What Is Rooibos Good For? What the Human Studies Show

Rooibos is a caffeine-free, low-tannin herbal tea made from the South African shrub Aspalathus linearis, and the human evidence for it is small: a 2023 scoping review found 18 studies with 488 participants in total, the best known a six-week trial in which 40 adults at cardiovascular risk drank six cups a day and saw LDL cholesterol fall from 4.6 to 3.9 mmol/L and markers of lipid oxidation drop.^{3, 4} None of the 18 human studies reviewed in 2023 tested rooibos for sleep, hormones, kidneys, skin or weight; four case reports describe liver injury in people drinking it daily; and in the one iron-absorption study among those 18, rooibos did not block iron absorption as black tea does.^{3, 9, 10, 11, 12, 13}

What is rooibos, and what is in it?

Rooibos, Afrikaans for "red bush" and sold in America as red tea or red bush tea, is the needle-like leaf of Aspalathus linearis, a legume grown only in South Africa's Cederberg. Red rooibos is fermented (oxidised) after harvest, which turns it red-brown and sweet; green rooibos is dried unoxidised and keeps far more of its signature polyphenol, aspalathin, found in no other food plant.^{1, 2} Rooibos contains no caffeine and little tannin, which is why South African babies have been given it for colic for generations, a traditional use, not a tested one.¹ Its nearest relative is honeybush (Cyclopia).¹

What is rooibos good for? What the human studies show

The 2023 scoping review is the fairest summary: 18 human studies, 488 participants aged six to 83, with better lipid profiles, antioxidant status and blood glucose reported in some and inconsistent results the reviewers put down to the range of doses and tea types.³ Three studies carry most of the weight. In the six-week trial, 40 adults at risk of heart disease drank six cups of fermented rooibos a day: LDL cholesterol fell from 4.6 to 3.9 mmol/L and two markers of lipid peroxidation roughly halved.⁴ In 17 healthy volunteers a single 400 mL cup inhibited angiotensin-converting enzyme for an hour, a laboratory marker rather than a blood-pressure reading.⁵ A 12-week placebo-controlled trial of rooibos extract capsules recorded small echocardiographic changes.⁶

The blood-sugar story is mostly animal: a 2018 meta-analysis pooled 12 rodent studies and found lower glucose with rooibos extracts; the aspalathin work is in cells and animals.^{2, 7} The plant compound with human glucose trials behind it is berberine. No rooibos claim is authorised in Great Britain, so a UK label may describe it and no more.¹⁵

Does rooibos make you sleepy or help you sleep?

It contains no caffeine, which is not the same as being a sedative. No trial has measured sleep in people drinking rooibos, so "is rooibos good for sleep" has no number to report.³ What it offers at night is a hot drink that adds no caffeine, where black tea adds about 75 mg a cup.¹⁴ If you feel sleepy after it, the likelier explanations are the evening, the warmth and the missing stimulant. The ingredients trialled for sleep, with their effects in minutes, are on which sleep supplements have evidence behind them.

Does rooibos affect hormones or oestrogen?

None of the 18 human studies reviewed in 2023 measured hormones in rooibos drinkers.³ The oestrogen question comes from a 2006 laboratory paper that isolated 25 compounds from the leaf and found three with oestrogenic activity in a test-tube assay: a chemistry finding, not evidence that a cup of tea changes anything in a woman's body in either direction.⁸ Rooibos is neither "high in oestrogen" nor an oestrogen blocker on any existing evidence; anyone with a hormone-sensitive condition asks their specialist.

Is rooibos safe every day, and who should be careful?

At ordinary intakes nothing in the human studies raised a safety signal; the six-week trial ran at six cups a day with liver and kidney blood tests monitored.⁴ The cautions are specific.

Liver. Four case reports describe acute liver injury attributed to rooibos, from Finland, the United States (twice, one involving a rooibos-and-buchu blend) and France; where follow-up is reported, liver function recovered once the tea stopped, and the authors call the injury rare, probably under-recognised and possibly linked to heavy intake or to the rest of the blend.^{9, 10, 11, 12} Anyone with liver disease asks a GP first; dark urine or yellowing while drinking a lot of any herbal tea means stop and be tested.

Kidneys. No trial has studied rooibos in kidney disease, so "is rooibos good for kidneys" has no evidence either way; anyone with kidney disease keeps to their renal team's fluid advice.³

Iron. Here rooibos differs from black tea. In 30 young men given a test dose of iron with rooibos, ordinary tea or water, absorption was 7.25%, 1.70% and 9.34% respectively: rooibos did not reduce it significantly, ordinary tea cut it by four-fifths.¹³ For a woman watching her ferritin that makes rooibos the better drink with an iron-rich meal or tablet; the detail is on iron supplements for heavy periods.

Pregnancy and children. The NHS limits herbal teas in pregnancy to four cups a day, as little is known about any of them, and caps caffeine at 200 mg; rooibos adds no caffeine, but the four-cup rule applies and a GP or midwife is the person to ask about a daily habit.¹⁴ Children drink it in South Africa and the studies included participants from age six; there is no UK guidance for children.^{1, 3}

Rooibos versus green and black tea: what each contains

Not a ranking: the right one depends on whether you want caffeine and whether you drink it with iron.

