The current trends of rising obesity levels and poor dietary choices have led to an increased incidence of cardiovascular diseases (CVD), dyslipidemia, and metabolic syndrome 1. Nonmedicinal, cost-effective therapeutic approaches for dyslipidemia that would be readily accepted by individuals who are reluctant to make drastic dietary changes, such as eliminating consumption of red meat, are needed. As opposed to the use of supplements, such as omega-3 fatty acids, niacin, and plant sterols, whole foods may have greater appeal 234. Research into medicinal uses and therapeutic applications of mushrooms is increasing; however, there has been little, if any, investigation into the acute effects of mushrooms on postprandial lipemia (PPL) or postprandial glycemia (PPG), especially in humans 56. There is currently no widely agreed upon technical definition of PPL 7, however certain characteristics of identifying PPL have been acknowledged. Generally, PPL is defined as a complex condition that is characterized by non-fasting hypertriglyceridemia, which is associated with an increased risk of cardiovascular events 7. This pilot study investigated the acute effects of selected mushroom powder supplementation on PPL and PPG following a high-fat meal using the indicators of serum triglycerides, serum high-density lipoprotein (HDL), serum low-density lipoprotein (LDL), and serum glucose.

Mushrooms are a widely available commodity and are heavily consumed for their health-promoting properties, in addition to their palatable and culinary appeal 8. Mushrooms contain high levels of bioactive compounds, such as ergothioneine, a powerful antioxidant, and ergosterol, a hypercholesterolemic agent and a Vitamin D precursor 6. These bioactive compounds are thought to be potential mechanisms for reducing triglyceride and cholesterol absorption from the bloodstream, which could be beneficial for individuals who suffer from metabolic syndrome that includes diabetes, obesity, and cardiovascular disease 9. Soluble dietary fiber (e.g., β-glucans found in certain types of mushrooms) may reduce the rate of nutrient absorption, which has been associated with reduced postprandial blood glucose and higher satiety levels 10. Ergothioneine may also have a role in the reduction of postprandial triglyceride levels 11. Given the versatile uses of mushrooms, mushroom supplementation of high-fat foods may be a promising therapeutic application to lower PPL and PPG, and thus conditions associated with metabolic syndrome or syndrome X, such as obesity, diabetes, and CVD.

Besides their favorable biochemical properties, mushrooms also have a fleshy texture akin to meat products, such as soy 12, that might be used as a meat substitute as an approach to treat dyslipidemia 1314. In this study, we utilized shiitake (SH) and white button (WB) mushroom powder as supplements, since they are widely commercially available, and SH is the second most commonly produced edible mushroom in the world 8. In addition, several important anti-inflammatory, lipid-lowering, and antimicrobial compounds have been isolated from SH mushrooms including lentinan, a polysaccharide, which is well studied 8. β-glucan is the major bioactive component in lentinan 15. Eritadenine, a compound isolated from SH mushrooms, is thought to be the major mediator of the lipid-lowering effect 616. Both SH and WB are thought to have cardioprotective effects 11. WB mushrooms, part of the genus Agaricus, have been demonstrated to reduce total daily energy and fat intake 11. They also have been shown to have antidiabetic properties including lowered index of insulin resistance, increased plasma adiponectin, improved hepatic glucose uptake, and reduced oxidative stress 11.

In this pilot study, we sought to determine the acute effects on PPL and PPG by supplementing a high-fat meal, a hamburger, with either WB or SH mushroom powder. We hypothesized that mushroom powder supplementation of a high-fat meal will result in decreased serum lipid concentrations and follow a standard postprandial glucose pattern.

