For many years, phytates were maligned as inhibitors of mineral absorption, which is why you might have heard advice to roast, sprout, or soak your nuts to get rid of the phytates. In theory, this would allow you to absorb more minerals, such as calcium. This belief stemmed from a series of laboratory experiments on puppies from 1949 that suggested that phytates had a bone-softening, anti-calcifying effect,38 as well as from subsequent studies with similar findings on rats.39 But more recently, in light of actual human data, phytates’ image has undergone a complete makeover.40 Those who eat more high-phytate foods actually tend to have a greater bone mineral density,41 less bone loss, and fewer hip fractures.42 Phytates appear to protect bone in a manner similar to that of antiosteoporosis drugs like Fosamax,43 but without the risk of osteonecrosis (bone rot) of the jaw, a rare, potentially disfiguring side effect associated with that class of drugs.44
Phytates may also help protect against colorectal cancer. A six-year study of about thirty thousand Californians found that higher meat consumption was associated with higher risk of colon cancer. Unexpectedly, white meat appeared to be worse. Indeed, those who ate red meat at least once each week had about double the risk of developing colon cancer; that risk appeared to triple, however, for those who ate chicken or fish once or more a week.45 Eating beans, an excellent source of phytates, was found to help mediate some of that risk, so your colon cancer risk may be determined by your meat-to-vegetable ratio.
There may be as much as an eightfold difference in colorectal cancer risk between the two extremes—high-vegetable, low-meat diets and low-vegetable, high-meat diets.46 So it may not be enough to just cut down on how much meat is in your diet; you also need to eat more plants. The National Cancer Institute’s Polyp Prevention Trial found that those who increased their bean consumption by even less than 70 grams a day appeared to cut their odds of precancerous colorectal polyp recurrence by up to 65 percent.47
Of all the wonderful nutrients in beans, why do we credit the phytates with reduced risk? Petri-dish studies have shown that phytates inhibit the growth of virtually all human cancer cells tested so far—including cancers of the colon, breast, cervix, prostate, liver, pancreas, and skin48—while leaving normal cells alone.49 This is the mark of a good anticancer agent, the ability to discriminate between tumor cells and normal tissue. When you eat whole grains, beans, nuts, and seeds, phytates are rapidly absorbed into the bloodstream and readily taken up by tumor cells. Tumors concentrate these compounds so efficiently that phytate scans can be used to trace the spread of cancer within the body.50
Phytates target cancer cells through a combination of antioxidant, anti-inflammatory, and immune-enhancing activities. Besides affecting the cancer cells directly, phytates have been found to boost the activity of natural killer cells, which are white blood cells that form your first line of defense by hunting down and disposing of cancer cells.51 Phytates can also play a role in your last line of defense, which involves starving tumors of their blood supply. There are many phytonutrients in plant foods that can help block the formation of new blood vessels that feed tumors, but phytates also appear able to disrupt existing tumor supply lines.52 Similarly, many plant compounds appear able to help slow down and even stop cancer cell growth,53 but phytates can sometimes also cause cancer cells to apparently revert back to their normal state—in other words, to stop behaving like cancer. This cancer cell “rehabilitation” has been demonstrated in vitro in colon cancer cells,54 as well as in cancer cells of the breast,55 liver,56 and prostate.57
Phytates do have side effects, but they all appear to be good. High phytate intake has been associated with less heart disease, less diabetes, and fewer kidney stones. In fact, some researchers have suggested that phytates be considered an essential nutrient. Like vitamins, phytates participate in important biochemical reactions in the body. Your levels fluctuate with dietary intake, and insufficient consumption is associated with diseases that can be moderated by eating adequate amounts. Maybe phytates should be considered “Vitamin P.”58
Reversing Rectal Polyps with Berries?
