I think of oil as the table sugar of the fat kingdom. Similar to the way manufacturers take healthy foods like beets and throw out all their nutrition to make sugar, they take wholesome corn and scorch-earth it down to corn oil. Like sugar, corn oil calories may be worse than just empty. In chapter 1, I touched on the impairment of artery function that can occur within hours of eating red-light fare like fast food and cheesecake. The same detrimental effect happens after the consumption of olive oil8 and other oils9 (but not after eating green-light sources of fat like nuts).10 Even extra-virgin olive oil may impair your arteries’ ability to relax and dilate normally.11 So, like any yellow-light food, its use should be curtailed.
Cooking without oil is surprisingly easy. To keep foods from sticking, you can sauté in wine, sherry, stock, vinegar, or just plain water. For baking, I’ve successfully used green-light ingredients such as mashed bananas or avocado, soaked prunes, and even tinned pumpkin to substitute for oil to provide a similar moistness.
The reduction of yellow-light foods is all about frequency and quantity. If you are going to trek outside the green zone, my advice is simple: Make it count. Don’t waste precious indulgences on crappy food. I don’t want to sound like a food snob, but if you’re going to eat something less than maximally healthy, I say pamper yourself and truly relish it. When I eat olives, there’s no way I’m going to eat those waxy black abominations in a tin. I’m going to slice up some purple kalamatas that actually have some flavor. If you’re going to spoil yourself once in a while, I say do it right!
Mangos
Mangos are my favorite fruit treat during spring and summer, but you have to know where to look to get good ones. Check out Hispanic markets and Indian supermarkets. The difference between a mango from Tesco and one from an Indian spice shop is like the difference between a hard, pale, tasteless, pink tomato and a ripe, flavorful, farmer’s market heirloom. You should be able to smell the mango at arm’s length.
My favorite way to eat a mango is like sipping a Capri Sun drink pouch. When the fruit gets soft and ripe, I roll it between my palms, kneading it with my fingers until it becomes essentially liquid pulp in a pouch. Then I nip off the tip with my teeth, gently squeeze, and suck the mango right out of its peel.
Watermelon
Are some whole fruits better than others? Berries contain the most antioxidants, whereas melons wallow down around iceberg lettuce levels. Watermelon seeds, on the other hand, have pretty respectable antioxidant levels, so I try to avoid seedless varieties. A spoonful of watermelon seeds may have as many antioxidants as 170 grams of melon balls.12 Seedless or not, watermelon contains a compound called citrulline that can boost the activity of the enzyme responsible for dilating the blood vessels in the penis that result in erections. A group of Italian researchers found that citrulline supplementation at the level of five servings of red watermelon a day improved erection hardness in men with mild erectile dysfunction, allowing for a 68 percent increase in monthly intercourse frequency.13 Yellow watermelon has four times more citrulline,14 though, so just about one wedge a day (one-sixteenth of a modest melon) may have the same effect. If this information is new to you, perhaps it’s because the advertising budgets of drug companies like Pfizer, which rake in billions of dollars each year from the sale of erectile dysfunction drugs, are about a thousand times15 that of the entire budget of the National Watermelon Promotion Board.16
Dried Fruit
I love dried mangos, but they are hard to find without added sugar. I remember naïvely asking a friend in the food business why the industry felt the need to sugar-up an already sweet fruit. “Added weight,” he explained. Just as poultry processors inject salt water into chickens to add water weight, processed food companies often use sugar as a cheap way to bulk up products sold by the pound.
This made me determined to make my own. I bought an inexpensive dehydrator from eBay, and I’m so glad I did. Fruit is about 90 percent water, so imagine intensifying the flavor of a fresh, ripe mango tenfold. Mind-blowing! Mangos can be a messy pain to peel, but once that’s done, I slice them about a centimeter thick and sprinkle them with chia seeds before putting them in the dehydrator. If I’m taking them on a plane or a hike, I’ll dry them completely. Otherwise, I only wait until just the outside is dry. The outer layer, encrusted with chia, gets a crispy texture while the core remains moist and ready to burst. It’s the kind of thing I can’t eat while watching a movie or reading a book. It tastes so good I just have to stop, close my eyes, and savor it.
