A small plate price ending in a nonrounded number – in this case .99 – increases the chances customers will consider that a fair price for a reduced portion and make the purchase, according to a new study.

A rounded price ending with .00 was less likely to result in an intention to order a small plate because the cost was perceived as unfair, results showed.

“Many people think pricing is part of revenue management. So they’re coming only from the cost control and bottom-line perspective. But pricing is a marketing and framing strategy,” said senior study author Stephanie Liu, associate professor of hospitality management at The Ohio State University.

“We need to understand consumer psychology and consumer behavior so that we can help consumers make better decisions. So what we do is change the price of a small plate from $5.00 to $4.99. It’s just one cent difference. But psychologically, consumers feel so much better: ‘It’s fair. Now I can order the small plate.’”

The paper was published recently in the Journal of Hospitality and Tourism Management.

First author Xi Yu, who completed this work as a PhD student in the Hospitality Management Program at Ohio State, was inspired to examine smaller-portion pricing during the pandemic lockdown, when she was ordering a lot of half-sized sandwiches but didn’t pay half the price of the full size.

“I cannot eat the full size, so I always ordered a 6-inch sandwich, but I thought the price was unfair,” said Yu, now an associate professor of Faculty of International Tourism and Management at the City University of Macau.

The mixed-methods study consisted of interviews with consumers and an experiment asking participants to rate perceived price fairness and intention to order either regular-sized or smaller meals with varied pricing structures.

The interviews with 36 consumers identified three themes: Restaurant customers often perceived small plates as overpriced compared to portion size; concerns about pricing fairness emerged as a central issue; and nonrounded prices were associated with better value and higher chances for a purchase.

Participants also commented on the things they liked about small plates – they were a healthier dining choice, reduced food waste and broadened a meal’s variety.

In the experiment, 244 U.S. adults were asked to imagine ordering a lunch soup-and-sandwich combo at a fictitious restaurant. They were shown an image of either a small- or regular-sized meal priced at either $7.99 or $8.00 for a small serving and $11.99 or $12.00 for the regular serving.

Statistical analysis showed that the nonrounded prices signaled a discount or fair pricing, which increased the intention to order – but only for small plates. Perceived fairness was determined to be the psychological mechanism that drove this effect.

“The rationale is that the nonrounded price will always signal a sense of a discount,” Yu said. “For the regular plates, people don’t actually care about whether you give them a rounded or nonrounded price.”

The findings suggest it makes good business sense to sweeten the deal for small plates not just to increase sales, but to satisfy customers, the researchers said.

“It’s a hot topic in the industry, but there hasn’t been sufficient attention paid to it. There is literally no guidance on how to price small plates,” Liu said. “In our context, we want consumers to order the small plates if they fit their appetite. We don’t want them to choose the regular plate just to save money.”

Additional co-authors were Jay Kandampully, professor, and Huiling Huang, a PhD graduate, both of Ohio State’s Hospitality Management Program. Huang is now an assistant professor in integrated resort and tourism management at the University of Macau. 

The analysis showed that over a dozen pesticides influence human gut bacteria growth patterns, affect how gut microorganisms process nutrients and camp out inside some bacteria. Researchers say the resulting “atlas” of molecular mechanisms, which they have made publicly available, is a resource that can be leveraged for targeted studies on relevant diseases and potential therapeutic strategies. 

Experiments in mice showed that one gut bacteria species provides some protection against pesticide toxicity, hinting at the possibility for a probiotic approach to preventing some of their damaging health effects – in this case, inflammation. 

“We’ve provided further understanding of how pesticides or environmental pollutants impact human health by modulating an important collection of microorganisms,” said senior author Jiangjiang Zhu, associate professor of human sciences at The Ohio State University.  

“We also identified certain microbes that can degrade, remove or clear some of these pesticides from biological systems, which may be potential therapeutics in the future to help people clear toxicity from the gut that have been introduced by food and water intake, providing better solutions for human health.” 

The research was published recently in Nature Communications. 