There are many ways the healthfulness of different fruits and vegetables can be compared, such as by nutrient content or antioxidant activity. Ideally, we would use a measure involving actual biological activity. One way to do this is by measuring the suppression of cancer cell growth. Eleven common fruits were tested by dripping their extracts on cancer cells growing in a petri dish. The result? Berries came out on top.59 Organically grown berries in particular may suppress cancer cell growth better than those grown conventionally.60 But a laboratory is different from real life. These findings are only applicable if the active components of the food are absorbed into your system and manage to find their way to budding tumors. Colorectal cancer, however, grows out of the inner lining of your intestines, so what you eat may have a direct effect regardless. So researchers decided to give berries a try.
Familial adenomatous polyposis is an inherited form of colorectal cancer caused by a mutation in your tumor-suppression genes. People who are affected develop hundreds of polyps in their colons, some of which inevitably turn cancerous. Treatment can involve prophylactic colectomy, where the colon is removed early in life as a preventive step. There was a drug that appeared able to cause polyps to regress, but it was pulled from the market after it killed tens of thousands of people.61 Could berries also cause polyps to retreat without the fatal side effects? Yes. After nine months of daily treatment with black raspberries, the polyp burden of fourteen patients with familial adenomatous polyposis was cut in half.62
Normally, polyps would have to be surgically removed, but the berries seemed to have made them disappear naturally. The method by which the berries were administered, though, was anything but natural. The researchers used a shortcut, giving the berries as suppositories. Don’t try this at home! After they inserted the equivalent of eight pounds of raspberries into patients’ rectums over those nine months, some of the patients suffered from torn anuses.63 The hope is that research will one day show similar cancer-fighting effects of berries taken the old-fashioned way—through the mouth.
Too Much Iron?
In 2012, the results from two major Harvard University studies were published. The first, known as the Nurses’ Health Study, began following the diets of about 120,000 women aged thirty to fifty-five starting back in 1976; the second, the Health Professionals Follow-Up Study, followed about 50,000 men aged forty to seventy-five. Every four years, researchers checked in with the study participants to keep track of their diets. By 2008, a total of about 24,000 subjects had died, including approximately 6,000 from heart disease and 9,000 from cancer.64
After the results were analyzed, the researchers found that the consumption of both processed and unprocessed red meat was associated with an increased risk of dying from cancer and heart disease and shortened life spans overall. They reached this conclusion even after controlling for (factoring in) age, weight, alcohol consumption, exercise, smoking, family history, caloric intake, and even the intake of whole plant foods, such as whole grains, fruits, and vegetables. In other words, the study subjects apparently weren’t dying early because they ate less of some beneficial compound like phytates in plants. The findings suggest there may be something harmful in the meat itself.
Imagine the logistics of following more than 100,000 people for decades. Now imagine a study five times that size. The largest study of diet and health in history is the NIH-AARP study, cosponsored by the National Institutes of Health and the American Association of Retired Persons. Over the course of a decade, researchers followed about 545,000 men and women aged fifty to seventy-one in the largest study of meat and mortality ever conducted. The scientists came to the same conclusion as the Harvard researchers: Meat consumption was associated with increased risk of dying from cancer, dying from heart disease, and dying prematurely in general. Again, this was after controlling for other diet and lifestyle factors, effectively excluding the possibility that peopl
e who ate meat also smoked more, exercised less, or failed to eat their fruits and veggies.65 The accompanying editorial in the American Medical Association’s Archives of Internal Medicine (titled “Reducing Meat Consumption Has Multiple Benefits for the World’s Health”) called for a “major reduction in total meat intake.”66
What does meat contain that may raise the risk of premature death? One of the possibilities is heme iron, the form of iron found predominantly in blood and muscle. Because iron can generate cancer-causing free radicals by acting as a pro-oxidant,67 iron can be considered a double-edged sword—too little of it and you risk anemia, too much and you may increase risk of cancer and heart disease.
