A real study of 826 people with stage III colon cancer, all receiving standard cancer treatment, found that those who ate two servings of tree nuts a week had a 57% improvement in overall survival compared to those who ate none. That’s a genuinely striking number from real, published research — and it’s part of a broader picture of how food can support the body’s own defenses alongside medical treatment. (Based on the insights of Dr. William Li)
Key Takeaways
- A real, published study of 826 stage III colon cancer patients found tree nut consumption (2+ servings/week) linked to a 57% improvement in overall survival alongside standard treatment.
- A gut bacterium called Akkermansia muciniphila is associated with better response to cancer immunotherapy, and can be supported by foods like pomegranates, cranberries, and chili peppers.
- Anti-angiogenic foods (soy, tomatoes, green tea, berries, brassica vegetables) work by targeting the blood supply tumors need to grow.
- Cancer stem cells drive recurrence after treatment — purple potatoes, green tea, coffee, and walnuts have been studied for effects on these specific cells.
- None of this replaces cancer treatment — food is a complementary tool to use alongside, not instead of, medical care from an oncology team.
The Tree Nut Study
This comes from a real analysis of the CALGB 89803 trial, published in the Journal of Clinical Oncology. Among 826 patients with stage III colon cancer who had already completed standard chemotherapy, those eating at least two 1-ounce servings of nuts per week showed a 42% improvement in disease-free survival and a 57% improvement in overall survival compared to those who ate none. The benefit was specifically tied to tree nuts (like walnuts, almonds, and cashews) rather than peanuts, which are technically a legume. The proposed reasoning: nuts provide healthy fats that support immune function, along with dietary fiber that feeds beneficial gut bacteria, which in turn helps regulate inflammation. This is an observational finding, not a controlled trial testing nuts directly, so it shows a real association worth knowing about rather than definitive proof of cause and effect — but it’s a genuinely notable result from serious cancer research.
The Gut Bacteria Connection to Immunotherapy
A separate study of 249 cancer patients receiving immunotherapy — treatment that activates a patient’s own immune system against cancer, rather than chemotherapy — found that patients who didn’t respond to the treatment tended to be lacking a specific beneficial gut bacterium called Akkermansia muciniphila. This bacterium is associated with lower inflammation and stronger immune function, and it’s naturally supported by eating foods like pomegranates, cranberries, mangoes, chili peppers, and Chinese black vinegar.
If you’re curious whether you have healthy levels of this bacterium, a gut microbiome test — typically a mail-in stool sample kit — can check for it, along with screening for potentially harmful bacteria contributing to inflammation. Bringing these results to your oncologist can help inform your broader treatment conversation, since this kind of information may help predict how well certain treatments will work for you specifically.
There’s No One-Size-Fits-All List
Every cancer patient is different — someone managing diabetes alongside cancer will need a different food approach than someone with celiac disease or another autoimmune condition. That said, there are general principles worth understanding that apply broadly.
Principle #1: Cutting Off a Tumor’s Blood Supply
Cancers grow their own blood vessels to feed themselves, a process called angiogenesis. Research has found that once blood vessels reach a tumor, that tumor’s growth rate can increase dramatically within just a couple of weeks. Certain foods contain naturally occurring compounds that work against this process, sometimes called anti-angiogenic foods: soy, tomatoes, green tea, coffee, oily fish (or omega-3 supplements), berries (raspberries, blueberries, strawberries, blackberries), red grapes, and brassica vegetables like broccoli, cauliflower, kale, and bok choy.
Principle #2: Targeting Cancer Stem Cells
Cancer stem cells are a particularly dangerous subset of cells within a tumor — they’re capable of regenerating the cancer even after treatment appears successful, which is part of why cancer sometimes returns after a period of remission. Certain foods have been studied for their ability to work against these specific cells: purple potatoes (their anthocyanin pigments have been studied for effects on colon cancer stem cells specifically), green tea, coffee, and tree nuts like walnuts.
Principle #3: Strengthening Immune Defenses
A strong immune system plays a direct