Posted: August 1, 2025
The Soils, Plants and Consumers Network bridges gap between agriculture and nutrition
Joshua Lambert and Helene Hopfer collaborate with fellow scientists to explore how soil and cultivation shape food characteristics. Photo: Michael Houtz
Chocolate has a flaw that science is still working to fix. A heavy metal called cadmium makes its way from the soil where cacao trees grow into the cocoa beans that are harvested, roasted and made into chocolate.
While trace amounts of cadmium in chocolate don't present a serious risk to public health, long-term exposure to too much cadmium can lead to bone fragility as well as kidney and lung damage, explained Siela Maximova, research professor of plant biotechnology in Penn State's College of Agricultural Sciences. Cadmium is not limited to cocoa — it can be found in small amounts in all kinds of plants we regularly consume, such as lettuce, spinach, parsley and mustard greens.
"Cadmium uptake by plants is a problem because cadmium is a heavy metal, and too much exposure to heavy metals can have serious health consequences," Maximova said. "But we still don't fully understand the mechanism behind cadmium accumulation in plants, so we're doing very basic research, trying to understand how the cadmium gets into cocoa beans, the fundamental mechanisms of uptake and accumulation."
To answer that question and many others related to the plants that humans eat and use, a team of scientists in the college is taking a new approach to studying how plants are grown, processed and consumed.
It is a network of researchers focused on understanding the effects of soil on food quality and consumer perception. The group, called the Soils, Plants and Consumers Network (SPCN), involves experts from various disciplines who aim to bridge the gap between the fields of soil science, plant genetics and consumer behavior.
Their research initiatives span the globe, from cocoa farms in South America to spice farms in Asia. They have investigated clove oil variability in Indonesia and the medicinal qualities of a parasitic plant native to North America. They are studying the coffee tree forests of Belize to develop agroforestry methods that support local communities and protect rainforests. The network has ongoing collaborative research on tea, grapes, hops, American ginseng and goldenseal.
"This is the first interdisciplinary network of research that examines the entire supply chain of plants," said Joshua Lambert, professor of food science and SPCN director. "When plants reach consumers, whether through processed foods, produce, herbs, or nutritional, medicinal or botanical supplements, they are taking a very complex road from where they originate to where they are consumed. Our goal is to understand how each step along that pathway, from soil to consumer, impacts the final product."
Lambert noted that the work involves collaboration with industry and academic partners, including soil scientists and botanists. The goal is to provide actionable insights for growers, processors and consumers, with an eye toward enhancing food stability, quality and sustainability around the world.
"The challenge with plants is they exist in a very dynamic environment, so there are numerous factors that play a role in shaping their overall chemical profile," said SPCN research partner Joshua Kellogg, assistant professor in the college's Department of Veterinary and Biomedical Sciences. "They're complex biological organisms, and their environment directly impacts a plant's chemistry and ultimately the quality and health properties of any final product. That's why we are going deeper to understand how the soil, the genetics, the climate, harvesting and processing all play a role in that final product."
A Problem Like Cadmium
One of the key challenges in cacao farming is managing cadmium levels in the beans, especially in regions where the soil naturally contains cadmium, Maximova explained. If the soil doesn't have cadmium, the plants won't absorb it, and the beans won't contain it. But in areas with contaminated soil, the only solution may be to plant varieties of cacao trees that do not accumulate cadmium.
"This requires identifying and breeding naturally resistant varieties or using biotechnology to develop new ones, aiming to reduce cadmium uptake while maintaining high yield, disease resistance and good flavor," she said.
This process requires more time and resources than with other plants, she pointed out. It typically takes researchers about 20 years to breed cacao trees to develop new varieties, unlike other fruit trees such as apple and peach that require less time. Also, cacao is grown in poorer countries, where farmers lack the resources and methods — such as the use of seasonal pruning, chemicals and pest management — available to growers in more developed regions.
Cacao farming often uses traditional methods on small-scale farms, making it nearly impossible to implement interventions such as lime treatments or other remedies for soil issues.
"This is why basic, interdisciplinary research is crucial in this process," Maximova said. "Understanding the genes responsible for cadmium uptake will allow for targeted solutions, such as nontransgenic, edited plants that can be introduced safely to farmers. This approach offers a long-term solution to farmers that is feasible in variable, jungle-like conditions."
Joshua Kellogg's lab collaborates across disciplines to explore how small molecules critically impact human, plant and environmental health.
High-flavor cacao, particularly from regions such as Peru and Colombia, often comes from soils rich in cadmium, according to Mark Guiltinan, J. Franklin Styer Professor of Horticultural Botany and professor of plant molecular biology. A 2018 study by researchers from the Food and Drug Administration found that dark chocolate in U.S. markets contained an average of 7.6 micrograms of cadmium per 1-ounce serving, and some products had three or four times as much.
