Until now, my entries about rooibos have focused on the history, processing and especially on the delicious flavor of this unique bush. Today, I'd like to focus (in the most readable and accessible way possible) on the chemical composition and potential health benefits of rooibos.
Many people are aware that rooibos is naturally caffeine-free, but it's somewhat less-known that the plant has a low tannin content and is full of polyphenols, minerals and flavonoids. In addition to containing the flavonoids rutin, orientin, iso-orientin, vitexin, iso-vitexin, luteolin, qurcetin, chrysoeriol, and nothofagin, rooibos contains a flavonoid--aspalathin--that is found nowhere else in nature. Rooibos also contains the minerals iron, potassium, calcium, copper, zinc, magnesium, fluoride, and manganese.
It's pretty easy to toss off a list of minerals and impressive-sounding flavonoids, but this can be confusing for non-scientists (which describes most of us!) and, by itself, this list doesn't really tell us anything concrete about the health benefits of rooibos. For years and years, rooibos drinkers have listed numerous health benefits, reporting that it slows aging, aids digestion, alleviates nausea, heartburn, ulcers and constipation, promotes bone and teeth strength, and is a mild relaxant good for drinking before bed. In the scientific and medical worlds, these types of reports are called "anecdotal evidence," meaning that they may have merit, but are in no way scientifically-supported or produced. This is the dilemma scientists in South Africa were facing in the 1980's, and a number of them resolved to close the gap and subject rooibos to scientific study, which began in 1990.
Scientific Studies: Animals
I recently had the privilege of listening to a presentation by Jeanine Marnewick, a South African scientist who has spearheaded the push for more scientific study of rooibos and its health benefits. I'd rather not get unnecessarily over-scientific about the results of the studies, so instead I'll try to sum up the important points of the results.
Some of the first studies were conducted using rats. In one study, the scientists cut the hair from the rats' backs, applied a rooibos solution topically to the rats' skin, then applied a skin cancer initiator twice weekly for 20 weeks. Compared to the control group of rats that didn't have the rooibos solution applied, the rooibos rats had dramatically-reduced instances of skin tumor development, including some rats with cancer-free skin and some with much more mild symptoms, such as decreased tumor size. A similar study showed that traditional rooibos arrested the growth of pre-cancerous lesions in rats' livers, and green rooibos actually reduced the total number of pre-cancerous lesions, and in an esophageal cancer study, green rooibos significantly reduced the number and size of papillomas in the esophagi of the rats.
Two things must be noted when considering these studies. The first is that the objects of study are rats! Although the anti-cancer effects of rooibos in relationship to rats is exciting and promising, we have to remember that rats and humans are very different animals, and results of rat studies do not guarantee similar results with humans. The second is that, in the scientific community, before a health claim can become widely-accepted, that claim must be supported by a large body of evidence that has been approved by other scientists who work in the same field. A single study's results are certainly not set in stone--another study could produce completely opposite results--and only after numerous studies produce similar results can people like me, an employee of the tea industry, begin confidently saying things like "Rooibos will prevent cancer." Instead, it's important to be honest about the cutting-edge information about rooibos health benefits, provide customers with the facts we have so far in proper context, and eagerly await more studies and more conclusive information.
Encouraged by the favorable animal studies involving rooibos, Marnewick and her associates recently (2007!) pushed ahead and began the first ever rooibos human health study. Since previous studies showed rooibos to have high antioxidant capabilities, Marnewick et al deduced that it would aid in the prevention of heart disease, which is often the result of oxidative stress--an imbalance between oxidants and antioxidants that can damage lipids, proteins, and DNA.
41 participants completed the study--26 females and 15 males--and all of them had at least one or more risk factors for developing heart problems within 10 years. The participants drank 6 cups of rooibos per day for 6 weeks and provided the scientists with blood and urine samples for study. The incomplete data analysis process for this study is very detailed, complicated, and lengthy, and results are only in an extremely preliminary stage. However, Marnewick has provisionally stated that rooibos has no apparent detrimental effects on the health of study participants and that it may prove to decrease oxidative damage to blood lipids.
At first glance, these results may not seem very impressive, but with a little perspective, they're pretty exciting. If, when all of the lab analysis is completed, the provisional conclusions are verified, then the likelihood that more and more rooibos human health studies will be conducted is very good. With an increased body of results and evidence relating to rooibos health benefits, we can more confidently confirm or deny the anecdotal evidence that has been floating around for quite a while. Most excitingly, we get to witness the scientific study of rooibos health benefits in its nascent stages. This first study is only the tip of the iceberg when it comes to what we can learn about rooibos, and hopefully it is the first of many (including ones with larger participant bases and stronger control measures) that we can reference when discussing rooibos as a healthy beverage option. For now, we can mainly refer to this information in a tentative way, making sure to note that the study of rooibos health benefits are in very beginning stages. At the very least, though, these early studies are pointing in a promising and exciting direction.
Since the final results and analyses are not completed, this study is not up for online access at this point. If you google Jeanine Marnewick, though, you'll get a lot of results relating to past studies about rooibos (including the rat studies mentioned above) as well as other infused beverages. I hope this info was helpful, understandable, and not too complicated. As usual, I'm happy to field any questions (though scientific health studies aren't really my specialty!).
This post wraps up the festivities for Rooibos Month at Miro Tea, though our specials and promotions will last until the beginning of July--Chinese Green Tea month! Stay tuned for some exciting happenings involving Chinese green tea, including detailed fresh 2008 tea tasting notes, tasting events, and more specials and promotions!