Participants were enrolled in a prospective, double-blind, randomized study approved by the University at Buffalo (UB) Institutional Review Board. All participants provided written informed consent prior to study entry. Inclusion criteria included ages 18 to 35 years, overall healthy, non-diabetic, and normal to mildly hypercholesterolemic (total cholesterol (TC): 200 – 239 mg/dL, low density lipoprotein cholesterol (LDL-C): 130 – 159 mg/dL), and body mass index (BMI) of <30 or body fat percentage (% BF) by gender (men: <25%, women: <32%). Participants were also screened for liver and gallbladder disease by self-report, lipid metabolism dysfunction, and normal lipemic responses to a lipid challenge (i.e., control meal) 1718. Participants completed three-day diet records to confirm their specific caloric and macronutrient intakes. Caloric and macronutrient intakes were determined using a nutrient analysis software entitled “Nutritionist Pro” (Axxya Systems LLC, Redmond, WA, USA). Participants were excluded if they failed to meet any inclusion criteria, failed any of the screenings, or had a self-reported mushroom allergy.

In this pilot investigation, we evaluated the postprandial effects of WB or SH mushroom supplementation into a high-fat meal regarding serum lipids (LDL, HDL, and triglycerides) and serum glucose amongst nine healthy participants. LDL levels differed significantly for both SH and WB burgers compared to the control burger over six hours. Subsequent statistical analysis demonstrated that SH-supplemented burgers significantly lowered serum LDL levels in both genders. Burger type did not affect triglyceride, HDL, and glucose levels. Triglyceride levels were higher in males and HDL levels were higher in females. Triglyceride and glucose levels were significantly higher during the postprandial timepoints 2 (t = 2 hours) and 3 (t = 4 hours). By timepoint 4 (t = 6 hours), triglyceride and glucose levels had returned to baseline (t = 0 hours) values.

Primarily in industrialized countries, metabolic syndrome is an increasing health condition. The ineffectiveness of and/or the variable adherence of individuals to current therapeutic approaches has promoted searching for novel strategies to address obesity-related conditions. High-fat food supplementation with mushroom powder has been proposed as a potential therapeutic intervention to improve cardiovascular and overall health status 6. In our study, we found that SH mushroom-powder supplementation of a high-fat meal significantly lowered LDL levels in comparison with WB mushroom-powder supplementation or no supplementation (control meal). Mushroom-supplementation of burgers did not significantly affect triglyceride, HDL, and glucose levels in both genders.

Previous literature has documented no significant differences between glucose or triglyceride levels among participants who consumed a control meal and a meal fortified with mushrooms. For example, Dicks et al. did not observe any differences in glucose or triglyceride levels among 22 participants with impaired glucose tolerance when comparing a meal supplemented with 20g of Oyster mushroom powder rich in β-glucans to a control meal (i.e., a meal without mushroom supplementation) 20. β-glucans have been shown to alter lipid and glucose metabolism as well as to reduce cholesterol, which has led to their investigation as potential therapies for metabolic syndrome and obesity 21. Metabolic syndrome is a constellation of conditions associated with an increased risk of developing diabetes, obesity, and CVD that are caused by insulin resistance, including central obesity, hypertension, hyperglycemia, high serum triglyceride levels, and HDL levels 2223. The cholesterol-lowering effects of SH mushrooms are attributed to the mycochemical, eritadenine 24. Studies in rats have shown lower serum concentrations of triglycerides, non-HDL cholesterol, and total cholesterol in rats fed SH 16.

Gender is an important modifying factor regarding postprandial lipemia. For example, in response to fat obtained from either butter, coconut oil, olive oil, or canola oil, men exhibited a greater peak triglyceride response than women 25. Among men, those with a greater BMI (>23 kg/m²) compared to men with a lower BMI (<23 kg/m²) exhibit a greater increase in postprandial lipemia in response to a high-fat meal 26. Differences in visceral adipose accumulation sites between men and women may account for the amplified postprandial response observed between the genders 27. Men tend to store fat primarily in the android regions (trunk/abdomen) and to experience visceral tissue fat accumulation. In a rodent study evaluating the lipid lowering effect of SH, female rats had lower triglyceride and higher HDL levels compared with male rats 16. This study also illustrated that, at least in rats, SH’s ability to lower plasma lipids was equivalent between the genders, an effect that had previously been thought to be limited to male rats 28.

