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Hibiscus Tea May Have Cholesterol-lowering Effects
Date 09-28-2007
HC# 050672-337
Hibiscus (HIbiscus sabdariffa)

Lin T, Lin H, Chen C, Lin M, Chou M, Wang C. Hibiscus sabdariffa extract reduces serum cholesterol in men and women Nutr Res. 2007;27:140-145.

Hibiscus (Hibiscus sabdariffa) tea and soft drinks are popular in Taiwan, where hibiscus is also a valued medicinal herb. The popular Mexican soda Jamaica is flavored with hibiscus. Hibiscus flowers contain constituents known to have cardioprotective effects, including anthocyanins, flavonoids, and polyphenols. Previous in vivo studies by this group have shown that hibiscus extract lowers cholesterol levels in rats and rabbits.1,2 In addition, a previous in vitro study by this group has shown that hibiscus extract inhibits low density lipoprotein (LDL) oxidation.1 The purpose of this clinical trial was to assess the effect of hibiscus extract capsules on serum cholesterol levels in subjects with high cholesterol levels (<175 mg/dL).

The hibiscus extract capsules contained 500 mg of a hot aqueous extract prepared by macerating 150 g of hibiscus flowers in 6 L of hot water for 2 hours and then drying and filtering the resulting extract. The hibiscus extract contained 2.5% anthocyanins, 1.7% polyphenols, and 1.43% flavonoids. Therefore, each 500 mg capsule contained 20.1 plus/minus 3.0 mg anthocyanins, 10.0 ± 2.5 mg flavonoids, and 14.0 plus/minus 2.8 mg polyphenols. A total of 42 subjects were randomized to 3 groups for the study, conducted at Chung Shan Medical University Hospital in Taichung, Taiwan. The randomization method used was not described in the paper. The study was divided into 2 study periods lasting 2 weeks for a total duration of 4 weeks. The study was designed as a randomized crossover , with each subject acting as his or her own control. This was done by comparing cholesterol levels at week 2 and week 4 with each subject's baseline levels. Group 1 received 1 capsule of extract 3 times daily (1,500 mg/day), group 2 received 2 capsules 3 times daily (3,000 mg/day), and group 3 received 3 capsules 3 times daily (4,500 mg/day). All subjects took the capsules at mealtimes to mimic usage of cholesterol medications. The subjects maintained food diaries to track their use of the capsules.

Overall, subjects in group 2 (2 capsules 3 times daily) responded best to the hibiscus extract treatment. Groups 1 and 2, but not group 3, experienced a significant reduction in serum cholesterol levels at week 4, compared with baseline levels (P<0.05 for groups 1 and 2). In addition, group 2 experienced a significant reduction in serum cholesterol levels at week 2, compared with baseline levels (P<0.05). At week 2, 6 out of the 14 subjects (42.9%) responded to the hibiscus extract in groups 1 and 3; and 9 out of the 14 subjects (64.3%) responded to the treatment in group 2. By week 4, group 2 had the most responders with 10 out of the 14 subjects (71.4%) experiencing reductions in serum cholesterol levels. In group 1, 7 out of 14 subjects (50.0%) were responders, and 6 out of the 14 (42.9%) subjects in group 3 were responders at week 4. Despite receiving a higher dosage, the responders in group 3 had the smallest response to the hibiscus extract with an average 8.3% reduction in serum cholesterol levels at week 4 (-17.7 plus/minus 8.1 mg/dL, P<0.05). Group 1 responders experienced an average 14.4% reduction in serum cholesterol levels at week 4, compared with baseline levels (-29.3 plus/minus serum cholesterol level reduction of 12.0% at week 4 (-26.7 plus/minus 36.6 mg/dL, P<0.01).

The results indicate that hibiscus flower extracts can reduce serum cholesterol levels in hypercholesterolemic adults. The authors conclude that 1,000 mg of hibiscus extract taken 3 times daily may be the optimal dose. A month of continuous treatment may be required before a significant reduction in serum cholesterol levels occurs. Future studies using a randomized placebo control design will be useful in confirming the results of this study. In addition, although the anti-hyperlipidemic effects are presumed to be due to the anti-oxidant effects the exact mechanism for the observed effects needs further investigation. .

-Marissa Oppel, MS

1.Chen CC, Chou FP, Ho YC, et al. Inhibitory effects of Hibiscus sabdariffa L. extract on low-density lipoprotein oxidation and anti-hyperlipidemia in fructose-fed and cholesterol-fed rats. J Sci Food Agric. 2004; 84:1989-1996.
2.Chen CC, Hsu JD, Wang SF, et al. Hibiscus sabdariffa extract inhibits the development of atherosclerosis in cholesterol-fed rabbits. J Agric Food Chem. Aug 27, 2003; 51(18):5472-5477.