Chapter Seventeen


Mainstream Nutritional Science and the Unconventional Nutritional Cancer Therapies

Chapter Seventeen

Keith Block–Integrating Diet, Fitness, and Psychological Support into an Oncology Practice

Keith Block, M.D., is one of the significant figures in the emerging “middle ground” approach to integrated management of cancer. Although he has received considerable publicity in the Midwest, he is not highly visible either in conventional cancer therapy or in alternative cancer therapy. Rather, like many of the best individual therapists I have met, he is known to a network of people around the country who respect his work.

Block is an example of the kind of physician we are going to need more of in the future: a clinical internist who has conducted postgraduate research in nutritional and behavioral oncology and who is dedicated to the judicious and effective use of conventional cancer treatments. At the same time, he places a strong emphasis on the use of appropriate complementary therapies as adjunctive treatments. Although little objective evidence exists as yet on the efficacy of Block’s approach, it is nevertheless a model that could fit easily into the future mainstream practice of hematology-oncology.

Block’s Biography

Soon after entering medical school, Keith Block developed an illness that conventional medicine was unable to remedy. After attempting a number of different therapies, he found clinical relief with a macrobiotic diet. He emerged from medical school as a practicing physician publicly committed to investigating the macrobiotic approach to health. Early in his involvement, however, he recognized what he thought were numerous weaknesses in the macrobiotic system and gradually became aware that he had some significant differences with the way macrobiotics approached cancer and other health problems. He separated himself from macrobiotics and began to develop his own adjunctive treatment program.

Currently, Block has a private practice in Evanston, Illinois, and has developed a unique and multifaceted cancer care program which includes an inpatient ward at Edgewater Medical Center (EMC) in Chicago, an affiliate hospital of the University of Illinois School of Medicine. He is medical director of the cancer treatment program at EMC and, additionally, is vice president of a Chicago chapter of the American Cancer Society. A large proportion of the people who come to see him–both locally and from across the country–are cancer patients.

I came to know Block well when he joined a community of other progressive practitioners and researchers concerned with new approaches to cancer at Commonweal’s annual Lloyd Symington Foundation Conference on New Directions in Cancer Care. We also worked together on the advisory board of the Office of Technology Assessment Report on Unconventional Cancer Therapies for the U.S. Congress.

Medical Caritas

Block describes his program as being based on medical caritas (Latin caritas, charity), meaning “compassionate caring for others.” He says: “At the heart of the model is a carefully developed, very special doctor-patient relationship. … The primary care physician seeks not only to understand and treat the patient’s ailments but also to identify the patient’s psychological, biomechanical, nutritional and physiological resources. In addition, the physician functions as a … coordinator of medical care for patients.”1

Block’s treatment model consists of six components: biomedical, biopsychosocial, biochemical, biomechanical, medical gradualism, and the use of innovative diagnostic and therapeutic tools which are minimally invasive. The last two components exemplify Block’s philosophy and “caritas” approach. By “gradualism” he means using the most effective, least invasive procedures first, before adopting more invasive procedures as and if they become necessary. He also uses innovative diagnostic and therapeutic tools which are noninvasive or only modestly invasive. These include sensitive laboratory evaluations which assess the activity and aggressiveness of malignancies; antagonists to side effects from conventional therapy (SEAs); and therapeutic agonists (TEAs), which consist of treatments or pharmacologic agents aimed at enhancing the effectiveness of conventional cancer therapies. SEAs and TEAs include a variety of food components that may enhance immune response. Where necessary, Block uses a modified version of enteral (via the small intestine) and parenteral (by injection) feeding intended to nourish the patient rather than the tumor. He is currently researching psychological interventions aimed at disrupting adverse conditioned responses to chemotherapy, and plants that have interesting immune system activities.2

One of Block’s fundamental premises, echoing one of the great themes in medical history, is the need for compassionate caring that focuses not only on the diagnosis of a physical disease, such as cancer, but also on understanding what kind of person has this disease. This concept receives lip service in conventional medicine, but Block focuses fully on its importance and on how to implement it systematically:

