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Diet and Supplements

What you eat matters. A simple, perhaps obvious fact, but one that is too frequently overlooked. There is little doubt that what we eat has an impact on our risk of diseases such as cancer, and on the progression of those diseases after diagnosis. The nature of this connection has been, and continues to be, the subject of much scientific research. Although we have a lot more to learn, certain guidelines are becoming well established.

Excessive consumption of red meat, highly processed meats, and other sources of animal fat seems to promote cancer, whereas increased consumption of fruits, vegetables, whole grains, and low-fat animal foods may help to hinder it. Some important basic principles follow. A prospective study of 4,577 men with prostate cancer found that eating foods with trans fat, also called unsaturated fat, was associated with increased risk of all-cause death. Replacing carbohydrates and animal fat with vegetable fat may reduce the risk of all-cause death in prostate cancer, and consumption of vegetable fat may benefit men with prostate cancer.¹

In a major overview of large, high-quality studies in patients with breast cancer, most found that higher intake of saturated fat before diagnosis was associated with increased risk of death. Moreover, higher monounsaturated fat intake both before and after breast cancer diagnosis was associated with increased risk of cancer-specific and all-cause mortality. Although further research is needed, it appears that consumption of “bad” fats increases breast cancer recurrence and mortality, whereas omega-3 fats seem to be beneficial.²

The bottom line is that lifestyle choices matter for improving survival after a cancer diagnosis. Survivors should continue to focus on maintaining a healthy weight, being physically active, avoiding smoking, and choosing a diet comprised of fruits and vegetables, lean protein, whole grains, and low-fat foods, including dairy. Replacing carbohydrates and animal fat with vegetables is a smart move. It improves survival in patients with cancer.³

Being diagnosed with cancer brings up many questions. Should I change my diet? Should I gain or lose weight? What diet will help me lose weight? Would I benefit from taking a multivitamin or other dietary supplements? Do healing diets work, and if so, which is best? You may also have heard inconsistent or confusing answers to these kinds of questions. That’s because some promises are false and because some definitive data are not yet in place, but the goal of this chapter is to provide you with an overview of what we know today.

Dietary Fats

As outlined on the Mayo Clinic website,⁴ there are two main types of harmful dietary fat: saturated fat and trans fats. These are solid at room temperature and include beef fat, pork fat, shortening, stick margarine, and butter.

Saturated fat. This comes mainly from animal sources of food. Saturated fat raises total blood cholesterol levels and low-density lipoprotein (LDL) cholesterol levels, which increase your risk of disease and could impact survival after cancer.

Trans fat. This occurs naturally in some foods, especially foods from animals. But most trans fats are made during food processing through partial hydrogenation of unsaturated fats, which creates fats that are easier to cook with and less likely to spoil than are natural oils. However, that can increase unhealthy LDL cholesterol and decrease healthy high-density lipoprotein (HDL) cholesterol, increasing the risk of disease.

Healthier dietary foods contain mostly monounsaturated and polyunsaturated fats. They are liquid at room temperature and include olive oil, safflower oil, peanut oil, and corn oil.

Monounsaturated fat. Found in a variety of foods and oils, studies show that eating foods rich in monounsaturated fats improves blood cholesterol levels, which can decrease your risk of disease and produce better health.

Polyunsaturated fat. Found mostly in plant-based foods and oils, eating foods rich in polyunsaturated fats improves blood cholesterol levels, which can decrease risk of heart disease and type 2 diabetes. Omega-3 fatty acids, found in some types of fatty fish, appear to be especially healthy.

First, when living with cancer, eating a wholesome diet and maintaining a healthy body weight are priorities. Such lifestyle factors, along with regular physical activity (discussed in the next section), can help maximize the effectiveness of your treatments and help maintain good quality of life, all while minimizing unwanted side effects. In the longer term, they can help reduce your risk of cancer recurrence and your risk of other chronic diseases, and they promote longevity.

