Oesophageal Cancer
Oesophageal cancer occurs when cancer cells develop in the oesophagus, the muscular tube carrying food from your mouth to your stomach. Typically, the cancer arises in the lining of the oesophagus and then invades the outer layers before metastasizing (spreading) to other organs. Early on, there may be few symptoms—if any at all. But as the cancer grows, swallowing difficulties can develop.
Every year, there are about eighteen thousand new cases of oesophageal cancer and fifteen thousand deaths.99 The primary risk factors include smoking, heavy alcohol consumption, and gastroesophageal reflux disease (GERD, also called acid reflux), in which acid from the stomach gurgles up into the oesophagus, burning the inner layer and causing inflammation that can eventually lead to cancer. Besides avoiding tobacco and alcohol (even light drinking appears to increase risk),100 the most important thing you can do to prevent oesophageal cancer is to eliminate acid reflux disease—and that can often be accomplished through diet.
Acid Reflux and Oesophageal Cancer
Acid reflux is one of the most common disorders of the digestive tract. The usual symptoms include heartburn as well as the regurgitation of stomach contents back up toward the throat, which can leave a sour taste in the mouth. GERD causes millions of doctor visits and hospitalizations each year and represents the highest annual cost of all digestive diseases in the United States.101 Chronic inflammation caused by acid reflux can lead to Barrett’s oesophagus, a precancerous condition that involves changes in the oesophageal lining.102 To prevent adenocarcinoma, the most common type of oesophageal cancer in the United States, this sequence of events must be stopped—and that means halting acid reflux in the first place.
That’s a tall order in the United States. Over the past three decades, the incidence of oesophageal cancer in Americans has increased sixfold103—an increase greater than that of breast or prostate cancer, and it may be chiefly because acid reflux is on the rise.104 In the United States, about one in four people (28 percent) suffer at least weekly heartburn and/or acid regurgitation, compared to just 5 percent of the population in Asia.105 This suggests that dietary factors may play a key role.
Over the past two decades, about forty-five studies have examined the link between diet, Barrett’s oesophagus, and oesophageal cancer. The most consistent association with cancer was the consumption of meat and high-fat meals.106 Interestingly, different meats were associated with cancers in different locations. Red meat is strongly associated with cancer in the oesophagus itself, whereas poultry was more strongly associated with cancer down around the stomach-oesophagus border.107
How does this happen? Within five minutes of eating fat, your sphincter muscle at the top of your stomach—which acts like a valve to keep down food inside the stomach—relaxes, allowing acids to creep back up into the oesophagus.108 For example, in one study, volunteers consuming a high-fat meal (McDonald’s sausage, egg, and cheese sandwich) experienced more acid squirting up into their oesophagus than those eating a lower-fat meal (McDonald’s hotcakes).109 Part of this effect may be due to the release of a hormone called cholecystokinin, which is triggered by both meat110 and eggs111 and may also relax the sphincter.112 This helps explain why those who eat meat have been found to have twice the odds of reflux-induced oesophageal inflammation compared with vegetarians.113
Even without the cancer risk, GERD itself can cause pain, bleeding, and scar-tissue narrowing of the oesophagus that can interfere with swallowing. Billions of dollars are spent on medications to alleviate heartburn and acid reflux by reducing the amount of stomach acid produced, but these drugs can contribute to nutrient deficiencies and increase the risk of pneumonia, intestinal infections, and bone fractures.114 Perhaps the better strategy would be to just keep the acid in its place by minimizing the intake of foods that allow acid to escape.
The protection afforded by plant-based eating may not be based just on the foods that are reduced, though. Centering your diet around antioxidant-rich plant foods may cut in half your odds of oesophageal cancer.115 The most protective foods for cancer at the oesophagus-stomach border appear to be red, orange, and dark-green leafy vegetables, berries, apples, and citrus fruits,116 but all unprocessed plant foods have the advantage of containing fibre.
Fibre and Hiatal Hernia
While fat intake is associated with increased risk of reflux, fibre intake appears to decrease that risk.117 High fibre intake may reduce the incidence of oesophageal cancer by as much as one-third118 by helping to prevent the root cause of many cases of acid reflux: the herniation of part of the stomach up into the chest cavity.
Hiatal hernia, as this condition is known, occurs when part of the stomach is pushed up through the diaphragm into the chest. More than one in five Americans suffer from hiatal hernias. In contrast, hiatal hernias are almost unheard of among populations whose diets are plant based, with rates closer to one in a thousand.119 This is thought to be because they smoothly pass large, soft stools.120
People who don’t eat an abundance of whole plant foods have smaller, firmer stools that can be difficult to pass. (See box here.) If you regularly strain to push out stool, over time the increased pressure can push part of the stomach up and out of the abdomen, allowing acid to flow up toward the throat.121
This same pressure from straining on the toilet week after week can cause other problems. Similar to the way squeezing a stress ball causes a balloon bubble to pop out, the pressure from straining at the toilet may herniate outpouchings from the wall of the colon, a condition known as diverticulosis. The increased abdominal pressure may also back up blood flow in the veins around the anus, causing hemorrhoids, and even push blood flow back into the legs, resulting in varicose veins.122 But a fibre-rich diet can relieve the pressure in both directions. Those who eat diets that revolve around whole plant foods tend to pass such effortless bowel movements that their stomachs stay where they’re supposed to,123 which can reduce the acid spillover implicated in one of our deadliest cancers.
