Clearing the Confusion: Nitrates, Nitrites, and Nitrosamines
Although fresh meat also contains nitrosamines, processed or cured meat like deli slices may be particularly harmful. In Europe, the world’s second-largest prospective study on diet and cancer calculated that a reduction in processed meat consumption to less than twenty grams a day—less than a small matchbook-sized portion—would prevent more than 3 percent of all deaths.105 In the largest such investigation the NIH-AARP study of more than five hundred thousand Americans (see here) found the preventable fraction of deaths may be even higher. The researchers suggested, for example, that 20 percent of heart disease deaths among American women could be averted if the highest consumers of processed meat would cut down to the equivalent of less than half a rasher of bacon a day.106 No wonder the American Institute for Cancer Research recommends that you simply “avoid processed meat such as ham, bacon, salami, hot dogs and sausages.”107
Nitrites are added to cured meat as a “color fixative” and to help prevent the growth of botulism bacteria (a rare but serious paralytic illness).108 What about “uncured” bacon? It says right on the package: “No nitrites or nitrates added.” But study the fine print and you may see a little footnote that reads something like “except those naturally occurring in celery juice.” Vegetables do contain nitrates that can be fermented into nitrites, so adding fermented celery juice to bacon is just a sneaky way of adding nitrites. Even commentators in the journal Meat Science have realized this may be perceived by consumers as “incorrect at best or deceptive at worst.”109
But the same fermentation that converts nitrates to nitrites can happen when you eat vegetables, thanks to bacteria on your tongue. So why are vegetable nitrates and nitrites okay but the same compounds from meat are linked to cancer?110 Because nitrites themselves are not carcinogenic; they turn into carcinogens. Nitrites only become harmful when they turn into nitrosamines and nitrosamides. For them to do that, amines and amides must be present, and amines and amides are found in abundance in animal products. This transformation can happen in the meat itself or in your stomach after you eat it. In the case of plant foods, the vitamin C and other antioxidants that are found naturally in them block the formation of these carcinogens in your body.111 This process would explain why intake of both nitrate and nitrite from processed meat has been linked to kidney cancer, but no increased risk was found for nitrate or nitrite intake from plant sources.112
While nitrite from animal sources—not just processed meats—was associated with an increased risk of kidney cancer, some of the highest nitrate-containing vegetables, such as rocket, kale, and collards, are associated with significantly reduced risk for kidney cancer.113
Kidneys are tasked with the monumental responsibility of filtering your blood all day, every day. That’s a lot of work for two fist-sized organs. Kidneys are extremely resilient, but they aren’t indestructible. When they begin to fail, the body can start failing too. Toxic substances that healthy kidneys would ordinarily filter out can pass through and build up in the bloodstream.
To keep your kidneys strong and your blood clean, you must carefully consider what you eat. The meat-sweet American diet can slowly damage your kidneys one meal at a time, forcing the kidneys into a state of hyperfiltration. Imagine how long your car engine would last if you always revved it near the red line? Thankfully, medical science has proven that you can reduce your kidneys’ workload (and acid load) by moving toward a more plant-based diet.
CHAPTER 11
How Not to Die from Breast Cancer
“You have breast cancer.”
These are among the most feared words a woman can hear, and for a good reason. Besides skin cancer, breast cancer is the most common cancer among American women. Every year, about 230,000 are diagnosed with breast cancer, and 40,000 die from it.1
Breast cancer does not occur overnight. That lump you feel in the shower one morning may have started forming decades ago. By the time doctors detect the tumor, it may have been present for forty years or even longer.2 The cancer has been growing, maturing, and acquiring hundreds of new survival-of-the-fittest mutations that allow it to grow even more quickly as it tries to outmaneuver your immune system.
The scary reality is that what doctors call “early detection” is actually late detection. Modern imaging simply isn’t good enough to detect cancer at its earliest stages, so it can spread long before it’s even spotted. A woman is considered “healthy” until she shows signs or symptoms of breast cancer. But if she has been harboring a malignancy for two decades, can she truly be considered healthy?
