Rooibos & Health - What Does Science Say?
Rooibos tea, often called red tea, is a caffeine-free herbal tea from South Africa, made from Aspalathus linearis, a legume native to a small region of the West Cape Province. Rooibos has exploded in popularity in recent years, both as a beverage and as a plant used in herbal medicine.

Honeybush, a similar and related plant, also native to South Africa, is used to make a similar tea. In addition to the usual "red" rooibos and honeybush, recently people have begun processing both plants similarly to green tea, yielding beverages lighter in color which are usually called, respectively, green rooibos and green honeybush.
Traditionally, rooibos has been used to treat a variety of ailments, including tension, allergies, and indigestion. The scientific literature studying rooibos is relatively sparse and mostly quite young, and studies on humans are largely absent from the body of research. It is hard to draw many conclusions about the health benefits of rooibos. However, some studies have found evidence of various positive effects, including antioxidant activity and the potential of rooibos to treat asthma.
Honeybush is only beginning to be studied scientifically. The amount of research conducted on honeybush is less even than that on rooibos, but the plants are related and have a similar ecology, and much of the research has so far found them to be similar or comparable. Furthermore, no adverse effects have yet been reported or observed from consumption of rooibos or honeybush in herbal teas.
Antioxidant Effects:
Antioxidants are chemicals that have been the focus of a lot of health and nutrition research in recent years due to their potential to promote overall health and protect against cancer, heart disease, and other diseases. Rooibos is often promoted as having a high antioxidant content, much like green tea.

A study published in 1996 compared the antioxidant content of red and green rooibos to green, black, and oolong teas, and found that the antioxidant content was similar between rooibos and tea. More recent studies have been sparse, but have continued to support the conclusion that rooibos, like tea, is rich in antioxidants.
Treating Asthma & Respiratory Ailments:
Rooibos is sometimes presented as a treatment for asthma and other respiratory ailments. A study on rats, published in 2006, found that rooibos acts as a bronchodilator, a medication to facilitate breathing, like those commonly administered to people suffering from asthma. While this study seems to validate or support the use of rooibos to treat respiratory problems, it is only one study, and only points to the likelihood that rooibos is effective for these purposes.

Still, since it is both delicious and safe to consume, rooibos tea is certainly worth considering drinking for those suffering from asthma or having trouble breathing.
Allergy Treatment & Prevention:
Rooibos is often promoted as being effective for the treatment, or at least for the prevention, of allergy. There has been some research on this topic, and there is as of yet no evidence that rooibos can be used to treat existing allergies.

Rooibos is likely, however, to treat some of the symptoms of respiratory allergies by facilitating breathing, and it is also likely to promote overall healthy functioning of the immune system, which may prevent the formation of new allergies. Allergy is an area of medicine that is still poorly understood, and we can only hope that more research is conducted in this area in the future.
In summary, the research on Rooibos is young and inconclusive. The science so far points to the likelihood of rooibos having a number of health benefits. The most well-established benefits are the antioxidants, which are comparable to those found in tea. There is some evidence that Rooibos can be an effective treatment for asthma and other respiratory problems.

Perhaps most importantly, however, rooibos is a delicious, caffeine-free beverage which is safe to consume. There is little to be lost and potentially much to be gained by exploring this traditional South African drink.