Antioxidants are compounds that have the potential to block the activity of other chemicals called free radicals. Free radicals are highly reactive chemicals that have the potential to harm cells. The damage done to the cells, particularly to the DNA of the cells, may play a role in the development of cancer and other diseases (NCI, 2014). Antioxidants are sometimes called free radical scavengers.
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While some antioxidants can be made by the body, others are obtained from the diet. Examples of dietary sources of antioxidants include:
• Vitamin A
• Vitamin C
• Vitamin E
The mineral selenium is sometimes considered a dietary antioxidant, although the antioxidant activity of proteins that contain selenium is more likely to provide the antioxidant activity than the element on its own (Davis, Tsuji and Milner 2012).
Because of the role that free radicals play in the development of cancer and due to the potential for antioxidants to block this activity, people are curious about using antioxidant supplements for cancer prevention and treatment. In a review of nine clinical trials conducted to study the effect of antioxidant supplementation on cancer prevention, the National Cancer Institute (NCI) has determined that, “Overall, these nine randomized controlled clinical trials did not provide evidence that dietary antioxidant supplements are beneficial in primary cancer prevention” (NCI 2014). The U.S. Preventive Services Task Force (USPSTF) has also concluded that there is no clear benefit for the use of antioxidant supplements in the prevention of cancer (Fortmann et al. 2013). Antioxidant supplements also do not appear to be useful for people who already have cancer, and in some cases, outcomes were actually worse, especially for those who were smokers (Lawenda et al. 2008).
Nutrition and Cancer Treatment.
For people already diagnosed with cancer, healthy eating and maintaining optimal nutrition can help maintain strength, keep body tissue healthy, and fight against infection. Because cancer can change the way your body utilizes certain nutrients, additional vitamin and/or mineral supplements or alterations to the diet may be recommended as a part of a cancer patient’s treatment plan. Cancer, its side effects, and the effects of treatment such as chemotherapy and radiation can also change the body’s relationship with food and the ability to ingest food (NCI 2014a). Some common nutrition-related side effects include:
• Anorexia (loss of appetite)
• Mouth sores or dry mouth.
• Trouble swallowing.
• Nausea and vomiting.
• Diarrhea and constipation.
• Pain, depression, and anxiety.
Cancer treatments and medications can interfere with the way food tastes and smells. These, along with the side effects listed above, can all contribute to a reduced intake and resultant malnutrition. Malnutrition may worsen as the cancer advances, making it increasingly difficult for the person with cancer to adequately eat the amount and types of foods needed to help keep the body strong during treatment. Table 3.4 offers high calorie, high protein recommendations for meeting increased needs during cancer treatment.
High Fat, High Calorie Ideas to Increase Intake in Cancer Patients.
Add oils, butter, or margarine to foods, soups, and casseroles.
Saute vegetables and meats in oil.
Use full fat condiments such as mayonnaise or salad dressings and cream cheese.
Try half-and-half and cream, whole milk.
Snack on nuts, cheese, eggs, or add high fat meats to menu items.
Drink oral supplements between meals.
Consume beverages between meals to increase calorie intake from foods at meals.
Determining Protein Needs.
Alongside a reduction in muscle protein synthesis, protein turnover rates increase in cancer. Evidence-based guidelines state that protein needs are elevated beyond the standard 0.8 g/kg RDA for those with head and neck cancer, in those undergoing radiation therapy, and in those with hematological malignancies undergoing allogeneic hematopoietic stem cell transplants. Protein needs are 0.8 to 1.0 g/kg for normal maintenance, 1.0 to 1.2 g/kg for non-stressed patient with cancer, 1.2 to 1.5 g/kg for those undergoing treatment, 1.5 to 2.0 g/kg for stem cell transplant, and 1.5 to 2.5 g/kg for those with protein-losing enteropathies or wasting (AND, 2015b), (Hurst and Gallagher 2006). Protein should be limited to 0.5 to 0.8 g/kg with hepatic or renal compromise, when BUN is approaching 100 mg/dL, or in light of elevated ammonia levels (Cohen 2011). Dietetics practitioners can also request labs for serum proteins such as albumin, prealbumin, and transferrin to monitor nutrition status. C-reactive protein (CRP) may also be a useful biomarker, as it is sensitive to inflammation and may serve as a precursor to cachexia.