Introduction
The Th1/Th2 ratio describes how your immune system divides its labor between two different kinds of defense. Most people never hear the term, and almost no laboratory measures it in routine practice. That balance still shapes how you answer infection, allergy, and autoimmune attack. I have published two papers characterizing this ratio in two clinical populations, and the two datasets point opposite ways at baseline. This article explains what the ratio is, what my research measured, and why one cytokine breaks the tidy version of the story. I will put the limits of my own data in front of you before I put the results.
What the Th1/Th2 Ratio Measures in Your T Helper Cells
Your immune system runs two broad programs against two broad categories of threat. Immunologists call the cells that direct those programs T helper cells. They are CD4+ white blood cells (i.e., cells that instruct other immune cells rather than doing the killing themselves). Th1 cells organize the attack on threats hiding inside your cells, such as viruses. Th2 cells organize the answer to threats outside your cells, including parasites and allergens.
Mosmann and Coffman separated the two programs by the molecules each one secreted (Mosmann & Coffman, 1989). Their original work was performed in mouse T cell clones grown in culture. That division proved useful enough to organize immunology for the next three decades.
Researchers rarely count the cells themselves. We measure the cytokines (i.e., short-lived signaling proteins) that each program releases, and we divide one by the other. Interleukin-2 and interferon-gamma stand in for the Th1 side. Interleukin-4 and interleukin-10 stand in for the Th2 side.
A value near one means the two arms carry roughly equal weight. A high number means Th1 dominance, meaning the cell-mediated arm is speaking louder than its counterpart. In the healthy adults we tested, every ratio sat near unity (Lewis et al., 2023). That observation is what makes a departure from unity worth examining at all.
Th1 vs Th2: Neither Side of the Immune Balance Is the Good One
Supplement marketing usually needs a hero and a villain. Immunology declines to supply them. Both arms of the response exist because both categories of threat exist, and losing either one would leave you defenseless against half the world.
Excess Th1 activity is associated with autoimmune conditions, in which the body attacks its own tissue. Excess Th2 activity is associated with allergy and asthma. Neither pattern is a goal, and pushing hard in either direction simply trades one problem for a different one.
The paradigm itself has aged, and honesty requires saying so. Ruterbusch and colleagues reviewed work in living animals showing that CD4+ T cells do not sort neatly into two fixed types (Ruterbusch et al., 2020). Additional subsets exist, including Th17 cells and regulatory T cells, and individual cells can shift between programs.
I use the ratio anyway, and you deserve to know why. Cytokine balance remains a workable summary of which direction an immune response is leaning. My own paper states plainly that the ratio is a broad oversimplification of how the immune system actually works (Lewis et al., 2024). A model that admits its own limits is still more useful than no model.
Why TNF-α Refuses to Sit on One Side
One molecule declines to take a side, and that fact sits at the center of this article. Tumor necrosis factor-alpha (TNF-α) carries a reputation as a purely destructive inflammatory signal. That reputation is incomplete. We stated in our multiple sclerosis paper that TNF-α associates with Th1 and Th2 cells alike (Lewis et al., 2024).
Kalliolias and Ivashkiv reviewed TNF biology and called the molecule pleiotropic (Kalliolias & Ivashkiv, 2016). Pleiotropic means one molecule produces many different effects depending on where and when it acts. TNF-α does defensive work against bacterial and fungal threats, and switching on is precisely its assignment in that setting.
Half of our six ratios use TNF-α as the denominator, which carries a consequence. A signal belonging to both arms cannot serve as a clean marker of either one. We wrote in the same paper that ratios containing it may not reflect a pure Th1 to Th2 relationship (Lewis et al., 2024).
I raised this same problem in my article on the immune system and brain function, where growth factors behave the same way. A number that moves up is not automatically good news, and a number that moves down is not automatically bad news. Context decides, and direction alone decides nothing.
The Th1/Th2 Ratio in Two of My Published Patient Populations
I want the constraints on my own data in front of you first. Each trial ran open-label, so everyone involved knew what the participants consumed. No placebo group existed in either study. Each sample was small. Every participant in both trials carried a neurological diagnosis, so neither trial describes a healthy person.
One further limit belongs in this paragraph rather than in a footnote. Our healthy comparison group averaged 33.6 years of age, which was significantly younger than either patient group. Immune signaling changes with age, so every baseline comparison below carries that confound.