The human body has no specific mechanism to rid itself of excess iron.68 Instead, humans have evolved to tightly regulate the amount of iron absorbed. If you don’t have enough iron circulating in your body, your intestines begin boosting iron absorption; if you have too much iron in circulation, your intestines decrease absorption. But this thermostat-like system only works effectively with the primary source of iron in the human diet: the nonheme iron variety found predominantly in plant foods. Once you have a sufficient amount of iron in your blood, your body is about five times more effective at blocking the absorption of excess iron from plant foods than from animal foods.69 This may be why heme iron is associated with cancer70 and heart disease risk.71 Similarly, heme iron is associated with higher risk of diabetes, but nonheme iron is not.72
If we remove iron from people’s bodies, can we decrease cancer rates? Studies have found that people randomized to give regular blood donations to reduce their iron stores appear to cut their risk of getting and dying from new gut cancers by about half over a five-year period.73 The findings were so remarkable that an editorial in the Journal of the National Cancer Institute responded that “these results almost seem too good to be true.”74
Donating blood is great, but we should also try to prevent the excess buildup of iron in the first place. The meat industry is working on coming up with additives that “suppress the toxic effects of heme iron,”75 but a better strategy may be to emphasize plant sources in your diet, which your body can better manage.
Getting Enough Iron on a Plant-Based Diet
Compared with people who eat meat, vegetarians tend to consume more iron (as well as more of most nutrients),76 but the iron in plant foods is not absorbed as efficiently as the heme iron in meat. While this can be an advantage in preventing iron overload, about one in thirty menstruating women in the United States lose more iron than they take in, which can lead to anemia.77 Women who eat plant-based diets do not appear to have higher rates of iron deficiency anemia than women who eat a lot of meat,78 but all women of childbearing age need to ensure adequate iron intake.
Those diagnosed with iron deficiency should talk with their doctors about first trying to treat it with diet, as iron supplements have been shown to increase oxidative stress.79 The healthiest sources of iron are whole grains, legumes, nuts, seeds, dried fruits, and green, leafy vegetables. Avoid drinking tea with meals, as that can inhibit iron absorption. Consuming vitamin C–rich foods can improve iron absorption. The amount of vitamin C in a single orange can enhance iron absorption as much as three- to sixfold, so those trying to boost their iron absorption should reach for some fruit instead of a cup of tea.80
Pancreatic Cancer
My grandfather died of pancreatic cancer. By the time the first symptom arose—a dull ache in his gut—it was too late. That’s why we need to prevent it in the first place.
Pancreatic cancer is among the most lethal forms of cancer, with just 6 percent of patients surviving five years after diagnosis. Thankfully, it’s relatively rare, killing only about forty thousand Americans each year.81 As many as 20 percent of pancreatic cancer cases may be a result of tobacco smoking.82 Other modifiable risk factors include obesity and heavy alcohol consumption.83 As we’ll see, specific dietary factors may also play a significant role in the development of this deadly disease.
For instance, how the fat in one’s diet may contribute to pancreatic cancer risk has long been a subject of debate. The inconsistency of research findings on the impact of total fat intake may be partly because different fats affect risk differently. The previously mentioned NIH-AARP study was large enough to be able to tease out what kind of fat was most associated with pancreatic cancer. It was the first to separate out the role of fats from plant sources, such as those found in nuts, seeds, avocados, and olive and vegetable oils, versus all animal sources, including meats, dairy products, and eggs. The consumption of fat from all animal sources was significantly associated with pancreatic cancer risk, but no correlation was found with the consumption of plant fats.84
Chicken and Pancreatic Cancer Risk
Starting in the early 1970s, a series of laws have restricted the use of asbestos, yet thousands of Americans continue to die every year from exposure to it. The Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the Environmental Protection Agency have estimated that over a period of thirty years, approximately one thousand cases of cancer will occur among people exposed to asbestos in school buildings as children.85
It all started generations ago with the asbestos workers. The first asbestos-related cancers occurred in the 1920s among miners digging up the stuff. Then came a second wave among shipbuilders and construction workers who used asbestos. We are now in the third wave of asbestos-related disease, as buildings constructed with asbestos are beginning to deteriorate.86
As the history of asbestos shows, to see if something causes cancer, scientists first study those who have the greatest exposure to it. That’s how we’re now learning about the potential cancer-causing effects of poultry viruses. There has been long-standing concern about the possibility that wart-causing chicken cancer viruses are being transmitted to the general population through the handling of fresh or frozen chicken.87 These viruses are known to cause cancer in the birds, but their role in human cancers is unknown. This concern arises out of studies that show that people who work in poultry slaughtering and processing plants have increased risk of dying from certain cancers.