This clinical model can be used to develop treatment modalities that are based not simply on a diagnosis of a patient’s condition but on a deep understanding of that patient’s total psychosocial-cultural gestalt. Without a clear recognition of what is deeply important to the patient–e.g., prestige, libido, safety needs, control issues–the physician may propose a treatment that the patient cannot psychologically, culturally, or socially accept. As many physicians have found to their dismay, treatment urged on a frightened or unwilling patient often compounds the problem rather than alleviating it. Unfortunately, rather than examine their own clinical approach, many physicians may blame the patient or even the procedure for the failure. What is required is not an adjustment in technical procedures, but a change in the clinical model itself.3

The significance of this statement cannot be overemphasized. Block is going beyond the common contribution of many alternative and adjunctive therapies which propose the addition, or substitution, of complementary therapies for conventional therapies. Rather, he is saying that the entire package of both conventional and complementary therapies needs to be designed around the specific persona of the individual patient, and that this design process is the focus of a special and profound relationship between the patient and the physician. What Block is saying is not new–it is as old as the oldest shamanic tradition–but he is adept at reminding us of it and practicing it.

The key points from the other four components of Block’s medical caritas model are:

The biomedical profiles: Block does a full workup on each patient, including etiologic review, physical examination, laboratory work, diagnostic testing, and review of pathology specimens. His innovations fall primarily in the technical use he makes of a panel of biomedical tests for nutritional and immune assessment.4

The psychosocial profiles: In a careful interview with each patient, Block develops four key psychosocial profiles of the patient: a patient-needs profile, an attitudinal profile, a stress level profile, and a learning profile. He also investigates the patient’s support systems and lifestyle. From the results of these profiles–together with the biomedical evaluation–he designs an individualized treatment regimen.

Based in part on Abraham Maslow’s well-known “hierarchy of needs,” the patient-needs profile explores what the patient feels is basic to his survival as a person. “To develop this profile,” says Block,

I try to determine whether a patient is driven most strongly by the degree of safety needs (the need to be physically, biologically, psychologically secure), membership needs (the need for warm, mutually satisfying relationships), self-esteem needs (meeting one’s own self-imposed criteria and standards of performance), or status-prestige needs (to receive acknowledgement, recognition, or approval from others). This knowledge … enables me to relate to the patient in an informed way and to establish the kind of relationship that provides me with the most significant feedback I need to accomplish our diagnostic and therapeutic goals.5

For example, a patient with high safety needs usually responds well to support and reassurance. “On the other hand,” says Block, “a patient with high self- esteem needs can be challenged to perform (e.g., meet treatment goals), and, if safety needs are low, provided with information and counseled in a direct manner that a person with high safety needs could find paralyzing.”6

The attitudinal profile is based on Steven Greer’s work with breast cancer patients at Kings College in England. Greer divided breast cancer patients into four groups: hopeless-fatalistic, stoic-suppressor, denier, and feisty fighter. He found that the “feisty fighters” and, surprisingly, the “deniers” had the longest survival, while the “stoics” and the “hopeless-fatalistic” patients did less well. Says Block:

This particular profile must be correlated with the Patient-Needs Profile. It serves no purpose to identify someone as belonging to the stoic-suppressor group if one does not recognize that this is a manifestation of high self-esteem needs … To the clinician, this is a signal that forcing “reality” on some people can break through a defense that is critical for their survival. Such qualifications on “truth-telling” are critical for clinicians to understand if they are to serve their patients’ best interests. This particular area of communication requires great skill and tact to maintain an honest response while affirming a patient’s emotional integrity.7

The stress level profile uses the well-known Hohme Stress Rating Scale and other instruments to assess the stress that patients have been under during the previous year. Says Block, “Stressful events in themselves do not always precipitate a health crisis. Rather, it is how the patient perceives those stressful events–how the events affect the patient’s social needs and coping capacity–that can result in a major health problem.”8

The learning profile focuses on the learning pathways through which a particular person processes information about himself and the rest of the world. Some techniques involve assessing whether the patient is more auditory, visual, or kinesthetic in information processing. Others address the level of the patient’s hypnotizability or “suggestibility quotient.” Still others look at how the patient can manage stress or learn progressive deep relaxation.

