The Impact of a Whole Food, Plant-Based Diet on Amino Acid Levels in Patients with Metastatic Breast Cancer

Research Background

The growth and survival of cancer cells depend on significant metabolic demands, particularly for amino acids. Tumors meet these demands by acquiring amino acids from the surrounding microenvironment, and dietary amino acid intake may influence serum amino acid levels. Studies suggest that plant-based diets contain fewer amino acids than animal-based diets, but it remains unclear whether a plant-based diet can reduce serum amino acid levels in cancer patients. Therefore, researchers aimed to explore the impact of a whole food, plant-based diet on serum amino acid levels in patients with metastatic breast cancer through a clinical trial and assess the potential synergistic effects of this dietary approach with cancer therapies.

Source of the Paper

This paper was authored by Tashjaé Q. Scales and colleagues from institutions such as the University of Rochester Medical Center and the Wilmot Cancer Institute. Published in 2024 in the journal Cancer & Metabolism, the study is titled “A whole food, plant-based diet reduces amino acid levels in patients with metastatic breast cancer.” The research was supported by multiple grants, including funding from the American Cancer Society and the NIH.

Research Process and Experimental Design

1. Study Subjects and Dietary Intervention

The study enrolled 17 patients with metastatic breast cancer who followed an ad libitum (free-eating) whole food, plant-based diet for 8 weeks without calorie or portion restrictions. During the intervention, participants consumed three meals and one snack daily, consisting of plant-based foods such as fruits, vegetables, whole grains, legumes, nuts, and seeds. The diet strictly prohibited any animal-derived foods, cooking oils, and solid fats.

2. Data Collection and Analysis

Data were collected through the following methods: - Dietary Records: Participants completed 3-day food records at baseline and 8 weeks, documenting two weekdays and one weekend day. The records were analyzed using the Nutrition Data System for Research (NDSR) to calculate intake of calories, fat, carbohydrates, protein, fiber, and amino acids. - Serum Sample Analysis: Serum samples were collected at baseline and 8 weeks and analyzed for amino acid levels using liquid chromatography-mass spectrometry (LC-MS). The experiments utilized an Orbitrap Exploris 240 mass spectrometer and a Vanquish Flex liquid chromatography system, with data processed using El-MAVEN software.

3. Experimental Methods

• Serum Sample Processing: Serum samples were mixed with methanol extraction solution, centrifuged, and the supernatant was dried and reconstituted in acetonitrile for LC-MS analysis.
• LC-MS Analysis: A Waters XBridge XP BEH Amide column was used, with mobile phases consisting of water and acetonitrile containing ammonium formate and formic acid. The mass spectrometer operated in positive ion mode with a mass-to-charge ratio range of 70-800 m/z.

Research Findings

1. Changes in Dietary Intake

The study found that after adopting a whole food, plant-based diet, participants significantly reduced their intake of calories, fat, and protein while increasing fiber intake. Specific data include: - Caloric intake decreased by approximately 20%. - Fat intake decreased by approximately 30%. - Protein intake decreased by approximately 25%, with animal protein almost entirely replaced by plant protein. - Fiber intake increased by approximately 40%.

2. Changes in Serum Amino Acid Levels

The study showed that the whole food, plant-based diet significantly reduced serum amino acid levels in patients: - Essential Amino Acids: Levels of ⁵⁄₉ essential amino acids (isoleucine, leucine, lysine, phenylalanine, and threonine) were significantly reduced. - Non-Essential Amino Acids: Levels of ⁴⁄₁₁ non-essential amino acids (alanine, glutamate, proline, and tyrosine) were significantly reduced.

3. Changes in Other Metabolic Indicators

• Weight and BMI: Participants experienced significant reductions in weight and BMI.
• Insulin and IGF: Serum levels of insulin and insulin-like growth factor (IGF) were significantly reduced, suggesting that the dietary intervention may suppress pro-tumorigenic signaling pathways.
• Cholesterol: Serum levels of total cholesterol, HDL, and LDL were significantly reduced.

Research Conclusions

The study demonstrates that a whole food, plant-based diet can significantly reduce serum amino acid levels in patients with metastatic breast cancer, particularly essential and non-essential amino acids. This dietary approach not only reduces caloric and fat intake but also lowers levels of pro-tumorigenic factors such as insulin and IGF. The findings provide a feasible clinical strategy for limiting amino acid levels in cancer patients through dietary intervention and lay the groundwork for future research on the relationship between diet and tumor progression.

Research Highlights

1. Innovative Dietary Intervention: The study is the first to systematically evaluate the impact of a whole food, plant-based diet on serum amino acid levels in patients with metastatic breast cancer.
2. Multidimensional Data Analysis: Through dietary records and serum metabolomics analysis, the study comprehensively assessed the metabolic effects of the dietary intervention.
3. Clinical Feasibility: The study demonstrates that a whole food, plant-based diet is highly feasible and well-accepted in clinical practice.

Research Significance

This study not only provides a potential strategy for limiting tumor growth in cancer patients through dietary intervention but also offers new insights for developing cancer therapies based on metabolic vulnerabilities. Additionally, the findings support the positive role of plant-based diets in improving metabolic health in cancer patients, highlighting their significant clinical value.