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.
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
