Unexpectedly, this nut extract can prevent fat accumulation

Compiled by: Gong Zixin

Obesity is a significant risk factor for a variety of metabolic diseases and, in many cases, leads to ectopic fat accumulation (i.e., accumulation of fat around organs where it should not be), inflammation, and insulin resistance, which in turn leads to dysfunctional white adipose tissue (cells that store excess energy as fat) and excessive adipogenesis.

Meanwhile, cashew nuts are popular worldwide, but only 10% of the harvest weight is harvested, with the remaining 90% of byproducts (pulp and shell) usually discarded. Several studies have previously shown that cashew pulp and shell have the potential to reduce obesity and improve metabolic health, but their direct effects on adipocyte differentiation have not been clearly established.

Recently, researchers from the University of Tsukuba in Japan published a study in Scientific Reports showing that extracts from cashew kernels, pulp and shells can inhibit lipid accumulation and adipogenesis by downregulating transcription factors involved in adipocyte differentiation.

Cashew (flower) Source: Chinese Academy of Sciences, South China Botanical Garden

The cashew fruit consists of an enlarged fleshy receptacle (the flesh, i.e. the false fruit) and a nut (the true fruit) attached to the receptacle. It has a peculiar shape, as if one end is pressed into the fruit stalk of a pear-shaped enlarged stem. The "false fruit" contains rich fruit juice and vitamin C, and can be eaten raw as a fruit or used to make jam; the kidney-shaped nut is peeled and dried to become the delicious cashew kernel that we often eat. Cashew kernels are rich in nutrients, containing 45% fat, 20% protein, vitamins, and trace elements such as zinc, calcium, and iron.

Comparison of total phenolic compounds and antioxidant activity, and effects on 3T3-L1 cell viability

In the study, scientists extracted ethanol extracts of cashew kernels, cashew meat and cashew shells and measured their total phenolic content and antioxidant activity. The results showed that cashew shell extract had the highest total phenolic content, and cashew kernel and cashew meat extracts had higher antioxidant capacity.

In experiments on 3T3-L1 adipocytes, the researchers found that cashew kernel and cashew meat extracts did not affect cell viability at a certain concentration, while cashew shell extract reduced cell viability at higher concentrations.

The study further analyzed the effects of these extracts on genes and proteins related to adipocyte differentiation and lipid metabolism. Cashew shell extract blocked adipocyte differentiation and lipid synthesis by inhibiting key transcription factors of adipogenesis. Cashew kernel and cashew meat extracts reduced lipid content in adipocytes by 25% and 45%, respectively. Cashew meat extract showed potential anti-obesity effects by reducing lipid accumulation. Cashew kernel extract may have a positive effect on improving metabolic health by increasing the secretion of adiponectin.

This study is the first to systematically evaluate the direct effects of cashew extracts from different parts on adipocyte differentiation, revealing the potential application value of cashew by-products in preventing metabolic diseases and promoting health. These findings provide a scientific basis for the further development and utilization of cashew by-products, which are expected to be transformed into functional foods or drug ingredients.