Nikhil Prasad Fact checked by:Thailand Medical News Team May 20, 2026 52 minutes ago
Medical News: Scientists have discovered that two naturally occurring amino acids, L-arginine and L-citrulline, could help the immune system fight tuberculosis more effectively while also boosting the power of existing TB drugs. The findings are creating excitement because the approach may offer a cheaper and safer way to improve tuberculosis treatment outcomes worldwide.
Natural amino acids may strengthen immune cells and improve the effectiveness of tuberculosis drugs
Researchers from the Public Health Research Institute at Rutgers New Jersey Medical School in the United States and Nestlé Health Science in Bridgewater, New Jersey, carried out the study, which focused on how immune cells called macrophages respond to Mycobacterium tuberculosis, the bacterium that causes TB.
How TB Hides Inside the Body
Tuberculosis remains one of the world’s deadliest infectious diseases, causing millions of infections every year. The TB bacterium is particularly dangerous because it can hide inside macrophages, which are immune cells meant to destroy invading germs.
Normally, macrophages kill bacteria using toxic molecules such as nitric oxide. However, TB bacteria have evolved ways to weaken this defense system. The new study found that supplying macrophages with extra L-arginine and L-citrulline helped restore their ability to attack TB bacteria more aggressively.
L-arginine is important because the body uses it to produce nitric oxide, a chemical weapon that immune cells use against infections. L-citrulline acts like a backup source that helps replenish arginine levels when they become depleted.
Powerful Reduction in TB Bacterial Loads
The researchers tested the amino acids in human immune cells, mouse immune cells, and laboratory-grown macrophage cells infected with tuberculosis bacteria. They found that both arginine and citrulline significantly reduced the amount of TB bacteria living inside the cells over a five-day period.
Higher doses produced stronger and faster effects. In some experiments, the bacterial load dropped dramatically within just one day after treatment. The effects became even stronger when the immune cells were activated with interferon-gamma, a powerful immune signaling molecule known to stimulate antimicrobial activity.
Interestingly, combining arginine and citrulline together produced even better results than using either one alone. The combined treatment appeared especially effective in mouse immune cells where individual amino acids had weaker effects.
Researchers believe the two compounds work together because arginine immediately fuels nitric oxide production while citrulline continuously recycles back into arginine, ensuring a steady supply for the immune system.
Existing TB Drugs Worked Better Too
One of the most important discoveries was that the amino acids improved the performance of standard TB antibiotics such as isoniazid and rifampicin.
When infected macrophages received both the amino acids and antibiotics, TB bacteria were eliminated more quickly compared to ant
ibiotic treatment alone. The improvements were most noticeable during the early stages of infection and in immune-activated cells.
This
Medical News report highlights how the findings support the growing idea of “host-directed therapy,” where treatments do not just attack bacteria directly but also strengthen the body’s own immune defenses.
Scientists said this strategy could become especially valuable in difficult TB cases where antibiotic treatment alone is not enough.
Important Changes Inside Immune Cells
The study also revealed major changes in immune-related genes inside the macrophages. Arginine supplementation strongly increased the activity of a gene called NOS2, which is directly involved in nitric oxide production and bacterial killing.
At the same time, harmful inflammation appeared to be better controlled. Levels of the inflammatory molecule TNF were reduced, while IL-6 activity increased. Another gene called ARG1, which can interfere with nitric oxide production, was suppressed in activated immune cells.
The researchers believe these changes create a more balanced immune response that helps destroy TB bacteria without causing excessive tissue damage.
What The Findings Could Mean
The researchers cautioned that the experiments were performed in laboratory cell models and not yet in human patients. More studies and clinical trials will be needed before doctors can recommend arginine or citrulline supplements as part of standard TB treatment.
Still, the findings are highly encouraging because both compounds are already naturally found in the human body and are relatively inexpensive. Scientists believe future therapies could combine nutritional immune support with conventional antibiotics to shorten treatment times and improve recovery rates.
The conclusions of the study suggest that arginine and citrulline may become promising supportive therapies for tuberculosis by helping immune cells regain their natural ability to control infection. The researchers also believe the amino acids may reduce inflammation while improving the effectiveness of existing TB medications. If future human studies confirm these benefits, the approach could become an important new weapon against global TB, especially in regions where treatment failure and drug resistance remain major public health challenges.
The study findings were published in the peer reviewed journal: Frontiers in Immunology.
https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2026.1810985/full
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