Besides inflammation, CBD impacts arthritis; learn more about CBD and how to improve joint health
For thousands of years, cannabis has been used by people suffering from pain, including joint-related disorders. Today, joint pain is the largest medical reason for requesting use of the drug.1
In comparison, it is only relatively recently that researchers have started to investigate cannabidiol (CBD), a non-psychoactive component of cannabis, for its beneficial effects on the joints. Many of the pre-clinical findings confirm what chiropractors and doctors are witnessing in clinical practice — that CBD is likely an effective option for patients with arthritis.
The endocannabinoid system and joint health
Although an extensive discussion of the endocannabinoid system is outside the scope of this article, it is necessary to recap some basic functions of this system to understand its effects on pain. The endocannabinoid system comprises the cannabinoid receptors 1 and 2 (CB1 and CB2), their endogenous ligands known as endocannabinoids, and the enzymes responsible for their synthesis and degradation.
The two primary endocannabinoids are anandamide and 2-arachidonoylglycerol (2-AG). It has recently been discovered that other receptors such as transient receptor potential cation channel subfamily V member 1 (TRPV1), peroxisome proliferator-activated receptor alpha (PPARα), and G-protein coupled receptor 55 (GPR55) play a critical role in the endocannabinoid system.2
Although CBD is a phytocannabinoid, its effects on joint health and inflammation are not primarily mediated directly through the traditional endocannabinoid receptors CB1 and CB2. Rather, it acts through PPARα, TRPV, and G-protein coupled receptors.³ CBD’s modulation of the endocannabinoid system also occurs through its ability to inhibit FAAH, the enzyme that breaks down the endocannabinoid anandamide.4 Additionally, CBD has immunoregulatory effects that are of special interest in rheumatoid arthritis, which is characterized by immune cell infiltration into joints.3 For example, CBD can dose-dependently suppress lymphocyte proliferation.5 It also induces regulatory T-cells.3
It’s important to note that CBD does not inhibit either the COX-1 or COX-2 enzymes.6,7 Inhibition of these enzymes can lead to gastrointestinal ulcers and bleeding (COX-1) or myocardial infarctions and cerebrovascular events (COX-2).
Promising preclinical studies
A number of preclinical studies in rodent models have yielded promising results in regards to CBD and how to improve joint health. Philpott and associates induced osteoarthritis (OA) in rats and then measured joint pain, inflammation, and joint nerve myelination.8 The researchers then observed the effects of both therapeutic and prophylactic peripheral CBD administration.
In rats suffering from end-stage OA, CBD dose-dependently reduced joint afferent firing rate and improved weight bearing. CBD treatment also decreased acute, transient joint inflammation. CBD administered prophylactically blocked the development of induced joint pain at later time points. Furthermore, CBD was neuroprotective. In summary, local CBD administration inhibited OA pain while prophylactic CBD treatment stopped the later development of pain and nerve damage in joints with OA.
In another rat model of arthritis, Hammell and colleagues induced arthritis in rats and then administered transdermal CBD for four consecutive days afterward.9 In a dose-dependent manner, transdermal CBD markedly improved joint swelling, spontaneous pain, immune cell infiltration, and thickening of the synovial membrane. The rats’ increased sensitivity to pain (hyperalgesia) was reduced after CBD administration. Additionally, levels of proinflammatory biomarkers declined after CBD.
Oral administration of CBD
Costa and coworkers determined the effect of oral administration of CBD.10 The researchers induced inflammation in rat paws. For three days after the onset of acute inflammation, the researchers administered 5-40 mg/kg of oral CBD to the animals. A single dose of CBD dose-dependently improved edema. Additional daily doses led to further reductions. Prostaglandin E2 plasma levels, generation of oxygen free radicals — all markers of inflammation — also declined after three doses of CBD.
A mouse model found similar results as the preceding rat studies. CBD administered either orally or through i.p. after the onset of clinical symptoms interfered with the progression of arthritis.5 CBD protected the joints against severe damage. There was also a decline in tumor necrosis factor release by knee synovial cells.
The clinical and the pre-clinical research that exists on CBD and joint health is intriguing. Given the results of the existing studies, it is somewhat surprising that larger-scale human studies investigating CBD and how to improve joint health have not been more actively pursued. The promising results achieved with CBD in clinical practice indicate it is safe and effective.
It should be noted, however, that the goal of CBD supplementation is balancing rather than overstimulating the endocannabinoid system. This is why it is recommended for patients to start with a lower dosage of CBD and work up to a sufficient amount to produce optimal results.
CHRIS D. MELETIS, ND, is an educator, international author and lecturer. His personal mission is “Changing World’s Health, One Person at a Time.” He is widely recognized as a world-renowned expert on the science of CBD and has authored 16 books and more than 200 national scientific articles. He can be contacted at drmeletis.com.