Rooibos may deter fat cell development
Dr Micheline Sanderson, first author of a recent paper about the effects of Rooibos on adipogenesis (or the development of fat cells), preparing a cell culture used in Rooibos research at South Africa’s Medical Research Council.

A new in vitro study in mouse cells suggests that Rooibos could inhibit the development of fat cells, or adipocytes, if the active compounds are able to reach pre-adipocytes (immature fat cells). The study, which was a collaboration between the Medical Research Council (MRC) and the Agricultural Research Council (ARC), has been accepted for publication and is currently in press in Phytomedicine

Fatty tissue develops when pre-adipocytes grow into mature, lipid-accumulating adipocytes during a process known as adipogenesis. After previous Rooibos studies hinted at the anti-obesity potential of Rooibos, researchers decided to investigate the effect of hot water-soluble matter from traditional Rooibos on the differentiation of mouse embryonic fibroblasts (a pre-adipocyte) into adipocytes.

“Every cup of tea is different,” says the MRC’s Dr Christo Muller, “but the ‘standard’ infusion process we used to obtain the soluble matter of Rooibos is a starting point for investigating the possible health benefits of this South African household favourite.”

“Standard” in this case refers to a 5-minute infusion of 2,5 g “normal” (fermented in the traditional way) Rooibos tea leaves in 200 ml of boiling water.

After filtering and freeze-drying the infusion, Muller and his team re-dissolved the product into the mouse cells’ nutritional liquid environment. They prepared a fresh batch of this Rooibos-supplemented media every day for nine days, in order to achieve “chronic” exposure of the cells to the tea.

Microscopic and gene expression analyses were then used to determine the effect of Rooibos on the cells: fat accumulation, as well as the expression of key genes involved in adipogenesis (the process whereby fat cells develop), decreased significantly.

“The results suggest that if the active compounds in a regular cup of fermented Rooibos tea was able to reach pre-adipocytes after ingestion, it could curb adipogenesis,” says Muller. But, he cautions that this does not mean Rooibos can prevent or reverse obesity.

“No medication or dietary supplement can replace exercise and a healthy, energy-controlled diet as a treatment for obesity. Our findings merely suggest that Rooibos could help people maintain a healthy weight,” he says. Muller also made it clear that this preliminary study does not give an indication of how many cups of Rooibos one would need to drink to observe anti-adipogenic effects. “Studies like these give us insights into the effects of Rooibos at a cellular level, and thus about the potential for investigating these effects further in rodents, and eventually in humans.”

Since these early results are positive, research into this area will continue. For example, researchers still need to discover the precise molecular mechanism behind the observed anti-adipogenic effects. They also need to look at which active compounds are absorbed by the body after drinking a cup of tea (bioavailability), in high enough concentrations to exert the positive effects that have been observed in cellular studies.

The study was supported by the South African Rooibos Council, as well as the MRC and ARC.

Dr Christo Muller, Medical Research Council
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