Extracts made from parts of the cashew plant that are usually thrown away when the nuts are processed commercially were found to significantly limit the development of fat cells and the accumulation of fat, according to new research. It suggests the cashew plant is a novel way of improving health.
Obesity affects more than one billion people globally. Caused by a combination of genetic, environmental and social factors and a contributor to morbidity and mortality, it’s little wonder that scientists are focused on finding safe and effective ways to treat the condition.
A new study led by Professor Hiroko Isoda from the Institute of Life and Environmental Sciences at the University of Tsukuba in Japan has found that different parts of the humble cashew plant, from the nut to the shell, affect the development of fat cells, called adipocytes, and the accumulation of fat.
“Various precedent studies have shown the common potential of cashew plant parts, either apple, shell, or nut in reducing body weight, adiposity, and lipid-lowering capacity in human and animal models, however, the direct effect on adipocyte differentiation and its downstream molecular pattern still remain unexplored,” said the researchers. “Therefore, here we sought to evaluate the direct effect of extracts prepared from cashew nut, cashew apple, and cashew shell on adipocyte differentiation and lipid accumulation.”
The cashew tree (Anacardium occidentale) produces the cashew nut and a fleshy part that grows above the nut called the cashew apple. However, when cashew nuts are processed, the cashew apple, although edible, is often discarded or left unused in many commercial nut processing systems. Oftentimes, so is the tough shell that surrounds the nut, which contains a toxic resin called urushiol, which is also found in poison ivy.
Prior research using cashew nuts and cashew apples in rodents and humans has found that they reduce body weight and blood lipid (fat) levels and affect fat storage. For the present study, the researchers prepared extracts of cashew kernel, dried cashew apple, and cashew shell and tested them in various concentrations on 3T3-L1 cells, which are cells that transform into mature adipocytes. They specifically examined each extract’s effect on that transformation process and lipid accumulation, which is the build-up of fat within cells, particularly adipocytes. While some fat in the body is normal and needed for energy storage and insulation, too much can lead to health problems.
They found that cashew shell extract strongly inhibited the formation of adipocytes by downregulating specific transcription factors that normally promote fat cell differentiation. Transcription factors are proteins that act like switches to control when and how genes are turned on and off in a cell. In the context of adipocytes and adipocyte formation, they’re key to controlling how regular cells turn into fat cells and regulating how fat is stored and used.
Dried cashew apple extract also reduced the activity of these transcription factors but did so slightly differently than cashew shell extract. It appeared to reduce lipid accumulation – how much fat cells store – without altering how new fat cells are made. Cashew kernel extract didn’t affect adipocyte formation but, interestingly, it did significantly increase levels of a beneficial protein called adiponectin. Produced by adipocytes, adiponectin tries to keep things in balance by helping the body use insulin more effectively, helping burn fat for energy, particularly during exercise or fasting, and which has anti-inflammatory properties.
“Taken together, we demonstrated the biological effect of different parts of the cashew plant, namely cashew kernel, cashew apple, and cashew shell, in adipocyte differentiation by evaluating gene expression and protein level of adipogenic transcription factors and adipocyte markers,” the researchers said. “These distinct activities have shown that cashew nut as well as other parts of the cashew plant may contain active ingredients that can be used as a valuable resource for further natural compound screening study and better management of metabolic complications and wellbeing.”
The study was published in the journal Scientific Reports.
Source: University of Tsukuba