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Research Round Up
PREBIOTIC EFFECTS OF WHOLE MUSHROOM POWDER AND MUSHROOM EXTRACTS IN HEALTHY AND OSTEOPENIC WOMEN
Following data suggesting that gut microbiota manipulation could be a promising strategy for the prevention and/or treatment of metabolic diseases including disorders of bone metabolism, a new study looked at the impact of Oyster Mushroom and Reishi powder and hot-water extracts on the intestinal flora and indicators of bone metabolism in healthy and osteopenic women.
They found that both powders and extracts of the two mushrooms produced a drastic decrease in markers associated with bone breakdown. Positive prebiotic changes were also noted in both groups with those induced by Oyster Mushroom powder being particularly pronounced and accompanied by increased production of short chain fatty acids.
This confirms other research suggesting that consumption of mushrooms and their extracts may offer benefits for osteoporosis through beneficial changes in gut flora.
MUSHROOMS AS A NOVEL PROTEIN SOURCE FOR FUNCTIONAL FOODS
Mushrooms are in many ways an attractive additive for a range of functional foods, and with their high protein content it is not surprising that there is interest in them as a novel protein source with commercial mushroom protein products coming on the market and a recent review focusing on their potential in this area.
By dry weight the common button mushroom Agaricus bisporus contains roughly as much protein as lean steak (26.99% dry weight) while others have considerably more: Agaricus subrufescens (syn. A. brasiliensis) – 33.39% d.w. and black Oyster Mushroom (Pleurotus ostreatus) – 36.96% d.w.
In terms of protein to energy ratio black oyster mushrooms had the highest level (0.098 g/kcal) with A. subrufescens not far behind at 0.09 g/kcal and both considerably higher than beef (0.08 g/kcal).
When used as functional food ingredients mushroom powder significantly enhanced the protein content of common foods with the protein content of pasta enriched with 15% A. bisporus increasing from 6.23% to 30.52% and bread baked with P. ostreatus increasing from 9.1% to 25.6%. Addition of mushroom powder to the pasta was also reported to enhance the antioxidant content and modulate the predictive glycaemic response of pasta.
While there has been research looking at the benefits of individual mushrooms, especially Lion’s Mane, for depression it now appears that as well as their other health benefits regular dietary consumption of mushrooms may also help reduce the risk of depression.
In this study researchers analysed data on diet and mental health over twelve years for 24,699 US adults with an average age of 45 and found a significant correlation between regular mushroom consumption (median intake 4.9g/day) and lowered risk of depression (69% reduction) after accounting for socio-demographics and other factors.
Increased mushroom inta ke (median intake 19.6g/day) did not translate to a further decrease in risk of depression.
EVIDENCE FOR VIABLE FUNGAL CONTROL OF A HONEY BEE PARASITE
Varroa destructor is a devastating parasite of honey bees and vector of some of the most destructive honey-bee viruses that has plagued beekeepers and their colonies for decades. Although chemical pesticides can kill it these can harm the bees themselves and there is also evidence of resistance evolving. There is thus a growing need for alternative approaches to its control.
Drawing inspiration from the ability of certain fungal species to kill varroa mites researchers first encouraged the development of a heat-resistant strain of the fungus Metarhizium brunneum with mite killing ability by forced selection and then by repeatedly cultivating the fungus from the bodies of mites it had killed created a strain with greatly enhanced mite-killing ability.
Then comparing the effectiveness of this strain to that of oxalic acid, a common natural treatment for varroa mite, in 20 colonies selected at random they found that the fungus was just as good as the acid at controlling the number of mites with a trend towards controlling mites better.
Mushrooms are full of surprises and one particularly shocking finding in the 1980’s was that Oyster Mushrooms, far from being just benign decomposers of fallen trees are actually carnivorous, supplementing their nitrogen-poor diet by feasting on nematodes, the small worm-like creatures that are the most abundant animals in the soil (there are approximately 60 billion nematodes for each human on the planet).
Although they are the only culinary species known to have this predilection Oyster Mushrooms are far from unique in their taste for flesh with over 200 species of fungi known to use a variety of either active traps (constricting rings) or passive traps (adhesive structures) to take advantage of this nitrogen-rich food source.
When starved Oyster Mushrooms hyphae produce sticky drops containing a toxin that paralyses the nematode within minutes of it touching them by causing massive calcium influx ultimately leading cell death throughout the neuromuscular system.
Because it targets the cells producing the fine hair-like structures (cilia) that the nematode relies on for sensing its environment this cilia-dependent predatory mechanism is effective against widely divergent nematode species. It is also highly conserved between different Pleurotus species being present in all 15 tested.
Defective clearance of amyloid β protein (Aβ) is considered to play a critical role in the pathogenesis of Alzheimer’s disease (AD) and Impaired uptake of Aβ by dysfunctional monocytes is deemed to be one of the major mechanisms involved.
In the first paper polysaccharide krestin (PSK), more usually associated with anti-cancer activity, was found to enhance Aβ uptake and intracellular processing by human monocytes in vitro. AD-model mice were also found to perform better in behavioural tests after injection with PSK and to have reduced Aβ deposition, neuroinflammation, neuronal loss, and tau hyperphosphorylation indicating promise for enhancing Aβ clearance and alleviating AD-like pathology.
In a separate in vitro study Cordyceps militaris ethanol extract was seen to reduce the level of reactive oxygen species production and increase the expression of brain-derived neurotrophic factor in glial cells (supportive cells in the nervous system) protecting against Aβ induced damage.