As we start our discussion about diet and nutrition, a few guidelines are worth mentioning:

• No food, vitamin, mineral, or other supplement is going to immediately and miraculously cure your disease or cause you to drop 50 pounds. That’s not to say the benefits of a healthy diet are insignificant, just that eating well is not an immediate fix. To achieve the benefits—and there are many—it takes regular, long-term commitment to a healthier lifestyle. The key is to choose a way of eating that makes the most sense for you, given your personal goals and tastes. Short-term bouts on a healthy diet aren’t likely to do much good. But sticking to a healthier diet long term, even if you don’t follow it perfectly all the time (moderation is always important!), can make a significant improvement to your health.

• If you are overweight or obese, weight loss is critical. The importance of achieving or maintaining a healthy body weight cannot be overstated. Evidence is beginning to accumulate in support of what doctors have long suspected: that losing weight, even after diagnosis, can lead to longer survival. Being overweight is associated with increased risk of recurrence and decreased disease-free survival. Moreover, gaining weight after diagnosis is a frequent complication of treatment, which must be avoided. Managing your weight requires a combination of diet and exercise. It doesn’t have to be as daunting as it sounds—the tips in this chapter and the activity chapter will help.

• Vitamin supplements do not produce the same benefits as diets high in those vitamins. This has been demonstrated time and again in single-vitamin studies over the past 25 years. Whole-foods diets rich in vegetables, fruits, whole grains, beans, and fish or lean meats, and low in refined sugar, red meat, and high-fat foods, have protective effects against cancer. But the benefits are most likely due to synergistic effects of the many nutrients and phytochemicals present in whole food and not as the result of any one or two nutrients. Supplements can be useful in some cases, such as to meet recommended levels of any vitamins or minerals lacking in your diet, but they cannot replicate the benefits of whole foods. Vitamin D is an example of a nutrient that cancer patients (and others) are frequently deficient in and that may require supplementation (discussed later in this chapter).

• It is important to make sure you are getting enough protein. This is important for everyone, but all the more so for cancer patients during all stages of treatment, recovery, and long-term survival. When selecting sources of animal protein, it’s best to choose foods that are low in saturated fat, such as fish, lean meat, skinless poultry, eggs, or low-fat dairy. Plant sources of protein, such as beans, nuts, and seeds, have the added benefit of being high in fiber and rich in antioxidants and other healthy plant compounds.

• Consider seeking individualized nutrition advice. We all have unique needs, and those of cancer patients are particularly variable depending on the nature of your disease and treatment. As a result, personalized advice can be invaluable. This can be from a doctor who is knowledgeable about nutrition or from a registered dietitian (RD) who has experience with the unique needs of cancer patients. Ask for a referral to an RD who is also a Certified Specialist in Oncology (CSO).

Body Mass Index

Body mass index (BMI) is a good way to determine if you are at a healthy weight or are overweight or obese. There are many free automatic calculators online, such as the U.S. National Institutes of Health website (http://apps.usa.gov/bmi-app.shtml). Simply insert your height and weight in their calculator and your BMI will appear. The website contains information about how to interpret and, if necessary, to reduce your BMI.

Specific Dietary Regimens

In choosing a diet to follow, it’s helpful to consider your priorities—whether you need to lose weight or gain it, for instance. Some diets are particularly focused on preventing chronic diseases such as diabetes and heart disease, and that is particularly important if you have a family history of these illnesses or are otherwise at increased risk. And it goes without saying that you’ll want to decrease your risk of secondary cancers or recurrences. It’s a good idea to consult with a dietitian who can help you consider your options and develop the best plan for you. In this next section, we provide an overview of a few diets that cancer patients may hear about and consider. Some have little, if any, value but are popular among some cancer patients. However, a Mediterranean-type diet is considered by experts as the absolute best so we’ll start with that one.