The first population produced an unambiguous result. In adults with moderate-to-severe Alzheimer’s disease, all six ratios ran significantly higher than in the healthy adults (Lewis et al., 2023). Those adults showed Th1 dominance on every measure we calculated. The healthy adults sat near unity on all six.
The second population did not match the first. In adults with multiple sclerosis, only two ratios ran significantly higher than in the same healthy adults (Lewis et al., 2024). Those two were interleukin-2 to interleukin-10 and interferon-gamma to interleukin-10. The other four ratios in those adults resembled the healthy comparison group.
That contrast is the reason both papers needed to be written. Two neurological conditions that both involve immune activity did not share one immune signature. Any claim that a single ratio describes brain health falls apart on that evidence alone.
How the Ratios Moved Over 12 Months in Each Trial
In the adults with moderate-to-severe Alzheimer’s disease, two ratios changed significantly across 12 months (Lewis et al., 2023). Interleukin-2 to interleukin-10 decreased, at p = 0.004. Interleukin-2 to interleukin-4 decreased, at p = 0.048. The paper notes that decreasing values indicate more balanced ratios in that sample.
In the adults with multiple sclerosis, one ratio changed significantly across the same 12 months (Lewis et al., 2024). Interferon-gamma to interleukin-10 increased, at p = 0.05. That movement ran upward, opposite to the direction the Alzheimer’s ratios traveled.
The remaining ratios in both trials drifted in those same directions without reaching statistical significance. I do not count them, and I will not present them to you as results. Movement that fails a significance test is a hypothesis for the next study, not a finding for this page.
Changes in several ratios tracked with changes in individual cognitive subscales in the Alzheimer’s sample (Lewis et al., 2023). The ADAS-cog total score correlated with none of the six ratios. However, the subscale correlations also showed improved cognitive function with a rebalancing of the ratios.
Our Alzheimer’s paper described the overall pattern as a rebalancing of the Th1/Th2 ratio (Lewis et al., 2023). Our multiple sclerosis paper called the regimen immunomodulatory, a word describing adjustment of immune signaling rather than a push in one fixed direction. An open-label design without a placebo group cannot separate that reading from the ordinary course of either condition. We also reported finding no other published study that had tracked these ratios against a dietary supplement over time (Lewis et al., 2024).
What the Th1/Th2 Ratio Is Good For, and What It Is Not
No physician tracks your Th1/Th2 ratio in routine practice. No reference range defines a healthy value for one individual. Any panel sold directly to you on the promise of optimizing that number is offering precision the science does not currently support.
The unglamorous inputs are still the ones carrying evidence. Teodoro and colleagues reviewed 14 studies covering 525 older adults (Teodoro et al., 2025). A single exercise session raised interleukin-4, interleukin-6, and interleukin-10 immediately afterward in those older adults. Those values returned toward baseline within one hour. Regular training across 24 weeks was associated with lower TNF-α and interleukin-6 and higher interleukin-10 in the same review.
Sleep, whole-food plant nutrition, and body composition belong in the same discussion for the same reason. I have eaten whole-food, plant-based meals for 27 years, and immune signaling is one reason among many. If you are weighing one product against another, I worked through that comparison in the best supplements for memory loss.
My research supports one practical standard more than it supports any single number. A formula should be tested whole, in people, over a period long enough to matter. Aloe polysaccharides anchored the formulation we put through a full year of testing. Meeting that standard is what persuaded me to put my own name on Daily Brain Care. My academic appointments and publication record appear on the about page.
Conclusion
The Th1/Th2 ratio describes the direction of an immune response rather than its quality. My Alzheimer’s sample ran high on all six measures, while my multiple sclerosis sample matched healthy adults on four of them. Ratios fell significantly in one trial and rose significantly in the other, and both movements make sense once TNF-α stops being cast as a villain. Daily habits still carry the foundation because no formula substitutes for sleep, movement, and real food. Put those in place first, then choose a product whose evidence you can actually read. Begin with Daily Brain Care today!
Frequently Asked Questions
What is the Th1/Th2 ratio?
The Th1/Th2 ratio compares the signaling output of two arms of your adaptive immune system. Researchers divide a Th1 cytokine, such as interleukin-2 or interferon-gamma, by a Th2 cytokine, such as interleukin-4 or interleukin-10. A value near one indicates roughly equal weight between the two arms. In the healthy adults we tested, all six ratios sat near unity (Lewis et al., 2023).
