3 trends you should never recommend to patients, according to an oncologist
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“Sugar doesn’t feed cancer." — Yousuf Zafar, MD, MHS, FASCO, oncologist
"Eat a balanced, healthy diet that helps you maintain your weight and tolerate chemotherapy." — Dr. Zafar
You know that just because a nutrition trend is popular on social media doesn’t mean it belongs in your patients' diets. In fact, some popular nutrition fads can do more harm than good.
In a recent TikTok video, Yousuf Zafar, MD, MHS, FASCO, a medical oncologist and associate professor of medicine at Duke University, tackled three nutrition trends that many patients consistently ask about—despite there being little-to-no clinical benefit.
Read his hot takes on these lingering fads and why you should also caution patients against jumping on the health BS-bandwagon.
Alkaline Water
The trend: The popularity of alkaline water among some cancer communities stems from the unproven theory that an acidic environment promotes cancer. []
Dr. Zafar’s take: “If you could change the pH of your blood by something you eat or drink, you’d be in the intensive care unit,” he said. "Your lungs and your kidneys are too smart for that."
What this means for your practice: As oncologists know, blood pH is tightly regulated by the lungs and kidneys—regardless of what a patient drinks. While it’s not dangerous in moderation, alkaline water shouldn’t be recommended or prioritized. When patients bring it up, it’s a teachable moment about the body’s regulatory systems and the importance of evidence-based interventions.
Related: Common nutrition myths debunked by scienceJuicing
The trend: Many oncology patients believe juicing is a shortcut to “super nutrition” during treatment. But juices often spike blood sugar without delivering the fiber, phytonutrients, and satiety benefits of whole produce. []
Dr. Zafar’s take: "Yes, fruits and vegetables are healthy, but when you juice, you eliminate all of that very healthy fiber and other nutrients," he said.
What this means for your practice: Encourage patients to eat their fruits and veggies rather than drink them—especially when maintaining stable blood sugar and GI function is critical during chemotherapy.
Eliminating Sugar
The trend: The myth that sugar “feeds” cancer persists, despite evidence showing cancer metabolism adapts even under glucose restriction. []
Dr. Zafar’s take: “Sugar doesn’t feed cancer. If you eliminate carbs, cancer cells will just create more from fats and proteins," he said.
What this means for your practice: Over-focusing on sugar avoidance can lead to malnutrition or poor treatment tolerance. Emphasize balanced, sustainable nutrition. A healthy, whole-food diet that supports weight maintenance and treatment adherence is far more beneficial than carb restriction for most patients.
Related: Expert dietary tips that every doctor should knowThe Bigger Picture
As patients increasingly turn to social media for guidance, oncologists should feel empowered to debunk pseudoscience and recenter the conversation on evidence-based, achievable dietary habits that optimize outcomes.
Bottom line, says Dr. Zafar in his video: "Eat a balanced, healthy diet that helps you maintain your weight and tolerate chemotherapy."