Benefits
Skin wrinkles, elasticity and hydration in a 12-week extract trial
In a placebo-controlled trial in 120 Korean adults with crow's feet wrinkles, 400 or 800 mg a day of a fermented honeybush extract for 12 weeks improved wrinkle grade, skin elasticity and hydration and reduced skin water loss compared with placebo. It is the only human trial, it tested one proprietary extract, and half the authors worked for a drug company.
UV-related skin wrinkling in mice given honeybush by mouth
In hairless mice exposed to UVB light, oral honeybush extract or fermented honeybush reduced the length and depth of wrinkles and limited collagen breakdown and skin thickening. A later mouse study of the fermented extract found less loss of skin hydration after UVB. These are animal results only, with small groups.
Glucose and fat metabolism in rodent studies
In rats given a beta-cell toxin, an unfermented honeybush extract lessened the rise in fasting glucose and improved glucose tolerance and triglycerides. In genetically obese mice, a polyphenol-rich fraction raised fat-burning proteins in brown fat and cut liver fat. No human study has tested honeybush for blood sugar or weight.
Antioxidant polyphenols in the tea
Water extracts of honeybush scavenge free radicals and limit lipid peroxidation in test-tube assays, with antioxidant activity similar to or lower than rooibos and Camellia teas; fermentation lowered nearly every measure of it. In rats, unfermented honeybush tea raised the liver glutathione ratio. No human study has measured antioxidant status after drinking honeybush.
A caffeine-free, low-tannin herbal tea
Like rooibos, honeybush contains no caffeine and is very low in tannin compared with black or green tea, so it can be drunk in the evening by people avoiding caffeine. This describes the drink itself, not a tested health effect.
Mechanism of action
Mangiferin and hesperidin are absorbed and broken down
In pigs fed a honeybush extract, the mangiferin breakdown product norathyriol appeared in blood, and about 26 to 31% of the hesperidin dose but under 2% of the mangiferin dose was recovered in urine. The body therefore changes these polyphenols extensively before they act. How this applies to people is untested.
Liver detoxifying enzymes and glutathione
In rats, honeybush tea raised the activity of the phase II enzyme glutathione S-transferase alpha, and unprocessed honeybush raised the liver ratio of reduced to oxidized glutathione, a sign of stronger cellular antioxidant defenses. This is animal work.
Plant-estrogen activity at estrogen receptors
In cell assays, Cyclopia extracts, including a cup-of-tea extract, blocked estrogen receptor alpha and activated estrogen receptor beta when each receptor was tested alone (with both receptors present they only activated), and C. subternata extracts given by mouth did not cause uterine growth in young rats. These lab findings explain interest in honeybush polyphenols as plant estrogens; no human hormone effects have been measured.
Thermogenic proteins in brown fat
In obese db/db mice, a honeybush polyphenol fraction raised uncoupling protein 1 and PPAR alpha, proteins linked to heat production and fat burning, and computer modeling pointed to hesperidin and neoponcirin. This is a mouse and modeling finding.
Clinical trials
Randomized, double-blind, placebo-controlled trial of an oral fermented Cyclopia intermedia extract (HU-018) at two doses; four of the eight authors were affiliated with Huons Co., a Korean drug company. (Choi et al. 2018, J Cosmet Laser Ther)
120 Korean adults with crow's feet wrinkles, randomized to 400 mg/day, 800 mg/day or a dextran placebo for 12 weeks.
Both doses significantly improved global skin wrinkle grade, skin elasticity and hydration and lowered transepidermal water loss compared with placebo; no adverse effects were reported. The abstract does not give effect sizes or a dose response. It is a single trial of one proprietary extract and has not been repeated by an independent group.
Animal study of oral honeybush extract and fermented honeybush given daily, with UVB exposure three times a week for 12 weeks. Two of the six authors were affiliated with Huons Co. (Im et al. 2014, BMC Complement Altern Med)
HR-1 hairless male mice, 5 per group (unexposed control, UVB plus vehicle, UVB plus honeybush extract 100 mg/kg, UVB plus fermented honeybush).
Both honeybush preparations reduced wrinkle length and depth, limited thickening of the epidermis and reduced collagen breakdown compared with UVB-exposed vehicle mice. Very small groups; mouse data only.
Cell and animal study of the scaled-up fermented extract HU-018 against UVB damage. (Im et al. 2020, Evid Based Complement Alternat Med)
Human HaCaT keratinocyte cells, and hairless mice (10 per group) given HU-018 80 or 160 mg/kg orally for 12 weeks with UVB exposure.
HU-018 limited the UVB-induced fall in hyaluronic acid and skin-barrier protein genes in cells, and in mice it lessened the loss of stratum corneum hydration and the rise in water loss and redness, with less collagen disorganization. Not a human study.
Rat and cell study of pretreatment with an aqueous unfermented Cyclopia maculata extract before the beta-cell toxin streptozotocin. (Chellan et al. 2014, Planta Med)
Wistar rats given 30 or 300 mg/kg/day of extract, with streptozotocin used to induce diabetes; RIN-5F insulin-producing cells in vitro.
Extract-treated rats had lower fasting glucose, a smaller glucose-tolerance area under the curve, better serum triglycerides and a larger beta-cell area; beta-cell proliferation rose only at the higher dose. Serum catalase, glutathione and liver lipid peroxidation were unchanged. Animal data only.
Mouse study with western blot and computer docking analysis of a polyphenol-enriched Cyclopia intermedia fraction. (Jack et al. 2023, Int J Mol Sci)
Female obese, diabetic db/db mice given the fraction (351.5 mg/kg) by gavage for 28 days, with vehicle-treated db/db and lean controls (6 to 8 per group).
The fraction raised UCP1 3.4-fold and PPAR alpha 2.6-fold in brown fat, raised liver PPAR alpha 2.2-fold and reduced liver fat droplets by 31.9%. The earlier report on these mice found lower body weight gain. Mouse data only.
Animal absorption and metabolism study of an oral Cyclopia genistoides extract. (Bock et al. 2008, Nutr Res)
Pigs given up to 74 mg/kg mangiferin and 1 mg/kg hesperidin a day from the extract for 11 days.
Norathyriol, the aglycone of mangiferin, was found in plasma at 7.8 to 11.8 micromol/L. Urine held 26.0 to 30.8% of the hesperidin dose but only 1.4 to 1.6% of the mangiferin dose, and about 8.2% of the mangiferin dose was found in feces. Shows absorption and metabolism, not a health outcome.