Nutrition and Cancer: Separating Fact from Fiction

Countless diets and nutritional tips circulate, promising to stop or even cure cancer. But what role does nutrition truly play in cancer prevention and support? We explore the science-backed evidence, debunking myths and offering guidance for those navigating a cancer diagnosis.

Is There a Diet That Can Cure Cancer?

To be immediately clear: there is no single diet or nutritional pattern that can slow down, let alone cure, cancer. There is no scientific evidence supporting the claim that a specific diet can cure cancer or replace conventional cancer treatment. While interest in nutrition and cancer has grown, many complementary or alternative fad diets are highly restrictive and make unsubstantiated claims.

Eliminating entire food groups, such as dairy or carbohydrates, during cancer treatment is generally not advisable. Such restrictions can lead to nutritional deficiencies and hinder the ability to maintain weight, potentially compromising the treatment plan. If a diet, food, or supplement could effectively slow or cure cancer, it would already be widely used in medicine – and it isn’t.

Does Diet Play a Role in Cancer Development?

Approximately 40%–50% of all cancers and cancer deaths are linked to modifiable, preventable risk factors. Major contributors include smoking (19%–30% of cases), obesity (7.8%), and diet and alcohol consumption (5.6%). It’s estimated that 90%–95% of cancers are due to environmental and lifestyle factors, with only 5%–10% being hereditary.

Certain nutrients can slow down cancer development and, in some cases, even help prevent it. Examples include glucosinolates (found in cabbage), green tea, coffee, various fruits and vegetables, selenium, and vitamin D3. However, food too contains substances that can promote cancer development, such as polycyclic aromatic hydrocarbons and heterocyclic amines, which form when protein-rich foods are burned.

These nutritional effects are best considered in the context of prevention, not treatment of existing cancer.

Debunking Popular “Alternative Cancer Diets”

The Ketogenic Diet

The ketogenic diet may create an unfavorable metabolic environment for cancer cells and could be considered as an adjunctive strategy within a patient-specific, multifactorial therapy. Preclinical studies and some clinical trials suggest potential benefits when combined with standard therapies, potentially enhancing their antitumor effects. The diet is generally well-tolerated and may improve quality of life. However, leading cancer organizations do not recommend the ketogenic diet as a sole treatment for cancer or for cancer prevention.

The Alkaline Diet

The pH of blood is precisely regulated by the kidneys and lungs, and it’s not possible to change it through diet. The alkaline diet is based on the idea that an acidic environment promotes disease, while an alkaline environment fosters good health. However, studies supporting this claim have been conducted in laboratory settings and aren’t directly applicable to the human body.

There is no scientific evidence that an alkaline diet reduces cancer risk or offers protection against it. Such a diet, often avoiding meat and dairy, doesn’t alter blood pH and can lead to unwanted weight loss and nutrient deficiencies, impacting health and treatment. A highly alkaline environment could even reduce the effectiveness of chemotherapy.

Intermittent Fasting

Intermittent fasting, involving prolonged periods of fasting or severely restricted eating, is not recommended for individuals diagnosed with cancer. Fasting can impair nutrient absorption, and cancer treatment requires ample energy, protein, vitamins, and minerals. It also increases the risk of weight loss, which should be avoided during treatment. Research on intermittent fasting is still in its early stages, primarily conducted on animals and isolated cells, providing limited evidence for its use in cancer patients, especially those at risk of malnutrition or with diabetes.

What Should a Cancer Patient Eat and Drink?

A nutritious diet is essential during cancer treatment. Research shows that weight loss due to cancer or its treatment can decrease response to therapy, worsen side effects, and lower overall survival. Unintentional weight loss is also stressful and significantly impacts quality of life.

A healthy diet includes a variety of foods – carbohydrates, proteins, fats, vitamins, and minerals. Energy- and protein-rich diets help patients maintain a healthy weight during treatment. However, disease or therapy side effects can make eating and maintaining weight challenging.

A helpful resource is the publication “Nutrition in Cancer” from Ghent University Hospital, available for free download. https://www.uzgent.be/en/patient-information/nutrition-cancer This brochure provides practical and accessible information about nutrition for people undergoing cancer treatment.

Expert Advice on Nutrition and Cancer

There is no “magic bullet” diet, superfood, vitamin, or drink that can cure cancer. Cancer typically results from years of genetic damage caused by environmental factors and lifestyle choices, and to a lesser extent, genetic predisposition. Once diagnosed, no amount of kale or vitamins will make the disease disappear.

Focus on prevention, where nutrition plays a vital role. If you have cancer, rely on conventional medicine and well-established treatments. Cancer treatment techniques have dramatically improved, increasing the chance of cure with early detection. Organizations like ‘Kom op tegen Kanker’ and ‘Stichting tegen Kanker’ invest millions in scientific research annually.

Avoid dubious diets and quacks promoting unproven supplements or treatments. There’s no scientific evidence they help, and relying on them can be risky, potentially delaying valuable, proven medical care.

References:

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• De Maerteleire, Dr. Ir. Eric – Slowing down aging through nutrition. Manteau, August 2024, 330 pages.
• Weber DD, Aminzadeh-Gohari S, Tulipan J, Catalano L, Feichtinger RG, Kofler B. (2020). Ketogenic diet in the treatment of cancer – Where do we stand? Mol Metab; Mar:33:102-121.
• Schwalfenburg GK (2012) The Alkaline Diet: Is there evidence that an alkaline pH diet benefits health? Journal of Environmental and Public Health. Vol. 7.
• Fenton TR & Huang T (2016) Systematic review of the association between dietary acid load, alkaline water and cancer. BMJOpen. Volume 6; Issue 6.
• Piersol B. Intermittent Fasting and Breast Cancer: What You Need to Grasp | Memorial Sloan Kettering Cancer Center. https://www.mskcc.org
• Clifton KK, Ma CX, Fontana L, Peterson LL. (2021). Intermittent fasting in the prevention and treatment of cancer. CA A Cancer J Clin; Nov;71(6):527–46.