Mediterranean Diet

The Mediterranean diet has become an established eating regimen for decreasing the risk of cancer and its recurrence, as well as the risk of many other chronic diseases. The hallmark of this dietary regimen is low consumption of meat and dairy products. Participants consume fruits, vegetables, legumes (beans, lentils, and the like), and whole grains, with moderate amounts of nuts, seeds, fish, and oils (primarily olive oil). Herbs and spices are generally used in place of salt, and a moderate amount of red wine is consumed with meals. (It must be noted, however, that despite the documented benefits of red wine, alcohol has been shown to increase the risk of certain cancers, so moderation is important.) A recent issue of the New England Journal of Medicine was devoted in large part to articles on the Mediterranean diet for prevention of cardiovascular disease. Moreover, the relationship between adherence to the Mediterranean diet and incidence of cancer was studied in a sample of 25,623 people in Greece. At follow-up almost 8 years later, researchers found that better adherence to the diet was associated with lower overall cancer incidence.⁵

Key Components of the Plant-Based Mediterranean Diet

• Fruits and vegetables

• Whole grains—breads, pasta, polenta (from corn), bulgur and couscous (from wheat)

• Legumes—beans and lentils

• Seeds and nuts

• Olive oil and other healthy oils

• Fish and poultry

• Red wine once daily

Avoid, or eat rarely, saturated fat from butter, red meat, and eggs. Also avoid deli, luncheon, and cured meats. Eat refined sugars and sweets rarely.

Vegetarian Diets

By definition, a vegetarian diet excludes meat and seafood, emphasizing plant-based foods instead. However, the term “vegetarian” means different things to different people, and as such, vegetarian eating patterns vary widely. Lactoovo-vegetarians avoid only meat and seafood, but will eat other animal foods such as dairy and eggs. Lacto-vegetarians exclude eggs in addition to meat and seafood, but consume dairy. Finally, vegans, or total vegetarians, avoid all animal products including dairy and eggs. Other variations exist as well, such as diets that include fish but are otherwise vegan. All vegetarian diets involve significant consumption of whole grains, vegetables, fruit, and beans, including soy products. People often choose plant-based diets out of concern for the environment, for ethical or philosophical reasons (relating to animal welfare), and, increasingly, for their many health benefits.

As long as they are well planned to ensure adequate nutrition, vegetarian diets can be very healthful. The health advantages include lower cholesterol levels and a decreased risk of heart disease, high blood pressure, and type 2 diabetes. Moreover, vegetarians generally have a lower body mass index (BMI) than their meat-eating counterparts and a lower risk of cancer. Vegetarian diets are low in saturated fat and cholesterol (cholesterol is found only in animal foods) and are rich in dietary fiber, minerals such as magnesium and potassium, vitamins C and E, folate, carotenoids (like beta-carotene/vitamin A), flavonoids, and other beneficial phytochemicals. Many of these nutrients are shown to have cancer-protective properties. Consuming them together in the form of whole foods (as compared to individually in dietary supplements) allows them to act in an additive and synergistic manner, maximizing the benefits.

Plant protein can fulfill protein requirements as well as animal protein can, so long as you consume a variety of plant foods each day in sufficient quantities to meet your caloric needs. Together, whole grains and beans consumed in an approximate two-to-one ratio can supply all of the amino acids we need. Calcium requirements, too, can be met through regular consumption of leafy green vegetables, calcium-fortified plant food such as cereals, soy milk, and rice milk, and/or dairy products. Furthermore, diets high in fruit and vegetables help the body hold on to the calcium it already has. The potassium and magnesium content of fruits and vegetables slows loss of calcium from the bones.

However, vegetarian diets can be low in some important nutrients, particularly vitamin B₁₂ and vitamin D. It should be noted that humans receive only a very small amount of vitamin D from food. Most vitamin D is obtained from sunlight. However, dark skin and use of sun protector creams, necessary to prevent the deadly skin cancer melanoma, also prevent vitamin D from being synthesized by the body. Therefore, many people are vitamin D deficient. It is worth considering taking a vitamin D supplement to avoid vitamin deficiency. Vitamin B₁₂ is found in animal products, including fish, meat, poultry, eggs, milk, and milk products. It is generally not present in plant foods, but fortified breakfast cereals are a readily available source, and supplementation is available.

Vegetarian diets may initially sound dull and boring, but there are many recipes and cookbooks that can help you create attractive, tasty, satisfying, and varied dishes. As more and more people adopt this way of eating, restaurants are increasingly catering to vegetarian and vegan diners as well.

