So are women who eat a lot of green vegetables less likely to get breast cancer? A study of fifty thousand African American women (a sadly neglected demographic in medical research, but a population group who tends to regularly eat more greens) found that those who ate two or more servings of vegetables a day had a significantly decreased risk of a kind of breast cancer that’s hard to treat, estrogen- and progesterone-receptor-negative.106 Broccoli appeared especially protective among premenopausal women, but collard green consumption was associated with less breast cancer risk at all ages.107
Breast Cancer Stem Cells
What if you’re already fighting breast cancer or are in remission? Green vegetables may still be protective. Over the past decade, scientists have been developing a new theory of cancer biology based on the role of stem cells. Stem cells are essentially the body’s raw materials—the “parents” from which all other cells with specialized functions are generated. As a result, stem cells are a critical component of the body’s repair system, including regrowing skin, bone, and muscle. Breast tissue naturally has many stem cells in reserve, which are used during pregnancy to create new milk glands.108 However, as miraculous as stem cells are, their immortality can also work against us. Instead of rebuilding organs, if they turn cancerous, they can build tumors.109
Cancerous stem cells may be why breast cancer can return, even up to twenty-five years after being fought off successfully the first time.110 When people are told that they are cancer-free, it may mean their tumors are gone, but if their stem cells are cancerous, the tumors still might reappear many years later. Sadly, someone who has been cancer-free for ten years might consider herself cured but actually may just be in remission. Smoldering cancerous stem cells may be just waiting to reignite.
The current battery of sophisticated chemo drugs and radiation regimens is based on animal models. Success of a given treatment is often measured by its ability to shrink tumors in rodents—but rats in laboratories only live for about two or three years in any case. Doctors may be shrinking tumors, but mutated stem cells may still be lurking, able to slowly rebuild new tumors over the ensuing years.111
What we need to do is strike at the root of cancer. We need to devise treatments aimed not just at reducing tumor bulk but at targeting what has been called the “beating heart of the tumor”:112 cancer stem cells.
That’s where broccoli may come in.
Sulforaphane, a dietary component of cruciferous vegetables like broccoli, has been shown to suppress the ability of breast cancer stem cells to form tumors.113 This means that if you’re currently in remission, eating lots of broccoli could theoretically help keep your cancer from returning. (I say theoretically because those results were from a petri dish.)
To be useful as a cancer fighter, sulforaphane would have to first be absorbed into your bloodstream when you eat broccoli. Then it would have to build up to the same concentration in breast tissue found to counter cancer stem cells in the lab. Is that possible? An innovative group at Johns Hopkins University sought to find out. The researchers asked women scheduled for breast reduction surgery to drink broccoli-sprout juice an hour before their procedure. Sure enough, after dissecting their breast tissue postsurgery, the researchers found evidence of significant sulforaphane buildup.114 In other words, we now know that the cancer-fighting nutrients in broccoli do find their way to the right place when we swallow them.
To reach the concentration of sulforaphane in the breast found to suppress breast cancer stem cells, however, you would have to eat at least 12 grams of broccoli sprouts a day.115 You can buy broccoli sprouts in the produce aisle, but they are cheap and easy to grow at home. They have a bit of a radishy bite to them, so I like to mix them into a salad to dilute their intensity.
There have yet to be randomized clinical trials to see if breast cancer survivors who eat broccoli live longer than those who don’t, but with no downside and only positive side effects, eating broccoli and other cruciferous vegetables is something I would recommend for everyone.
Flaxseeds
Flaxseeds are one of the first items ever considered to be health foods, treasured for their purported healing properties since at least the times of ancient Greece, when the renowned physician Hippocrates wrote about using them to treat patients.116
Better known as one of the richest plant sources of essential omega-3 fatty acids, flaxseeds are really set apart by their lignan content. Though lignans are found throughout the plant kingdom, flaxseeds have around one hundred times more lignans than other foods.117 What are lignans?