[These] can provide the physician with additional insight into what degree of influence they may have on the patient, the patient may have on himself, and what particular techniques best suit the patient–i.e., biofeedback, hypnosis, repetitive work techniques–and whether they should use primarily verbal, visual or kinesthetic methods. … Developing and implementing this profile is [essential] since it is in this area that patients are frequently able to experience the most control in taking charge of their medical care and their ability to heal.9

While Block addresses a professional audience in discussing these issues, we can (and Block does) readily adapt these issues to self-care. Block is in effect suggesting that each of us seeking healing in the face of serious illness should ask:

What are my needs? What matters to me fundamentally as a person? Who am I, at the deepest level I can reach, and what matters to me most at that level?

How do I face a serious challenge in my life? What is my style in meeting such a problem, and what does that say about the kinds of interactions and information that are most helpful to me?

What are the stresses in my life, and how do I experience those stresses? How have they affected my deepest experience of myself over the past year?

How do I learn? How do I process information about myself and the world? What are the approaches to cognitive and affective information that work best for me? What do I find most relaxing and healing?

In short: what we need, how we respond to challenges, what we experience as stress, and how we learn are the four psychological areas Block suggests we need to address, either with a physician or for ourselves.

The biochemical profile: “Since I use diet as an important part of my clinical methodology,” says Block, “I need to know a patient’s eating habits and attitudes toward food. Trying to change someone’s diet without understanding what food means to him can simply add another level of stress to a patient’s life.”10 To assess eating habits, Block uses a food/social profile which helps him distinguish between the biological and the social needs for food and thereby develop a realistic nutritional program for each patient.

The biomechanical profile: Block does better work in the area of physical conditioning than most other practitioners involved with complementary approaches to cancer, who typically focus on spiritual, psychological, nutritional, or immunosupportive approaches, but rarely on biomechanical or physical approaches. He uses “the body composition analysis along with the patient’s exercise history, past and present, and his current cardiovascular, respiratory, and muscle-skeletal needs. These factors help me determine what type of exercise regimen is best suited for his condition, keeping in mind not only what he is capable of but willing to do.” His approach is cardiovascular, aerobic, isometric, structural, and neurokinesthetic (using movements that reinforce a “cross-crawl” patterning). The movements are patterned after specific components modified from Western and Eastern systems of exercise.11

Block describes three objectives for his physical conditioning protocol:

1. Produce maximum possible efficiency in terms of all life support systems–cardiovascular, pulmonary, skeleto-muscular, neurologic, metabolic, immunologic, and total organic functioning. Programs that produce results in only one organo-physiologic system are severely deficient [emphasis added].

2. Maintain in the individual the capacity to work hard and to function at the level of peak performance possible to each. …

3. Produce a heightened sense of well-being, vitality, and emotional resilience. It seems pointless to achieve great physical results if the patient is emotionally depleted most of the time. An appropriate program must be able to help the patient overcome the impact of psychological stress–regardless of whether the stress comes from internal or external pressures.12

Block’s basic physical conditioning program often starts with 30 minutes of vigorous walking 5 days a week for patients who are able to do so. Others may start with isometric, flexibility, or minimal aerobic exercise. All patients then gradually work into a more comprehensive program.

Applying the Findings to Diagnosis, Treatment, and Patient Training

In presenting the diagnosis, Block discusses at length the high art of finding an approach “that immediately begins marshalling the patient’s own inner resources in the fight against his disease.”13

In treatment planning, he distinguishes between the biomedical therapy and the complementary adjunctive program. Block’s approach to biomedical therapy is based firmly on the Hippocratic doctrine of “doing no harm.” The complementary adjunctive program consists of individualized programs that “help patients break out of negative thinking patterns and adopt life-affirming patterns.”

The adjunctive program is designed to enhance and support the biomedical therapy. One of the primary benefits is that the patient always has something constructive and positive to do on behalf of his own care. He is not simply a passive recipient of medical treatment. … Even in what may prove to be a terminal case, these combined activities can help a patient come to terms with his life, optimize what time remains, achieve resolution of many issues before the finality of his death, and be able to bid farewell to family and friends who have shared so much of his life.14

Block has designed a 3 1/2 day training program that includes practicing the biochemical, biopsychosocial, and biomechanical protocols developed for each patient. It includes nutritional instruction, physical conditioning counseling, and stress-reduction programs. “The objective of the Intensive Health Training sessions,” Block says, “is to create a sense of control and competence on the part of the patient, an ingredient I believe is deeply missing in the treatment of disease of all types. Giving the patient personal responsibility and a sense of personal power regarding his care is as important as prescribing the right medication.” Minimizing negative physical or psychological factors and enhancing emotional vitality “builds a foundation upon which invasive techniques, when needed, can work most effectively. There isn’t a physician or surgeon practicing today who wouldn’t prefer to have a patient attain maximum condition prior to dealing with the compromises inherent in any invasive procedure [emphasis added].”

