Nutrition in Cancer Care

This information is provided by the NCI. In order to receive the most updated information it’s best to visit their site:
https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-hp-pdq?cid=eb_govdel#link/_255_toc

Present information regarding
Special Diets
Vegetarian or vegan diet
Macrobiotic diet
Ketogenic diet
Dietary Supplements
Vitamin C
Probiotics
Melatonin
Oral glutamine

Special Diets

Maintaining adequate nutrition while undergoing treatment for cancer is imperative because it can reduce treatment-related side effects, prevent delays in treatment, and help maintain quality of life. However, many patients view their diet as a way to enhance treatment effectiveness, minimize treatment-related toxicities, or target the cancer itself, often done by following a specific diet with supposed cancer-fighting benefits or by taking dietary supplements. Patients are likely to search the Internet and other lay sources of information for dietary approaches to manage cancer risk and to improve prognosis. Unfortunately, much of this information is not supported by a sufficient evidence base.

The sections below summarize the state of the science on some of the most popular diets and dietary supplements.

Vegetarian or vegan diet

A vegetarian diet is popular, is easy to implement and, if followed carefully, does not result in nutrition deficiencies. There is strong evidence that a vegetarian diet reduces the incidence of many types of cancer, especially cancers of the gastrointestinal (GI) tract. However, it is unknown how following a vegetarian or vegan diet can affect treatment-induced symptoms, cancer therapies, or outcomes for someone undergoing cancer therapy. There are no published clinical trials, pilot studies, or case reports on the effectiveness of a vegetarian diet for the management of cancer therapy and symptoms. There is no evidence suggesting a benefit of adopting a vegetarian or vegan diet upon diagnosis or while undergoing cancer therapy. On the other hand, there is no evidence that an individual who follows a vegetarian or vegan diet before cancer therapy should abandon it upon starting treatment.

One pilot study has suggested that following a plant-based diet can prevent tumor progression in men with localized prostate cancer. A randomized controlled trial based on this pilot study is under way to determine effectiveness. No other current clinical trials are studying the role of a vegetarian or vegan diet in cancer therapy.

Macrobiotic diet

A macrobiotic diet varies according to a person’s sex, their level of activity, and the climate (and season) in which they live, among other variables. It is a high-carbohydrate, low-fat, plant-based diet stemming from philosophical principles promoting a healthy way of living. The diet consists of 35% to 50% (by weight) whole grains, 25% to 35% vegetables, 5% to 10% soup, 5% to 10% cooked vegetables and sea vegetables, and 5% to 10% fish.

Although there are anecdotal reports on the effectiveness of a macrobiotic diet as an alternative cancer therapy, none have been published in peer-reviewed, scientific journals. No clinical trials, observational studies, or pilot studies have examined the diet as a complementary or alternative therapy for cancer. In fact, two reviews of the diet and its evidence for effectiveness in cancer treatment concluded that there is no scientific evidence for the use of a macrobiotic diet in cancer treatment. Because the current research is severely lacking, recommendations for or against the diet in conjunction with standard cancer treatment cannot be made. No current clinical trials are studying the role of the macrobiotic diet in cancer therapy.

Ketogenic diet

A ketogenic diet has been well established as an effective alternative treatment for some cases of epilepsy and has gained popularity for use in conjunction with standard treatments for glioblastoma. The theory behind the diet as cancer treatment is that reducing glucose availability to a tumor can reduce tumor activity, and that this reduction can be achieved through entering a state of ketosis via the ketogenic diet’s restriction of carbohydrates and increased fat intake.

The ketogenic diet can be difficult to follow and relies more on exact proportions of macronutrients (typically a 4 to 1 ratio of fat to carbohydrates and protein) than do other complementary and alternative medicine (CAM) diets. Therefore, most studies have focused on the diet’s feasibility, tolerability, and safety, all of which have been shown for glioblastoma patients at various stages of the disease.