The findings are based on investigating the interactions in the lab between 18 pesticide compounds selected for their widespread agricultural use around the world and 17 species from four major bacterial domains in the human gut that are associated with either health maintenance or disease states. Among the pesticides included were DDT (banned in the United States but used indoors in some countries to control malaria-carrying mosquitoes), atrazine, permethrin and chlorpyrifos. Even with limitations on their use, residues from some legacy pesticides still circulate in soil and water, Zhu said. 

“We grew bacteria in culture and exposed them to relevant concentrations of pesticides to see how microbes responded to those pesticide exposures,” said first author Li Chen, a senior research associate in Zhu’s lab, who managed over 10,000 samples that were analyzed in the study. 

Based on the findings, the team developed a bacteria-pesticide interaction network detailing which pesticides either promoted or inhibited bacterial growth and the bacteria that absorbed pesticide chemicals – an indication of one way exposure to pesticides can be prolonged in the body.  

“Most previous environmental health studies reported that pesticide contamination affects the overall composition of gut bacteria,” Chen said. “We showed those pesticides really can affect specific gut bacteria and detailed how these changes will affect the general composition.” 

The analysis identified specific metabolic changes in 306 pesticide-gut microbe pairs, leading to examination of how those altered growth patterns and accumulation of chemicals affected metabolites – the molecular products of biochemical reactions that break down nutrients to produce energy and perform other essential functions. Metabolites have numerous roles, from altering the metabolic process itself to sending signals related to multiple cell functions and immune system activation. 

In addition, the study team performed a separate analysis zeroing in on another important class of molecules that can be produced by gut microbes – the fatty, oily and waxy compounds called lipids that are essential to many body functions. 

Researchers also studied the effects of pesticide exposure in healthy mice first given antibiotics to clear their digestive systems of microbes. The team introduced Bacteroides ovatus, a common strain of human gut bacteria, to one group of mice and compared them to controls after four weeks of exposure to pesticides. 

Results verified what was seen in the lab, showing that pesticides generated inflammation in multiple organs in the mice and that the presence of the introduced bacteria after chemical exposure set off a range of changes in metabolic activity and lipid production. Specifically, an increase in some classes of lipids inhibited the signaling pathway of a protein linked to oxidative stress. 

“We identified microbes that may modulate the toxic effect of pesticides to the host by somehow buffering the inflammation process,” said Zhu, also an investigator in The Ohio State University Comprehensive Cancer Center Molecular Carcinogenesis and Chemoprevention Research Program.  

“We know inflammation is generally bad for the body. If something toxic is going to induce it, and there are other molecules that can counteract that agent, you may have a solution to intervene or prevent larger-scale damage.” 

In the next phrase of this work, Zhu’s lab plans to further explain where metabolic changes to gut microbes fit into various health and disease conditions after pesticide exposure. He expects other scientists will do the same. 

“We are mapping out this central interaction between pesticides and gut microbes. And then other labs can leverage what we have discovered – for example, after exposure to a pesticide, gut microbe reactions may lead to downstream consequences that contribute to disease research and eventually help with predicting targets or identifying an intervention strategy,” he said. 

This research was supported by the National Institute of General Medical Sciences. Zhu is also supported by the Provost’s Scarlet and Gray Associate Professor Program at Ohio State. 

Additional co-authors include Chao Guo, Huan Zhang, Shiqi Zhang, Andrew Gold, Ming Hu and Dayong Wu, all of Ohio State; Hong Yan and Caroline Johnson of Yale University; Shanshan Di and Xinquan Wang of Zhejiang Academy in Hangzhou, China; and Yu Wang of Johns Hopkins University.

The analysis of biological samples from more than 1,000 people also revealed metabolic shifts associated with changing disease severity and with genetic mutations known to increase the risk for colorectal cancer. 

Though there is more analysis to come, the resulting “biomarker discovery pipeline” shows promise as a noninvasive method of diagnosing colorectal cancer and monitoring disease progression, said Jiangjiang Zhu, co-senior author of the study and an associate professor of human sciences at The Ohio State University. 

“We believe this is a good tool for disease diagnostics and monitoring, especially because metabolic-based biomarker analysis could also be utilized to monitor treatment effectiveness,” said Zhu, also an investigator in The Ohio State University Comprehensive Cancer Center Molecular Carcinogenesis and Chemoprevention Research Program. 

