A question I asked my NotebookLM containing 50 most recent research articles

Which amino acid supplements may prevent cancer?
Based on the sources, several amino acid supplements have shown potential in animal models or contribute to factors linked to cancer prevention, though direct evidence for cancer prevention in humans through amino acid supplementation is often noted as needing further research.
Here are the amino acid supplements that may prevent cancer or enhance anticancer defenses:
• Glycine
    ◦ In mice, glycine supplementation was shown to lower the incidence of pulmonary adenocarcinoma.
    ◦ Dietary glycine supplementation has been reported to produce anticancer effects in rodents.
    ◦ It was found to prevent the development of hepatic tumors in rats.
    ◦ Glycine also demonstrated the ability to inhibit the growth of melanoma tumors in mice and in a mammary adenocarcinoma cell line.
    ◦ Studies suggest that glycine may help treat inflammation and prevent and treat carcinoma. It has been shown to decrease angiogenic signaling in human hepatocellular carcinoma cells, which could be a promising additive to chemotherapy for highly vascularized tumors.
    ◦ Additionally, glycine is a main component of collagen, which forms the extracellular matrix acting as a mechanical barrier against cancer cell invasion.
    ◦ However, it’s important to note that glycine metabolism can also be associated with rapid cancer cell proliferation in some contexts, highlighting a complex and heterogeneous role.
• GlyNAC (Glycine and N-acetylcysteine)
    ◦ This combination supplement provides precursors for glutathione (GSH) synthesis: glycine and cysteine (from N-acetylcysteine).
    ◦ In older adults, GlyNAC supplementation lowered biomarkers of oxidative stress and DNA damage (8-hydroxy-deoxyguanosine), which are linked to an increased risk of developing cancers such as colon, prostate, and breast cancer.
    ◦ In mice, GlyNAC supplementation increased lifespan by correcting glutathione deficiency, oxidative stress, mitochondrial dysfunction, and genomic damage. Genomic instability is an aging hallmark linked to cancer.
    ◦ The benefits of GlyNAC are attributed to the “Power of 3″—the combined effects of glycine, N-acetylcysteine, and glutathione, which helps neutralize harmful oxidative stress and support mitochondrial function.
    ◦ The sources explicitly state that whether GlyNAC can lower cancer risk in humans is unknown and requires further evaluation in future studies.
• Tryptophan and Arginine (with Tetrahydrobiopterin, BH4)
    ◦ Dietary supplements of tryptophan and arginine, when combined with BH4, have the potential to enhance anticancer immunity.
    ◦ This enhancement involves boosting the proliferation and function of T cells, which are crucial for the immune system’s fight against cancer.
    ◦ Tryptophan is considered the least used and available essential amino acid, and its degradation can be utilized by the immune system to inhibit cancer cell growth.
Other Amino Acids and Cancer: It’s important to differentiate between supplementation for prevention and other roles of amino acids in cancer:
• Methionine and Lysine: These are primarily discussed in the context of dietary restriction as potential strategies for cancer therapy or prevention, as cancer cells can be dependent on methionine, and lysine restriction has shown effects on cancer cell proliferation. They are not generally recommended as supplements for prevention.
• Branched-chain amino acids (BCAAs – Leucine, Isoleucine, Valine): While preparations rich in BCAAs are recommended for cancer patients to improve muscle loss and liver function, and in postoperative recovery, some studies suggest that elevated plasma BCAA levels may raise the risk of pancreatic cancer. Therefore, their role in cancer prevention through supplementation is not supported and may even be a risk factor in some cases.
• Histidine: Supplementation with histidine has been shown to enhance the sensitivity of cancer cells to chemotherapy, acting as an adjuvant to treatment rather than a preventative measure.
• Serine: Serine metabolism is often enhanced in cancer cells, and its consumption can support cancer cell proliferation. Consequently, serine starvation is being explored as a therapeutic strategy.
• Taurine: This amino acid has been reported to decrease human cervical cancer cell proliferation and may be useful in diagnosing breast cancer. It is also suggested as a promising approach for intervening with cancer cachexia, but these roles are primarily in treatment or diagnosis rather than prevention.
In summary, while there is promising preclinical evidence for glycine and GlyNAC in cancer prevention, particularly in animal models, and for tryptophan and arginine (with BH4) in enhancing anticancer immunity, human clinical trials specifically demonstrating amino acid supplements prevent cancer are limited, and further research is needed.