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Oyster mushroom reduced blood glucose and cholesterol in diabetic subjects: a short term intervention trial
1. Khaleda Khatun- Department of diet and Nutrition, BIRDEM, 122 kazi Nazrul Islam Avenue,
Dhaka 1000
2. Hajera Mahtab- Department of Epidemiology, BIRDEM, 122 kazi Nazrul Islam Avenue,
Dhaka 1000
3. Parveen Akter Khanam- Department of Epidemiology, BIRDEM, 122 kazi Nazrul Islam
Avenue, Dhaka 1000
4. M Abu Sayeed- Ibrahim Medical College, Ibrahim Swarani, Segunbagicha, Dhaka 1000
5. A. K. Azad Khan- Department of Epidemiology, BIRDEM, 122 kazi Nazrul Islam Avenue,
Dhaka 1000
Corresponding author – M. Abu Sayeed; email: sayeedma@dab-bd.org
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Oyster mushroom reduced blood glucose and cholesterol in diabetic subjects: a short term
intervention trial
ABSTRACT
Background - It has been postulated that mushroom has beneficial effect of lowering blood glucose and
cholesterol in diabetic subjects. The literature so far searched and found that there was no
published data in this regard.
Objectives - This study was undertaken to assess the effect of reducing blood glucose, cholesterol and
triglycerides in diabetic patients. Additionally, this study addressed whether there was any hepatic and
renal toxicity of mushroom.
Subjects and Methods - This clinical investigation was conducted in BIRDEM hospital from July 2005
to January 2006. Eighty-nine subjects were recruited. Baseline investigations included height, weight,
blood pressure (SBP, DBP), plasma glucose for fasting (FPG) and 2-h after-breakfast (2hPG), total
cholesterol (T-chol), triglycerides (TG) and high-density lipoprotein (HDL-c). Twenty- four days’ study
constitutes 7-days mushroom, 7-days no mushroom and then 7-days mushroom. Investigations were done
at the start and each after every 7-days.
Results - Thirty subjects (M / F = 17 / 13) followed to ensure full compliance with the designed protocol
for 24 days. The mean (SD) age of the participants was 46.3 (10) years. Mushroom significantly reduced
systolic and diastolic blood pressure (SBP, p<0.01; DBP, p<0.05). It also lowered both plasma glucose
significantly (FPG & 2-hPG, p<0.001). Mushroom also lowered total cholesterol and TG significantly;
whereas, there was no significant change in weight and HDL-c. When mushroom was withdrawn, there
were significant increases of DBP, FPG, 2hPG, T-cholesterol and TG, whereas, no significant change was
observed in weight, SBP and HDL-c. Restarting mushroom there was again significant reduction of blood
glucose, TG and cholesterol.
Conclusions - We conclude that mushroom significantly reduced blood glucose, blood pressure, TG and
cholesterol of diabetic subjects without any deleterious effect on liver and kidney. The effect of
mushroom may be investigated in a large sample for a longer duration to evaluate its efficacy and
toxicity.
____________________________________________________
ALT – Alanine aminotransferase, FPG – fasting blood glucose, 2hPG – 2h after-breakfast plasma glucose, SBP – systolic blood
pressure, DBP – diastolic blood pressure, T- Chol – total cholesterol, TG – Triglycerides, HDL – high density lipoprotein, Inv –
Investigation.
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Introduction
Mushroom is a good source of digestible proteins and fiber, which is low in fat and energy, but makes a
useful contribution to vitamin and mineral intake [1]. It is estimated that 80 g mushroom represent one
portion of vegetables. Its dried form and extracts are also used as medicines and dietary supplements. A
mushroom characteristically contains many different bioactive compounds with diverse biological
activity, and the content and bioactivity of these compounds depend on how the mushroom is prepared
and consumed [2]. It is estimated that approximately 50% of the annual 5 million metric tons of cultivated
edible mushrooms contain functional "nutraceutical" or medicinal properties [2]. It was suggests that 5%
mushroom (Pleurotus ostreatus) supplementation provides health benefits, at least partially, by acting on
the atherogenic lipid profile in the hypercholesterolaemic condition [3,4].Some species were proved to
have strong anti-tumour and antioxidant activity by enhancing various immune system functions and
lowering cholesterol levels [4-6].
