A new scientific review challenges popular beliefs about vitamins and dietary trends in cancer prevention and treatment, warning that unsupervised use of supplements and restrictive eating plans could do more harm than good. The study, led by Dr. Salvatore Cortellino and Professor Antonio Giordano, President of the Sbarro Health Research Organization (SHRO), was published in Expert Review of Anticancer Therapy.
The research highlights that, while vitamin deficiencies are common among cancer patients and may increase cancer risk, simply taking over-the-counter or pharmaceutical-grade multivitamins has not shown clear benefits in improving outcomes. Instead, the authors emphasize the proven value of a balanced diet—especially the Mediterranean diet—for maintaining proper nutrition and supporting overall health.
“Following dietary fashions without clinical guidance can be not only ineffective but potentially harmful for cancer patients,” said Professor Giordano, also a molecular oncologist at Temple University and the University of Siena.
The review also raises serious concerns about hypervitaminosis, a condition caused by excessive vitamin intake. In cancer patients, this imbalance may even promote tumor growth. Similarly, popular diet trends such as the ketogenic diet, intermittent fasting, or strict veganism, while promising in early lab studies, lack solid evidence of effectiveness in humans. These diets may worsen malnutrition, especially in elderly or vulnerable patients.
Significant contributions to the study were made by Dr. Teresa Esposito of ASL Napoli 3 Sud in Naples and Dr. Francesca Pentimalli of LUM University in Bari. Together, the authors stress the importance of consulting healthcare professionals before making any major changes to diet or starting supplements.
“Health is best preserved through physiological balance,” the study concludes. This includes eating a varied and wholesome diet, getting enough calories, and staying physically active. These lifestyle principles, drawn from the European Code Against Cancer and the Mediterranean way of life, continue to be the foundation of cancer prevention and patient wellbeing.
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