I also like drying thin apple slices. I either sprinkle them with cinnamon or rub them with freshly grated ginger. They can be just dried until chewy or completely dehydrated into crunchy apple chips. Eating a dozen dried apple rings a day may drop LDL cholesterol levels 16 percent within three months and 24 percent within six months.17
If you buy dried fruit, I recommend choosing unsulfured varieties. Sulfur-containing preservatives, such as sulfur dioxide in dried fruit and sulfites in wine, can form hydrogen sulfide in your gut—this is the rotten egg gas implicated in the development of the inflammatory bowel disease ulcerative colitis. The main source of hydrogen sulfide is the metabolism of animal protein,18 but you can further lower your exposure by avoiding sulfur additives (either by reading labels or choosing organic, in which such preservatives are forbidden). The sulfur naturally contained in cruciferous vegetables does not appear to elevate colitis risk,19 so feel free to add kale crisps to your healthy snacking menu.
Prescribing Kiwifruit
There appear to be a disproportionate number of articles in the medical literature about the clinical benefits of kiwifruit. Is that because they’re better than other fruits? Or is it because the kiwi industry has more research money? One country, New Zealand, holds a substantial share of the global kiwi market, so it’s in its best interest to underwrite research on the fruit. As a result, there is no shortage of papers touting the benefits of kiwifruit.
Kiwi is one of the fruits I’ve prescribed to my patients with insomnia (two an hour before bedtime appears to significantly improve sleep onset, duration, and efficiency)20 and also to help with constipation-type irritable bowel syndrome (two kiwifruit a day seem to significantly improve bowel function). Kiwi certainly seems like a better option than the leading IBS drug, which was pulled from the market for apparently killing too many people.21
Kiwifruit also appear to benefit immune function. Preschoolers randomized to eat gold kiwifruits every day appeared to cut their risk of contracting a cold or flu-like illness nearly in half compared to those randomly selected to eat bananas instead.22 A similar experiment was tried on elderly individuals, another high-risk group. Those in the banana control group who got an upper-respiratory-tract infection suffered for about five days with a sore throat and congestion, compared to the kiwifruit eaters, who felt better after just a day or two.23 About 1 in 130 children may be allergic to kiwifruit, though,24 which may rank kiwis as the third-most-common food allergen (second only to milk and eggs),25 so they are not for everyone.
Citrus
Adding citrus zest to your meals not only adds color, flavor, aroma, and a bit of culinary flair but also nutrition. Citrus zest lives up to its name in terms of enlivening dishes, and it may do the same to your DNA-repair capabilities. On average, humans appear to suffer eight hundred hits to their DNA per hour. If not fixed, this can cause mutations that give rise to cancer.26 Comparing identical and fraternal twins, researchers have determined that only part of your DNA-repair function is determined genetically. The rest may be under your control.27
The dietary factor found best able to boost DNA repair was citrus fruit.28 Within two hours of consuming citrus, your DNA becomes significantly more resistant to damage,29 which may help explain why citrus consumption is associated with lower risk of breast cancer.30 Some of the citrus compounds thought responsible—which concentrate in the breast31 and enhance DNA repair 32—are found in the peel, though. This may be why people who eat at least some
citrus peel appear to have lower skin cancer rates than those who don’t.33
Stick with the whole fruit, because supplements don’t appear to boost DNA repair,34 and citrus juice doesn’t appear to help, either. In fact, drinking orange juice every morning may even increase skin cancer risk.35 Green-light forms of foods always seem to be the best, and you can eat citrus in an even less processed way by slipping some of the rind into your diet through zesting. I like to freeze lemons, limes, and oranges whole so we always have them on hand to grate onto meals that could use a little zing.
My only whole-citrus caveat: Inform your physician if you eat grapefruit. This fruit can suppress the enzymes that help clear more than half of commonly prescribed drugs, and less drug clearance means higher drug levels in the body.36 This may actually be good if you want a better caffeine buzz from your morning coffee37 or if your doctor wants to help you save money by boosting the effects of expensive drugs instead of just peeing them away.38 But higher drug levels may also mean higher risk of side effects, so if you regularly eat grapefruits, your physician may want to change your prescription or alter the dosing.