That amount is unlikely to be harmful, and consumption of chocolate containing elevated levels of cadmium has not been shown to increase cadmium levels in consumers, Guiltinan explained. But he advised that frequent chocolate eaters and vulnerable groups such as children and pregnant people may want to be mindful of their exposure to the heavy metal.
Another big concern for producers is regulations. While small amounts of cadmium are not shown to have negative health impacts, there are strict regulations in Europe that limit even trace amounts of the element in food products. The presence of cadmium in chocolate limits the markets in which producers can operate, Guiltinan added.
"Without proper research, the farmers growing this cacao — and the premium chocolate brands that rely on it — may be at risk," he said. "Our team's research into cadmium-resistant cacao is essential to ensure farmer livelihoods and the continued production of high-quality chocolate."
Consumer Behavior
For Helene Hopfer, associate professor of food science, consumers are arguably the most important part of any food system. Hopfer studies what she calls the "human-food interface," the ways in which our perceptions of food are shaped by the variability of its raw ingredients — and the genetic and biological underpinnings that lead us to experience the same foods in different ways, our sense of taste and preference.
"If nobody eats what you're growing, what's the point?" she said. "We can do all this work to make sure food is healthy and produced sustainably, but if no one wants to eat it, then all that work is for nothing."
Creating acceptable, healthy food at scale has plenty of challenges, Hopfer suggested. The food industry strives to create consistent products, even though the raw ingredients inside those foods are highly variable, changing from harvest to harvest due to several factors, including weather. While certain foods, such as wine, embrace these differences with vintages, consumers generally expect products to taste the same year after year.
"Take Gala apples, for example," Hopfer said. "Consumers expect them to taste the same all the time, even though they understand, perhaps subconsciously, that these fruits come from trees affected by changing conditions."
Consumer demand for consistency inspired Hopfer to collaborate with Lambert and other scientists to better understand how soil and growing conditions contribute to the characteristics of common foods. That collaboration helped launch the SPCN. Now, Hopfer focuses her research on plant-derived products and how the natural variation in these products can lead to different bioactivities in our bodies. The goal is understanding how farming practices and growing conditions influence consumer preference and health.
Into The Wild
With cacao plants, there is a long history of production and its associated farming practices, but with other plants, such as North American ghost pipe, farming is not yet part of the equation.
Savannah Anez, a fourth-year doctoral candidate and a member of the SPCN research cohort through Joshua Kellogg's lab, is leading research on the potential medicinal qualities of ghost pipe (Monotropa uniflora), a native plant found in wet areas across the Appalachian Mountains, around the Great Lakes and throughout the Pacific Northwest.
Despite its flower-like shape, the plant often is mistaken for a mushroom due to its white coloring. That's because, unlike most plants, ghost pipe doesn't have chlorophyll. It doesn't photosynthesize to make its food; instead, it derives nutrients by parasitizing fungi in the soil.
Historically, ghost pipe has been used as a medicinal plant, with a long-standing presence in the traditional medicine of several Native American tribes. It reached its peak of popularity during the 19th century when a tincture of the plant was marketed through the Eclectic Medical Movement, a plant-based response to conventional medical practices.
The plant saw a resurgence in popularity during the COVID-19 pandemic when alternative medicine gained traction online, and more people were foraging the woods near their homes for plants, explained Anez, a student in the Huck Institutes of the Life Sciences' intercollege graduate program in plant biology.
"It was social media that reignited interest in ghost pipe, and it became a widely known medicinal plant," said Anez, whose research focuses on ghost pipe's historical uses and its ongoing relevance in contemporary ethnobotany. "For whatever reason, ghost pipe really got the 'algorithm treatment.' There was this perfect storm in the pandemic; we were also in an opioid crisis with a lot of people looking for alternative treatments for chronic pain and alternative medicine more generally. And people were spending more time outdoors, so there was increased interest in foraging. That all led to the idea of ghost pipe as a pain reliever spreading through the internet."
Despite ghost pipe's long history as a medicinal plant, very little is known about its biochemistry, she said. Most of the research on its active compounds is outdated, with the only direct reference to its potential toxicity coming from a paper published in the 1880s.
Siela Maximova and Mark Guiltinan are researching cadmium-resistant cacao, aiming to ensure farmer livelihoods and the continued production of high-quality chocolate. Photo: Michael Houtz
The paper suggested the presence of grayanotoxin, a neurotoxin found in other plants in the same family, including rhododendron. However, no follow-up studies have confirmed or disproven this, Anez said, which is why she is studying the plant's biochemistry to determine if it is toxic. Preliminary findings indicate that it is not, but she is still analyzing data.
