Hibiscus: This plant can help lower cholesterol and even defend against cancer

There are over 200 species of hibiscus (rose mallow) that make up the Malvaceae family. These plants with their distinctive colourful, trumpet-like flowers thrive in tropical and subtropical regions throughout the world, particularly in China, India and Taiwan.

The stunning flowers they produce come in a variety of different colours and it is not difficult to see why certain species have been adopted by countries as their national flower. For example, Hibiscus brackenridgei (mao hau hele) with its bright yellow flowers is the state flower of Hawaii; Hibiscus syriacus (Rose of Sharon), which produces white flowers with a contrasting deep red centre, is the national flower of South Korea; and Hibiscus rosa-sinensis (Chinese hibiscus), which produces large, showy flowers in a variety of colours is the national flower of Malaysia.

As well as producing beautiful flowers, a growing body of research shows that hibiscus extracts also have a wide range of health-giving properties from lowering cholesterol and high blood pressure to improving liver diseases such as hepatitis and protecting against cancer (J Sci Food Agric. 2004;84:198996; Phytomedicine 2004;11:37582; Life Sci 2005;77:26678). These plants also have a long history of use for alleviating constipation, bladder infections, stomach upset and anxiety, in addition to acting as an antiseptic when applied directly to the skin.

One particular variety hibiscus sabdariffa (roselle), which is used as a fortifying herbal tea in several countries including Mexico, Egypt and Sudan is the most well studied of the hibiscus plants from a medicinal standpoint. Scientists attribute its numerous therapeutic benefits to the fact that it contains large amounts of both vitamin C and antioxidants (Toxicol Appl Pharmacol. 2005;205:20112).

Hibiscus protects against heart disease by lowering high levels of LDL (bad) cholesterol

Recently, scientists from the School of Applied Chemistry, Chung Shan Medical University in Taiwan revealed that hibiscus is active against the bad form of cholesterol (LDL). Their research revealed that the plant is able to lower high levels of LDL cholesterol in the blood and also protect various tissues in the body against LDL-related damage (Food Chem Toxicol. 2006 Jul;44(7):1015-23).

Commenting on the findings, Dr Chau-Jong Wang, the scientist who led the study, said: Experiments have shown that compounds extracted from red wine and tea reduce cholesterol build-up in the arteries. This is the first study to show that hibiscus has the same effect. Our data strongly suggest that hibiscus extracts could be useful in the prevention and even treatment of a number of cardiovascular diseases in which cholesterol plays a major role.

Another team of scientists from the Institute of Forensic Medicine, Veracruz University in Mexico have also confirmed that hibiscus is able to lower harmful LDL cholesterol levels. In an animal study they found that hibiscus was able to reduce LDL cholesterol levels significantly or very significantly and also promoted weight loss.   The scientists believe that acids in hibiscus are activated by bacteria in the gut, which then bind to and inactivate excess cholesterol (Plant Foods Hum Nutr. 2005 Dec;60(4):153-9).

A similar study carried out by Thai researchers from the Department of Pharmacology, Mahidol University in Bangkok revealed that hibiscus sabdariffa extracts given for a period of six weeks, were able to not only reduce LDL cholesterol but also protected the arteries against age-related damage. Better still, they found that the extracts do not affect the good form of cholesterol: HDL. A high HDL cholesterol level combined with a low LDL level has been found to offer the greatest protection against heart disease (J Ethnopharmacol 2006;103(2):252-60).

Helps eliminate cancer-causing free radicals from your body

The same scientists from Chung Shan Medical University in Taiwan, who conducted studies on hibiscus regarding its cholesterol-lowering abilities, also examined the plant in addition to several other herbal supplements used in Oriental medicine for potential cancer-fighting properties.

They found that hibiscus was the most effective anti-cancer herb of those tested. Reporting on their findings, the scientists explained that the plant contains polyphenols natural chemicals that perform a variety of actions in the body. In particular, they found that the polyphenols in hibiscus are able to attack and neutralise cancerous cells in the brain and skin (Anticancer Agents Med Chem. 2006;6(4):347-65). Several other scientific studies have also confirmed that hibiscus extracts have anti-cancer benefits.

It is thought that the plant helps protect against cancer as a result of its ability to inactivate free radicals toxic by-products of your metabolism. Free radicals are widely accepted as being the main culprit for causing cancer and premature ageing, by slowly destroying organs in the body.

But the high concentration of antioxidants (chemicals that destroy free radicals) in hibiscus, help ensure that any circulating free radicals are inactivated and eliminated from your body. This has been confirmed by Thai scientists who explain that: Water extracts from dried fruit of hibiscus sabdariffa show strong antioxidant activity (Biol Pharm Bull. 2005;28(3):481-4).

Finally, an additional and hitherto unknown property of hibiscus, until very recently, is that the plant may protect against malaria. A team of researchers from the Indian Malaria Research Centre reported that hibiscus root extract is effective at killing the mosquitoes that carry malaria parasites (J Am Mosq Control Assoc. 2006;22(1):155-7).

What to take for best results

The recommended dosage for hibiscus in tea form is 10 grams of the dried flower taken twice a day or as otherwise directed on the products label. The tea can be drunk either hot or cold.

Contraindications: You should be aware that hibiscus can interfere with the workings of paracetamol, so as a precaution it is best not to take the two together (Eur J Drug Metab Pharmacokinet 2004;29:259). Hibiscus may be used together with other nutritional supplements that can help protect against heart disease, such as vitamin E (400 units a day) and fish oils.