Lignans are phytoestrogens that can dampen the effects of the body’s own estrogen. This is why flaxseeds are considered a first-line medical therapy for menstrual breast pain.118 In terms of breast cancer risk, eating about a daily tablespoonful of ground flaxseeds can extend a woman’s menstrual cycle by about a day.119 This means she’ll have fewer periods over the course of a lifetime and, therefore, presumably less estrogen exposure and reduced breast cancer risk.120 Just as broccoli doesn’t technically contain sulforaphane (only the precursors that turn into sulforaphane when chewed—see here), flaxseeds don’t contain lignans, only lignan precursors, which need to be activated. This task is performed by the good bacteria in your gut.
The gut bacteria’s role may help explain why women with frequent urinary tract infections may be at a higher risk of breast cancer: Every course of antibiotics you take can kill bacteria indiscriminately, meaning it may stymie the ability of the good bacteria in your gut to take full advantage of the lignans in your diet.121 (Yet another reason you should take antibiotics only when necessary.)
Lignan intake is associated with significantly reduced breast cancer risk in postmenopausal women.122 This effect is presumed to be due to lignans’ further estrogen-dampening effects. But since lignans are found in healthy foods like berries, whole grains, and dark, leafy greens, could they just be an indicator of a healthy diet?
In a petri dish, lignans do directly suppress the proliferation of breast cancer cells.123 But the strongest evidence to date that there really is something special about this class of phytonutrients comes from interventional trials, starting with a 2010 study funded by the National Cancer Institute. Researchers took about forty-five women at high risk of breast cancer—meaning they had suspicious breast biopsies or had previously suffered from breast cancer—and gave them the equivalent of about two teaspoons of ground flaxseeds every day. Needle biopsies of breast tissue were taken before and after the yearlong study. The results: On average, the women had fewer precancerous changes in their breasts after the year of flax lignans than before they started. Eighty percent (thirty-six of forty-five) had a drop in their levels of Ki-67, a biomarker (indicator) of increased cell proliferation. This finding suggests that sprinkling a few spoonfuls of ground flaxseeds on your oatmeal or whatever you’re eating throughout the day may reduce the risk of breast cancer.124
What about women who already have breast cancer? Breast cancer survivors who have higher levels of lignans in their bloodstreams125,126 and diets127 appear to survive significantly longer. This outcome may be due to the fact that women who eat flaxseeds may also see a rise in the levels of endostatin in their breasts.128 (Endostatin is a protein produced by your body to help starve tumors of their blood supply.)
The evidence from studies like these appeared so compelling that scientists performed a randomized, double-blind, placebo-controlled clinical trial of flaxseeds for breast cancer patients—one of the few times a food has ever been so rigorously put to the test. Researchers located women with breast cancer scheduled for surgery and divided them randomly into two groups: Every day, group one ate a muffin containing flaxseed, while group two ate a muffin that looked and tasted the same, but had no flaxseed in it. Biopsies of the tumors in the flax and no-flax groups were taken at the beginning of the study and then compared with the pathology of the tumor removed during surgery about five weeks later.
Was there any difference? Co
mpared with the women who ate the placebo muffins, women consuming the muffins with flaxseed, on average, witnessed their tumor-cell proliferation decrease, cancer-cell death rates increase, and their c-erB2 scores go down. C-erB2 is a marker of cancer aggressiveness; the higher your score, the higher the potential for breast cancer to metastasize and spread throughout the body. In other words, the flaxseeds appeared to make the subjects’ cancer less aggressive. The researchers concluded, “Dietary flaxseed has the potential to reduce tumor growth in patients with breast cancer. . . . [F]laxseed, which is inexpensive and readily available, may be a potential dietary alternative or adjunct to currently used breast cancer drugs.”129
Soya and Breast Cancer
Soyabeans naturally contain another class of phytoestrogens called isoflavones. People hear the word “estrogen” in the word “phytoestrogens” and assume that means soya has estrogen-like effects. Not necessarily. Phytoestrogens dock into the same receptors as your own estrogen but have a weaker effect, so they can act to block the effects of your more powerful animal estrogen.