Identifying mushrooms growing wild, at least the common species, is not overly difficult given sufficient knowledge and experience but identifying dried shop-bought mushrooms, especially once they have been cut into pieces, can be virtually impossible and we often have no choice but to rely on their labelling.
Unfortunately, judging by the findings of this survey labelling of wild mushroom products can leave a lot to be desired. Samples of 21 products claiming to contain wild mushrooms were bought in the US and analysed with DNA authentication to identify the species they contained. In the majority of cases the products contained only commonly cultivated species of mushrooms such as white button/ portabella (Agaricus bisporus), oyster (Pleurotus spp.), and shiitake (Lentinula edodes), as well as wild-collected species with inferior culinary quality such as slippery jacks (Suillus spp.).
Fortunately help may be on the way with the FairWild Foundation recently launching a technical consultation for fungi certification standards. Although focussed primarily on sustainability, confirmed identification of species would be a welcome secondary benefit of certification.
To date research on the health benefits of Ganoderma species has overwhelmingly focused on Ganoderma sichuanense (syn. G. lingzhi) but as this paper shows, it is not the only Ganoderma species with health-promoting properties. Ganoderma applanatum, also known as the ‘Artist’s Conk’ has long been used therapeutically by many traditional cultures for cancer as well as other health conditions.
In this study both aqueous and methanolic extracts of G. applanatum were shown to have antidiabetic, cholesterol-lowering and hepatoprotective properties when fed to mice over nine days with doses of 500mg/kg having a slightly higher impact than 250mg/ kg and the methanolic extract having slightly greater response than the aqueous extract.
NEW RESEARCH INTO MYCOTEXTILES MADE BY INDIGENOUS COMMUNITIES IN ALASKA
While the production of mushroom felt (Amadou) in Transylvania is widely known and a growing number of companies are using mushroom mycelium to produce leather substitutes it appears that the production of mushroom-derived textiles by traditional cultures was more widespread than hitherto realised.
Made in 1903 by a Tlingit woman in Lingít Aaní in present day Alaska, two wall pouches in the collection of the Hood Museum of Art, Dartmouth College and described as ‘fungus bags’ have been confirmed as having been made from fungal mycelial mats. This is the first documentation of fungal textiles in North America.
Although DNA sequencing failed to yield a taxonomic identification electron microscopy and comparison with the mycelia of other species suggests that they were produced from Laricifomes officinalis, commonly known as Agarikon (syn. Fomitopsis officinalis), an important mushroom in the culture of the local indigenous peoples. There are currently no plans to repatriate the mats and the provenance indicates they were a gift. The Hood Museum has historically complied with requests.
AN EXPANDING ROLE FOR MYCOREMEDIATION IN ENVIRONMENTAL CLEANUP
It has long been known that mushrooms have a tendency to take up heavy metals from the substrate on which they are growing and also an impressive ability to utilise diverse carbon sources for growth. Taken together these have spawned a growing interest in using mushrooms to address environmental contamination with Oyster mushroom species emerging as some of the most promising.
In one recent study Pleurotus florida was reported to have a high mycoremediation capacity in relation to gas oil (red diesel) contamination with associated increases in production of biosurfactants, laccase and tyrosinase.
In a second study the potential of Pleurotus pulmonarius for mycoremediation of soil contaminated with PCDD/F (two similar classes of chlorinated aromatic chemicals) was investigated with a 60% reduction in the level of level of PCDD/F after 30 days’ incubation.
SEVEN DAYS’ INTAKE OF LION’S MANE IS SUFFICIENT TO PRODUCE POSITIVE CHANGES IN THE GUT MICROBIOME
Thirteen heathy adults (7 female and 6 male) with an average age of 30 and ‘normal’ BMIs took 1g of powdered H. erinaceus mycelium (grown by liquid fermentation) three times a day for seven days and their blood and stool samples analysed.
H. erinaceus supplementation was found to be correlated with positive changes in the gut microbiome with increased diversity and increases in populations of some short-chain fatty acid (SCFA) producing bacteria (Kineothrix alysoides, Gemmiger formicilis, Fusicatenibacter saccharivorans, Eubacterium rectale, Faecalibacterium prausnitzii), and downregulation of some pathobionts (Streptococcus thermophilus, Bacteroides caccae, Romboutsia timonensis.)
Further it was found that supplementation was correlated with marked decreases in alkaline phosphatase (a marker for liver damage), low-density lipoprotein (‘bad cholesterol’), uric acid (linked to gout) and creatinine with these changes linked to changes in specific bacterial populations.
POSSIBLE ROLE OF INONOTUS OBLIQUUS FOR MALE SEXUAL DYSFUNCTION
Although Cordyceps has traditionally been the main mushroom used to address male sexual dysfunction and infertility Chaga has also shown promise with some practitioners preferring it due to its stronger antioxidant activity (poor sperm quality has been linked to oxidative stress and antioxidant supplements have been suggested as a possible treatment option although results from clinical studies have been mixed).
It now seems that Chaga, like Cordyceps, may also have benefits for erectile dysfunction with both alcohol and aqueous extracts inducing nitric oxide synthesis in-vitro. However, only with the alcohol extract was there subsequent accumulation of cGMP (responsible for the smooth muscle relaxation that leads to an erection), probably because the water extract but not the alcohol extract also increased expression of the enzyme responsible for its breakdown.
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