Our results are consistent with several prior publications that have demonstrated that HDL levels are elevated in women while triglyceride levels are higher in men. Prior studies have shown that men have almost two-fold greater quantities of visceral adipose tissue compared to premenopausal women (as would be relevant to our participants who were all premenopausal) 29, and the accumulation of abdominal fat is associated strongly with alterations in lipoprotein concentrations. Von Hafe reported that in a study containing 77 men and 84 women, men had higher levels of visceral fat, higher plasma insulin, higher glucose, higher triglycerides, and lower HDL than women 30. Another study by Godsland et al. in 1987 reported that men are characterized by high fasting triglyceride and low HDL-cholesterol levels compared with women 31. Couillard et al. investigated the postprandial triglyceride response to a standardized meal and found that men had a significantly greater plasma triglyceride response compared with women 27. These investigators also found that men had decreased HDL-cholesterol compared with women. Kolovou et al. replicated the same findings in a much larger cohort of participants (n=1385). Among these individuals (40% female), high triglyceride and low HDL-cholesterol were two times more common in men than women 32.

Edible mushrooms have been shown to contain active compounds that exhibit antioxidant 33, anti-atherosclerotic 34, and hypoglycemic 35 activities. An important consideration is specifically how WB or SH mushrooms mediate their lipid-lowering effects. WB mushrooms have been shown to lower serum total cholesterol by upregulating hepatic LDL receptor mRNA expression 36. SH mushrooms have also been shown to reduce plasma cholesterol 37. Eritadenine, a compound isolated from SH mushrooms, is hypothesized to be the major mechanism by which total cholesterol and non-HDL cholesterol are decreased 16. Another potential lipid lowering mechanism is through decreased absorption of lipids from the gastrointestinal tract, such as through β-glucans 7. Further research is needed to clarify the exact pathways for lipid lowering mechanisms for both SH and WB mushrooms. Mushrooms have also been proposed to mediate their anti-obesogenic and antidiabetic effects through a variety of biochemical and anti-inflammatory pathways 153839.

In this pilot study, we sought to investigate the antilipemic effects of a high-fat meal supplemented with WB or SH mushroom powder compared to a control hamburger. The strength of this investigation is the longitudinal sampling and follow-up that enabled us to observe these effects on humans. The limitations of this work are the relatively small numbers of individuals enrolled and the only one-time meal administration (as opposed to assessing repeated measures of the same meal). However, Sciarrillo et al. recently published a study that included ten participants that evaluated the postprandial lipemic responses in triglycerides to four dietary fat sources 25. Our pilot study provides valuable information for how to design, execute, and scale similar dietary interventions using mushroom powder as a functional food in a conventional, Western high-fat meal.

We observed that LDL levels were significantly decreased in individuals who consumed SH burgers compared to WB or control burgers. Specifically, males had significantly higher serum triglyceride and lower serum HDL levels in comparison with female participants. While glucose levels were significantly affected by ingestion of any burger as expected, the levels did not vary significantly when comparing the three burger types, and they followed a standard postprandial glucose curve. Further investigation is required to assess whether SH and WB mushroom supplementation is effective in decreasing serum lipid concentrations in humans and whether these differences vary by gender. Further research is also needed to assess whether the postprandial effects on glucose and on lipids observed with SH and WB powder supplementation are generalizable to other types of mushrooms. Additional investigation is also needed to assess whether the effects of SH and WB mushroom supplementation persist in individuals who have metabolic conditions, such as diabetes or hypercholesterolemia. These studies should also attempt to follow participants for a longer postprandial period (e.g., 12 or 24 hours).

Horvath Laboratory Group: Harry Marsales, Theodore J. Robak, Courtney Miller, Alyssa Massaro, Taylor Furst, Zach Lamacchia; Dr. Todd C. Rideout, Associate Professor, UB Department of Exercise and Nutrition Science; Oakshire Farms, who generously donated the mushroom powders; Dedicated to Matthew J. Morris, whose work was crucial to project.

This research was funded by State University of New York (SUNY), University at Buffalo (UB) Center for Undergraduate Research and Creative Activities (CURCA) Undergraduate Research Award. Oakshire Farms generously donated the shiitake and white button mushroom powders for this research.