"Which is healthier" has no evidence-based answer: green tea has far more human research, rooibos has no caffeine and no measurable effect on iron, and both are drinks, not treatments.

How do you drink rooibos, and what does it taste like?

Red rooibos tastes naturally sweet and slightly woody, without black tea's astringency; green rooibos is grassier. Brew it longer if you like it strong; it does not turn bitter. South Africans take it with milk and sugar, as the British take black tea, and it works plain, iced or as a latte. There is no best time of day, as nothing in it keeps you awake. Like any red-brown drink it may mark teeth over years.

Rooibos also appears in warm-drink sachets made for the days around a period, typically as a leaf extract alongside other botanicals such as chamomile, saffron or green tea and nutrients such as vitamin D, vitamin B6, magnesium, iron and zinc, prepared like a cup of tea; the wording such a sachet may carry belongs to those nutrients, for example vitamin D contributes to the maintenance of normal bones and teeth and to normal muscle function.¹⁵ Rooibos carries no authorised claim, so it is listed as an ingredient and nothing more. Where a sachet includes green tea extract it is not caffeine-free, and labels say consult a GP if pregnant, breastfeeding or taking medication.

Rooibos comes up in women's health searches beside iron and periods; the Wellgard women's health guide begins with what causes BV and why it comes back.

Frequently asked questions

Is rooibos tea really healthy?

A pleasant caffeine-free drink with a small body of human evidence: better lipids and oxidative-stress markers in one six-week trial of 40 people, and no authorised health claim in Great Britain.^{3, 4, 15}

Is rooibos good for your stomach or your skin?

Its traditional use is for infant colic; no trial has tested it for indigestion or bowel symptoms, and rooibos extracts have been studied on skin cells in the laboratory, never in people drinking it.^{1, 3}

How many cups of rooibos can you drink a day?

No upper limit is set. The lipid trial used six cups a day for six weeks; the liver case reports involved people drinking it daily; in pregnancy the NHS limit for any herbal tea is four cups.^{4, 9, 14}

What should you not mix with rooibos?

Nothing is confirmed in people. Laboratory work suggests rooibos extracts may affect how some blood-sugar and cholesterol medicines are metabolised; mention a heavy habit to a pharmacist.²

Sources

1. Joubert E, Gelderblom WC, Louw A, de Beer D. South African herbal teas: Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides: a review. Journal of Ethnopharmacology, 2008. PubMed 18621121.
2. Johnson R, et al. Aspalathin from rooibos (Aspalathus linearis): a bioactive C-glucosyl dihydrochalcone with potential to target the metabolic syndrome. Planta Medica, 2018. PubMed 29388183.
3. Afrifa D, et al. The health benefits of rooibos tea in humans (Aspalathus linearis): a scoping review. Journal of Public Health in Africa, 2023. PubMed 38204815.
4. Marnewick JL, et al. Effects of rooibos (Aspalathus linearis) on oxidative stress and biochemical parameters in adults at risk for cardiovascular disease. Journal of Ethnopharmacology, 2011. PubMed 20833235.
5. Persson IA, et al. Effects of green tea, black tea and rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers. Public Health Nutrition, 2010. PubMed 20144258.
6. Hartnick MD, et al. Impact of chronic consumption of herbal rooibos on cardiovascular function in adults with cardiovascular risk. Journal of Medicinal Food, 2024. PubMed 38958559.
7. Sasaki M, Nishida N, Shimada M. A beneficial role of rooibos in diabetes mellitus: a systematic review and meta-analysis. Molecules, 2018. PubMed 29642387.
8. Shimamura N, et al. Phytoestrogens from Aspalathus linearis. Biological and Pharmaceutical Bulletin, 2006. PubMed 16755032.
9. Sinisalo M, Enkovaara AL, Kivistö KT. Possible hepatotoxic effect of rooibos tea: a case report. European Journal of Clinical Pharmacology, 2010. PubMed 20072844.
10. Engels M, et al. Tea not tincture: hepatotoxicity associated with rooibos herbal tea. ACG Case Reports Journal, 2013. PubMed 26157822.
11. Reddy S, et al. Hepatotoxicity due to red bush tea consumption: a case report. Journal of Clinical Anesthesia, 2016. PubMed 27871602.
12. Carrier P, et al. Rooibos, a fake friend. Clinics and Research in Hepatology and Gastroenterology, 2021. PubMed 32828746.
13. Hesseling PB, Klopper JF, van Heerden PD. The effect of rooibos tea on iron absorption. South African Medical Journal, 1979, PubMed record 462276; summarised in the Joubert 2008 review, doi.org/10.1016/j.jep.2008.06.014.
14. NHS. Foods to avoid in pregnancy. nhs.uk/pregnancy/keeping-well/foods-to-avoid.
15. Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. gov.uk.

General information, not medical advice: anyone with liver or kidney disease, pregnant or breastfeeding, or on regular medicine asks a GP, midwife or pharmacist before making any herbal tea a daily habit.