The most recent, a study of thirty thousand poultry workers, was designed specifically to test whether “exposure to poultry cancer-causing viruses that widely occurs occupationally in poultry workers—not to mention the general population—may be associated with increased risks of deaths from liver and pancreatic cancers.” The study found that those who slaughter chickens have about nine times the odds of both pancreatic cancer and liver cancer.88 To put this result in context, the most carefully studied risk factor for pancreatic cancer is cigarette smoking. But even if you smoked for fifty years, you’d have “only” doubled your odds of getting pancreatic cancer.89
What about people who eat chicken? The largest study to ever address that question is the European Prospective Investigation into Cancer and Nutrition (EPIC) study, which followed 477,000 people for about a decade. The researchers found a 72 percent increased risk of pancreatic cancer for every fifty grams of chicken consumed daily.90 And that’s not much meat, under two ounces—just about a quarter of a chicken breast.
The researchers expressed surprise that it was the consumption of poultry—not red meat—that was more closely tied to cancer. When a similar result was found for lymphomas and leukemias, the same EPIC research team acknowledged that while the growth-promoting drugs fed to chickens and turkeys could be playing a role, it might also be cancer viruses found in poultry.91
The reason the connection between asbestos and cancer was comparatively easy to nail down is that asbestos caused a particularly unusual cancer (mesothelioma), which was virtually unknown before widespread asbestos use.92 But because the pancreatic cancer one might get from eating chicken is the same pancreatic cancer one might get from smoking cigarettes, it’s more difficult to tease out a cause-and-effect relationship. There are diseases unique to the meat industry, such as the newly described �
�salami brusher’s disease” that only affects people whose full-time job is to wire-brush off the white mold that naturally grows on salami.93 But most diseases suffered by meat industry workers are more universal. So despite the compelling evidence linking poultry exposure to pancreatic cancer, don’t expect an asbestos-type ban on KFC anytime soon.
Treating Pancreatic Cancer with Curry
Pancreatic cancer is among the most aggressive forms of cancer. Untreated, most patients die two to four months after diagnosis. Unfortunately, only about 10 percent of patients appear to respond to chemotherapy, with the majority suffering severe side effects.94
Curcumin, the colorful component of the spice turmeric, appears able to reverse precancerous changes in colon cancer and has been shown in laboratory studies to be effective against lung cancer cells. Similar results were obtained using pancreatic cancer cells.95 So why not try using curcumin to treat patients with pancreatic cancer? In a study funded by the National Cancer Institute and performed at the MD Anderson Cancer Center, patients with advanced pancreatic cancer were given large doses of curcumin. Of the twenty-one patients the researchers were able to evaluate, two responded positively to the treatment. One had a 73 percent reduction in his tumor size, though eventually a curcumin-resistant tumor developed in its place.
The other patient, however, showed steady improvement over the course of eighteen months. The only time cancer markers bumped up was during a brief three-week period when the curcumin therapy was halted.96 Yes, the tumors of only two out of twenty-one participants responded, but that’s about the same as the chemo regimen, and zero adverse effects were reported with the curcumin treatment. As a result, I’d certainly suggest curcumin to pancreatic cancer sufferers regardless of what other treatments they choose. Given the tragic prognosis, though, prevention is critical. Until we know more, your best bet is to avoid tobacco, excess alcohol intake, and obesity and to eat a diet low in animal products, refined grains, and added sugars97 and rich in beans, lentils, split peas, and dried fruit.98
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