Research Shows Rooibos A Boon To The Heart

If you’re keen on living a long and happy life, it’s time to fall back on that great South African classic: rooibos tea. Exciting new research shows that the popular beverage could help prevent heart disease.


Reporting at a press conference in Cape Town, researchers from the Cape Peninsula University of Technology said on Wednesday that drinking six cups of rooibos tea a day had a significant, positive impact on oxidative lipid damage, redox status and the overall lipid profile of participants who took part in a 14-week study. All these factors are thought to contribute to the growing pandemic of heart disease, which claims millions of lives around the globe every year.


This is the very first time that any potential health benefits of rooibos tea have been tested in human subjects, and researchers such as study leader Dr Jeanine Marnewick are excited that this study will pave the way for future research, and possibly other important findings.


Unique Flavonoid Aspalathin Only Found In Rooibos

Animal studies have shown that the benefits of rooibos tea can be attributed to a class of beneficial antioxidants called flavonoids, which are found in tea, chocolate and wine. However, rooibos is unique in that it’s the only plant that’s ever been found to contain the asphalatin flavonoid.


How the study was done


Forty men and women between the ages of 30 and 60 were enrolled for the study. Each participant had two or more of the following risk factors for heart disease: raised cholesterol, raised blood pressure, smoking, increased body mass index (BMI) and/or family history. However, none of the participants were taking oral medication for these conditions.


Participants had to drink six cups of rooibos every day for a period of six weeks, with the six cups spread across the day. In order to maintain a high degree of consistency, the preparation was standardised as 2% weight of dried rooibos to volume of water. Each cup consisted of 200ml boiling water added to one rooibos tea bag, brewed for five minutes before drinking.


Subjects drank the rooibos with or without milk and/or sugar, as previous research on green and black teas have demonstrated that milk doesn’t eliminate the increase in plasma antioxidant activity in humans.


The participants were asked to omit other flavonoid-rich foods and beverages from their diet for two weeks before the start of the study, so as to ensure that any possible effects were from the rooibos alone. Analysis of the participants’ fasting blood samples taken after this period served as a baseline standard to help determine the extent of participant compliance with the study guidelines.


Great news for rooibos tea lovers


The researchers measured the effects of rooibos by looking at two markers in the blood that are indicators of oxidative lipid damage, namely conjugated dienes (CDs) and malondialdehydes (MDAs).


“We observed a decrease of nearly 35% in CDs in the blood of the rooibos-drinking participants and a 50% decrease in MDAs,” Marnewick said.


Oxidative damage in lipids is accepted as a very important step in the development of atherosclerosis. CDs are formed during the early stages of oxidation (destruction) of important cellular components such as lipids (fats). MDAs are oxidation end products of polyunsaturated fatty acids that causes defects in protein synthesis and enzyme inactivation in human cells. Patients with coronary artery disease usually have a higher MDA level than normal.


The researchers also monitored oxidative stress by measuring the ratio of oxidized vs. reduced glutathione (GSH) in the blood. Their results show a significant improvement – and therefore decreased risk of heart disease – in the study participants who drank six cups of rooibos per day.


“We’ve found that rooibos is particularly effective at reducing oxidative damage to lipids (fats), thereby helping to prevent or slow down atherosclerosis, or the hardening of arteries,” Marnewick said.


Apart from the potential heart benefits, rooibos tea is also caffeine-free and contains low levels of tannin. The tea also has no known toxicity, making it a safe, inexpensive drink that everyone can enjoy.


(this article was first published in Health24, November 2008)