The Block Nutritional Program

Block developed his nutritional program from macrobiotics. But, while macrobiotics generally makes fewer excessive claims than many of the other alternative nutritional approaches to cancer, Block is even more cautious, and takes what I regard as the most reasonable stance. Says Block,

Although the nutrition and diet part of my clinical program has received the widest attention, it is neither more nor less important than the other components. I am not a nutritionist or dietitian, nor do I claim that the diet has miraculous or curative powers. I believe strongly that diet is a critical factor in health–that what we eat makes a significant difference in our body’s ability to resist disease and maintain health. I believe that diet can act therapeutically as well as adjunctively in treatment.15

The Block diet is based on traditional diets that have historically been considered to support good health in countries around the world. Its principle components are whole cereal grains, vegetables, legumes, fruits, nuts and seeds, and optional use of animal products. (When desired, Block permits limited use of certain fish and free-range poultry.) The Block diet is also remarkably similar to the diets that the American Cancer Society, the National Cancer Institute, the American Academy of Sciences, and the American Heart Association have endorsed as having some preventive value in protection against cancer and coronary disease.16 As part of an ongoing scientific literature review of the latest nutritional findings, Block and his staff continue to modify and individualize regimens based on the patient’s disease, his physical condition, and his food needs and therapeutic adjustments.

For most physicians, nutrition is the least understood and most poorly used tool in the treatment arsenal against cancer. Most physicians received little or no training in nutrition during their medical school years. As a result, they remain unaware of the potential of diet and nutrition, either as an adjunct to conventional therapy or as a therapeutic tool … to maintain patient morale and well-being before, during and after treatment. While many physicians support the National Cancer Institute and American Cancer Society nutritional guidelines for a “cancer prevention diet,” few are versed in the rationale behind these guidelines or what makes it a “prevention” diet.

Unfortunately, once their patients develop cancer, the prevention diet is abandoned and nutritional support for the patient, if it is considered at all, becomes a matter of trial and error. Or worse, it is either completely discarded or switched to a regimen that is comparable to a diet identified as cancer promoting. Thus, it is not surprising that one of the leading causes of mortality among cancer patients is death from severe malnutrition [emphasis added].17

The importance of this point is difficult to overemphasize. What, we may reasonably ask, is the scientific basis for encouraging people who develop cancer to abandon a diet known to offer some protection against the development of cancer in favor of a diet identified as cancer-promoting? There is, actually, an answer, which goes like this: There is no reason to assume that the diet that prevents cancer also slows its development once it is established. And, precisely because malnutrition is a major threat with many cancers, the patient should be encouraged to eat a diet as high in caloric intake as possible. But while this is a reasonable argument, can we in any way say that it represents a more “scientific” position than the one Block has taken?

Nutrition researcher Lawrence Kushi points out that

If we believe that dietary factors act as promoters of carcinogenesis, then the influence of diet on tumor growth and spread should not necessarily be much different before or after clinical expression of the tumor. … Specifically, one can make a strong case that the time of clinical presentation of cancer is fairly arbitrary. This is particularly so when one considers the evolving technology and acceptance of screening procedures. Of course, there will be cases where caloric support is paramount, but for the otherwise healthy cancer patient … the same dietary approach for prevention, broadly speaking, could be used for treatment as well.18

In his 12 years of clinical experience, Block reports that the diet he uses provides four major benefits:

(1) Patients manage their disease and treatment better. The dietary regimen gives patients both a continual reinforcement that they are doing something for themselves by being involved in their treatment and a strong sense of control in dealing with their fight against cancer. (2) Patients experience fewer side effects as they undergo conventional treatments. They report a reduction or cessation of pain, nausea, vomiting, skin irritations, and other side effects commonly produced by cancer treatments. … (3) Some patients appear to experience slower rates of tumor growth, fewer tumors at cancer sites, reversals of early stages of tumor development, and increases in survival time. This appears to occur even among patients with advanced disease. (4) Terminal patients are often more comfortable in the final stages of their disease, suffering less pain, requiring less medication, and experiencing diminished mental and emotional difficulties. There have been a stream of responses from patients’ families regarding patients’ unusual levels of activity, alertness, and ability to interact and engage with loved ones during the last days.19

