Quantity and quality of fats can influence your long-term outcome.
“Can the amount and type of fat I eat affect how I respond to my treatment and whether I stay in remission?” I bet I hear this question about the cancer-fighting potential of diet from new patients entering my clinic at least twice a week. Based on the overall evidence to date, the answer to this question is a resounding “yes!” It turns out that dietary fat can have a major impact on progression, remission and even treatment. In other words, what choices you make when it comes to consuming dietary fat can influence cancer growth, cancer regrowth and even how well you tolerate and respond to treatment!
How can dietary fat have such far-reaching effects? To begin with, diets high in fat tend to cause more DNA damage, allowing malignant cells to accumulate more mutations – hence more aggressive cancer. In addition, a diet high in fat can weaken your immune system, while also increasing inflammation, angiogenesis (formation of new blood vessels that support tumor growth), and blood levels of tumor-promoting growth factors. Eating too much of the wrong types of fats – such as trans fats, which are found in partially hydrogenated oils – can also wreak havoc with your body’s cancer-promoting terrain. These connections could help explain why people on the standard American diet tend to have a higher rate of cancer and a worse prognosis than populations that adhere to a plant-based, low saturated-fat diet that is rich in fruits and vegetables. A growing base of research suggests that the healthier plant-based diet provides a greater abundance of calorically dilute foods. Consuming a lower caloric intake, as long as one is not in the middle of treatment or already malnourished, appears to slow growth and reduce the risk of recurrence.
My own interest in working with diet and cancer actually began with an exploration of the potential healing benefits of the Standard Macrobiotic Diet, which closely resembles the traditional Japanese diet. While I ended up modifying several aspects of this approach for my patients, the evidence supports a whole food, plant-based regimen that limits or eliminates heavy animal food intake and processed foods. Ever since the 1980s, studies have consistently found that breast cancer patients in Japan have higher survival rates and lower recurrence rates compared to their counterparts in the United States and Europe. Moreover, these superior survival rates are seen regardless of the type of conventional treatment the patient had received, indicating that medical treatment is not the reason for this improvement.
What could account for the differences in survival? Nutritional factors are certainly one contributing factor. The traditional Japanese diet is low in total fat content, but also relatively high in omega-3 fats (EPA and DHA) from coldwater fish and sea vegetables. These “good fats” can have a favorable impact on cancer survival. In a recent clinical trial in Tours, France, patients with aggressive metastatic breast cancer supplemented with 1.8 grams of DHA per day for one week prior to chemotherapy and then for five months during chemo. At the end of the study, those individuals with the highest amount of DHA in their tissues had the best responses to chemotherapy and a near doubling in their overall survival rate.[i] The same research team had previously shown that, among 121 early-stage breast cancer patients who had undergone a lumpectomy, those with the lowest omega-3 levels in their breast adipose tissues had a doubling in their recurrence rate compared to those with the highest omega-3 levels.[ii]
It’s also important to keep saturated fat to a minimum. A 2008 Study in the International Journal of Cancer found that men who ate the least saturated fat were half as likely to have their prostate cancer recur after their initial treatment. And breast cancer patients with the highest consumption of saturated fat were twice as likely to die from their disease as patients with the lowest intakes. To break this down further, for every increase of 5 percentage points in the calories obtained from saturated fat (roughly equivalent to adding 2 tablespoons of cream, or 1 ounce of cream cheese to your daily diet), the risk of dying from breast cancer increased by 50%![iii]
As of this writing, at least seventeen studies have examined the relationship between dietary fat intake and breast cancer outcomes. Though the findings have been mixed, in some cases the outcomes have been dramatic. For example, in a 2004 study involving 603 breast cancer patients in Vancouver, Canada, those with the highest fat intake level were about five times less likely to survive than those with the lowest fat intake.[iv] However, most studies to date have been observational, meaning that the studies were merely measuring what patients were already doing, rather than trying to guide their dietary choices upfront.
The gold standard of all medical research is the randomized controlled trial. Two such studies have been completed in recent years. The first of these was the Women’s Intervention Nutrition Study (WINS). After five years, there was a 24% reduction in the relative risk of recurrence for the women on the low-fat diet. The largest risk reduction – 42% – appeared to be among women on the low-fat diet whose tumors did not respond to the presence of the hormone estrogen. The WINS intervention group also showed significant weight loss, which is consistent with research showing that obese survivors are at increased risk of relapse.
The other randomized clinical trial, known as The Women’s Healthy Eating and Living (WHEL) Study, focused on a plant-based diet that included some emphasis on lowering dietary fat. This study did not initially show any reduction in recurrences. However, among the 900 WHEL participants who did not report hot flashes at the start of the study, there was a 60% lower risk of recurrences among those who made the low-fat, high-fiber dietary changes, and this was not explained by other factors; additionally, this was unrelated to hormone receptor status.
The Bottom Line:
The amount and type of fat you consume after a cancer diagnosis does matter. Evidence strongly suggests that a low-fat diet – in combination with omega-3 supplementation, high vegetable intake, and regular exercise – can improve your chances of staying in remission. And while much of the research to date has focused on breast cancer, we are increasingly seeing the relationships carry over to other types of cancer as well. Healthcare practitioners should be duty-bound to inform their cancer patients of this vital connection, and to guide their patients in adopting a high-fiber, low saturated-fat diet, comprised of plant-based proteins and rich in whole grains, cold water fish (which is rich in omega-3 fatty acids), and fruits and vegetables.
For more information on The Block Center for Integrative Cancer Treatment, visit BlockMD.com.[i] Bougnoux P, Hajjaji N, Ferrasson MN, Giraudeau B, Couet C, Le Floch O. Improving outcome of chemotherapy of metastatic breast cancer by docosahexaenoic acid: a phase II trial. Br J Cancer. 2009 Dec 15;101(12):1978-85.
[ii] Bougnoux P, Koscielny S, Chajes V, Descamps P, Couet C, Calais G. alpha-Linolenic acid content of adipose breast tissue: a host determinant of the risk of early metastasis in breast cancer. Br J Cancer. 1994 Aug;70(2):330-4.
[iii] ** This paragraph is adapted from page 62 of Life Over Cancer.
[iv] Borugian MJ, Sheps SB, Kim-Sing C, et al. Insulin, macronutrient intake, and physical activity: are potential indicators of insulin resistance associated with mortality from breast cancer? Cancer Epidemiol Biomarkers Prev. 2004; 13(7):1163-72
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