High-fiber plant-based diet could benefit patients at risk for developing multiple myeloma

Results from a new clinical trial suggest that a high-fiber plant-based diet could benefit patients at risk for developing multiple myeloma, the second most common type of blood cancer. The study showed that the diet was not only feasible and well-received but also improved several factors that could potentially delay the progression of precancerous conditions that can lead to multiple myeloma.

Multiple myeloma is often preceded by early, non-cancerous conditions involving abnormal plasma cells, a type of white blood cell found in the bone marrow. Having a high body weight, a poor-quality diet and an unhealthy balance of gut bacteria have been shown to increase the risk of developing these conditions and progressing to multiple myeloma.

With cancers being detected earlier and precancerous states identified more frequently, there is a growing opportunity to understand how modifiable risk factors-like diet and lifestyle-affect cancer progression. Our results highlight the importance of improved dietary quality in early disease states and could provide guidance for future clinical trials." 

Francesca Castro, clinical research dietitian, Memorial Sloan Kettering Cancer Center

Castro will present the findings at NUTRITION 2025, the flagship annual meeting of the American Society for Nutrition held May 31–June 3 in Orlando.

Current research in patients at risk for myeloma tends to focus on identifying genomic and immune drivers of progression and therapy options for people with the precursor conditions.

"With everything that patients cannot control during and before cancer treatment, studying diet provides an opportunity for patients to make a difference in their disease risk and the potential success of their treatment," said Urvi A. Shah, MD, a physician scientist at Memorial Sloan Kettering Cancer Center and principal investigator for the research. "Our study shows the power of nutrition in the preventative setting and showcases the potential to give patients a sense of agency in their diagnosis."

The pilot study, which is part of the NUTRIVENTION Trials, included 20 patients at risk for developing multiple myeloma due to precursor conditions and an elevated body mass index. Patients received 12 weeks of high-fiber, plant-based meals, 24 weeks of individualized nutritional counseling and were followed for 52 weeks.

Study participants were encouraged to eat to satiety as long as they consumed whole plant-based foods such as fruits, vegetables, nuts, seeds, whole grains and legumes. They were also asked to avoid refined grains, animal products, added sugar and highly processed foods.

The researchers found that the high-fiber, plant-based diet was feasible and well-received, leading to dietary adherence and weight loss. Before the study began, only 20% of total calories were from high-fiber plant-based foods whereas by the end of the 12-week dietary intervention, that number jumped to 91%. At 12 weeks, the median participants' BMI of had dropped 7% and this weight loss was sustained at 1 year. In addition, two patients experienced a slowing of disease progression while progression remained stable in the others.

The investigators also observed significant improvements in dietary quality, quality of life, metabolic markers such as insulin resistance and lipid profiles, inflammation, and the diversity and composition of the gut microbiome. These improvements were still observable at the end of the 12-week intervention and sustained through the 52-week follow-up.

"Our study had diverse racial enrollment as well as a comprehensive dietary and biomarker evaluation," said Shah. "Our comprehensive analysis of improved immune and metabolic response suggests that a high-fiber plant-based diet can also reduce risk for cardiovascular conditions, diabetes and other metabolic conditions."

When consuming fiber, most Americans fall short of the around 28 grams per day recommended by the US Dietary Guidelines. To boost fiber in the diet, the researchers suggest setting realistic daily goals and focusing on one meal at a time.

"Think about what foods you can add or swap to increase fiber intake," said Castro. "It can be very simple like adding a piece of fruit at the end of a meal or swapping out a refined grain for a whole grain. Eating more fiber can lower risk for many other conditions and can improve overall health, beyond just reducing cancer risk."

The investigators are currently enrolling participants in follow-up NUTRIVENTION Trials to evaluate the potential effects of a high-fiber, plant-based diet in larger groups of patients and to investigate the effects of diet versus supplements on the gut microbiome. They also plan to study the effects of the high-fiber plant-based diet on other precursor blood conditions, such as clonal hematopoiesis, which increases risk for other blood cancers, such as leukemia.

Castro will present this research at 4:12 – 4:24 p.m. EDT on Monday, June 2, during the Role of Diet in Cancer Prevention and Control session in the Orange County Convention Center.