Block specifically addresses the ongoing research debate, which I described in chapter 11, over whether a low calorie diet retards tumor growth without a dangerous level of weight loss or whether a high fat, high calorie diet is the only reasonable one for cancer patients with weight problems. His position is that appetite rather than weight is the critical factor: “As long as appetite is maintained and patients stabilize without continued loss [of weight], a limited initial drop in weight [as is often found with primarily vegetarian therapeutic diets] should not be a cause for concern.”20

The Block Diet

The Block diet provides 50% to 60% of nutrients in complex carbohydrates and a range of fat intake from 12% to 25%, as required, primarily from vegetable sources, with the remainder of calories coming from protein. Using that framework, the diet is tailored to the taste of the individual patient using extensive exchange lists.21 The exchange groups are: (1) grain, pasta, and bread, (2) legumes, (3) soy foods, (4) vegetables, (5) nuts, seeds, and oils, (6) fish, poultry, and dairy, and (7) fruits. Foods are grouped in each list by shared levels of nutrient and caloric value. Thus Block has made it easy for patients to “trade” different foods or drinks from the same list. Each patient is given an individualized menu based on his physical condition, cultural background and tastes, climate and geographical location, activity level, and physical needs.

Block works with three levels of dietary change: transitional, maintenance, and therapeutic. Transitional diets are for patients who are just beginning to make changes in their eating patterns. Maintenance diets are for healthy persons who follow all of the guidelines set out in Block’s programs. Therapeutic diets are for patients who have more or less active diseases that require intensive dietary management, and who are willing and able to follow the dietary program conscientiously. Seven different exchange lists were originally developed during Block’s research on the program; each one was based on a different protein type, since different protein sources vary widely in fat content. In clinical work, however, a single “averaged” exchange list has been found to be most practical for daily use by patients.22

The diet includes not only commonly eaten foods but also a variety of lesser-known foods that provide variety or special nutritive values: cereal grains such as quinoa, teff, and amaranth; soy products such as tempeh, tofu, and miso; shiitake mushrooms and a wider variety of leafy greens than most people are familiar with; and sea vegetables such as kombu, dulce, hijiki, arame, and wakame. Vegetables from above and below ground, including burdock root, daikon, and lotus root, also make their appearance on the diet.23 Many of these foods were initially popularized by macrobiotics.

Restricted or eliminated are most dairy products, eggs, red meat, refined sugar, caffeinated or alcoholic drinks, processed foods, some less healthy oils, and some vegetables in the nightshade family such as eggplant and green peppers.24

Scientific Rationale of the Block Nutrition Program

Block provides a very lengthy scientific rationale for each of the components of his nutritional program, discussing clinical, epidemiological, and laboratory evidence supportive of the choices he has made. A review of the literature is beyond the scope of this book, but Block’s theory of how the diet may work can be summarized:

1. The amounts and types of fat in the diet may affect tumor promotion and growth, especially in cancers of the reproductive and digestive systems. Rapidly growing cancer cells need large amounts of lipids, a critical component of cell membranes. Restricting fat intake may deny tumor cells this important nutrient. It is interesting to note that postmenopausal Japanese women with breast cancer following peasant diets have been observed to have much longer survival periods than postmenopausal American breast cancer patients following Western diets.25 There are also some preliminary investigations indicating that lower fat diets may increase natural killer cell activity in humans,26 which can be critical in destroying tumor cells in the body. The types of fat consumed may also influence tumor growth. Fats high in linoleic acid appear to promote tumor growth: Block emphasizes the use of low linoleic fats such as olive oil and canola oil for cancer patients.

2. Compounds in shiitake mushrooms (Lentinus edodes) and Laminaria sea vegetables (kombu, kelp) have been shown to have potent anticancer properties, even at relatively low levels of dietary intake. Some of these compounds act in a manner similar to interferon or boost the activity of interferon-like protein polysaccharides, which attack and destroy cells. They also interfere with the initiation and promotion stages of carcinogenesis.

