Chiropractic has been utilized as a treatment for many ailments, but primarily those related to musculoskeletal (MSK) problems, especially back and neck pain. However, there are many people who seek chiropractic services for ailments other than MSK conditions such as colds, flus, or just to “feel better.” Similarly, as chiropractors, we have observed in our own practices that patients will sometimes demonstrate improvement related to the immune system such as reduction of allergy symptoms, a quicker recovery, decreased frequency and/or severity of colds or other respiratory infections, and so on. Back in 1975, the National Institute of Health sponsored a meeting of all the professions that utilize spinal manipulative therapy (SMT). The purpose of the meeting was to review what research existed to support the various theories of SMT benefits and to determine what additional research was needed. The immune system was included as an area of research that was promising but required additional studies. So the question is, what research exists today that supports the theory that SMT does indeed stimulate the immune system and hence, enhance our body’s ability to fight infections and other disease processes?

As one might imagine, conducting research in this area is very challenging. Reports of isolated cases are available, but due to the difficulty of having a non-treatment control group, being double-blinded in the study design, and having a large enough study group to draw strong conclusions (among other factors), gives rise to criticism that chiropractic adjustments or SMT enhances immune function. There is however, a growing body of research that is building the case that SMT does indeed benefit the immune process. For example, a decrease in “pro-inflammatory cytokines” (the “bad guy” chemicals that increase inflammation), and an increase in blood levels of “immunoregulatory cytokines” (the “good guy” chemicals that help stimulate and regulate the immune system) has been reported to occur when SMT is received.

Within the last ten years, a series of studies have been published that describe this interplay between the nervous system and the immune system as “neural immunoregulation.” In other words, there is a balanced communication (reflexes) between our neurological and immune systems (through cytokines and neurotransmitters). This involves the discovery of a close relationship between the autonomic (sympathetic and parasympathetic) nervous system with white blood cells (macrophages and lymphocytes), which helps explain the “how” SMT helps to support the immune mechanism. The discovery of reflexes between the nervous system and neurotransmitters is an integral part of this process. This process has been shown to occur by a single thrust adjustment applied to the upper back region where the physiologic response by white blood cells increases via this “spinovisceral reflex,” thus reducing the inflammatory response that occurs with colds, flus, etc. This response is best achieved with spinal manipulation producing an audible release of gas (cavitation) or the “cracking” sound typically found with SMT. Pain generating chemicals have also been found to decrease when SMT was applied in cases with headaches, neck pain/stiffness, and in post-whiplash cervical disk herniations. Other immune markers (IgG and IgM) were also found to increase at least temporarily in subjects receiving upper back SMT.

The “take-home message” here is that there is accumulating evidence that with little to no negative side effects, SMT does indeed enhance and support the immune system. Though these preliminary findings are exciting, we cannot conclude that SMT has the ability to stop or reverse infection, inflammation, or a disease process. But, it appears appropriate to consider including SMT with other treatment approaches in this patient population – yet another needed area for future research!