Bitter melons may taste unpleasant to some people, but its health benefits cannot be denied. In particular, a study in China suggested that oil extracts from bitter melon seeds have the potential to support weight loss. The results of the study, published in the Journal of Nutrition & Intermediary Metabolism, also pointed out that consuming bitter melon seed oil could restore the balance between lipid intake and metabolism.
The study, led by researchers from the Hefei University of Technology and the Chinese Academy of Agricultural Sciences, built on popular knowledge on the health benefits of bitter melons. Earlier studies have also looked at the correlation between the vegetable and obesity. One such study, which was also led by the Hefei University of Technology, stated that bitter melon suppressed the abnormal enlargement of adipose tissue, a hallmark symptom of obesity, based on animal studies. In another study, researchers concluded that aside from obesity, it also can also decrease metabolic syndrome, a condition defined by the occurrence of high blood sugar, body fat accumulation around the waist, and abnormal cholesterol levels – which is a major risk factor for cardiovascular disease and diabetes. (Related: Bitter Melon Is a Safe and Effective Treatment for Type 2 Diabetes.)
Researchers for this study took it a step further: They looked at the effects of bitter melon seeds in a novel approach and investigated the mechanisms behind its anti-obesity capacity. To obtain bitter melon seed oil, the team used a process called supercritical extraction, which effectively separates the oil from the bitter melon seeds.
To understand the main ingredients in the oil extract, researchers subjected it to high-performance liquid chromatography (HPLC) analysis. Based on the results, the extract contained at least 43 percent of conjugated linolenic acid – a fatty acid that aids in regulating inflammation – and 14 percent of conjugated linoleic acid, which can help protect against neurodegenerative diseases.
The oil extract was then used in vivo experiments involving mice that were given a high-fat diet. The mice were separated into four groups, with three receiving differing amounts of bitter melon seed oil and the remaining one serving as a control group. Each group was given the following amounts: One gram of the oil extract per kilogram of body weight (g/kg), five g/kg, and 10 g/kg, respectively. After three weeks, the body weight and length of the mice were recorded, and the fat pads in the adipose capsule (perirenal) and the epididymis were harvested.
Based on the results, mice that were supplemented with bitter melon seed oil had a decrease in their body weight. According to researchers, this was mainly seen in mice that were given the highest dose of bitter melon seed oil, indicating that the effects would depend on the dosage of the extract. Moreover, the degree of obesity in mice that were given bitter melon seed oil was also reduced by at least five percent in mice with the highest dosage.
In addition, bitter melon seed oil also greatly reduced the size of fat cells, based on mice studies. According to researchers, this could be the anti-obesity effect of conjugated linoleic acid. While their results on whether it can reduce instances of non-alcoholic fatty liver disease (NAFLD) are unclear, the team indicated that the antioxidant content present in bitter melons could also offer some protection toward the liver.
In terms of lipid metabolism, that is, the breakdown or storage of fats for energy, bitter melon seed oil enhanced it. This was shown by the increased levels of free fatty acids, a biomarker for lipid metabolism activity. Leptin, the signaling molecule released by fat cells, was also affected by the oil extract.
Researchers deduced that bitter melon seed oil, with its anti-obesity property, could be used to support weight regulation. “This beneficial effect was partially interpreted as the increased lipid metabolism, and leptin also participated in the overall regulating process,” the researchers wrote of their study. “This is a detailed exploration of BME’s anti-obesity effect, facilitating the rational use of this herbal plant to address this increasingly severe issue, obesity.”