Exotic Fruits
The medical school I attended sits in the middle of Boston’s Chinatown. I remember the first time I perused the produce aisle at a large Asian supermarket. With options from bizarre-looking dragon fruit to tribble-like rambutans, I felt like I was on another planet. Every week I tried something new. Some stuck with me—I still sneak lychees into the movies—but others were onetime affairs. Let me share with you the Durian Incident.
Durians are the most badass of all fruits. Imagine a five-pound football covered in sharp spikes like some medieval mace. What other fruit could be described in the medical literature as causing “severe body injury” in papers with titles like “Penetrating Ocular Injury by Durian Fruit”?39 And I haven’t even got to its most distinctive quality: its smell. With an odor perhaps best described as “pig-shit, turpentine and onions, garnished with a gym sock,”40 durian fruits are banned from many public spaces, like subways and airports, in Southeast Asia, where they are grown.
I had to try eating one of these crazy things!
Durian fruits are sold frozen. (I would soon come to understand why.) I took one back to campus and managed to hack off a piece without impaling myself on a spike. The fruit tasted like a caramelized onion popsicle. I left the rest in my locker. Big mistake! I arrived the next day to find an entire floor of the medical center—including the dean’s office—cordoned off. They were going locker to locker, cutting off all the locks, searching in vain for the cause of a stench so overpowering you couldn’t even locate it. It was like a fog of stink. Hospital staff seriously thought someone had stolen body parts from the gross anatomy cadaver lab. And then it struck me. Uh-oh. The durian had thawed. When I realized it was all my fault, I crawled to the dean to beg forgiveness. I already had a history of run-ins with the administration over issues I had raised about the curriculum, and now this. I’ll never forget what he said to me that day: “Why am I not surprised you had something to do with this?”
When adding as much fruit as possible to your diet, you certainly don’t have to seek out weapons-grade stinky fruit, but you also don’t have to stick with the same old, same old. Treat yourself! Have fun sampling the many varieties of the many different fruits around. How lovely it can be to stroll through your farmers’ market on a weekend and pick up locally grown fruits that you can zest onto your meals, blend into smoothies, chew when dried, incorporate into your favorite dishes, or best of all, bite right into. The opportunities are ripe for the picking!
Cruciferous Vegetables
Dr. Greger’s Favorite Cruciferous Vegetables
Rocket, bok choy, broccoli, brussels sprouts, cabbage, cauliflower, collard greens, horseradish, kale (black, green, and red), mustard greens, radishes, turnip greens, and watercress
Serving Sizes:
30–80 g chopped
12 g brussels or broccoli sprouts
1 tablespoon horseradish
Daily Recommendation:
1 serving per day
When I used to teach medical students at Tufts, I gave a lecture about this amazing new therapeutic called “iloccorB.” I’d talk about all the evidence supporting it, the great things it could do, and its excellent safety profile. Just as the students would start scrambling to buy stock in the company and prescribe it to their future patients, I’d do the big reveal. Apologizing for my “dyslexia”, I would admit that I’d gotten it backward. All this time, I had been talking about broccoli.
I’ve mentioned broccoli more than any other food in this book, and for good reason. We’ve seen how cruciferous vegetables like broccoli can potentially prevent DNA damage and metastatic cancer spread in chapter 2, activate defenses against pathogens and pollutants in chapter 5, help to prevent lymphoma in chapter 9, boost your liver detox enzymes and target breast cancer stem cells in chapter 11, and reduce the risk of prostate cancer progression in chapter 13. The component responsible for these benefits is thought to be sulforaphane, which is formed almost exclusively in cruciferous vegetables. This is why they get their own spot on the Daily Dozen.
