Cancer is a complex disease that arises when normal cells undergo mutations and begin to divide uncontrollably, invading tissues and, in many cases, spreading to other parts of the body. According to data from the U.S. National Cancer Institute, nearly 10 million people worldwide died from this disease in 2020 alone. Despite advances in targeted therapies, chemotherapy, radiation, and immunotherapy, an essential factor in prevention and patient care continues to be sidelined: nutrition.
For years, research has focused on the genetic and molecular mechanisms that drive cancer, relegating the impact of diet and nutritional status in its development and management. However, there is growing evidence that what we eat can make a crucial difference, both in prevention and in treatment response. In fact, it is estimated that 30 to 40% of all cancers could be prevented through proper diet and a healthy lifestyle.
One of the most concerning findings is that between 40 and 80% of cancer patients suffer from malnutrition. This condition may be due to the disease itself, the side effects of therapy, or difficulty absorbing nutrients. Malnutrition is no minor detail: it reduces the body’s ability to tolerate treatments, weakens the immune system, and worsens quality of life.
Patients require more energy, protein, and fluids than a healthy person, since cancer generates a state of hypermetabolism. Therefore, an energy intake of 20–35 kcal/kg per day is recommended, with protein in the range of 1.2–1.5 g/kg to prevent muscle loss. Likewise, proper hydration (≈35 mL/kg) is vital to maintain electrolyte balance and remove toxic metabolites released during tumor destruction.
Nutrients as Therapeutic Targets
Beyond general support, modern research explores how certain nutrients are essential for the survival of cancer cells and could become therapeutic targets.
Asparagine: indispensable for the proliferation of some tumors, such as leukemia. Mouse studies have shown that a diet low in this amino acid reduces metastasis. In fact, drugs such as asparaginase already exist, eliminating it from the body as a therapeutic strategy.
Arginine: some tumors (such as melanoma, hepatocellular carcinoma, and prostate cancer) cannot produce it and depend on external sources. Dietary deprivation or the use of enzymes that degrade arginine has been shown to slow their growth.
Cystine: linked to the production of glutathione, a powerful antioxidant. Its deficiency can induce ferroptosis, a type of iron-dependent cell death to which cancer cells are particularly vulnerable.
Folate (vitamin B9): essential for DNA synthesis. In excess, it accelerates tumor proliferation, but it has also enabled the development of antifolate therapies such as methotrexate, used in leukemia and other cancers.
Glutamine and glutamate: fundamental for tumor energy and antioxidant metabolism. Blocking their utilization has been effective in some experimental models, though researchers are still investigating how to achieve this selectively.
This field, known as metabolic therapy, seeks to exploit the biochemical weaknesses of tumor cells to improve the effectiveness of conventional treatments.
Diets and Eating Patterns: Help or Risk?
The way we structure our diet also influences cancer risk and treatment response.
High saturated-fat diets: associated with higher incidence of colorectal and breast cancer, largely due to their negative impact on inflammation, gut microbiota, and hormonal metabolism. Excess saturated and processed fats can activate pathways that promote uncontrolled cell proliferation.
Ketogenic diet: studies in animal models have shown it can reduce tumor growth, improve tolerance to chemotherapy, and increase survival. Possible mechanisms include reducing glucose availability for the tumor, modulating mitochondrial metabolism, and lowering free radicals. However, its effectiveness depends on cancer type, and conclusive clinical trials in humans are still lacking.
Mediterranean diet: rich in fruits, vegetables, olive oil, fish, and nuts, it provides antioxidants, fiber, and omega-3 fatty acids that help regulate inflammation and protect against cancer. Preliminary studies suggest it may reduce the incidence of colorectal and breast tumors.
These dietary patterns show that nutrition can be both a risk factor and a protective factor, depending on the quality of the foods consumed.
Fig. 1. Key nutrients such as asparagine, arginine, cystine, and folate can directly influence tumor metabolism. While deficiencies in some of them weaken cancer cell survival, excess intake of others may accelerate tumor growth. This highlights the importance of tailored nutritional strategies in cancer care.
Clinical Nutrition: An Ally in All Stages of Treatment
The role of nutrition is not limited to prevention. It is also crucial during oncology therapy and in the recovery period.
In oncologic surgery, good nutritional status promotes wound healing, reduces complication risk, and accelerates recovery.
In radiotherapy, an adapted diet can lessen side effects such as mucositis, xerostomia, diarrhea, or taste alterations, improving adherence to treatment.
In chemotherapy, proper nutrition helps combat anemia, immunosuppression, and nausea. In some cases, specific diets such as the neutropenic diet are used, which restrict foods with high microbial content to prevent infections.
Implementing the Nutrition Care Process (NCP), which includes assessment, diagnosis, intervention, and monitoring, is essential to adapt diet to each patient. This systematic approach not only improves treatment tolerance but also quality of life and, in many cases, survival.
The Challenge: Integrating Nutrition into Oncology
Although the scientific evidence is clear, nutrition still does not receive the attention it deserves in clinical practice. Many healthcare professionals lack specialized training in this field, leading to low integration of nutritional counseling in treatment protocols.
The article highlights the need for public policies and health programs that recognize the importance of nutrition in oncology. This includes ensuring access to essential supplements, designing specific guidelines for patients undergoing new therapies (such as immunotherapy), and training professionals in the early detection and management of malnutrition.
It is also urgent to promote translational research to bring laboratory findings into clinical practice, with studies that evaluate the real effectiveness of dietary interventions in cancer patients.
Nutrition should not be seen as an optional complement, but as a central pillar in cancer prevention, treatment, and recovery. What we eat can influence tumor development, therapy effectiveness, and the body’s ability to withstand side effects. Adopting an integral approach that combines pharmacology, advanced therapies, and personalized nutrition will not only improve clinical outcomes but also offer patients a better quality of life.
The future of oncology requires greater integration of nutrition into clinical practice, both at the research and public policy levels. Understanding that diet is a therapeutic tool as powerful as drugs is a decisive step toward a more humane, comprehensive, and effective medicine.
Main Reference:
Zeb, F., Mehreen, A., Naqeeb, H., Ullah, M., Waleed, A., Awan, U. A., Haider, A., & Naeem, M. (2024). Nutrition and Dietary Intervention in Cancer: Gaps, Challenges, and Future Perspectives. Cancer treatment and research, 191, 281–307. https://doi.org/10.1007/978-3-031-55622-7_11
Other References:
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