Twenty-four weeks of supplementation with alpha-lipoic acid led to body weight reductions of about 5% for obese participants, while body fat levels also dropped by about 9%, according to findings published in the Journal of Nutrition. The researchers hailed from Oregon State University and Oregon Health & Science University.
The data also revealed that women showed greater benefits than men, as did more obese participants vs less obese.
“By the end of the study, some markers of inflammation declined,” said Tory Hagen, a professor of biochemistry and biophysics in the OSU College of Science and the study's corresponding author. “The findings also suggest that lipoic acid supplementation provides a mild reduction in oxidative stress. It is not a perfect panacea, but our results show that lipoic acid supplements can be beneficial.”
Hagen added that it would be important from clinical and economic perspectives to identify which consumer groups would benefit the most from lipoic acid supplementation, and what doses would be optimal.
“Lipoic acid supplements are often quite expensive,” he said. “So, understanding how we can maximize benefits with smaller amounts of the supplement is something we are interested in pursuing.”
What the literature already showed
Lipoic acid is a medium-chain fatty acid that has two sulfur atoms at one end of the chain. The body generally produces enough lipoic acid to supply the enzymes that require it for proper function. It is a cofactor for some mitochondrial enzymes.
When taken as a dietary supplement, properties may include the stimulation of glucose metabolism, antioxidant defenses and anti-inflammatory responses.
The new findings are consistent with other placebo-controlled clinical trials from Asia, Europe, and New Zealand. According to the Oregon researchers, of those 13 clinical trials, 10 reported weight loss or a decrease in BMI, compared with the placebo group.
However, Hagen noted that many previous clinical studies using lipoic acid focused on volunteers with pre-existing conditions like diabetes, “making it difficult to determine if lipoic acid supplements simply act as a disease treatment or have other beneficial health effects,” he said.
“Another issue is the formulation of the supplement. Many previous studies have used the S form of lipoic acid, which is a product of industrial synthesis and not found in nature. We only used the R form of lipoic acid - the form found in the body naturally.”
For the new study 81 overweight adults with elevated plasma triglycerides (at least 100 mg/dL) were recruited to participate in the randomized, double-blind, controlled trial. Participants were randomly assigned to receive either (R)-alpha-lipoic acid (LA) at a dose of 600 mg per day, or placebo for 24 weeks. The volunteers were also advised to not change their diet or physical activity.
The results showed that for the 64 participants who completed the trial (the rest withdrew or were otherwise lost during the trial) those receiving the lipoic acid supplements experienced significant reductions in BMI, body weight, and body fat, with the effects more pronounced in women and those classified as more obese.
In addition, a correlation between the effect of lipoic acid on BMI and changes in plasma triglycerides was recorded.
“The effect of lipoic acid supplements on blood lipids was limited, but people who lost weight on lipoic acid also reduced their blood triglyceride levels - that effect was clear,” commented study co-author Gerd Bobe from the Linus Pauling Institute at OSU.
In addition, the researchers reported that expression of antioxidant gene in mononuclear cells was greater in the lipoic acid group after 24 weeks, compared to placebo, while F2-isoprostanes and ICAM-1 were also significantly reduced compared to placebo.
“Although this study only marginally supports previous work that LA improves antioxidant capacity, these data must be couched in their proper context,” wrote the researchers. “This study population did not display overt inflammation or oxidative stress despite their level of obesity. Therefore, LA may be a useful adjunct in obese individuals who have yet to progress to a chronically inflamed status. LA may potentially limit inflammation-mediated sequelae associated with obesity and further progression to metabolic syndrome or other chronic disease.”
Source: The Journal of Nutrition
Published online ahead of print, doi: 10.1093/jn/nxaa203
“A Randomized Controlled Trial of Long-Term (R)-α-Lipoic Acid Supplementation Promotes Weight Loss in Overweight or Obese Adults without Altering Baseline Elevated Plasma Triglyceride Concentrations”
Authors: G. Bobe, et al.