3. A vegetarian diet contains a variety of plant foods whose protectivecompounds act as prohibitive, blocking, and suppressing agents.These agents, which include phenols, indoles, aromatic isothiocyanates, methylated flavones, coumarins, plant sterols, selenium salts, protease inhibitors, ascorbic acid, tocophereols, retinols, and carotenes, interrupt cancer initiation and promotion stages. Foods that contain these substances include vegetables in the cabbage family, onions and related vegetables, winter squashes, carrots, and a number of other plant foods. These compounds act on many stages of cancer development to detoxify carcinogenic substances, trap free radicals, combine with heavy metals to form inert products, repair damage to DNA and RNA, and suppress the formation of tumors. Protease inhibitors, such as those found in soybean products, also increase excretion of bile products and excess protein and protect cells from transformation due to ionizing radiation, including x-rays used in cancer therapy.

4. Dietary fibers play a protective role, particularly fiber rich in phytates, compounds which may be important inhibitors of colon cancer formation owing to their ability to lower production of certain types of oxygen free radicals (harmful chemical species that contain an unpaired electron, which makes them highly reactive). Phytates are found primarily in cereal grains. Fiber can increase fecal bulk, speed up transport of potentially carcinogenic substances through the bowel, and act as a prohibitive or blocking agent in the presence of carcinogens.

5. Though he deemphasizes the use of supplements in megadose quantities, Block uses both nutritional and botanical supplementation in cases where there is clinical evidence that such interventions are likely to be of value. Various nutrients, such as the fat-soluble vitamins A and E, and trace minerals, including selenium, working in combination, can boost both cell-mediated and antibody-mediated immune functions and increase the antigenicity of tumor cells. This has value not only as a protective measure against cancer but also as a therapeutic measure for cancer patients whose immune functions have been impaired through malnutrition, conventional treatment, or the effects of the disease itself.

Improved immune functions also can speed healing and reduce the risk of secondary or opportunistic infections, as well as aid in the fight against tumors. A vigilant, strong immune system may help to prevent a recurrence of cancer by destroying remaining cancer cells before they have an opportunity to proliferate.

Botanical supplements include such agents as Echinacea and garlic; their use is chiefly aimed at boosting immune function and counteracting side effects of cancer treatments. In the course of his clinical work, Block feels that he has consistently found that precise use of selected nutritional or botanical agents does indeed aid in diminishing side effects and enhancing effects of treatment.

6. The diet may be effective in helping patients remain in remission and help prevent the recurrence of neoplastic disease. Some researchers have suggested that the recurrence of some tumors may be due to the survival of “micrometastases” that escape conventional therapy. Components in the diet that block or suppress carcinogenesis may prevent these cells from establishing new colonies or may even destroy them.27


In my judgment, the Block program is clinically, scientifically, and historically significant for a number of reasons:

First, Block is not an alternative practitioner but a mainstream internist practicing within the paradigm of mainstream medicine and medical director of a multifaceted cancer care program which includes an inpatient ward in a Chicago medical center.

Second, I believe he has placed his nutritional program in precisely the right practice framework. It is a critical but coequal component of his program, whose six points include biomedical, biopsychosocial, biochemical-nutritional, and biomechanical-fitness components, as well as medical gradualism and therapy-mediating tools. I believe that is exactly as it should be.

Third, Block does not make excessive claims for the efficacy of good nutrition in cancer and at the same time he does not underplay its potential contribution. He has gathered the scientific evidence, made his clinical observations, and proposed a theory for how the scientific and clinical observations fit together, which I have outlined above. Block states clearly that while good nutrition is no panacea or cure for cancer, it appears clinically to enhance quality of life, to enhance resilience and response to conventional therapies, and possibly to slow tumor development, reduce the size and number of tumors that do occur, and reduce or delay recurrence in some patients.

In deemphasizing the standard use of supplements in megadose quantities, Block shares common terrain with macrobiotics and (to a large degree) the Gerson program, but not with Livingston and the majority of nutritional support programs for cancer. Whether or not a program that relies on diet alone for nutritional support in cancer is generally superior to a program that uses megavitamins is an important research issue that urgently requires further investigation.