Can Strawberries Reverse the Development of Oesophageal Cancer?
Oesophageal cancer joins pancreatic cancer as one of the gravest diagnoses imaginable. The five-year survival rate is less than 20 percent,124 with most people dying within the first year after diagnosis.125 This underscores the need to prevent, stop, or reverse the disease process as early as possible.
Researchers decided to put berries to the test. In a randomized clinical trial of powdered strawberries in patients with precancerous lesions in their oesophagus, subjects ate one to two ounces of freeze-dried strawberries every day for six months—that’s the daily equivalent of about a pound of fresh strawberries.126
All of the study participants started out with either mild or moderate precancerous disease, but, amazingly, the progression of the disease was reversed in about 80 percent of the patients in the high-dose strawberry group. Most of these precancerous lesions either regressed from moderate to mild or disappeared entirely. Half of those on the high-dose strawberry treatment walked away disease-free.127
Fibre consumption doesn’t just take off the pressure. Humans evolved eating huge amounts of fibre, likely in excess of one hundred grams daily.128 That’s up to about ten times what the average person eats today.129 Because plants don’t tend to run as fast as animals, the bulk of our diet used to be made up of a lot of bulk. In addition to keeping you regular, fibre binds to toxins, such as lead and mercury, and flushes them away (pun intended!).130 Our bodies were designed to expect an ever-flowing fibre stream, so it dumps such unwanted waste products as excess cholesterol and estrogen into the intestines, assuming they will be swept away. But if you aren’t constantly filling your bowels with plant foods, the only natural source of fibre, unwanted waste products can get reabsorbed and undermine your body’s attempts at detoxifying itself. Only 3 percent of Americans may even reach the recommended minimum daily intake of fibre, making it one of the most widespread nutrient deficiencies in the United States.131
CHAPTER 5
How Not to Die from Infections
I was still in medical school when I got a call to help defend Oprah Winfrey, who was being sued by a cattle rancher under a Texas food-disparagement law (thirteen states have so-called food-libel laws that make it illegal to make a comment that unfairly “implies that [a] perishable food product is not safe for consumption by the public”1).
Oprah had been talking on her television show with Howard Lyman, a former fourth-generation cattle rancher who decried the cannibalistic feeding of cow parts to other cows, a risky practice blamed for the emergence and spread of mad cow disease. Repulsed by the thought, Oprah told the viewing audience, “It has just stopped me cold from eating another burger.” The next day, cattle futures tumbled, and the Texas cattleman claimed to have lost millions.
My job was to help establish that Lyman’s comments were “based on reasonable and reliable scientific inquiry, facts, or data.”2 Despite the ease with which we did just that, not to mention the blatant violation of First Amendment protections inherent in the law, the Texas cattleman was able to tie Oprah up in a long and harrowing appeals process. Finally, five years later, a federal judge dismissed the case with prejudice, ending Oprah’s ordeal.
In a narrow legal sense, she won. But if the meat industry is able to drag one of the country’s richest and most powerful people through the courts for years and cost her a small fortune in legal fees, what kind of chilling effect does that have on others who want to speak out? Now the meat industry is trying to pass so-called ag-gag laws, which make it illegal to take pictures inside their operations. Presumably, they fear people might be less inclined to buy their products if they knew how these products are made.3
Thankfully, humanity dodged a bullet with mad cow disease. Nearly an entire generation in Britain was exposed to infected beef, but only a few hundred people died. We weren’t as lucky with swine flu, which the CDC estimates killed twelve thousand Americans.4 Nearly three-quarters of all emerging and reemerging human diseases arise from the animal kingdom.5
Humanity’s dominion over animals has unleashed a veritable Pandora’s ark of infectious diseases. Most modern human infectious diseases were unknown before domestication led to a mass spillover of animal disease into human populations.6 For example, tuberculosis appears to have been originally acquired through the domestication of goats7 but now infects nearly one-third of humanity.8 Meanwhile, measles9 and smallpox10 may have arisen from mutant cattle viruses. We domesticated pigs and got whooping cough, we domesticated chickens and got typhoid fever, and we domesticated ducks and got influenza.11 Leprosy may have come from water buffalo and the cold virus from horses.12 How often did wild horses have the opportunity to sneeze into humans’ faces until they were broken and bridled? Before then, the common cold was presumably common only to them.
Once pathogens jump the species barrier, they can then transmit person-to-person. HIV, a virus thought to have originated from the butchering of primates in Africa for the bush-meat trade,13 causes AIDS by weakening the immune system. The opportunistic fungal, viral, and bacterial infections AIDS patients contract—but to which healthy people are resistant—demonstrate the importance of baseline immune function. Your immune system is not just active when you’re lying in bed sick with a fever—it’s involved in a daily life-or-death struggle to save your life from the pathogens that surround and live inside you.