A final note, even those who eat semi-vegetarian diets experience health benefits, so it is not necessary to avoid all animal foods entirely unless you feel inclined to do so.

Dangerous Diets—Some Promoted as Cancer Cures

Macrobiotics

The macrobiotic diet is plant based, comprised largely of whole grains, beans, soups (such as miso soup), and sea vegetables. It excludes meat and dairy, but fish is permitted occasionally. Fruits, nuts, and seeds also are consumed at times, along with vegetable pickles and non-caffeinated teas. More than a diet, however, macrobiotics traditionally encompasses both a philosophy and a way of life. It emphasizes balance in the selection, preparation, and consumption of foods, as well as in day-to-day life.

In a 2009 report, the American Dietetic Association concluded that “appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases.”⁶ That said, your nutritional needs may vary compared to the average person, which is why it is important to discuss diet with your doctor and/or another nutrition-trained health professional.

Macrobiotic theory is based largely on the yin-yang principle of balance that was integral to ancient Chinese medicine. Yin and yang are seen to be equal but opposite forces that describe all components of life and the universe. The diet and philosophy were initially developed and popularized by Japanese philosopher George Ohsawa in the early twentieth century. An early disciple, Michio Kushi, led the macrobiotic movement from the mid-1900s. The macrobiotic diet was promoted as a cancer cure in the United States for many years, but that effort eventually waned as scientific studies failed to support the claims.

No diet or combination of foods, in fact, has ever been shown to cure cancer. Moreover, practicing macrobiotics and other extreme diets can lead to nutrient deficiencies, such as vitamin B₁₂ and calcium, and inadequate caloric intake.

Gerson Regimen and Metabolic Therapies

Developed in the 1930s by German physician Max Gerson, the Gerson regimen involves a strict metabolic diet, as well as coffee enemas and various supplements intended to aid in detoxifying the body. The diet is vegetarian and emphasizes fresh fruit and vegetable juice; each patient consumes about 20 pounds of fruits and vegetables each day, largely in the form of fresh juice. Supplemental digestive enzymes are frequently given, as well as coffee enemas, which are claimed to stimulate the excretion of bile from the liver and eliminate toxins from the body. This and many other extreme diets are based on the incorrect idea that cancer is caused by a buildup of toxins in the body, and that detoxification will cure the disease. The Gerson clinic advertises its cancer therapy as “a natural treatment that activates the body’s extraordinary ability to heal itself through an organic, vegetarian diet, raw juices, coffee enemas, and natural supplements.” Along with many other fanciful “therapies” for cancer, the Gerson clinic is located in Tijuana, Mexico, a hotbed of nonviable “alternative” disproved cancer treatments that do not work.

Fasting and Juice Therapies

Fasting eliminates all solid food and generally limits dietary consumption to certain liquids. Juice cleanses or juice fasts, during which only freshly juiced fruits and vegetables are consumed for a period of time that can vary from a few days to weeks, are very common today. Such therapies are promoted for general health maintenance, as well as for healing diseases. Advocates believe they facilitate internal cleansing and support the immune system.

Fresh fruit juice, in moderation, can be healthy as well as delicious. But regimens such as this, especially when continued over an extended period, can be dangerous, especially for cancer patients.

In summary, eat healthfully; seek professional advice if you have special swallowing or digestive issues; beware of bogus dietary or other cancer “cures”; enjoy the beneficial and delicious Mediterranean-type diet rich in fruits, vegetables, seafood, olive oil, beans, and whole grains.

Important Vitamins and Foods

When researching nutrition for cancer patients online, some vitamin and food entries can create more questions than answers. It is worth spending a bit of time discussing some of those common items.

Soy

Soy can be a confusing topic for cancer patients. On the one hand, it is widely touted as a health food. It contains compounds called isoflavones, which may help decrease the risk of heart disease and cancer and reduce menopausal symptoms in women, among other benefits. Soy foods are also an excellent source of plant-based protein, particularly valuable for vegetarians. As a result, soy protein is being added to all kinds of processed foods and is becoming ubiquitous in the food supply.