People who are doing the right thing by improving their diets in hopes of preventing cancer may in fact be successfully treating it as well. Autopsy studies have shown that as many as 20 percent of women aged twenty to fifty-four who died from unrelated causes, such as car accidents, had so-called “occult” (or hidden) breast cancers growing inside them.3 Sometimes there’s nothing you can do to prevent the initiation stage of cancer, when that first normal breast cell mutates into a cancerous one. Some breast cancers may even start in the womb and be related to your mother’s diet.4 For this reason, we all need to choose a diet and lifestyle that not only prevents the initiation stage of cancer but also hampers the promotion stage, during which the cancer grows to a size large enough to pose a threat.
The good news is that no matter what your mum ate or how you lived as a child, by eating and living healthfully, you may be able to slow the growth rate of any hidden cancers. In short, you can die with your tumors rather than from them. This is how dietary cancer prevention and treatment can end up being the same thing.
One or two cancer cells never hurt anyone. But how about a billion cancer cells? That’s how many may be in a tumor5 by the time it’s picked up by a mammogram.6 Like most tumors, breast cancer starts with just one cell, which divides to become two, four, and then eight. Every time breast cancer cells divide, the tumor can effectively double in size.7
Let’s see how many times a tiny tumor has to double to get to a billion cells. Take out a calculator. Multiply one times two. Then multiply that number by two. Keep doing that until you reach one billion. Don’t worry. It won’t take long. It’s only thirty doublings. In just thirty doublings, a single cancer cell can turn into a billion.
The key to how quickly you’d be diagnosed with cancer, then, is the doubling time. How long does it take tumors to double once? Breast cancers can double in size in anywhere from as few as twenty-five days8 to a thousand days or more.9 In other words, it could be two years, or it could be more than a hundred years, before a tumor starts to cause problems.
Where you fall on that timescale—two years or a century—may depend in part on what you eat.
When I was teen, I ate a lousy diet. One of my favorite meals was—no joke—chicken-fried steak. During my youth, I may have caused one of the cells in my colon or prostate to mutate. But I’ve been eating much healthier for the last twenty-five years. My hope is that even if I did initiate a cancerous growth, if I don’t promote it, I may be able to slow down its growth. I don’t care if I get diagnosed with cancer a hundred years from now. I don’t expect to be around at that point to worry about it.
Current controversy over the cost and effectiveness of mammograms10 misses an important point: Breast cancer screening, by definition, does not prevent breast cancer. It can just pick up existing breast cancer. Based on autopsy studies, as many as 39 percent of women in their forties already have breast cancers growing within their bodies that may be simply too small to be detected by mammograms.11 That’s why you can’t just wait until diagnosis to start eating and living healthier. You should start tonight.
Risk Factors for Breast Cancer
The American Institute for Cancer Research (AICR) is considered one of the world’s leading authorities on diet and cancer. Based on the best available research, it came up with ten recommendations for cancer prevention.12 Beyond never chewing tobacco, their bottom-
line dietary message was: “Diets that revolve around whole plant foods—vegetables, whole grains, fruits and beans—cut the risk of many cancers, and other diseases as well.”13
To demonstrate how dramatically lifestyle choices can impact breast cancer risk, over the course of about seven years, researchers followed a group of about thirty thousand postmenopausal women with no history of breast cancer. Achieving just three of the ten AICR recommendations—limiting alcohol, eating mostly plant foods, and maintaining a normal body weight—was associated with a 62 percent lower risk of breast cancer.14 Yes, three simple health behaviors appeared to cut risk by more than half.
Remarkably, eating a plant-based diet along with walking every day can improve our cancer defenses within just two weeks. Researchers dripped the blood of women before and after fourteen days of healthy living onto breast cancer cells growing in petri dishes. The blood taken after they started eating healthier suppressed cancer growth significantly better and killed 20–30 percent more cancer cells than the blood taken from the same women just two weeks before.15 The researchers attributed this effect to a decrease in levels of a cancer-promoting growth hormone called IGF-1,16 likely due to the reduced intake of animal protein.17
What kind of blood do you want in your body—what kind of immune system? The kind of blood that just rolls over when new cancer cells pop up, or blood that circulates to every nook and cranny in your body with the power to slow down and stop cancer cells in their tracks?