There are two types of estrogen receptors in the body, alpha and beta. Your own estrogen prefers alpha receptors, while plant estrogens (phytoestrogens) have an affinity for the beta receptors.130 The effects of soya phytoestrogens on different tissues therefore depend on the ratio of alpha to beta receptors.131
Estrogen has positive effects in some tissues and potentially negative effects in others. For example, high levels of estrogen can be good for the bones but can increase the likelihood of developing breast cancer. Ideally, you’d like what’s called a “selective estrogen receptor modulator” in your body that would have proestrogenic effects in some tissues and antiestrogenic effects in others.
Well, that’s what soya phytoestrogens appear to be.132 Soya seems to lower breast cancer risk,133 an antiestrogenic effect, but can also help reduce menopausal hot-flush symptoms,134 a proestrogenic effect. So, by eating soya, you may be able to enjoy the best of both worlds.
What about soya for women with breast cancer? There have been five studies on breast cancer survivors and soya consumption. Overall, researchers have found that women diagnosed with breast cancer who ate the most soya lived significantly longer and had a significantly lower risk of breast cancer recurrence than those who ate less.135 The quantity of phytoestrogens found in just 250 ml of soya milk136 may reduce the risk of breast cancer returning by 25 percent.137 The improvement in survival for those eating more soya foods was found both in women whose tumors were responsive to estrogen (estrogen-receptor-positive breast cancer) and those whose tumors were not (estrogen-receptor-negative breast cancer). This also held true for both young women and older women.138 In one study, for example, 90 percent of the breast cancer patients who ate the most soya phytoestrogens after diagnosis were still alive five years later, while half of those who ate little to no soya were dead.139
One way soya may decrease cancer risk and improve survival is by helping to reactivate BRCA genes.140 BRCA1 and BRCA2 are so-called caretaker genes, cancer-suppressing genes responsible for DNA repair. Mutations in this gene can cause a rare form of hereditary breast cancer. As has been well publicized, Angelina Jolie decided to undergo a preventive double mastectomy. A National Breast Cancer Coalition survey found that the majority of women believe that most breast cancers occur among women with a family history or a genetic predisposition to the disease.141 The reality is that as few as 2.5 percent of breast cancer cases are attributable to breast cancer running in the family.142
If the vast majority of breast cancer patients have fully functional BRCA genes, meaning that their DNA-repair mechanisms are intact, how did their breast cancer form, grow, and spread? Breast tumors appear able to suppress the expression of the gene through a process called methylation. While the gene itself is operational, the cancer has effectively turned it off or at least turned down its expression, potentially aiding the metastatic spread of a tumor.143 That’s where soya may come in.
The isoflavones in soya appear to help turn BRCA protection back on, removing the methyl straitjacket the tumor tried to place on it.144 The dose breast cancer researchers used to achieve this result in vitro was pretty hefty, though—the equivalent to eating about a cup of soyabeans.
Soya may also help women with variations of other breast cancer susceptibility genes known as MDM2 and CYP1B1. Women at increased genetic risk of breast cancer may therefore especially benefit from high soya intake.145 The bottom line is that no matter which genes you inherit, changes in your diet may be able to affect DNA expression at a genetic level, potentially boosting your ability to fight disease.
Why Do Women in Asia Have Less Breast Cancer?
Though breast cancer is the most common cancer specific to women globally, Asian women are up to five times less likely to develop breast cancer than North American women.146 Why?
One possibility is their intake of green tea, a common staple in many Asian diets. Green tea has been associated with about a 30 percent reduction in breast cancer risk.147 Another strong possibility is a relatively high intake of soya, which, if consumed consistently during childhood, may cut the risk of breast cancer later in life by half. If women consume soya primarily as an adult, though, their risk reduction may only be closer to 25 percent.148
While intake of green tea and soys might account for a twofold reduction in Asian women’s breast cancer risk, it doesn’t fully account for the disparity between Eastern and Western breast cancer rates.
