no adverse effects on weight, blood pressure, or triglycerides—all while lowering LDL (“bad”) cholesterol by an astounding thirty-eight points.22
Cholesterol lowering was not the only record broken: Participants were asked to eat forty-three servings of vegetables a day in addition to the fruit, the result of which was that the researchers recorded the largest-ever bowel movements documented in a dietary intervention.23
Are frozen berries as nutritious as fresh ones? Studies on cherries,24 raspberries,25 and strawberries26 suggest that most of their nutrition is retained even when frozen. I usually opt for frozen berries since they last longer, are available year round, and tend to be cheaper. If you looked in our freezer right now, you’d see it’s about half frozen greens and half frozen berries. What do I do with those berries? Make ice cream, of course.
The favored dessert in our home is soft-serve “ice cream” made by blending frozen fruit. You whip up frozen fruit in a blender, food processor, or juicer, and voilà! Instant all-fruit ice cream. You have to taste it to believe it. The simplest recipe has one ingredient: frozen bananas. Peel and freeze some ripe bananas (the riper, the better—I’m talking brown). Once frozen, throw them in a food processor and blend. They transform into a smooth, light, fluffy dessert cheaper, healthier, and tastier than anything you might get in a trendy frozen yogurt shop.
Of course making berry ice cream or at least a berry-banana mix is even healthier. My favorite is chocolate. To make it, blend dark, sweet cherries or strawberries mixed with a tablespoon of cocoa power, a splash of a milk of your choice (more if you want a milkshake), a capful of vanilla extract, and some pitted dates. If you didn’t yet get your nuts for the day, you can add some almond butter. Either way, you get an instant, decadent, chocolate dessert so nutritious that the more you eat, the healthier you are. Let me repeat that: The more you eat, the healthier you are. That’s my kind of ice cream!
Tart Cherries
Research dating back half a century suggests tart cherries are so anti-inflammatory that they can be used to successfully treat a painful type of arthritis called gout.27 Delicious dietary treatments are much welcomed, as some gout drugs can cost $2,000 (over £1,000) a dose,28 carry no clear-cut distinction between nontoxic, toxic, and lethal doses,29 or can cause a rare side effect in which your skin detaches from your body.30 Of course, the best way to deal with gout is to try to prevent it in the first place with a more plant-based diet.31
Cherries can reduce the level of inflammation among healthy people too (as measured by a drop in C-reactive protein levels),32 so I was excited to find a green-light source available year-round—a tinned product with only two ingredients: cherries and water. I drain off the liquid (which t
hen goes into my hibiscus punch recipe here) and mix the cherries in a bowl of cooked oatmeal along with cocoa powder and pumpkin seeds. If you sweeten it with date sugar or erythritol (see here), it’s like eating chocolate-covered cherries for breakfast.
A note of caution: For the same reason that high doses of anti-inflammatory drugs such as aspirin should be avoided during the third trimester of pregnancy, cocoa, berries, and other foods high in anti-inflammatory polyphenols should only be eaten in moderation in late pregnancy.33
Goji Berries
Tart cherries naturally contain melatonin and have been used to improve sleep without any side effects.34 Goji berries, however, have the highest concentrations of melatonin.35 Gojis have the third-highest antioxidant capacity of any common dried fruit—five times more than raisins and second only to dried pomegranate seeds and barberries (a fruit commonly found in Middle Eastern markets and spice shops).36 Gojis also have a specific antioxidant pigment that makes sweetcorn yellow—zeaxanthin. When eaten, zeaxanthin is shuttled into your retinas (the back of your eyes) and appears to protect against macular degeneration, a leading cause of vision loss.37
The egg industry boasts about the zeaxanthin content in yolks, but goji berries have about fifty times more than eggs.38 A double-blind, randomized, placebo-controlled trial found that gojis may even help people already suffering from macular degeneration.39 The researchers used milk to improve the absorption of zeaxanthin (which, like all carotenoids, is fat soluble), but a healthier way would be to use green-light sources of fat, such as nuts and seeds—in other words, goji trail mix!
Aren’t goji berries expensive, though? In natural foods stores, they can go for £13 a pound, but in Asian supermarkets, you can buy them as “Lycium” berries, and they’re even cheaper than raisins. So, however you used to eat raisins—as a snack, in baked goods, in your breakfast cereal or oatmeal, whatever—I recommend you make the switch to gojis.
Black Currants and Bilberries
Speaking of berries and eyesight, a double-blind, placebo-controlled, crossover trial of black currants found they can improve the symptoms of computer eye strain (known in doctor-speak as “video display terminal work-induced transient refractive alteration”).40 What passes for currants in the United States are usually champagne grape raisins, not actual black currants, which were banned in the country a century ago at the behest of the lumber industry. (The industry feared they might spread a plant disease that affects white pines, a tree we hardly harvest anymore, so the ban has since been lifted in some states.) Real black currants are currently making a comeback, but if—as the researchers suspected—the benefits have to do with the anthocyanin pigments, other berries like bilberries, blueberries, or blackberries may help as well. Anthocyanin pigments are responsible for many of the intense blue, black, purple, and red colors of berries and other fruits and vegetables. The highest concentrations are found in aronia berries and elderberries, followed by black raspberries, blueberries (especially the smaller “wild” varieties), and blackberries. The cheapest source, though, is probably red cabbage.41
Bilberries gained notoriety during World War II when it was said that pilots in the British Royal Air Force “were eating bilberry jam to improve their night vision.”42 It turns out this may have been a story concocted to fool the Germans. The more likely reason the Brits were able to suddenly target Nazi bombers in the middle of the night wasn’t because of bilberries but thanks to a top-secret new invention: radar.