It is a popular belief that mushroom has a beneficial effect of lowering not only cholesterol but also
plasma glucose. In some areas of Bangladesh, people take mushroom (Pleurotus ostreatus) for prevention
and treatment of diabetes. This has been reported by mushroom cultivators in Savar. We tried to find out
whether there was any scientific basis of this popular belief. The literature so far searched and found that
there has been a substantial evidence of lowering cholesterol in hypercholesterolemic rats and rabbits [3-
5]. But there was no study conducted on human subjects; neither there was any published data on
lowering plasma glucose. Contrary to the popular belief of many medicinal values, edible species of fungi
might be mistaken for poisonous ones [1]. High heavy-metal concentrations in wild edible fungi (WEF)
are a known source of chronic poisoning. The consumption of WEF can contribute markedly to the
radiocaesium intake of human subjects. As there was a report of harmful effects of wild-gathered fungi
for health and rural livelihoods, somebody should investigate the effects of mushroom whether be it
beneficial or be it harmful. This study was undertaken to assess whether mushrooms is effective in – a)
reducing plasma glucose; b) reducing cholesterol and triglycerides and c) to determine any impairment
of hepatic and renal function.
Subjects and Methods
This clinical investigation was conducted in BIRDEM hospital from July 2005 to January 2006. The
participants were informed about the objectives and procedural details of the study including its possible
side effects. They were also cautioned and advised to abandon and to report to the doctor if they feel any
minor discomfort. Eighty-nine subjects were recruited. The inclusion criteria were – a) diabetes
confirmed by an oral glucose tolerance test (OGTT) and b) the subjects having fasting plasma glucose 8–
20 mmol/l and dyslipidemia, according to NCEP ATPIII [7], irrespective of their complication status.
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Baseline investigations (Inv-1) included height, weight, blood pressure, plasma glucose (FPG, 2hPG]),
total cholesterol (T-chol), triglycerides (TG) and high-density lipoprotein (HDL). Clinical history and
clinical examination were also undertaken. After selection, each participant was discussed about his / her
regular diet. Hospital dietician estimated calorie requirement and exchange for each individual participant
when mushroom (Pleurotus ostreatus) was added as a part of vegetable. Cooking procedure and
measuring of required amount was demonstrated to the specified pantry-men and servers of BIRDEM
who serves foods. Each participant was followed up by keeping individual contact for reminding
mushroom, and receiving information about problems like vomiting, diarrhea, fever, jaundice that
developed after taking mushroom.
The first week was a “mushroom week-1” when each individual was taking cooked mushroom 50g thrice
daily (figure-1). At the end of 7 days (day 8), weight and blood pressure were recorded and two blood
samples were collected – fasting sample for estimation of FPG and fasting lipids and the second sample
for 2hPG (Inv-2). The second week was a “mushroom-free” week when no mushroom was taken. After 7
days of mushroom-free week (day-16), investigations (Inv-3) were done as Inv-2. The third week again
was a “mushroom week-2” when mushroom was taken for 7 days keeping the dose as before. After the
end of 7 days, investigations (Inv-4) were done as for the previous ones. A total of four investigations
were done (Inv-1 through Inv- 4), each after 7 days, with and without mushroom (Figure -1).
Statistical analyses –The data were expressed in mean and standard deviation (SD). We used paired t-
test for comparison of variables between investigations - e.g. Inv1 vs. Inv2 and so on. The level of
significance was accepted at <0.05. All data were analyzed by SPSS 10.01.
