healthy eating

In answer to your question 'What's the worst that can happen?" the answer, unfortunately, is that you can undermine your treatment.
I was all set to adopt a high anit-oxidant and reputedly 'cancer fighting' diet until my oncologist advised me that my chemotherapy worked by OXIDISING cancer cells. The diet could have worked against the chemotherapy. 

While I agree that there is a lot we can do to improve our survivial rates and quality of life by eating well I beleive we also need to be suspect of anyone trying to sell us supplements, books, remedies or miracles. Where there is money there is fraud and this is very true when it comes to cancer. Some of the 'diets' I've found are shockingly unhealthy, including the much touted 'alkaline diet' and another regime that prescribed coffee enemas!

Interpreting research is difficult because it's written in jargon, so most people just accept that when a journal article reports something has anti-cancer properties, it must be true. I often find that when I check the source research, the writer of the article has completely misunderstood the science or the findings.

Lots of things kill cancer cells in a petri dish or a test tube (in vitro). This does NOT mean they will kill cancer in something as complex as the human body. If you read that something prevents or cures cancer then see if you can find a double blind human trial with the results published in a peer reviewed journal. If it doesn't meet this standard then it's just 'promising' research. In other words, the substance being studied may OR MAY NOT cure cancer and more research is needed.

The same is true of research involving rats and other animals. Yes, results are interesting and will hopefully be used to argue for funding for a proper human trial, but don't use those results to conduct your own experiments on your body unless the substance being recommended is generally safe to eat. 

I don't know why there are people in this feed claiming that doctors can't recommend a healthy diet or a particular food. What's the basis for that claim? Of course a doctor can recommend changes to diet and you should certainly tell your doctor about anything you're doing because you might, without realising it, be undermining your treatment. Several medications come with a list of foods to avoid.

I think the real issue with food is that because it's one of the few things we can control it's tempting to believe that we can use it to take total control, to cure ourselves or to prevent recurrence. It's very appealing to believe that just by including certain foods or juices or supplements that we can be free forever from our fears and the appeal of that thinking tempts us to place far too much emphasis on the risks and benefits of a healthy diet.

Don't get me wrong. I believe that eating a healthy diet is one of the best things we can do to support our treatment. When it comes to 'superfoods' or anything 'cancer preventing' there are actually some things out there that pass the double blind trial standard, including omega 3, vitamin D and a diet rich in fruits and vegetables. But sorting out the legitimate research from the rubbish involves a lot more than just taking a journalist's word for it.

Be particularly mindful that having 'doctor' ahead of ones name doesn't qualify someone to give you medical advice. Always check what kind of 'doctor' a person really is, and whether they've been sanctioned for giving poor advice, as so many of the 'doctors' selling online products have been.