Rooibos tea: what red tea is good for, and is it good for you?

Strong = multiple human trials or a meta-analysis. Moderate = a few small trials. Preliminary = early, traditional or animal data.

1. 1

   Improves cholesterol and oxidative stress markers

   Moderate evidence

   In the largest rooibos trial so far, 40 adults with at least two risk factors for heart disease drank 6 cups (about 1.5 L) of fermented rooibos daily for 6 weeks, after a control period. LDL cholesterol and triglycerides fell significantly, HDL rose, and markers of lipid peroxidation (damage to fats in the blood) dropped, while glutathione, the body's main internal antioxidant, improved. Six cups is a lot, the study was not placebo-controlled, and it has not been repeated at a larger scale, which keeps this Moderate rather than Strong. Still, it is better human evidence than most herbal teas have.

   Key evidenceMarnewick et al., Journal of Ethnopharmacology 2011 (40 adults, 6 cups daily, 6 weeks)

2. 2

   Raises antioxidant capacity in the blood

   Moderate evidence

   Rooibos is the only known dietary source of aspalathin, a flavonoid alongside nothofagin, orientin and quercetin. In 15 healthy volunteers, a 500 mL serving of either green (unfermented) or red (fermented) rooibos raised total plasma antioxidant capacity, peaking about an hour after drinking; green rooibos, which keeps far more aspalathin, produced the bigger rise. Aspalathin itself is poorly absorbed, and whether a short-lived rise in blood antioxidant capacity improves health long term is not established, so this is a mechanism with early human support rather than a proven outcome.

   Key evidenceVillaño et al., Food Chemistry 2010 (15 volunteers, single 500 mL dose)

3. 3

   A genuinely caffeine-free evening tea

   Strong evidence

   The strong evidence here is about caffeine, which rooibos naturally lacks: in a controlled study, 400 mg of caffeine taken even 6 hours before bed cut measured sleep by more than an hour, and ordinary tea drinkers get 40–70 mg per cup. Decaf black and green teas still carry 2–10 mg per cup and lose polyphenols in processing. Rooibos needs no decaffeination, so an evening cup, or three, has no caffeine load at all. It is the closest thing to a 'real tea' taste you can drink at 9 pm without consequences.

   Key evidenceDrake et al., Journal of Clinical Sleep Medicine 2013 (caffeine 0, 3 and 6 hours before bed)

4. 4

   Does not block iron absorption like black tea

   Preliminary evidence

   Black tea polyphenols can cut absorption of non-heme (plant-source) iron by 60–90% when drunk with a meal. Rooibos has roughly a third of the tannins, and a South African study published in 1979 found rooibos did not significantly reduce iron absorption, whereas black tea did. The study is old and small and has not been repeated with modern methods, so we grade it Preliminary, but it is consistent with rooibos's low tannin chemistry and is the reason it is often recommended for anaemic patients, pregnant women and children in South Africa.

   Key evidenceHesseling et al., South African Medical Journal 1979

5. 5

   May help blood pressure (ACE inhibition)

   Preliminary evidence

   Angiotensin-converting enzyme (ACE) is the target of a whole class of blood pressure drugs. In 17 healthy volunteers, a single 400 mL serving of rooibos significantly inhibited ACE activity in blood samples taken 30 and 60 minutes later, an effect also seen with green and black tea in the same study, with no change in nitric oxide. No trial has yet measured actual blood pressure in people drinking rooibos for weeks, so this is a mechanism, not a proven benefit, and nobody should swap medication for tea.

   Key evidencePersson et al., Public Health Nutrition 2010 (17 volunteers, single dose)

6. 6

   May support blood sugar control

   Preliminary evidence

   Aspalathin improved glucose uptake in muscle cells and lowered fasting blood glucose and improved glucose tolerance in db/db diabetic mice fed 0.1–0.2% aspalathin for 5 weeks, and green rooibos extracts have done the same in diabetic rats. In people, aspalathin is poorly absorbed, and the 6-week trial in adults at cardiovascular risk did not find a change in fasting glucose. Drinking rooibos instead of a sugary drink is good for your blood sugar; expecting it to lower glucose on its own is not yet justified.

   Key evidenceKawano et al., Phytomedicine 2009 (db/db mice); human data lacking

7. 7

   Traditional use for colic, allergies and skin

   Preliminary evidence

   In South Africa rooibos has been given to babies for colic, used as a wash for eczema and nappy rash, and drunk for hay fever for over a century. Laboratory studies show rooibos flavonoids have anti-inflammatory and anti-allergic activity (for example, dampening histamine release from mast cells), and a mouse study found it reduced skin inflammation. There are no controlled human trials for any of these uses. It is safe enough to try and cheap enough not to regret, but nothing more can be claimed.

   Key evidenceJoubert and de Beer, South African Journal of Botany 2011 (review of rooibos research)

Is rooibos tea good for you?

• Yes: rooibos is one of the safest daily teas there is, caffeine-free, low in tannins and oxalate, calorie-free, and backed by one decent human trial on cholesterol and oxidative stress.
• Keep expectations proportionate. The heart-marker benefits took 6 cups a day; the blood-sugar and allergy claims rest on animals and tradition.
• It is the right swap for black tea if you are pregnant, anaemic, prone to kidney stones, caffeine-sensitive or sleeping badly.
• Very heavy intake (well over a litre a day for months) has been linked in two case reports to raised liver enzymes that reversed on stopping; if you have liver disease, keep to a few cups and mention it to your doctor.
• People with hormone-sensitive cancers may want to limit it to normal amounts, since rooibos extracts showed weak oestrogen-like activity in test tubes; there is no human evidence of harm.

• For the most antioxidants, simmer it: 10 minutes in a pot at a gentle boil extracts noticeably more than a quick cup steep.
• Green rooibos has several times more aspalathin than red and tastes grassier; red (fermented) is sweeter and rounder.
• It takes milk and honey well and makes a good caffeine-free chai base; cold-brewed overnight in the fridge it makes a tannin-free iced tea.

Frequently asked questions

1. Marnewick JL, Rautenbach F, Venter I, et al.. Effects of rooibos (Aspalathus linearis) on oxidative stress and biochemical parameters in adults at risk for cardiovascular disease. Journal of Ethnopharmacology (2011)
2. Villaño D, Pecorari M, Testa MF, et al.. Unfermented and fermented rooibos teas (Aspalathus linearis) increase plasma total antioxidant capacity in healthy humans. Food Chemistry (2010)
3. Persson IA, Persson K, Hägg S, Andersson RG. Effects of green tea, black tea and Rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers. Public Health Nutrition (2010)
4. Kawano A, Nakamura H, Hata S, et al.. Hypoglycemic effect of aspalathin, a rooibos tea component from Aspalathus linearis, in type 2 diabetic model db/db mice. Phytomedicine (2009)
5. Hesseling PB, Klopper JF, van Heerden PD. The effect of rooibos tea on iron absorption. South African Medical Journal (1979)
6. Joubert E, de Beer D. Rooibos (Aspalathus linearis) beyond the farm gate: from herbal tea to potential phytopharmaceutical. South African Journal of Botany (2011)
7. McKay DL, Blumberg JB. A review of the bioactivity of South African herbal teas: rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia). Phytotherapy Research (2007)
8. Sinisalo M, Enkovaara AL, Kivistö KT. Possible hepatotoxic effect of rooibos tea: a case report. European Journal of Clinical Pharmacology (2010)
9. Engels M, Wang C, Matoso A, et al.. Tea not tincture: hepatotoxicity associated with rooibos herbal tea. ACG Case Reports Journal (2013)
10. Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine (2013)