Results
Overall, 89 diabetic subjects agreed to volunteer the study. Of them, eight to ten subjects were selected at
a time. At the end of the study, it was found that only 30 subjects (M / F = 17 / 13) followed to ensure full
compliance with the designed protocol for 24 days (Figure-1). Among the non-compliant, 11participants
could not tolerate mushroom, 19 refused to give two samples blood for investigation, 9 used to take
excess calorie as witnessed by the nurse, 5 developed fever and anorexia, and 15 subjects discontinued
deliberately. None has reported any discomfort or sickness immediately after taking mushroom.
The mean (SD) age of the participants was 46.3 (10) years. Fifteen were selected from rural and 15 from
urban. Seventy five percent of the volunteers had annual family income below taka 22500.00 (USD
~375.00). The characteristics at baseline and that of subsequent investigations (Inv-1 through Inv-4) were
shown in table-1. The comparison between baseline and after 7-days’ mushroom therapy (Inv-1 vs. Inv-2
was shown in table-2. Mushroom significantly reduced systolic (SBP, p<0.01) and diastolic (DBP,
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p<0.05) blood pressure. It also significantly lowered plasma glucose, both fasting (FPG, p<0.001) and 2-h
after breakfast (2hPG, p<0.001). Total cholesterol and TG were also lowered significantly by mushroom;
whereas there was no significant change in weight and HDL-c.
When mushroom was withdrawn for 7 days there were significant increases of DBP, FPG, 2hPG, T-
cholesterol and TG (Table-3). However, no significant change was observed in weight, SBP and HDL-c.
Restarting of mushroom resulted in a significant decrease of DBP, FPG, 2hPG, T-cholesterol and TG;
whereas, no significant change was observed in weight, SBP and HDL-c (Table-4).
We also estimated serum creatinine and alanine amino transferase (ALT) at the start (Day 0) and at the
end of the study. This was to determine whether there were any abnormalities in liver or kidneys due to
intake of mushroom. There was no significant change in these biochemical tests.
Discussions
The study design was a self-controlled one, in which the same group remained as a test group (with
mushroom) and as a control group (without mushroom) [8]. Blood glucose, blood pressure and total
cholesterol were compared between the same individuals with and without mushroom (figure 1). As there
was no other control group there was a chance of spurious result. This is because the participants might
change their behavior for giving special attention to them. So, the study findings of dietary intervention
may not be due only to mushroom itself but to some ‘Hawthorne effect’ [8].
The study has other limitations. Ten subjects remained hospitalized and bed ridden and we could not take
their weight. The number of dropped off was 59, which might have some findings that could have
influenced the study results. Another limitation was that we had to rely mostly on patient’s statement
regarding the ‘amount’ and ‘regularity’ of mushroom consumption. Had we included some other
biochemical investigations for renal and hepatic functions weekly then we could have detected very
minor impairment, if there was any. Moreover, our findings were based on a short term interventional
trial. The short term exposure to Oyster mushroom may not produce any detectable change in serum
creatinine and ALT. So, our findings on the effect of mushroom on liver and kidney may not be
conclusive.
So far, this study on Oyster mushroom in diabetic subjects is first of its kind. Although a large number of
cases dropped off from the study the number of participants (n = 30) were not very negligible. The full
compliance by 30 subjects for 24 days increased the strength of the study.
Had there been some published report on mushroom effect on diabetic subjects we could have compared
those with this study findings. Some of our study findings are consistent with others but some are not,
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though the models are different. For example, lowering of cholesterol and triglycerides are consistent
with other findings in rat and rabbit models [3-6]. Some investigators demonstrated an increase of high-
density lipoprotein after dietary mushroom [3,6]; whereas, this study subjects showed no such increase.
Possibly, the increase of HDL needs longer duration of mushroom intake in humans. The cholesterol
lowering effect of mushroom is rapidly demonstrated. Possibly, mushroom (Oyster) causes increased
secretion of bile acids and loss of cholesterol through stool [6]. Some of the novel findings of this study
may be noteworthy. Oyster mushroom reduced not only cholesterol and triglycerides but also blood
glucose and blood pressure in diabetic participants though no change was observed for weight and HDL.
