A team of South African researchers has found additional evidence suggesting Rooibos may
be beneficial in countering Diabetes. According to findings published in the July 2013 edition of Phytomedicine, Rooibos can counteract insulin resistance in muscle cells.

Dr Johan Louw, of the South African Medical Research Council (MRC), says the researchers found that an aspalathin-enriched Green Rooibos extract, increased glucose uptake in these cells, made insulin-resistant through treatment with a saturated free fatty acid (palmitate). He says an excess of saturated free fatty acids in the bloodstream is associated with insulin resistance, a major risk factor in the development of Diabetes Type 2.

“In a normal individual, the insulin hormone controls the entry of glucose into muscle and
other cells, to provide them with energy. In type 2 diabetics, the cells become numb, or resistant to insulin. Glucose would then remain in the bloodstream, leading to high blood glucose levels that could potentially cause organ damage,” says Dr Louw.

The World Health Organisation estimates that 439 million people will have diabetes by 2030,
with the major increase occurring in developing countries. Research carried out at the South
African MRC, with researchers from the Agricultural Research Council’s Infruitec-Nietvoorbij research institute, the University of Zululand and the University of Stellenbosch, demonstrated that extracts prepared from Rooibos decreased palmitate-induced insulin resistance in muscle cells.

Dr Christo Muller, of the MRC, says glucose uptake by the insulin resistant-cells increased from 2.3% to 6.2% after three hours of exposure to a Green Rooibos extract. This extract was enriched with aspalathin, the major antioxidant found in Rooibos. He says with the added Green Rooibos extract, the glucose uptake of the insulin resistant cells was comparable to that of normal cells that were not exposed to palmitate.

“Furthermore, when the researchers stimulated the cells with both insulin and Green Rooibos, glucose uptake increased from about 2% to 9%. An extract produced from fermented
Rooibos also increased glucose uptake, but it was less effective than the Green Rooibos extract,” he says.

Dr Muller adds that it is important to remember these results do not prove that a cup of Rooibos is a cure for Diabetes Type 2. They are referring only to improving insulin sensitivity and the beneficial effects that Rooibos extracts have on regulating glucose levels.

“At this stage, the scientific evidence only suggests Rooibos might have anti-diabetic potential. To understand how Rooibos decreases insulin resistance in the cell line, scientists measure various proteins involved in glucose uptake and metabolism. The experiments indicate that Rooibos extracts may work by ultimately causing a protein known as glucose transporter type 4 (GLUT4) to become more abundant in the cell,” he says.