With every breath you take, you inhale thousands of bacteria,14 and with every bite you eat, you can ingest millions more.15 Most of these tiny germs are completely harmless, but some can cause serious infectious diseases, occasionally making headlines with sinister-sounding names like SARS or Ebola. Although many of these exotic pathogens receive a lot of press coverage, more lives are lost to some of our most common infections. For example, such respiratory infections as influenza and pneumonia kill nearly fifty-seven thousand Americans each year.16
Bear in mind that you don’t need to come in contact with a sick person to fall ill with an infection. There are latent infections that may exist within you, waiting to strike should your immune function falter. That is why it’s not enough to just wash your hands; you have to keep your immune system healthy.
Protecting Others
To protect others when you’re sick, you need to practice good respiratory etiquette by coughing or sneezing into the crook of your arm (into your bent elbow). This practice limits the dispersal of respiratory droplets and also avoids contaminating your hands. The Mayo Clinic has a slogan worth remembering: “The ten worst sources of contagion are our fingers.” When you cough into your hand, you can transfer contagion to everything from lift buttons and light switches to petrol pumps and toilet handles.17 It’s no surprise that during flu season, the influenza virus can be found on more than 50 percent of common household and daycare-center surfaces.18
Ideally, you should sanitize your hands after every bathroom visit and handshake, before all food preparation, and before touching your eyes, nose, or mouth after coming in contact with public surfaces. The latest recommendations from the World Health Organization favor the use of alcohol-based sanitizing rubs or gels over hand washing for routine disinfection of your hands throughout the day. (Products containing between 60 and 80 percent alcohol were found to be more effective than soap in every scientific study available for review.) The only time hand washing is preferable is when they are dirty or visibly contaminated with bodily fluids. For routine decontamination—that is, for all other times—alcohol-based products are the preferred method for hand sanitation.19
Still, some germs will always get past your first line of defense of practicing good hand hygiene. This is why you need to keep your immune system functioning at peak performance with a healthy diet and lifestyle.
Preventing Infectious Diseases with a Healthy Immune System
The term “immune system” is derived from the Latin word immunis, meaning untaxed or untouched, which is fitting, given that the immune system protects the body from foreign invaders. Composed of various organs, white blood cells, and proteins called antibodies that form alliances against trespassing pathogens threatening the body, the immune system, apart from the nervous system, is the most complex organ system humans possess.20
Your first layer of protection against intruders are physical surface barriers like your skin. Beneath that are white blood cells, such as neutrophils that attack and engulf pathogens directly, and natural killer cells that put your cells out of their misery if they become cancerous or infected with a virus. How do natural killer cells recognize pathogens and infected cells? They are often marked for destruction by antibodies, which are special proteins made by another type of white blood cell, known as B cells, that home in like smart bombs and stick to invaders.
Each B cell makes one type of antibody that’s specific for one foreign molecular signature. You don’t have one B cell that covers grass pollen and another that covers bacteria; instead, you have a B cell whose only job is to make antibodies against the pollen of purple Siberian onion grass and another whose only job is to make antibodies against the tail proteins of bacteria that live in the thermal vents at the bottom of the ocean. If each of your B cells produces only one type of antibody, then you’d need to have a billion different types of B cells given the incredible variety of potential pathogens on our planet. And you do!
Let’s suppose one day you’re walking along and suddenly get attacked by a platypus (they have poisonous spurs on their heels, you know). For your whole life up until that point, the B cell in your body that produces antibodies against duck-billed platypus venom was just hanging around, twiddling its thumbs, until that very moment. As soon as the venom is detected, this specific B cell begins dividing like crazy, and soon you have a whole swarm of clones each producing millions of antibodies against platypus poison. You fend off the toxin and live happily ever after. That is how the immune system works—aren’t our bodies spectacular?
As you get older, though, yo
ur immune function declines. Is this just an inevitable consequence of aging? Or could it be because dietary quality also tends to go down in older populations? To test the theory that inadequate nutrition could help explain the loss in immune function as you age, researchers split eighty-three volunteers between sixty-five and eighty-five years old into two groups. The control group ate fewer than three daily servings of fruits and vegetables, while the experimental group consumed at least five servings a day. They were all then vaccinated against pneumonia, a practice recommended for all adults over the age of sixty-five.21 The goal of vaccination is to prime your immune system to produce antibodies against a specific pneumonia pathogen should you ever become exposed. Compared with the control group, people eating five or more servings of fruits and vegetables had an 82 percent greater protective antibody response to the vaccine—and this was after only a few months of eating just a few extra servings of fruits and vegetables a day.22 That is how much control the fork may exert over immune function.
Certain fruits and vegetables may give the immune function an extra boost.
Kale
Americans eat far too little kale. According to the U.S. Department of Agriculture, the average American may consume about 0.05 pounds of kale each year.23 That’s about 90 grams per person . . . per decade.
As a dark-green, leafy vegetable, kale is not only one of the most nutrient-dense foods on the planet—it may also help fight off infection. Japanese researchers tried dripping a minute quantity of kale on human white blood cells in a petri dish, about one-millionth of a gram of kale protein. Even that miniscule quantity triggered a quintupling of antibody production in the cells.24
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