Ganoderma lucidum mushroom (lingzhi/reishi) for treating cardiovascular risk factors

What are cardiovascular risk factors?

Cardiovascular disease is the name given to any disease, such as heart attack or stroke, that affects the heart and circulatory system (which moves blood around the body). Risk factors for cardiovascular diseases include high blood pressure, and high levels in the blood of glucose and cholesterol. People with cardiovascular risk factors are more likely to have a heart attack or stroke than people without them.

What is Ganoderma lucidum?

Ganoderma lucidum (G lucidum), also known as 'lingzhi' or 'reishi', is a mushroom that is commonly used in traditional Chinese medicine. In China, G lucidum is taken in the traditional form of a decoction (mashed and boiled in water), or in tea or coffee. Recently it has been manufactured as an extract in tablets and capsules for the western market, as it is now being used in western countries in the hope that it might improve cardiovascular health.

The purpose of this review

Researchers from the Cochrane Collaboration tried to determine whether G lucidum, when compared with another medicine or a fake medicine – called a placebo – is an effective treatment for reducing cardiovascular risk factors.

What this review discovered

The researchers searched the medical literature up to June 2014 to identify all the relevant medical research. They identified a total of 5 medical studies that compared G lucidum with placebo in a total of 398 people with type 2 diabetes. Overall the quality of the studies was poor. Unpublished data was obtained for two of the included studies and one study was translated from Chinese. The daily doses of G lucidum taken varied between trials from 1.4 g to 5.4 g. In 1 trial participants in the G lucidum group took capsules that contained either G lucidum only, or a mixture of G lucidum (75% of capsule weight) and another fungus called Cordyceps sinensis (25% of capsule weight). Duration of trials varied from 12 to 16 weeks.

Two of the 5 trials reported results for the participants treated with G lucidum only, but not for those treated with placebo, and so the information from them could not be used. The remaining 3 trials with 157 participants provided information for analysis.

This information showed that G lucidum was not an effective treatment for reducing blood glucose, blood pressure, or cholesterol. It was not clear whether G lucidum might reduce blood glucose after a meal, as the only information for this came from a single study of indeterminable quality.

There was not enough information to determine the overall safety of taking G lucidum. One study showed some increased risk of mild harms in participants who took G lucidum in the form of nausea, diarrhoea or constipation.

Future research in this field should include clinical trials that are better reported.

Authors' conclusions: 

Evidence from a small number of randomised controlled trials does not support the use of G lucidum for treatment of cardiovascular risk factors in people with type 2 diabetes mellitus. Future research into the efficacy of G lucidum should be placebo-controlled and adhere to clinical trial reporting standards.

Read the full abstract...
Background: 

Ganoderma lucidum (also known as lingzhi or reishi) is a mushroom that has been consumed for its broad medicinal properties in Asia for over 2000 years. G lucidum is becoming increasingly popular in western countries as a complementary medicine for cardiovascular health.

Objectives: 

To evaluate the effectiveness of G lucidum for the treatment of pharmacologically modifiable risk factors of cardiovascular disease in adults.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL Issue 6 of 12, 2014) on The Cochrane Library, MEDLINE (OVID, 1946 to June week 3 2014), EMBASE (OVID, 1980 to 2014 week 26), Science Direct (1823 to 2013), Current Controlled Trials (1990 to 2013), Australian New Zealand Clinical Trials Registry (2005 to 2013), Chinese Biomedical Literature Database (2007 to 2013), Chinese Medical Current Contents (2007 to 2013) and other databases. We checked reference lists of included studies, contacted content experts and handsearched The International Journal of Medicinal Mushrooms. We applied no language or publication restrictions.

Selection criteria: 

Randomised controlled trials and controlled clinical trials of G lucidum for the treatment of cardiovascular risk factors. Primary outcomes were blood glucose level, blood pressure and lipid profile.

Data collection and analysis: 

Two authors independently selected trials, assessed risk of bias and cross checked data extraction and analysis. A third author arbitrated in the event of disagreement.

Main results: 

Five trials with a total of 398 participants were eligible for inclusion. Of these, one study was published in Chinese and translated to English; one study was published but study authors provided the additional data used in this review; one study was unpublished and the study authors provided data; and two studies did not provide comparison group data suitable for statistical analyses. The three studies from which data were used for statistical analyses compared G lucidum (1.4 g to 3 g per day) to placebo over 12 to 16 weeks of intervention. Although inclusion criteria varied, all participants of these three studies had type 2 diabetes mellitus. Of the five included studies, risk of bias was low for one study and unclear for the remaining four.

Results from two studies showed that G lucidum was not associated with statistically or clinically significant reduction in HbA1c (WMD -0.10%; 95% CI -1.05% to 0.85%; 130 participants), total cholesterol (WMD -0.07mmol/L; 95% CI -0.57 mmol/L to 0.42 mmol/L; 107 participants ), low-density lipoprotein cholesterol (WMD 0.02 mmol/L; 95% CI -0.41 mmol/L to 0.45 mmol/L; 107 participants), or body-mass index (WMD -0.32 kg/m2; 95% CI -2.67 kg/m2 to 2.03 kg/m2; 107 participants). All other analyses were from a single study of 84 participants. We found no improvement for fasting plasma glucose (WMD 0.30 mmol/L; 95% CI -0.95 mmol/L to 1.55 mmol/L). Measures of post-prandial blood glucose level found inconsistent results, being in favour of placebo for '2-hour post-prandial blood glucose' (WMD 0.7 mmol/L; 95% CI 0.29 mmol/L to 1.11 mmol/L) and in favour of G lucidum for 'plasma glucose under the curve at 4th hour' (WMD -49.4mg/dL/h; 95% CI -77.21 mg/dL/h to -21.59 mg/dL/h). As the Minimal Clinical Important Differences are unknown, the clinical significance of this effect is unclear. There were no statistically significant differences between groups for blood pressure or triglycerides. Participants who took G lucidum for four months were 1.67 times (RR 1.67 95% CI 0.86 to 3.24) more likely to experience an adverse event than those who took placebo but these were not serious side effects.

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