Diets for MGUS, Smoldering Myeloma, and Multiple Myeloma: Q&A With MSK Cancer and Nutrition Experts

MSK multiple myeloma specialist Urvi Shah

Myeloma specialist Dr. Urvi Shah is researching the role that whole-food and plant-based diets may play in slowing the progression of certain conditions into multiple myeloma.

Multiple myeloma is a cancer that arises from a type of white blood cell called a plasma cell, which is produced in the bone marrow. Multiple myeloma is sometimes preceded by conditions called monoclonal gammopathy of undetermined significance (MGUS) or smoldering myeloma, which may or may not develop into full-blown multiple myeloma.

Many people who are diagnosed with MGUS or smoldering myeloma want to know what they can do to prevent these conditions from progressing into cancer. MSK myeloma specialist Urvi Shah, MD, is currently researching the role that plant-based diets may play in slowing the progression of these conditions — or even preventing them altogether. She is currently conducting a clinical trial (research study) of plant-based diets in people with MGUS and smoldering myeloma.

We spoke with Dr. Shah and MSK dietitian-nutritionist Francesca Castro, MS, RDN, CDN, about plant-based diets and cancer.

What specific diet are you studying for its potential to delay the progression of MGUS and smoldering myeloma?

Castro: The diet we are researching is whole-food and plant-based. It’s basically vegan, with an additional emphasis on whole foods. We want patients to limit ultra-processed foods. But I tell them, “We’re looking for progress, not perfection.” We understand that this is a big transition for people, and to commit 100% may not be feasible for everyone. I really try to emphasize that and let them know that we’re here to help support them and navigate the journey of transitioning to a whole-food, plant-based diet.

If people eat a plant-based diet, will they be able to slow their MGUS or smoldering myeloma?

Dr. Shah: Our NUTRIVENTION research study seeks to answer that very question. Early signs suggest it’s possible, although we don’t have enough data yet. There is existing evidence that a plant-based diet helps with weight loss, diabetes, cardiovascular disease, renal (kidney) disease, and possibly also autoimmune disease. So there are a lot of overall lifestyle benefits to a plant-based diet.

There are many reasons to think that plant-based diets may affect MGUS and smoldering myeloma progression. For example, we know that the risk of these conditions increases in people with an elevated BMI (body mass index). A person with an elevated BMI and MGUS or smoldering myeloma is twice as likely to progress to myeloma as a person with a normal BMI.

Additionally, there are multiple studies showing that people who eat more plant-forward diets reduce their risk of myeloma and of cancer in general.

How should people switch to a plant-based diet?

Dr. Shah: People should try to get at least 80% to 90% of calories from unprocessed plant foods. Like Francesca said, perfection and progress are different things. If a patient tries to go 100% plant-based for a few weeks without planning the foods they will eat, then they may not be able to sustain the diet. So it’s more important that the changes are gradual and sustainable.

One of the biggest challenges comes from social pressure and not planning ahead. Because we live in a world where eating a plant-based diet is not the norm, it can feel isolating. If your friends want to go out to eat chicken wings or a steak, you may be left wondering what you will eat. Your solution could be choosing a restaurant with more options, or calling the restaurant in advance to see if they are able to modify any items on the menu, or eating something before you go so you’re not hungry.

What about supplements such as curcumin and omega-3 fatty acids? Are those beneficial for people with MGUS or smoldering myeloma?

Dr. Shah: There is not enough data to universally recommend these supplements to patients with plasma cell disorders, especially given their cost. Both these supplements have anti-inflammatory properties, and limited research in healthy people suggests the supplements benefit the gut microbiome, too.

Curcumin may help certain patients with smoldering myeloma, according to early clinical data. Omega-3 fatty acids have been shown in the lab to inhibit the growth of myeloma cells. Although the clinical data is limited, many patients with MGUS and smoldering myeloma decide to take these supplements. We’re trying to get better evidence by conducting the NUTRIVENTION3 trial.

Will eliminating carbohydrates from the diet starve multiple myeloma?

Dr. Shah: This is a common misconception. People often think that eating carbohydrates will feed their cancer, so they try to cut them out of their diet completely. Yes, carbohydrates break down into glucose, which is the main sugar in your blood. Glucose is the source of energy for our cells and is needed for them to function. People avoiding carbohydrates still produce glucose when they eat protein and fat. So it’s a myth that avoiding carbohydrates will starve the cancer.

However, it is important to know that not all carbohydrates are the same. They can be refined (simple) or complex. People should avoid refined carbohydrates such as cookies, cakes, and croissants. But they should not avoid complex carbohydrates such as whole grains, beans, fruits, and vegetables. They are associated with reduced cancer risk.

Castro: We always try to emphasize quality over quantity. Some patients on our trial will say, “I feel like I’m eating way more carbs than I used to.” Or they worry that the meals on the trial might be too carb-heavy. But they don’t realize that they are also high in fiber — whole grains, beans, vegetables. So it’s important to try to break down the myth that all carbs are bad.

What are some common questions about this diet program for MGUS and smoldering myeloma?

Castro: Many of the patients say they’re concerned they will not enjoy the food or be able to sustain eating this way. I tell them, “This diet doesn’t mean you won’t enjoy food anymore. You’re not eating bland vegetables. There are delicious ways to make veggies.” It’s important to us that people still enjoy their meals, because they’re more than just fuel. Mealtime means socializing, memories, connecting with one’s culture, and more.

Dr. Shah: Patients also wonder what exactly it means to eat whole-food, plant-based. I try to explain the difference between what’s vegetarian, what’s vegan, and what’s whole-food, plant-based.

  • Some people go vegan for ethical and environmental reasons, because they don’t want to hurt animals and know about the increased global-warming potential of animal-based foods. But technically, it is possible to be vegan and eat unhealthy junk foods such as french fries and cookies.
  • Vegetarians are often motivated by ethical or religious reasons. But some of them end up eating very high amounts of dairy, eggs, and refined or processed foods — and that’s not really a plant-based diet.
  • When we talk about whole-food, plant-based eating, that means at least 80% to 90% of the diet is coming from fiber-rich foods such as fruits, vegetables, whole grains, beans, nuts, and seeds.

I tell patients to make a choice for themselves — whether vegan, vegetarian, pescatarian, Mediterranean. All these are plant-based diets. But it’s important to try to get 90% of calories from whole plant foods.

What about the person who says they just can’t get full or satiated on a plant-based diet?

Dr. Shah: Yes, people will sometimes say, “A plant-based diet is not for me because I am not satisfied.” Or, “I won’t get enough protein.” However, contrary to popular belief, dietary fiber is associated with people feeling more satiated.

Perhaps they assume a plant-based diet means only eating salads. Most people don’t know how to cook beans and don’t eat them regularly. Beans are a great source of protein and fiber and therefore are very satiating.

Also, they should consider making small substitutions. For example, instead of adding chicken, maybe swap it out for tofu. Often, people will say they don’t like the taste of tofu, but that’s because it hasn’t been marinated well. Tofu is inherently tasteless like chicken, and it takes on the flavor of the way it’s prepared.

Patients shouldn’t think, “Oh no. I need to change everything about what I eat.” Instead, it’s about making small gradual healthy swaps for the long term.