What does a high Th1/Th2 ratio mean?
A high value indicates Th1 dominance, meaning the cell-mediated arm is producing more signal than its counterpart. Elevated ratios have been described in autoimmune conditions. In adults with moderate-to-severe Alzheimer’s disease, all six ratios ran significantly higher than in healthy adults (Lewis et al., 2023). A single number still cannot tell you whether an individual is healthy.
Should I get my Th1 and Th2 levels tested?
No clinical guideline recommends that testing for healthy people. No reference range defines an optimal value for one person, and no physician monitors it routinely. Discuss any immune testing with your own doctor rather than ordering it on your own. Money spent on exercise, sleep, and food does more measurable work.
Can a dietary supplement change the Th1/Th2 ratio?
Both of my trials measured ratio changes in adults who carried a neurological diagnosis. Two ratios decreased significantly in the Alzheimer’s sample and one increased significantly in the multiple sclerosis sample (Lewis et al., 2023; Lewis et al., 2024). No randomized controlled trial has shown that any supplement shifts these ratios in healthy adults. Nothing in those results carries over to a healthy person.
Is Th1 dominance bad for you?
Neither arm of the response is good or bad on its own. Th1 activity handles threats inside your cells, and Th2 activity handles threats outside them. Excess in either direction carries its own consequences, which is why immune balance matters more than a maximum. TNF-α complicates the question further, because it associates with both arms (Lewis et al., 2024).
References
Kalliolias, G. D., & Ivashkiv, L. B. (2016). TNF biology, pathogenic mechanisms and emerging therapeutic strategies. Nature Reviews Rheumatology, 12(1), 49–62. https://doi.org/10.1038/nrrheum.2015.169
Lewis, J. E., McDaniel, H. R., Agronin, M. E., Loewenstein, D. A., Riveros, J., Mestre, R., Martinez, M., Colina, N., Abreu, D., Konefal, J., Woolger, J. M., & Ali, K. H. (2013). The effect of an aloe polymannose multinutrient complex on cognitive and immune functioning in Alzheimer’s disease. Journal of Alzheimer’s Disease, 33(2), 393–406. https://doi.org/10.3233/JAD-2012-121381
Lewis, J. E., McDaniel, H. R., Woolger, J. M., & Khan, S. A. (2023). The characterization of the Th1/Th2 ratio in moderate-severe Alzheimer’s disease patients and its response to an aloe polymannose-based dietary supplement. Journal of Alzheimer’s Disease, 96(4), 1723–1737. https://doi.org/10.3233/JAD-230659
Lewis, J. E., McDaniel, H. R., Woolger, J. M., Anzola, E., & Kraft, G. (2024). The characterization of the Th1/Th2 ratio in multiple sclerosis patients and its response to a dietary supplement regimen. Journal of Dietary Supplements, 21(6), 771–790. https://doi.org/10.1080/19390211.2024.2386259
McDaniel, H. R., LaGanke, C., Bloom, L., Goldberg, S., Lages, L. C., Lantigua, L. A., Atlas, S. E., Woolger, J. M., & Lewis, J. E. (2020). The effect of a polysaccharide-based multinutrient dietary supplementation regimen on infections and immune functioning in multiple sclerosis. Journal of Dietary Supplements, 17(2), 184–199. https://doi.org/10.1080/19390211.2018.1495675
Mosmann, T. R., & Coffman, R. L. (1989). TH1 and TH2 cells: Different patterns of lymphokine secretion lead to different functional properties. Annual Review of Immunology, 7, 145–173. https://doi.org/10.1146/annurev.iy.07.040189.001045
Ruterbusch, M., Pruner, K. B., Shehata, L., & Pepper, M. (2020). In vivo CD4+ T cell differentiation and function: Revisiting the Th1/Th2 paradigm. Annual Review of Immunology, 38, 705–725. https://doi.org/10.1146/annurev-immunol-103019-085803
Teodoro, T. H., Costa, K. P. M., Prestes, J., Campanholi, J., Navalta, J., & Pereira, G. B. (2025). The effects of acute and chronic exercise on immune markers of TH1/TH2 cells in older adults: A systematic review. Frontiers in Physiology, 16, 1453747. https://doi.org/10.3389/fphys.2025.1453747