This self-controlled study is of explorative type. Thus, the observed findings should not be considered as
conclusive. The adverse effect of bioactive compounds of different bioactivity of mushroom in human
body has not been addressed well in this study. Only serum creatinine and alanine aminotransferase
estimation is not adequate to conclude that there was no adverse effect of Oyster mushroom in humans.
One must rule out the possible serious harmful bioactivity on human body. So, more study is needed in
this regard.
Conclusions
We conclude that Oyster mushroom (P. ostreatus) significantly reduced total cholesterol, triglycerides
plasma glucose and blood pressure in diabetic subjects without any deleterious effect on liver and kidney.
The effect of edible (Oyster) mushroom may be investigated in a larger sample for a longer duration to
evaluate its efficacy and toxicity.
Acknowledgement – We are very much grateful to the Department of Agricultural Extension (DAE), SAVAR,
who provided us with fresh Oyster mushroom regularly. We are also thankful to the participants who volunteered
sincerely the designed protocol. We are indebted to the dieticians and pantry-men of BIRDEM for their active
cooperation. We must thank the nurses and laboratory staff of BIRDEM for their continuous supervision and timely
investigations.
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References
1. de Roman M, Boa E, Woodward S. Wild-gathered fungi for health and rural livelihoods. Proc Nutr
Soc. 2006 May; 65(2):190-7.
2. Chang R. Functional properties of edible mushrooms. Nutr Rev. 1996 Nov;54(11 Pt 2):S91-3.
3. Hossain S, Hashimoto M, Choudhury EK, Alam N, Hussain S, Hasan M, Choudhury SK, Mahmud I.
Dietary mushroom (Pleurotus ostreatus) ameliorates atherogenic lipid in hypercholesterolaemic rats.
Clin Exp Pharmacol Physiol. 2003 Jul;30(7):470-5.
4. Bobek P, Galbavy S. Hypocholesterolemic antiatherogenic effect oyster mushroom (pleurotus
ostreatus) effectively prevents the development of atherosclerosis in rabbits. Nahrung
1999;43(5):339-42.
5. Bobek P, Galbavy S. The oyster mushroom (pleurotus ostreatus) effectively prevents the development
of atherosclerosis in rabbits. Ceska Slov Farm 1999;48(5):226-230.
6. Bajaj M, Vadhera S, Brar AP, Soni GL. Role of oyster mushroom (pleurotus florida) as
Hypocholesterolemic / antiatherogenic agent.
7. Hunt KJ, Resendez RG, Williams K, Haffner SM, Stern MP. National Cholesterol Education Program
versus World Health Organization metabolic syndrome in relation to all-cause and cardiovascular
mortality in the San Antonio Heart Study. Circulation. 2004 Sep 7;110(10):1251-7.
8. Saunders BD and Trapp RG (ed). Basic & Clinical Biostatistics. Second Ed. Lange medical book;
Prentice-Hall International (UK) Ltd, London 1994; p14-15.
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Inv1 Mushroom week-1 Inv2 Mushroom-free week Inv3 Mushroom week-2 Inv4
1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7
Day
0
1 2 3 4 5 6 7 Day
8
9 10 11 12 13 14 15 Day
16
17 18 19 20 21 22 23 Day
24
Figure-1. A flowchart of mushroom taking week, mushroom-free week and investigations (Inv 1 – 4) undertaken.
Table 1. Characteristics of the participants at the start (baseline), 7 days after mushroom (mushroom-1), 7 days
without mushroom (no mushroom) and again 7 days after mushroom (mushroom-2).
