The Immunotherapy Diet – Fighting Cancer with Nutrition.
One of the most promising developments in the treatment of cancer has been the field of immunotherapy. Recruiting the immune system in the fight against cancer has been around since Dr. William Coley triggered an immune response by injecting inactivated bacteria in cancer patients in the late 19th Century. However, over the many decades that followed, the approach gained little conventional acceptance. Fortunately, with the recent development of drugs like ipilimumab, nivolumab and pembrolizumab, oncologists are now gaining awareness of the vast potential held by immunotherapy.
While the specific mechanisms driving immunotherapy vary by medication, the general underlying theme is the recruitment or “re-training” of the patient’s immune system, to modulate the inflammatory cascade and better identify or destroy cancer cells. For example, the drug pembrolizumab acts by blocking a protein called PD-1 (“programmed cell death protein 1”), which binds to T cells in the immune system and prevents them from attacking certain types of cancer cells. By blocking the PD-1 protein, the drug enables the immune system to attack and destroy cancer cells. This approach differs from standard chemotherapy, in which the drug itself directly destroys cancer cells (often along with many healthy cells—essentially collateral damage). Stimulating our bodies’ own inherent anti-cancer processes sounds pretty ideal, right?
Unfortunately, at this time, immunotherapy has only been proven effective against a limited number of cancer types, including melanoma, kidney and lung cancers. While research continues to expand this list, it is nonetheless frustrating that more patients are unable to benefit from immunotherapy.
Actually, that’s not exactly true. While there may not be suitable immunotherapy drugs for every cancer type, it’s still possible to tap into this approach through diet and supplementation; Fighting Cancer with Nutrition. It has been well established that certain diets are pro-inflammatory (fatty, fried, preservative-laden Western diet, I’m looking at you!). These diets, typically rich in simple sugars, saturated fat and animal protein, and low in fibre, healthy fats, fruits and vegetables, increase blood levels of insulin, insulin-like growth factor 1 (IGF-1) and chemicals called interleukens (IL-17 and IL-21) – compounds that all add fuel to a developing cancer’s fire. Conversely, the adoption of a healthier, more balanced diet has proven equally impactful, strengthening and focusing the immune system to combat a wide variety of cancer types. But with frequent discussion of ketogenic, Mediterranean and other diets, which is best?
Fortunately, a recent article by Laura Soldati et.al. published in the Journal of Translational Medicine set out to answer just that question. First, the Mediterreanean diet was examined. Generally low in animal fats and high in fruits, vegetables and whole grains, with healthy fats from fish and olive oil, the Mediterranean diet shows great promise. In two very large studies, each involving over 1.5 million people, the adoption of such a diet showed significantly decreased overall mortality and mortality from cardiovascular disease, as well as lower cancer incidence and mortality. The diet specifically showed decreases in rates of breast, colorectal, gastric, prostate, liver, head and neck, pancreatic and lung cancers. The authors speculated that, among numerous other anti-cancer mechanisms, the nutrient-rich compounds found in foods such as healthy fats stimulate the immune system’s production of anti-inflammatory compounds IL-10 and IL-22. They also noted that these beneficial effects may also be due the diet’s general absence of harmful chemicals like pesticides and fertilizers.
The second diet investigated in the article was a vegetarian diet. While a diet rich in plant-based antioxidants, fibres and healthy fats certainly possesses anti-inflammatory benefits, the data regarding its actual anti-cancer benefits was less convincing. In fact, a study with nearly 700,000 patients diagnosed with breast, colorectal or prostate cancer failed to show any correlation between cancer status and a vegetarian diet. In addition, a systematic review of 96 studies of this diet also showed no significant decrease in cancer rates or mortality for breast, colorectal, prostate or lung cancer. Finally, those adhering to a strict vegetarian diet are also at increased risk of nutrient deficiencies, including B12, zinc, iron, omega 3 fats and possibly vitamin D, further impacting immune function and overall health.
Similarly beneficial to the Mediterranean diet is the Japanese diet, supported by Japan’s world-leading overall life expectancy. This low-calorie diet is rich in foods known to promote the immune system’s ability to fight cancer, including green tea (rich in flavonoids), meso soup (with wakame sea vegetable high in the carotenoid fucoxanthin), soybeans (with isoflavones and saponins) and fish.
As for low calorie and ketogenic diets, the results are a little less clear. While low calorie diets may lower risk of chronic diseases (including cancer), as well as increase life expectancy, a specific decrease in protein content can impede the development of tumours and suppress inflammation. Meanwhile, a very-low-carbohydrate ketogenic diet (VLCKD), high in protein and fat and providing under 50 grams of carbohydrates per day, may also slow the progression of cancer (in part by lowering the aforementioned insulin and IGF-1). Finally, a VLCKD containing more fat than protein has been shown to impede cancer growth while simultaneously protecting healthy cells from damage during chemotherapy.
Just as relevant in the discussion of natural immunotherapy effects as diet is the use of supplementation. Among the many potentially impactful supplements for cancer patients to consider are probiotics. A healthy gut flora has been shown to promote immune system production of anti-inflammatory compounds like IL-10, IL-25 and IL-33, while suppressing tumor growth. On the other hand, a gut microbiome overrun with harmful bacteria like E. Coli can have the opposite effect, fuelling both inflammation and tumor growth (especially with respect to colorectal cancer). Other powerful natural anti-inflammatory and anti-cancer supplements include curcumin, green tea, quercetin and resveratrol.
As we began our discussion, the role of immunotherapy in cancer treatment continues to expand with each new study. And despite the fact that many patients still receive a diagnosis for which no effective immunotherapy treatment exists, there is nonetheless hope that through proper diet and supplementation, all cancer patients may have this powerful weapon at their disposal.
Soldati L, Di renzo L, Jirillo E, Ascierto PA, Marincola FM, De lorenzo A. The influence of diet on anti-cancer immune responsiveness. J Transl Med. 2018;16(1):75.
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Erik Boudreau, ND