Kelay Trentham, a nutritionist with a particular specialty as an Oncology Dietician who works at MultiCare Regional Cancer Center in Tacoma, WA, joined us in a recent webinar to discuss several central questions about nutrition and cancer. Here are her comments on the pivotal question, “What is an Optimal Diet for a Patient with Cancer?”

If there are no barriers to eating during treatment or related to their cancer, the optimal diet is considered to be a plant-based diet. What that means is a diet that’s very high in whole grains, fruits and vegetables, and also legumes, nuts and seeds.

A “Plant-Based Diet” can include lean protein foods, lean meats, and low fat dairy items in more modest amounts, while tipping the balance a little bit from the typical American diet, which seems to be fairly high in animal protein, while not quite as high in fruits and vegetables, legumes, nuts and seeds.
What are the potential barriers to eating an optimal diet? These are things like nausea and vomiting that occur related to treatment. Occasionally if folks have had surgical treatments that might alter their GI tract and how they process foods or how they tolerate foods, that might also present some barriers. There are taste changes; there are appetite issues — things can even smell differently than they used to smell prior to someone either having the diagnosis or even starting treatment. So those are all things that might necessitate that you use foods that you might not consider optimally healthy, or you might find it hard to eat whole grains, fruits and vegetables in higher quantities.

A question that I think comes to mind though when you talk about a plant-based diet is “why?” Why is a diet high in fruits, vegetables and whole grains helpful? The term phytonutrients or phytochemicals, those terms are often used interchangeably, refers to the plant substances that are thought to be beneficial to human health.

Phyto- means plants and refers to substances found entirely in the plant world, and they are particularly in high concentrations in really colorful fruits and vegetables. These substances are being studied more and more for what possible effects they may have on cancer cells. For example, there are some substances, again found in plants — especially those that are very, very colorful — that they’re looking at how they might affect cancer cells in the sense that sometimes they may actually tell cancer cells, “Hey, you know what? Your life cycle is done; it’s time for you to die off and be gone.” .” Often times cancer cells have lost the ability to die — they just continue to grow and grow, while normal cells have a life cycle. They’re supposed to live for a time, do their job, and then die and be replaced. So when cancer cells lose that ability, they begin to take over and wreak the havoc that we know (as cancer). That’s just one example of what we are seeing in these phytonutrients, or these plants substances, where they might actually contribute to helping with cancer. That’s part of the rationale for a plant-based diet. Plant foods also contain a wealth of other nutrients – fiber, vitamins, minerals, energy, healthy fats, and even some protein – that the body needs every day.

So what are our goals with nutrition and cancer? I divide these concepts into pre-treatment, during treatment, and post-treatment.

Pre-treatment, when you know that you are about to start treatment but you haven’t quite gotten there yet. Before treatment I think it is important to start trying to improve your eating habits. I run into a lot of folks who perhaps eat on the go a lot, eat out a lot, use a lot of processed foods which don’t have a lot of nutrients, or perhaps eat one meal a day only. I know they are not really going to be able to meet a lot of their nutrient needs if they are only eating one meal a day. If people already have identified nutrient deficiencies, then that would be something where we would want to work towards correcting those prior to treatment starting. If someone has lost a lot of weight, it might be good to go ahead and try to put a few of those pounds back on just to have that as kind of a backup in the event that you have some trouble (with weight loss) or some barriers to eating. Address changes in gut function: for some cancers in the GI tract, there may be issues there with processing foods or moving things through your gut in a normal fashion, so we might work to figure out what do we need to do that could possibly help with that. And then I’m always hopeful that people will get some pre-treatment education on what kind of nutrition strategies they might follow to prepare them for managing some of the side effects that we mentioned.

During treatment, the number one thing really that we know about the importance of nutrition during treatment is that you maintain your weight. Most of what we know about during treatment and how nutrition can help has to do with folks who don’t maintain their weight. Folks who are unable to maintain their weight often will have more significant side effects. If you are losing weight, then it may be an indicator that you also are often having more difficulty with nausea and vomiting, or some of the other different side effects that we talked about, and therefore, it’s a sign that you are having trouble tolerating your treatment.

Other things we want to do are to prevent nutrient deficiencies. Some medications that people may need to use during their treatment or even some of the treatments themselves (including surgeries) can cause some issues with nutrient deficiency. So if somebody had a gastrectomy or part of their stomach removed, they are very likely to become B12 deficient because they’ve removed a large part of the body where there are factors that are produced that actually help someone to absorb B12 or if they have lost a lot of their absorptive capacity because they’ve had all of their stomach removed, we may have to work on dealing with that and ensuring they get all of their different vitamins so that they don’t become anemic.

Then the other thing is that we want to improve treatment tolerance. We want to address side effects. We want to say, “Okay, if you are having nausea, for instance, what can you do, what kind of foods might be helpful to either avoid or to include so that we decrease the nausea?” You’ll see that the focus there is really on quality of life. I would like to see people having as good a quality of life as they can during their treatment, and there are instances where nutrition strategies can help with that — particularly in addressing those side effects related to nutrition.

After treatment, Once your treatment is complete, you may want to know how good nutrition can help reduce risk of recurrence. Nobody wants to hear that their cancer has come back. We want to try to attain or maintain a healthy weight because, again, obesity is one of the primary nutritional issues that seems to be linked to the development of many cancers. Also, I think it is important to improve nutritional habits. If you had poor habits before, then you had treatment and you had some barriers and challenges to eating healthier or to changing your nutritional habits or your lifestyle, then after treatment, hopefully when a lot of side effects may have settled down, it is a good time to make some good nutrition and lifestyle changes. (This would be an excellent time to meet with a dietitian to discuss nutrition recommendations for cancer survivors.)

We also want to address long-term issues. Occasionally there will be persistent side effects from treatment, or even permanent effects from treatment, particularly sometimes in the bowel. An example might be radiation of the bowel area. There are some foods that folks may not tolerate very well after they have had radiation of their bowel. So we work to give people strategies, helping them figure out what foods they tolerate or in what forms will they tolerate those foods.

Next: Specific recommendations based on a report of thousands of reviewed articles about Nutrition and Cancer Prevention.