From reviewing both the conventional and unconventional nutritional approaches to cancer discussed in the preceding chapters, I have reached the following conclusions:

The preponderance of the scientific and clinical evidence supports the hypothesis that there may be some beneficial effect for many cancer patients from a nutritional component in cancer treatment and care. This conclusion is not yet supported by controlled clinical trials, but I believe that the dominant mainstream position–that there is “no evidence” that nutrition makes any difference in cancer–is also not supported by the evidence. We should more properly say that the available laboratory and animal evidence, and the fragmentary evidence from human studies, suggests the possibility of some positive effects in some people with some cancers from nutritional treatment, and that controlled clinical trials are warranted and urgently needed.

We do not yet know how much difference nutrition makes in cancer in general, how much difference it makes in specific cancers at different stages, or how much difference it makes in different kinds of people with different cultural backgrounds, different biochemistries, and different attitudes about using nutrition in their fight for survival. But for some significant proportion of these people facing cancer, I predict that adjunctive nutritional support will ultimately be shown to make at least a modest difference in cancer survival.

It is equally clear that nutritional support will not prove to be any kind of panacea. From the extensive efforts that have been made to find people who have done well on the Gerson, macrobiotic, and Livingston programs, it is apparent that while some individuals have achieved individual “cures” or lasting remissions on nutritional programs, nutrition does not approach being a cure for cancer for most people who use these therapies. At best, it shifts the survival curve up in the way an effective chemotherapy does. If this is true, there will be more people who achieve lasting remissions at one extreme end of the curve for very serious cancers (which we find in the well documented case reports of survival), and more people who live longer all along the curve. There would, most important, be more people who do not have recurrences of cancer. We have no idea whether nutritional therapies will function this way across the broad range of cancers or, more likely, to very different degrees for different cancers. There is also the strong probability that some nutritional therapies may prove genuinely counterproductive for some specific cancers.

I believe that what the available evidence supports is a middle ground between the typical claims of most alternative cancer therapists and the typical critiques of the “Quack Busters.” Many, if not most, supporters of nutritional therapies for cancer have made excessive claims for the efficacy of these therapies. Some have touted their therapies as suppressed “cures” for cancers. Others have given excessive publicity to cancer patients who have apparently done well on these therapies, while failing to provide prospective patients with adequate information on what the general experience of cancer patients is with a particular nutritional therapy. Quack Busters, by contrast, dismiss nutritional therapies as quackery, with equally dubious justification.

We are only at the beginning of objective scientific evaluation of nutritional approaches to cancer treatment. But the information that we do have shows that, for some cancers, nutrition does make a significant difference in prevention and may make a difference in treatment. The magnitude of that difference in treatment, the degree of individual variation, the responses of specific cancers to nutritional regimens, and the effectiveness of specific nutritional programs remains, for now, unknown.


1 Keith I. Block, “Part 1–Block Nutrition Program.” In New Clinical Care Model: Applications to Cancer Patient Care, November 1989, 1-2. Prepared for Office of Technology Assessment. Reference updated by personal communication from Keith Block to author, 14 September 1990.

2 Ibid.

3 Ibid., 3.

4 Ibid., 4-5.

5 Ibid., 7.

6 Ibid., 7-8.

7 Ibid., 8-9.

8 Ibid., 9-10.

9 Ibid., 12.

10 Ibid.

11 Ibid., 15.

12 Ibid., 15-16.

13 Ibid., 18.

14 Ibid., 20.

15 Ibid., 25.

16 Ibid., 25-6.

17 Ibid., 27-8.

18 Lawrence Kushi, personal communication with author, 24 January 1991.

19 Block, “Part 1–Block Nutrition Program.” In New Clinical Care Model, 29-30.

20 Ibid., 33.

21 Ibid., 45.

22 Ibid., 48.

23 Ibid., 53.

24 Ibid.

25 G. Sakamoto, H. Sugano, and W.H. Hartmann, “Comparative Clinicopathology Study of Breast Cancer Among Japanese and American Females,” Japanese Journal of Clinical Oncology 25:161-70 (1979). Cited by Keith Block in personal communication with the author, 14 September 1990.

26 J. Barone, J.R. Herbert, and M.M. Reddy, “Dietary Fat and Natural Killer Cells Activity,” American Journal of Clinical Nutrition 50:851-67 (1989). Cited by Keith Block in personal communication with author, 14 September 1990.

27 Block, “Part 1–Block Nutrition Program.” In New Clinical Care Model, 52-6.