Aged garlic extract supplementation modifies inflammation and immunity of adults with obesity: A randomized, double-blind, placebo-controlled clinical trial.

Obesity is accompanied by increased size and number of adipocytes as well as excess secretion of adipokines and inflammatory cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha). The chronic inflammation of obesity is associated with immune dysregulation, marked by decreased gamma delta T cells in peripheral blood. The free radicals, cytokines, and immune dysfunction of obesity-related chronic inflammation contribute to the increased risks of metabolic and cardiovascular disease.

Researchers at the University of Florida previously showed that aged garlic extract decreased secretion of inflammatory cytokines and increased proliferation of gamma delta T cells and natural killer (NK) cells in healthy, non-obese adults. They conducted a subsequent study to explore whether aged garlic extract would also modulate chronic inflammation in obese subjects.

Methods

The randomized, controlled trial included 51 obese adult participants. Subjects were randomized to take a placebo or aged garlic extract (supplied by Wakunaga of America, Mission Viejo, CA) at a dosage of 3.6 grams per day for 6 weeks. Blood inflammatory markers, immune cell populations, and lipids were evaluated at baseline and 6 weeks.

Aged garlic extract has demonstrated immune modulating and anti-inflammatory effects.

Results

Consistent with obesity-related inflammation, levels of serum CRP, IL-6, TNF-alpha, and leptin were elevated at baseline. After the 6-week intervention, participants consuming aged garlic extract had significantly lower serum IL-6 and TNF-alpha than participants consuming the placebo. No differences were noted for CRP or leptin.

Also consistent with obesity-related inflammation, percentages of gamma delta T cells were low, and percentages of natural killer T (NKT) cells were high at baseline. After the intervention, gamma delta T cells increased, and NKT cells decreased in the subjects supplemented with aged garlic extract—an indication that supplementation modulated their immunity.   

Finally, LDL cholesterol levels differed significantly between groups at the end of the study. LDL cholesterol increased in the placebo group (from 114 to 118 mg/dL) but decreased in the aged garlic group (from 114 to 108 mg/dL).

Conclusions

The authors of the study conclude that supplementation with aged garlic extract has an immune modulating and anti-inflammatory effect in adults with obesity. Reducing obesity-related chronic inflammation may reduce the risks of obesity-related metabolic and cardiovascular disease.  

Xu, C., Mathews, A.E., Rodrigues, C., Eudy, B.J., Rowe, C.A., O’Donoughue, A., & Percival, S.S. (2018). Aged garlic extract supplementation modifies inflammation and immunity of adults with obesity: A randomized, double-blind, placebo-controlled clinical trial. Clinical Nutrition ESPEN, 24, 148-155.