Within about a week of a cancer diagnosis, most people have been handed more nutrition advice than they will receive from their medical team over the entire course of treatment.
It arrives from everywhere. A cousin sends apricot seeds. A coworker forwards a video about sugar. Someone at church mentions a mushroom blend that cured their neighbor’s brother. A stranger in a waiting room says to cut out dairy. Most of it comes from people who love you, or at least mean well, and almost none of it comes with any way to tell whether it is true.
Meanwhile the person who could sort it out, a registered dietitian who works in oncology, is someone many patients never actually get referred to.
I am starting a series about that gap. It runs on Wednesdays, and it will run for a long time, because the subject is much larger than a handful of articles.
What it is called and why
The series is called What They’ll Tell You. Not because the advice is always wrong, but because the volume of it is the actual problem. When everything arrives with equal confidence, the true and the false and the dangerous all sound alike.
So the job of this series is not to tell you what to eat. It is to make you able to evaluate what you are being told, including by me.
The thing that reframed this for me
Here is the assumption underneath most of the advice that reaches cancer patients: chemotherapy is a poison, and natural things are gentle.
Both halves of that are worth examining.
Paclitaxel, one of the most widely used chemotherapy drugs in the world, was isolated from the bark of the Pacific yew tree. Vincristine and vinblastine come from the Madagascar periwinkle, a flowering plant. Etoposide derives from the mayapple. A meaningful share of the chemotherapy given today is, in the most literal sense, plant-derived.
The bark of a Pacific yew, Taxus brevifolia. This is the tissue paclitaxel was first extracted from, and stripping it does not leave the tree alive. Photograph by Walter Siegmund, CC BY 2.5, via Wikimedia Commons.
And apricot seeds, sold for decades as the gentle natural alternative, contain amygdalin, which the body converts into cyanide.
The polarity is not just wrong. It is inverted. “Natural” describes where a compound came from. It says nothing at all about whether it is gentle, whether it works, or whether it will interact with the treatment you are already receiving.
That is the idea the whole series is built on, and the first article is the history of it.
What the series will cover
Mechanism and origins. Where these drugs came from, what they actually do to a cell, and why the side effects follow from that rather than arriving at random. Once you understand why a treatment that targets rapidly dividing cells affects your mouth, your gut, your hair and your blood counts, the side effects stop being a series of unrelated cruelties and start being predictable. Predictable things can be planned for.
The food questions. Carbohydrates and muscle. Why weight loss during cancer is not one thing. Fasting during chemotherapy. The neutropenic diet, and why parts of it outlived the evidence. What to do when everything tastes like metal.
The supplements, one at a time. Not a single article waving at supplements in general, which is useless to someone holding a specific bottle. Apricot seeds. Fenbendazole. Turkey tail and the mushroom blends. High-dose vitamin C. Turmeric. Mistletoe. Moringa. Soursop. Black salve. Green tea extract. Milk thistle. Shark cartilage. One at a time, each with what the evidence actually shows.
Some of these will get a firm answer, because the evidence supports one. Others will not, and I will say so. Turkey tail is the case I want to flag early: there is a real trial literature behind one of its compounds, and pretending otherwise to make a cleaner story would be doing the same thing the sellers do, only in the other direction.
Caregivers. The most neglected part of this entire subject. What to do when someone will not eat and you cannot make them. What to actually bring a person in treatment, since most of what people bring cannot be eaten. How to say no to the supplement a relative mailed without wrecking the relationship. What happens when nutrition stops being the goal at all. And the one nobody asks about, which is whether the caregiver is eating.
The argument I care most about
Across every supplement article, the strongest honest point is almost never that a product does nothing.
It is that a product can interfere with treatment that does something.
That is a different claim, it is better supported, and it is the one that actually matters at the point of decision. A supplement that is merely useless costs money. A supplement that alters how a drug is metabolized, or blunts a mechanism that treatment depends on, can cost considerably more than that.
Which is why the single most useful thing in this entire series is also the least interesting to write: tell your oncology team everything you are taking. Everything. Including the things you expect them to dismiss, and especially the things somebody told you not to mention.
What this is, and what it is not
This is education. It is not medical advice, it is not a treatment plan, and it is not a substitute for your oncology team or a dietitian who knows your case.
Nothing here will tell you whether to take a specific supplement, because that decision depends on your diagnosis, your treatment, your labs, your kidney and liver function, and the other things you are taking. It requires someone who can see your chart. I cannot see your chart.
If something in your situation is urgent, contact your care team. If it is an emergency, call 911.
Where it is going
Wednesdays, starting with where chemotherapy came from.
Tuesday and Friday posts continue as they are, so if this series is not for you, nothing else changes. If it is for you, or for someone you are caring for, everything in it will be free.
I wrote two books on this before I wrote any of these articles, one for patients and one for caregivers, in English and in Spanish. They exist because I kept having the same conversations and wanted people to have something to take home. The articles will stand on their own, and the books are at the bottom of each one for anyone who wants the whole toolkit in one place.
Evidence over opinion. Always.