2025-10-16
Can a plant-based diet slow tumor progression by limiting amino acids?
Oncology
By Lila Rouland | Published on October 16, 2025 | 3 min read
Metastatic breast cancer relies heavily on amino acids for its growth and survival. These essential nutrients can be synthesized or absorbed directly from circulating serum, making them an attractive metabolic target. While enzymatic inhibition of amino acid biosynthetic pathways has shown limited success in clinical settings, reducing dietary intake may represent a more effective alternative.
In this context, plant-based diets—typically lower in protein and amino acids—are attracting growing interest. This clinical study aimed to evaluate the impact of a whole food, plant-based (WFPB) diet without calorie restriction on serum amino acid concentrations in patients with metastatic breast cancer.
Methodology: The clinical trial included 17 patients who followed a whole food, plant-based diet for 8 weeks, with no portion or calorie restrictions. Dietary monitoring was based on three-day food logs and unplanned phone recalls. Blood samples were collected at weeks 0 and 8. Metabolite concentrations were measured using high-resolution LC-MS, and dietary data were analyzed via the NDSR system.
Nutritional changes observed: Participants consumed a larger total food volume overall but with lower total calories, fats, and proteins. The diet induced an almost complete substitution of animal proteins with plant proteins, accompanied by a marked increase in dietary fiber intake.
Metabolic effects: After 8 weeks, participants showed significant decreases in body weight and BMI, as well as reductions in total, HDL, and LDL cholesterol levels (but not triglycerides). More importantly from an oncological perspective, insulin and IGF-1 (insulin-like growth factor 1) levels also fell significantly, despite no reduction in carbohydrate intake—suggesting an effect independent of glucose metabolism.
Impact on amino acids: The diet significantly reduced total amino acid intake. In serum, 5 of the 9 essential amino acids (isoleucine, leucine, lysine, phenylalanine, threonine) and 4 of the 11 non-essential amino acids (alanine, glutamate, proline, tyrosine) decreased significantly. Interestingly, valine increased, indicating serum regulation independent of dietary intake for certain amino acids.
Tumor markers: CA15-3 and CA27.29, both markers of breast cancer, showed a non-significant downward trend, suggesting a potential anti-tumor effect that warrants confirmation in longer-term studies.
The ad libitum whole food, plant-based diet proved feasible, well accepted, and non-harmful, with participants reporting subjective improvements in cognitive well-being, fatigue, and mood. It effectively lowered serum levels of several amino acids and pro-tumoral factors (IGF, insulin) without causing nutrient deficiencies or a reported decline in quality of life.
Study limitations included its short duration (8 weeks), lack of body composition analysis, and small sample size. Nonetheless, these results suggest that dietary reduction of amino acids—including essential ones—is clinically achievable without major side effects.
In the future, longer-term randomized trials, possibly in combination with therapies targeting tumor metabolism (e.g., PI3K inhibitors), could confirm the synergistic potential of this diet as a metabolic adjuvant in oncology.
About the author – Lila Rouland
With dual expertise in science and marketing, Lila brings her knowledge to the service of healthcare innovation. After five years in international academic research, she transitioned into medical and scientific communication within the pharmaceutical industry. Now working as a medical writer and content developer, she is committed to highlighting scientific knowledge and conveying it to healthcare professionals with clarity and relevance.
Metastatic breast cancer relies heavily on amino acids for its growth and survival. These essential nutrients can be synthesized or absorbed directly from circulating serum, making them an attractive metabolic target. While enzymatic inhibition of amino acid biosynthetic pathways has shown limited success in clinical settings, reducing dietary intake may represent a more effective alternative.
In this context, plant-based diets—typically lower in protein and amino acids—are attracting growing interest. This clinical study aimed to evaluate the impact of a whole food, plant-based (WFPB) diet without calorie restriction on serum amino acid concentrations in patients with metastatic breast cancer.
A significant reduction in pro-tumoral metabolic markers
Methodology: The clinical trial included 17 patients who followed a whole food, plant-based diet for 8 weeks, with no portion or calorie restrictions. Dietary monitoring was based on three-day food logs and unplanned phone recalls. Blood samples were collected at weeks 0 and 8. Metabolite concentrations were measured using high-resolution LC-MS, and dietary data were analyzed via the NDSR system.
Nutritional changes observed: Participants consumed a larger total food volume overall but with lower total calories, fats, and proteins. The diet induced an almost complete substitution of animal proteins with plant proteins, accompanied by a marked increase in dietary fiber intake.
Metabolic effects: After 8 weeks, participants showed significant decreases in body weight and BMI, as well as reductions in total, HDL, and LDL cholesterol levels (but not triglycerides). More importantly from an oncological perspective, insulin and IGF-1 (insulin-like growth factor 1) levels also fell significantly, despite no reduction in carbohydrate intake—suggesting an effect independent of glucose metabolism.
Impact on amino acids: The diet significantly reduced total amino acid intake. In serum, 5 of the 9 essential amino acids (isoleucine, leucine, lysine, phenylalanine, threonine) and 4 of the 11 non-essential amino acids (alanine, glutamate, proline, tyrosine) decreased significantly. Interestingly, valine increased, indicating serum regulation independent of dietary intake for certain amino acids.
Tumor markers: CA15-3 and CA27.29, both markers of breast cancer, showed a non-significant downward trend, suggesting a potential anti-tumor effect that warrants confirmation in longer-term studies.
A feasible, well-tolerated, and potentially synergistic dietary approach
The ad libitum whole food, plant-based diet proved feasible, well accepted, and non-harmful, with participants reporting subjective improvements in cognitive well-being, fatigue, and mood. It effectively lowered serum levels of several amino acids and pro-tumoral factors (IGF, insulin) without causing nutrient deficiencies or a reported decline in quality of life.
Study limitations included its short duration (8 weeks), lack of body composition analysis, and small sample size. Nonetheless, these results suggest that dietary reduction of amino acids—including essential ones—is clinically achievable without major side effects.
In the future, longer-term randomized trials, possibly in combination with therapies targeting tumor metabolism (e.g., PI3K inhibitors), could confirm the synergistic potential of this diet as a metabolic adjuvant in oncology.
Read next: Eugenol: clove against cancer?
About the author – Lila Rouland
Doctor of Oncology, specialized in Biotechnology and Management
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