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At the heart of rooibos’ benefits
Author: Liezel Engelbrecht
Published: 18/12/2017

​Scientists are closing in on their understanding of how the South African fynbos plant rooibos can help prevent the deadly effects of one of the worlds' fastest growing lifestyle diseases: type 2 diabetes.

This disease, characterised by high levels of blood glucose (sugar) due to increasing insulin insensitivity, has impelled many researchers to investigate alternative mechanisms through which glucose uptake into cells can be increased in an effort to find a cure.

Now Sybrand Smit, a PhD student under the guidance of Prof Barbara Huisamen of the Division of Medical Physiology at the Faculty of Medicine and Health Sciences, is one step closer to this breakthrough.

Smit's research for his master's degree focused on the use of aspalathin, a compound known to contribute to rooibos' beneficial effects, and its therapeutic potential for the diabetic heart by inducing glucose uptake.

“This would be cardio-protective in diabetic patients with a high circulation of blood glucose levels and thus provide a means for the heart to cope with excessive blood glucose," he explains. However, this could not be proven when aspalathin was briefly administered to cells prepared from a rat heart.

Aspalathin did induce glucose uptake in rat heart cells from young and aged control rats, but it did not show significant results for obese rats.

“But although the study casts doubt on the acute efficacy of aspalathin to be therapeutic in insulin-resistant cells, a novel find was discovering that insulin resistance delays aspalathin action," Smit explains. He is excited to have found a strong correlation between aspalathin sensitivity and insulin sensitivity.

So, what are the next steps for researchers, and how can this be applied to humans?

“It is known that rooibos consumption can be cardio-protective in patients at risk of heart disease. However, whether diabetic patients can benefit, requires further investigation. Therefore, for future studies, aspalathin as a dietary supplement needs to be used to investigate its long-term effects on insulin resistance (induced by a high-fat, high-caloric diet), obesity, heart function and protection following a simulated heart-attack, energy metabolism, oxidative status and anti-inflammatory properties."

Smit, a self-proclaimed natural product enthusiast who grew up with rooibos as the preferred hot beverage due to its abundance in his surrounding hometowns of Clanwilliam and Lambert's Bay, can't think of a better project to sink his teeth into.

For his PhD research he will be undertaking a rat dietary study of green rooibos (which has significantly higher levels of aspalathin than its fermented counterpart) and its hopefully beneficial effects in bridging the gap between the diabetic heart and normal heart functioning.