Alcohol
In 2010, the official World Health Organization body that assesses cancer risks formally upgraded its classification of alcohol to a definitive human breast carcinogen.18 In 2014, it clarified its position by stating that, regarding breast cancer, no amount of alcohol is safe.19
But what about drinking “responsibly”? In 2013, scientists published a compilation of more than one hundred studies on breast cancer and light drinking (up to one alcoholic beverage a day). The researchers had found a small but statistically significant increase in breast cancer risk even among women who had at most one drink per day (except, perhaps, for red wine—see box below). They estimated that, every year around the world, nearly five thousand breast cancer deaths may be attributable to light drinking.20
The carcinogen isn’t alcohol itself. The culprit is actually the toxic breakdown product of alcohol called acetaldehyde, which can form in your mouth almost immediately after you take a sip. Experiments show that even holding a single teaspoon of spirits in your mouth for five seconds before spitting it out results in the production of potentially carcinogenic levels of acetaldehyde that lingers for more than ten minutes.21
If even a single sip of alcohol might produce cancer-causing levels of acetaldehyde in the mouth, what about using mouthwash that contains alcohol? Researchers who tested the effects of a variety of retail mouthwashes and oral rinses concluded that, although the risk is slight, it is probably best to refrain from using such products if they contain alcohol.22
Red Wine Versus White Wine
The Harvard Nurses’ Health Study found that even less than one drink a day may be associated with a small increase in breast cancer risk.23 Interestingly, drinking only red wine was not associated with breast cancer risk. Why? A compound in red wine appears to suppress the activity of an enzyme called estrogen synthase, which breast tumors can use to create estrogen to fuel their own growth.24 This compound is found in the skin of the dark-purple grapes used to make red wine, which explains why white wine appears to provide no such benefit,25 since it’s produced without the skin.
The researchers concluded that red wine may “ameliorate the elevated breast cancer risk associated with alcohol intake.”26 In other words, the grapes in red wine may help cancel out some of the cancer-causing effects of the alcohol. But you can reap the benefits without the risks associated with imbibing alcoholic beverages by simply drinking grape juice or, even better, eating the purple grapes themselves—preferably ones with seeds, as they appear to be most effective at suppressing estrogen synthase.27
It’s good (and delicious) to know that strawberries,28 pomegranates,29 and plain white mushrooms30 may also suppress the potentially cancer-promoting enzyme.
Melatonin and Breast Cancer Risk
For billions of years, life on planet Earth evolved under conditions of about twelve hours of light and twelve hours of darkness. Humans controlled fire for cooking about a million years ago, but we’ve only been using candles for about five thousand years and electric lights for a mere century. In other words, our ancient ancestors lived half their lives in the dark.
These days, though, because of the electric-light pollution at night, the only Milky Way your children may see is inside a sweet wrapper. Electric lighting has enabled us to remain productive well into the wee hours, but might this unnatural nighttime light exposure have any adverse health effects?