But the very same isoflavones credited with many of these benefits are similar in structure to the hormone estrogen. Doctors and scientists are therefore concerned that they may mimic estrogen’s activity in the human body, potentially encouraging hormone-sensitive tumors (such as estrogen receptor (ER)–positive breast cancer) to grow. So, the question is, how do these benefits and risks balance out? Is soy something you should be eating at all, and if so how much is too much?

Soy’s journey to mainstream began decades ago, when researchers observed that rates of breast and other cancers were significantly lower in Asia than in Westernized countries. They assumed that diet was a factor and zoomed in on soy as a possible source of this health disparity. Since soy foods were eaten all the time in Asia but were almost entirely absent from the Western diet, it seemed a solid hypothesis. Fast-forward 20 years, however, and the research results have been mixed.

Regular consumption of soy foods has been associated with a reduced risk of cancer in many studies, but some laboratory and animal research suggests that soy can promote growth of estrogen-sensitive tumors. It’s worth underscoring that virtually all of the studies showing harm were conducted using isolated cells growing in a petrie dish or in rodents—not in humans. And most of them used isolated soy isoflavones, not the soy in its whole-food form. So the degree to which such findings apply to us is not clear. No conclusions can be drawn without considering results in humans.

In recent years, there have been several large public health studies of soy consumption in humans, and all have found it to be safe and perhaps beneficial, even in women with ER-positive breast cancer. Three large studies, two in U.S. breast cancer patients and one in Chinese patients, found no adverse effects of soy consumption on outcome, and suggested it may even offer some protection against recurrence and cancer-related death. The largest of these followed 9,514 U.S. and Chinese breast cancer survivors and found that patients who consumed at least 10 milligrams of isoflavones (about 3 grams of soy protein) per day had a significantly lower risk of cancer recurrence.⁷

Interestingly, it appears that soy is most beneficial when it is eaten regularly early in life and through puberty. Studies suggest that this may decrease the risk of breast cancer, but that introducing soy into the diets of adult women may not do much to change their cancer risk, either positively or negatively.

The bottom line, considering all of the findings so far, is that eating moderate amounts of soy should be fine. In its most recent set of guidelines, the American Cancer Society concluded that for breast cancer patients “current evidence suggests no adverse effects on recurrence or survival from consuming soy and soy foods.”

That said, it is wise to avoid supplements that contain high doses of isolated soy isoflavones. Stick to soy-containing foods, such as miso soup, tofu, tempeh, soymilk, edamame, and even soybeans in their original form.

Vitamin D

Vitamin D is a fat-soluble vitamin (technically a hormone precursor) that is produced in our skin when exposed to sunlight, and is also found in plants, fish, and dairy products. Its effects in the body are widespread: thousands of genes are regulated directly or indirectly by vitamin D. Scientists know that it is important for bone formation and that it assists in the absorption of calcium; adequate vitamin D levels are necessary to prevent osteoporosis and bone fractures. Although far more equivocal, some studies suggest that vitamin D may play a role in cancer, cardiovascular disease, diabetes, physical functioning, autoimmune diseases, infections/immune function, and mental health, among other diseases. Many argue that vitamin D supplementation can prevent or improve these conditions. But study results have been mixed, and evidence is lacking for virtually all uses except bone health.

Our need for this vitamin is not surprising; through most of human evolution, vitamin D was readily available. Our hunter-gatherer ancestors spent most of their time outside in the sun and presumably produced high levels of vitamin D. But our modern indoors lifestyle has made vitamin D deficiency a widespread problem. Deficiency is even more prevalent among darker-skinned people, who make less vitamin D to begin with than their lighter-skinned counterparts.

Of particular relevance for this book, there is limited but promising evidence that vitamin D may have a role in decreasing the risk or progression of some cancers. While vitamin D supplementation has not been shown to improve outcomes in cancer patients, some studies, especially those involving colon cancer, are suggestive of anticancer effects.⁸ However, the numerous efforts to delineate a causal relationship between vitamin D and a wide array of human cancers have produced conflicting results, and large-scale randomized trials will be required to provide definitive answers.⁹