Beyond being a promising anticancer agent,1 sulforaphane may also help protect your brain2 and your eyesight,3 reduce nasal allergy inflammation,4 manage type 2 diabetes,5 and was recently found to successfully help treat autism. A placebo-controlled, double-blind, randomized trial of boys with autism found that about two to three cruciferous vegetable servings’ worth6 of sulforaphane a day improves social interaction, abnormal behavior, and verbal communication within a matter of weeks. The researchers, primarily from Harvard University and Johns Hopkins University, suggest that the effect might be due to sulforaphane’s role as a “detoxicant.”7
Strategies to Enhance Sulforaphane Formation
The formation of sulforaphane in cruciferous vegetables is like a chemical flare reaction. It requires the mixing of a precursor compound with an enzyme called myrosinase, which is inactivated by cooking8 (though microwaved broccoli appears to retain some cancer-fighting capacity). This may explain why we see dramatic suppression of test-tube cancer-cell growth by raw broccoli, cauliflower, and brussels sprouts, but hardly any reaction when they’re cooked.9 But who wants to eat raw brussels sprouts? Not me. Thankfully, there are ways to get the benefits of raw vegetables in cooked form.
Biting into broccoli is like snapping that chemical flare. When raw broccoli (or any other cruciferous vegetable) is chopped or chewed, the sulforaphane precursor mixes with the myrosinase enzyme and sulforaphane is created as the vegetable sits on the cutting board or lies in your upper stomach waiting to be digested.10 Though the enzyme is destroyed by cooking, both the precursor and the final product are resistant to heat. So here’s the trick: Use what I call the “Hack and Hold” technique (maybe I should call it Whack and Wait?).
If you chop the broccoli (or brussels sprouts, kale, collards, cauliflower, or any other cruciferous vegetable) and then wait forty minutes, you can cook it as much as you want. At that point, the sulforaphane has already been made, so the enzyme is no longer needed to achieve maximum benefit. It’s already done its job. (You can also buy bags of fresh greens and other crucifers that are prechopped or shredded, which can presumably be cooked immediately.)
Given this understanding, can you see how most people prepare broccoli soup incorrectly? Typically, they first cook the broccoli and then blend it. But, when you blend it, you’re merely mixing the precursor with an enzyme that’s been inactivated by cooking. Do it in the opposite order: First blend your veggies and then wait forty minutes before cooking them. This way, you can maximize sulforaphane production.
What about frozen broccoli and other crucifers? Commercially produced frozen broccoli lacks the ability to form sulforaphane because the vegetables are blanched (flash-cooked) before they’re frozen for the very purpose of deactivating enzymes.11 This process prolongs shelf life, but when you take the veggies out of
your freezer, the enzyme is inert. At that point, it doesn’t matter how much you chop or how long you wait—no sulforaphane is going to be made. This may be why fresh kale has been shown to suppress cancer cell growth in vitro up to ten times better than frozen kale.12
The frozen crucifer is still packed with the precursor, though—remember, it’s heat resistant. You could make lots of sulforaphane from it by adding back some enzyme.13 But where can you get myrosinase? Scientists buy theirs from chemical companies, but you can just walk into any supermarket.
Mustard greens are also cruciferous vegetables. They grow from mustard seeds, which you can buy ground up in the spice aisle as mustard powder. If you sprinkled some mustard powder on frozen broccoli that’s been cooked, would it start churning out sulforaphane? Yes!
Boiling broccoli prevents the formation of any significant levels of sulforaphane due to inactivation of the enzyme. However, the addition of powdered mustard seeds to cooked broccoli significantly increases sulforaphane formation.14 Then it’s almost as good as eating it raw! So, if you don’t have forty minutes to spare between chopping and cooking, or if you’re using frozen greens, just sprinkle the crucifers with some mustard powder before you eat them, and you’ll be all set. Daikon radishes, regular radishes, horseradish, and wasabi are all cruciferous vegetables and may have the same effect. All it appears to take is a pinch to revitalize sulforaphane production.15 You can also add a small amount of fresh greens to your cooked greens. So when I add shreds of purple cabbage to my finished dishes, it not only adds a beautiful garnish with a delightful crunch, it’s filled with the sulforaphane-producing enzyme.
One of my first tasks every morning used to be chopping greens for the day, using my Hack and Hold technique. But now, with the Mustard Powder Plan, I have one less to-do on my list.
How Not to Die Page 39