Baseline (Inv1) Mushroom-1 (Inv2) No mushroom (Inv3) Mushroom-2 (Inv4)
N Mean SD Mean SD Mean SD Mean SD
Weight 20 61.55 12.713 61.53 12.686 61.60 12.742 61.60 12.742
SBP 30 125.67 15.906 121.00 14.468 122.67 15.071 121.00 14.937
DBP 30 82.83 9.886 81.17 9.531 82.50 9.262 81.33 9.279
FPG 30 10.5867 3.84032 8.2300 3.35129 9.3333 3.78585 7.1700 2.64551
2hPG 30 13.4700 6.10552 10.3433 4.30474 12.3933 5.79934 10.4100 4.90541
CHOL 30 190.73 44.768 175.53 39.017 186.63 45.641 162.70 46.989
TG 30 171.27 77.117 123.93 46.339 137.93 54.413 125.43 52.324
HDL 30 44.0333 10.74945 44.7333 10.41528 44.2333 9.23518 43.4333 9.16020
*CREAT 18 .9333 .14552 - - - - .9444 .18542
*S. ALT 18 28.72 9.761 - - - - 25.33 7.562
* - S. creatinine and alanine aminotransferase (ALT) were estimated at baseline and at the end of the study to determine any
deleterious effect of mushroom in the liver and the kidneys (p>0.5 for both ). Other statistical tests for comparison (t-test) are
given the subsequent tables.
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Table 2. Comparison of characteristics of the participants at the start and seven days after mushroom therapy (n = 30).
Baseline (Inv1) After mushroom (Inv2) Paired t-test
Mean SD Mean SD P
Weight (kg, n = 20) 61.6 12.7 61.5 12.7 0.330
Systolic BP (mmHg) 125 15.9 121 14.5 0.003
Diastolic BP (mmHg) 82 9.8 81 9.5 0.010
FPG (mmol/l) 10.6 3.8 8.2 3.4 0.000
ABF (mmol/l) 13.5 6.1 10.3 4.3 0.000
T-chol (mg/dl) 190 44.8 175 39.0 0.002
TG (mg/dl) 171 77.1 123 46.3 0.000
HDL (mg/dl) 44.0 10.7 44.7 8.2 0.546
Inv1 – Investigation on day 0, Inv2 – Investigation on day 8 after mushroom week
Table 3. Comparison of characteristics of the participants while taking and not taking mushroom (n = 30).
After mushroom (Inv2) No mushroom (Inv3) Paired t-test
Mean SD Mean SD p
Weight (kg, n = 20) 61.5 12.7 61.6 12.7 0.419
Systolic BP (mmHg) 121 14.5 122 15.1 0.096
Diastolic BP (mmHg) 81 9.5 82 9.3 0.018
FPG (mmol/l) 8.2 3.4 9.3 3.8 0.014
ABF (mmol/l) 10.3 4.3 12.4 5.8 0.002
T-chol (mg/dl) 175 39.0 186 45.6 0.017
TG (mg/dl) 123 46.3 138 54 0.011
HDL (mg/dl) 44.7 10.4 44.2 9.2 0.567
Inv2 – Investigation on day 8 after mushroom week, Inv3 – Investigation on day 16 after mushroom free week
Table 4. Comparison of characteristics of the participants between subjects with and without mushroom (n = 30).
Characteristics No mushroom (Inv3) After mushroom (Inv4) Paired t-test
Mean SD Mean SD p
Weight (kg, n = 20) 61.6 (a) 12.7 61.6 (a) 12.7 NS
Systolic BP (mmHg) 122 15.1 121 14.9 0.096
Diastolic BP (mmHg) 82 9.3 81 9.3 0.017
FPG (mmol/l) 9.3 3.8 7.2 2.6 0.000
ABF (mmol/l) 12.4 5.8 10.4 4.9 0.000
T-chol (mg/dl) 186 45.6 162 46.9 0.000
TG (mg/dl) 137 54 125 52 0.050
HDL (mg/dl) 44.2 9.2 43.4 9.2 0.427
Inv3 – Investigation on day 16 after mushroom free week, Inv4 – Investigation on day 24 after mushroom week.
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