Cancer cells are metabolically flexible and can derive energy from various sources, including sugars in juices. The body's vital organs and immune system also require protein and calories to function. A prolonged, extreme fast can weaken the patient before it affects the tumor.

2. Severe Risk of Malnutrition and Catabolism

A 42-day, protein-free, ultra-low-calorie regimen is dangerously malnourishing. It leads to:

• Severe muscle wasting (catabolism), including heart muscle.

• Dramatic weakening of the immune system, the body's primary defense against cancer.

• Critical nutrient deficiencies (e.g., vitamin B12, essential fatty acids, complete proteins).

• Extreme fatigue, dizziness, and organ stress.

3. No Reputable Scientific Evidence

There are no credible, peer-reviewed clinical studies published in reputable medical journals demonstrating that the Breuss protocol can cure cancer. Anecdotal testimonials are not scientific evidence and do not account for spontaneous remission, the effects of concurrent conventional treatments, or misdiagnosis.

4. Interaction with Conventional Treatment

Undergoing such an extreme regimen while receiving chemotherapy, radiation, or surgery can be extremely dangerous. It can:

• Reduce the patient's strength and resilience needed to tolerate treatment.

• Alter drug metabolism.

• Lead to treatment delays or dose reductions due to poor health status.

The Nuanced Truth About Juice and Nutrition in Cancer Care

While the Breuss protocol itself is not supported, the role of nutrition is undeniably crucial in supportive care.

• Juices as a Supplement, Not a Cure: Vegetable juices can be a valuable supplement to a balanced, protein-rich diet for cancer patients, especially those with appetite or swallowing difficulties. They provide hydration, antioxidants, and easily absorbed vitamins.

• The Goal is Strength, Not Weakness: Modern oncology nutrition focuses on maintaining muscle mass, strength, and immune function to better endure and recover from treatment. This requires adequate calories and protein.

• Individualized Plans: A registered dietitian specializing in oncology can create a safe, evidence-based nutrition plan tailored to a patient's specific cancer, treatment, and needs.

The Bottom Line: A Potentially Dangerous Path

The Breuss 42-Day Juice Therapy is considered a dangerous and unsupported alternative cancer treatment by the global medical and oncological community. Its core premise is scientifically invalid, and its practice poses a serious and direct risk of severe malnutrition, physical decline, and harm.

What to Do Instead

If you or a loved one is considering complementary nutritional support:

1. Never abandon or delay proven conventional treatments (surgery, chemotherapy, immunotherapy, radiation).

2. Consult your oncologist and a registered dietitian (RD) who specializes in oncology nutrition.

3. Focus on an evidence-based, balanced diet designed to support strength and recovery.

4. Be highly skeptical of any protocol that promises a "cure" that medicine has overlooked, requires abandoning standard care, or is based on a single, simple theory.