“When a patient is taking drug A versus drug B, especially for cancer, time is essential. If they don’t have a good response, we want to know that as soon as possible so we can change the treatment regimen. If metabolites can help indicate a treatment’s effectiveness faster than traditional methods like pathology or protein markers, we hope they could be good indicators for doctors who are caring for patients.” 

The tool is not intended to replace colonoscopy as the gold standard for cancer screening, Zhu said, and further study with additional samples is planned before the pipeline would be ready for translation to a clinical setting. 

The research was published recently in the journal iMetaOmics. 

This work also represents an advance in machine learning techniques, combining two established methods to design the new platform: partial least squares-discriminant analysis (PLS-DA) for big-picture differentiation of molecular profiles, and an artificial neural network (ANN) that, in this case, pinpoints molecules that improve the platform’s predictive value. The team called the resulting biomarker pipeline PANDA, short for PLS-ANN-DA.

“We took the best of both worlds and put them together to leverage their strengths and complement each other to offset their potential weaknesses,” Zhu said. “We were looking at all kinds of possibilities to tease out the biomarkers that could be predictive or indicative of disease progression and the different stages of the disease. That gave us some strong confidence that this method has great potential for future diagnoses.” 

Two sets of biological data extracted from blood samples were analyzed: metabolites, products of biochemical reactions that break down food to produce energy and perform other essential functions, and transcripts, RNA readouts of DNA instructions that predict related protein changes. 

The biological samples are a significant part of the study’s strength, Zhu said, because they were collected as part of large research projects: The Ohio Colorectal Cancer Prevention Initiative (OCCPI) and an Ohio State Wexner Medical Center clinical laboratory biobank. In all, 626 samples came from people with colorectal cancer – including patients with high-risk genetic mutations. Another 402 samples from age- and gender-matched healthy individuals were obtained by Jieli Li, co-senior study author and associate professor-clinical of pathology in Ohio State’s College of Medicine. 

“We, as humans, at different stages of our lives, actually have quite different biochemistry,” Zhu said. “This valuable collection of samples enabled us to run high-throughput metabolomics analysis to understand the molecular changes from people who don’t have cancer with people who have cancer, and also from early-stage to late-stage disease. 

“We also have data from patients with genetic mutations that we can compare to the metabolite data to look at whether metabolic changes are an indication of predictive values for the genetic mutations. To our knowledge, this is the first time this has been done at this scope and scale because we are looking at literally hundreds of patients.” 

Biomarkers are tricky to rely on for diagnostics across different populations because of the many conditions that affect molecular profiles in living systems – so this study highlights several molecular changes with potential, but not certainty, in assessing colorectal cancer’s presence and progression in a nationally representative group of patients. 

The metabolism pathways linked to one family of compounds called purines, which are needed for DNA formation and degradation, stood out in the analysis because they were more active overall in cancer patients compared to healthy controls, and were less active with more advanced tumor stages.   

“It’s certainly an indication that this biomarker may be associated with the underlying mechanisms of cancer biology,” Zhu said. “We are cautiously optimistic in saying that we’re not only doing biomarker discovery, but we’re also providing clues for mechanistic investigations.” 

The team plans to continue analyzing metabolites related to different types of biological signals to refine the PANDA biomarker pipeline. 

“Some of the markers we identified are a little bit finicky, and there’s a lot of noise within those signals, but we have pushed the field forward to develop potential next-generation biomarkers and the novel bioinformatics pipeline for colorectal cancer diagnosis and monitoring,” Zhu said. 

This work was supported by the National Institute of General Medical Sciences, an Ohio State fellowship and Pelotonia, which funded the statewide OCCPI. Zhu is also supported by the Provost’s Scarlet and Gray Associate Professor Program at Ohio State. 

Additional co-authors include first author Rui Xu, Hyein Jung, Fouad Choueiry, Shizi Zhang, Rachel Pearlman and Ning Jin, all of Ohio State, and Heather Hampel of the City of Hope National Cancer Center.