Unfortunately, these anthocyanin pigments take a hit when berries are processed into jam. As much as 97 percent of anthocyanins are lost when strawberries are turned into strawberry jam.43 Freeze-drying, however, appears to be remarkably nutrient preserving.44 I remember trying “astronaut ice cream” as a kid when I visited the Smithsonian’s Air and Space Museum. That’s what freeze-dried strawberries taste like to me. They just melt in your mouth. Delicious, nutritious, but expensive.
Fresh berries, of course, are divine. My family enjoys pick-your-own outings and then freezes the abundance. I’ve also been known to lay a sheet under branches of mulberry trees that grow in a park by our house and gently knock down a ripe bounty with a broom handle. Evidently, nearly all wild “aggregate” berries (meaning berries that look like clusters of little balls, like blackberries, raspberries, and mulberries) in North America are edible,45 but please be sure you make an ironclad identification before foraging.
Berries in all their colorful, sweet, and flavorful glory are protective little antioxidant powerhouses. The issue shouldn’t be how you are going to get your one minimum daily serving but rather how you are going to pry yourself away from them. In your smoothie, as a dessert, on your salad, or just popped right into your mouth—they are nature’s sweets.
Other Fruits
Dr. Greger’s Favorite Other Fruits
Apples, dried apricots, avocados, bananas, cantaloupe, clementines, dates, dried figs, grapefruit, honeydew, kiwifruit, lemons, limes, lychees, mangos, nectarines, oranges, papaya, passion fruit, peaches, pears, pineapple, plums (especially black plums), pluots, pomegranates, prunes, tangerines, and watermelon
Serving Sizes:
1 medium-sized fruit
120 g cut-up fruit
40 g dried fruit
Daily Recommendation:
3 servings per day
It took years for nearly five hundred researchers from more than three hundred institutions in fifty countries to develop the 2010 Global Burden of Disease Study. Funded by the Bill & Melinda Gates Foundation, it is the largest analysis of risk factors for death and disease in history.1 In the United States, the massive study determined that the leading cause of both death and disability was the American diet, followed by smoking.2 What did they determine to be the worst aspect about our diet? Not eating enough fruit.3
Don’t limit yourself to eating fruit just the way it comes plucked off the tree. Although fruit makes for a perfect, quick snack, don’t forget that it can be cooked as well. Think baked apples, poached pears, and grilled pineapple.
If you like drinking your fruit, blending is better than juicing to preserve nutrition. Juicing removes more than just fibre. Most of the polyphenol phytonutrients (see chapter 3) in fruits and vegetables appear to be bound to the fibre and are only liberated for absorption by the friendly flora in your gut. When you merely drink the juice, you lose out on the fibre and all the nutrition that was attached to it.4 Even just cloudy apple juice, which retains a bit of the fruit fibre, appears to have nearly triple the phenolics compared to clear apple juice.5
Whereas greater consumption of whole fruits has been associated with a lower likelihood of developing type 2 diabetes, Harvard University researchers found that greater juice consumption was associated with higher diabetes risk. So, by choosing yellow-light sources of fruit, like juice or jam, you may not only be missing out on nutrients but actively working against your health.6
An Apple a Day
Anyone who says they don’t have time to eat healthfully has never met an apple. Talk about a convenience food! For those who grew up in a world dominated by Red Delicious and Granny Smith, I’m happy to report there are thousands of varieties. Health-wise, crab apples (gross!) probably top the charts,7 but taste-wise, my personal favorite is Honeycrisp—or any pick-your-own variety I can find locally. If you’ve never tried an apple you picked right off a tree, you don’t know what you’re missing. Failing that, farmers’ markets can offer good deals on great produce. My family buys apples by the half bushel.
Dates
My favorite fruit snack in the autumn and winter is apple slices with dates, for the perfect mix of tart and sweet. Growing up, I never liked dates. They tasted dry and kind of waxy. But then I discovered there were soft, plump, moist varieties that didn’t taste like the chalky ones that haunted my childhood. Barhi dates, for example, are wet and sticky, but when frozen, they acquire the taste and chew of caramel. Seriously. Paired with my Honeycrisp, it’s like eating a butterscotch-
flavored caramel apple.
Locally, you should be able to find decent Medjool dates in Middle Eastern grocery stores and many natural foods markets, but for the too-moist-to-be-sold-commercially varieties, you’ll probably have to shop online. I have tried dates from most of the major online retailers and always go back to ordering from the Date People, a small farm in California. I am averse to commercial endorsements, but I’ve never tasted consistently better dates from any other source (although Black Sphinx dates from Phoenix come close!). Date People’s annual harvest comes in around my birthday in October, and I always splurge as a present to myself and get a big box to put in our freezer.
Olives and Olive Oil
Olives and extra-virgin olive oil are yellow-light foods. Olive consumption should be minimized because they’re soaked in brine—a dozen large olives could take up nearly half your recommended sodium limit for an entire day. Olive oil is sodium-free, but most of its nutrition has been removed. You can think of extra-virgin olive oil a little like fruit juice: It has nutrients, but the calories you get are relatively empty compared to those from the whole fruit. (Olives are, after all, fruits.)
Freshly squeezed olive juice already has less nutrition than the whole fruit, but then olive-oil producers also throw away the olive wastewater, which contains the water-soluble nutrients. As a result, you end up getting just a small fraction of the nutrition of the whole fruit by the time extra-virgin olive oil is bottled. Refined olive oil (nonvirgin) is even worse. I would classify it, along with other vegetable oils, as red-light foods, as they offer such scant nutrition for their heavy caloric loads. One tablespoon of oil can contain more than one hundred calories without filling you up. (Compare that single tablespoon to the one-hundred-calorie serving sizes of other foods here.)
How Not to Die Page 38