Asian populations also eat more mushrooms.149 As noted in the box on red wine here, white mushrooms have also been shown to block the estrogen synthase enzyme, at least in a petri dish. So researchers decided to investigate if there was a link between mushroom intake and breast cancer. They compared the mushroom consumption of one thousand breast cancer patients to one thousand healthy subjects of similar age, weight, and smoking and exercise status. The women whose mushroom consumption averaged just about half a mushroom or more per day had 64 percent lower odds of breast cancer compared with women who didn’t eat mushrooms at all. Eating mushrooms and sipping at least half a tea bag’s worth of green tea each day was associated with nearly 90 percent lower breast cancer odds.150
Oncologists, doctors who treat cancer, can take pride in the strides they’ve made. Thanks to improvements in cancer treatment, cancer patients are living longer and healthier as has been celebrated in oncology journal editorials with such titles as “Cancer Survivors, 10 Million Strong and Growing!” Yes, more than 10 million cancer patients are still alive today, with “perhaps as many as 1 million new individuals in the United States joining those ranks each year.”151 That is an accomplishment, but wouldn’t it be even better to prevent those million cases in the first place?
In medicine, a cancer diagnosis is considered a “teachable moment” when we can motivate a patient to improve his or her lifestyle.152 By then, though, it may already be too late.
CHAPTER 12
How Not to Die from Suicidal Depression
Healthy food can have a powerful effect on mood. But don’t take only my word for it. Take Margaret’s too. After hearing me speak at her church, she sent me this e-mail:
Dear Dr. Greger,
I was diagnosed with clinical depression by a psychiatrist when I was ten years old. I spent all my teenage years and twenties on a cocktail of medications for depression. Even on medications, I was still haunted by intrusive thoughts of suicide on a daily basis. Worse yet, the medications gave me headaches, nausea, and vivid, often frightening, dreams. I was sleepy all the time, and despite the scary dreams, I had to nap every day. I slept a lot—a couple of hours midday and then close to ten hours every night. Even with these side effects, I was afraid not to take these medications because I really wanted to live, and I was scared that without meds I might get so depressed I would kill myself.
Eventually I got married . . . and divorced. Was hospitalized several times during my marriage for depression. To be honest, I just n
ever had any sex drive, and my husband took it personally. I guess I’ll never know if my missing libido was just a side effect of all the medications I was on or the depression itself.
About nine years ago, I heard you speak at my church. I realized I had just spent the last two decades in a medication-induced haze. And without ever really feeling good a single one of those days. I talked to my psychiatrist about how I wanted to completely overhaul my diet and try to back off the medications under her supervision. Much to my surprise, she was supportive. Well, I’ve been whole food and plant based for nine years and haven’t had a further relapse. Not that I haven’t been sad from time to time but I haven’t had any more thoughts of suicide or any more hospitalizations. I sleep like a normal person now! Everyone tells me I am a different person since I changed my diet. I just wanted to thank you. My fiancé would like to thank you too! I owe you my life!
How can you prevent death by suicide? For those unfamiliar with the ravages of mental illness, the flippant answer is: Just don’t do it. In fact, death from other leading killers, such as heart disease, type 2 diabetes, and hypertension, may be just as much a choice as death from suicide, since psychiatric disorders can cloud your judgment. Nearly forty thousand Americans take their own lives each year,1 and depression appears to be a leading cause.2 Thankfully, lifestyle interventions can help repair your mind as well as your body.
In 1946, the World Health Organization defined health as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”3 In other words, you can be in excellent physical shape—enjoying low cholesterol, a healthy body weight, and good overall physical fitness—but that doesn’t necessarily mean you’re healthy. Mental health can be just as important as physical health.
Major depression is one of the most commonly diagnosed mental illnesses. An estimated 7 percent of American adults suffer from serious depression—that’s about sixteen million people who have at least one depressive episode each year.4 Now, everyone feels sad occasionally. A full range of emotions is part of what makes us human. Depression, however, is not just sadness. It is characterized by weeks of such symptoms as low or sad mood, diminished interest in activities that used to be pleasurable, weight gain or loss, fatigue, inappropriate guilt, difficulty concentrating, and recurrent thoughts of death.
How Not to Die Page 26