In philosophy, there’s a flawed argument called the appeal-to-nature fallacy, in which someone proposes that something is good merely because it’s natural. In biology, however, this may hold some truth. The conditions under which our bodies were finely tuned over millions of years can sometimes give us insight into our optimal functioning. For example, we evolved running around naked in equatorial Africa. Therefore, it’s not surprising that many of us modern humans become deficient in vitamin D (the “sunshine vitamin”) if we live in Northern climes or in countries where the culture dictates full-body coverings for women.31
Could something as ubiquitous as the lightbulb be a mixed blessing? Right in the middle of your brain sits the pineal gland, your so-called third eye. It’s connected to your actual eyes and has just one function: to produce a hormone called melatonin. During the day, the pineal gland is inactive. But once the sky darkens, it activates and begins pumping melatonin into your bloodstream. You start getting tired, feel less alert, and start thinking about sleep. Melatonin secretion may peak between 2:00 A.M. and 5:00 A.M. and then shuts off at daybreak, which is your cue to wake up. The level of melatonin in your bloodstream is one of the ways your internal organs know what time it is. It functions as one hand on your circadian clock.32
Besides helping to regulate your sleep, melatonin is thought to play another role—suppressing cancer growth. Think of melatonin as helping to put cancer cells to sleep at night.33 To see if this function applies to preventing breast cancer, researchers from Brigham and Women’s Hospital in Boston and elsewhere came up with the clever idea of studying blind women. The thought was that because blind women can’t see sunlight, their pineal glands never stop secreting melatonin into their bloodstreams. Sure enough, the researchers found that blind women may have just half the odds of breast cancer as sighted women.34
Conversely, women who interrupt their melatonin production by working night shifts appear to be at increased risk for breast cancer.35 Even living on a particularly brightly lit street may affect the risk. Studies comparing nighttime satellite photos against breast cancer rates have found that people living in brighter neighborhoods tend to have a higher breast cancer risk.36,37,38 Therefore, it’s probably best to sleep without any lights on and with the blinds down, though the evidence to support these strategies is limited.39
Melatonin production can be gauged by measuring the amount of melatonin excreted in our first pee in the morning. And, indeed, women with higher melatonin secretion have been found to have lower rates of breast cancer.40 Other than minimizing nighttime light exposure, is there anything else you can do to keep up your production of melatonin? Apparently so. In 2005, Japanese researchers reported an association between higher vegetable intake and higher melatonin levels in the urine.41 Is there anything in your diet that may lower melatonin production, thereby potentially increasing breast cancer risk? We didn’t know until a comprehensive study of diet and melatonin was published in 2009. Researchers at Harvard University asked nearly a thousand women about their consumption of thirty-eight different foods or food groups and measured their morning melatonin l
evels. Meat consumption was the only food significantly associated with lower melatonin production, for reasons that are yet unknown.42
Minimizing melatonin disruption may therefore mean putting curtains on your windows, eating more vegetables, and lowering the curtain on eating too much meat.
Exercise and Breast Cancer
Physical activity is considered a promising preventive measure against breast cancer43 not only because it helps with weight control but because exercise tends to lower circulating estrogen levels.44 Five hours a week of vigorous aerobic exercise can lower estrogen and progesterone exposure by about 20 percent.45 But do you need to work out that long for it to be protective?
Although even light exercise is associated with lowered risk of some other types of cancer, for breast cancer, leisurely strolls don’t appear to cut it.46 Even an hour a day of activities such as slow dancing or light housework may not help.47 According to the largest study ever published on the subject, only women who worked up a sweat at least five or more times a week appeared to get significant protection.48 Moderately intense activity may offer as much benefit as vigorous exercise, though.49 Walking at a moderate pace for an hour a day is considered a moderately intense level of exercise, but it wasn’t put to the test until a 2013 study reported that, indeed, walking an hour a day or more is associated with significantly lower breast cancer risk.50
Darwin was right: It’s survival of the fittest—so get fit!
Heterocyclic Amines
In 1939, a curious finding was published in a paper titled “Presence of Cancer-Producing Substances in Roasted Food.” A researcher described how he could induce breast cancers in mice by painting their heads with extracts of roasted horse muscle.51 These “cancer-producing substances” have since been identified as heterocyclic amines (HCAs), described by the National Cancer Institute as “chemicals formed when muscle meat, including beef, pork, fish, and poultry, is cooked using high-temperature methods.”52 These cooking methods include roasting, pan frying, grilling, and baking. Eating boiled meat is probably the safest. People who eat meat that never goes above 100 degrees Celcius produce urine and feces that are significantly less DNA-damaging compared to those eating meat dry-cooked at higher temperatures.53 This means they have fewer mutagenic substances flowing through their bloodstreams and coming in contact with their colons. On the other hand, baking chicken for as few as fifteen minutes at about 175 degrees Celsius leads to HCA production.54
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