Because safety and feasibility have been proven, several trials are recruiting patients to study the effectiveness of the ketogenic diet on glioblastoma. Therefore, if a patient diagnosed with glioblastoma wishes to start a ketogenic diet, it would be safe if implemented properly and under the guidance of a registered dietitian, but effectiveness for symptom and disease management remains unknown.

Dietary Supplements

Vitamin C

Current information:
Vitamin C is an essential nutrient with redox functions at normal physiologic concentrations.

High-dose vitamin C has been studied as a treatment for cancer patients since the 1970s.

Laboratory studies have reported that high-dose vitamin C has redox properties and decreased cell proliferation in prostate, pancreatic, hepatocellular, colon, mesothelioma, and neuroblastoma cell lines.

Two studies of high-dose vitamin C in cancer patients reported improved quality of life and decreases in cancer-related side effects.

Studies of vitamin C combined with other drugs in animal models have shown mixed results.
Intravenous vitamin C has been generally well tolerated in clinical trials.

Probiotics

The use of probiotics has become prevalent within and outside of cancer therapy. Strong research has shown that probiotic supplementation during radiation therapy, chemotherapy, or both is well tolerated and can help prevent radiation- and chemotherapy-induced diarrhea, especially in those receiving radiation to the abdomen. Therefore, if a patient is undergoing radiation to the abdomen or receiving a chemotherapy agent with diarrhea as a common side effect, starting a probiotic supplement upon initiation of therapy could be beneficial.

Melatonin

Melatonin is a hormone produced endogenously that has been used as a CAM supplement (along with chemotherapy or radiation therapy) for targeting tumor activity and for reducing treatment-related symptoms, primarily for solid tumors.

Several studies have shown tumor response to, or disease control with, chemotherapy alongside oral melatonin, as opposed to chemotherapy alone; one study has shown tumor response with melatonin in conjunction with radiation therapy.The combination of melatonin with chemotherapy may, in fact, increase survival time compared with chemotherapy alone, for up to 5 years. However, another study did not demonstrate increased survival with melatonin, but did demonstrate improved quality of life.

Melatonin taken in conjunction with chemotherapy may help reduce or prevent some treatment-related side effects and toxicities that can delay treatment, reduce doses, and negatively affect quality of life. Melatonin supplementation has been associated with significant reductions in neuropathy and neurotoxicity, myelosuppression, thrombocytopenia, cardiotoxicity, stomatitis, asthenia, and malaise. However, one study found no benefit in taking supplemental melatonin for reducing toxicities or improving quality of life.

Overall, several small studies show some evidence supporting melatonin supplementation alongside chemotherapy, radiation therapy, or both for solid tumor treatment, for aiding tumor response and reducing toxicities, while negative side effects for melatonin supplementation have not been found. Therefore, it may be appropriate to provide oral melatonin in conjunction with chemotherapy or radiation therapy to a patient with an advanced solid tumor.

Oral glutamine

Glutamine is an amino acid that is especially important for GI mucosal cells and their replication. These cells are often damaged by chemotherapy and radiation therapy, causing mucositis and diarrhea, which can lead to treatment delays and dose reductions and severely affect quality of life. Some evidence suggests that oral glutamine can reduce both of those toxicities by aiding in faster healing of the mucosal cells and entire GI tract.

For patients receiving chemotherapy who are at high risk of developing mucositis, either because of previous mucositis or having received known mucositis-causing chemotherapy, oral glutamine may reduce the severity and incidence of mucositis.

For patients receiving radiation therapy to the abdomen, oral glutamine may reduce the severity of diarrhea and can lead to fewer treatment delays. However, one study found no benefit to oral glutamine for preventing chemotherapy-related diarrhea.

In addition to reducing GI toxicities, oral glutamine may also reduce peripheral neuropathy in patients receiving the chemotherapy agent paclitaxel Larger randomized controlled trials need to be conducted to further determine the effectiveness of oral glutamine in treating peripheral neuropathy.

Oral glutamine is a safe, simple, and relatively low-cost supplement that may reduce severe chemotherapy- and radiation-induced toxicities.