"The lack of information fuels this ongoing debate about the plant's safety and efficacy — some claim it's a miracle cure, while others warn it's highly toxic," she said.
Ghost pipe's unique relationship with its host makes it a fascinating and particularly challenging specimen to study, Anez said. Nutrients flow from trees through a network of fungi into the ghost pipe, influencing its chemical profile. This led her to ask a larger research question: How does the host plant's environment affect ghost pipe's medicinal properties? She led a team of citizen scientists from around the country who gathered samples of the plant in wide ranges of environments and ecosystems. She currently is examining the chemical profiles of each sample to determine how growing conditions influence the biochemistry of the plant.
So far, the team has analyzed samples from Oregon, Michigan, Vermont and North Carolina — and they all show distinct chemical profiles compared to Pennsylvania's plants, which was an exciting and unexpected finding, Anez said.
"Processing all the extracts and running them on the mass spectrometer took a significant amount of time, and we're still working to make sense of such a large dataset," she said. "Our goal is to identify patterns in the chemistry, explore relationships between the samples and their host environments, and ultimately generate preliminary data to study the plant's medicinal qualities in preclinical animal models."
Anez and her team are particularly interested in exploring whether ghost pipe relieves pain through anti-inflammatory properties or interacts with neuroreceptors. Ultimately, they hope testing in animal models will help them determine its effectiveness in pain relief and possibly open the door to an alternative to certain opioid-based therapies for pain.
While the team studies the chemical attributes of the plant, the researchers are simultaneously surveying how people are harvesting and using the plant today. The scientists also are exploring archival resources to learn more about how the plant was used historically to compare that information with its contemporary uses.
"I'm really proud of this project because we are allowing the experience of the consumer to actually guide the research," Anez said. "This not only makes our work more efficient, because we can design our chemical and biological analyses based on how the plant is being used, but this also ensures that the results we get are relevant to the people already using this plant."
Economies Built On Healthy Ecosystems
The Soils, Plants and Consumers Network is expanding its approach to look beyond soil to the entire ecosystem in which plants are grown. There are multiple agroforestry projects underway in Belize, focusing on farming within forested areas. These farms often border native lands, integrating agricultural production with the surrounding ecosystem, Guiltinan noted.
"Ecosystems are vital not only for insects, animals and conservation but also for the communities that live, work and rely on them for sustenance," he said. "Human health is deeply interconnected with ecosystems. Infectious diseases often emerge from natural environments like jungles, making this a crucial area of research. Designing agroforestry systems with this knowledge allows us to teach farmers not only how to cultivate their farms but also how to create safer and healthier environments."
He added that this interconnectedness highlights the importance of a systems approach, in which understanding these complex dynamics requires collaboration among diverse fields. For example, the Belize fieldwork involves entomologists who are studying the spread of tick-borne disease on cacao farms. There also are forestry experts researching best-growing practices for farmers and landholders for a range of woody plant species, studying their uses and benefits, as well as evaluating various practices and offering adoption guidance. Hopfer is working on a project to study the taste profiles of cacao grown in the region, with consideration for the agroforestry practices that produced the product.
"The time for easy research questions is over," Hopfer said. "We are focused on complex problems that require an entire network of experts working together, uniting to peel away a problem piece by piece until we understand the entire system and the fundamental, underlying mechanisms that shape it."
Student Spotlight: Kelsey Custer
Custer, of New Freedom, is majoring in pharmacology and toxicology and minoring in biology. In addition to academic pursuits, she serves as the public relations director for Alternative Breaks at Penn State, a program that facilitates student-led service trips throughout the academic year.
Custer is an undergraduate researcher in the lab of Assistant Professor of Veterinary and Biomedical Sciences Joshua Kellogg, where she supports a project to identify the anticancer compounds found in Dovyalis abyssinica, a plant used in traditional Ethiopian medicine.
What sparked your interest?
Funny enough, I first learned about pharmacology through a career aptitude test. After researching the topic, I knew it was the right major for me. I chose Penn State specifically after attending an Ag Sci open house, which allowed me to sit down with the program coordinator one-on-one. After that conversation, I knew this was the place for me.
What are you learning that excites you? How does that fit with your big-picture career goals?
Currently, I am diving into the topic of natural products drug discovery, or pharmacognosy. So many of the life-saving drugs on the market are derived from plants, and there are still so many more to be studied. This has inspired me to pursue a doctoral degree in this topic, hoping to one day discover the next miracle drug.
Why is your major important to the world?
Pharmacology and toxicology are critical to the world. The field is highly diverse, encompassing many things, including drug discovery (my personal interest), environmental toxicology, drug interactions, pharmacodynamics and kinetics, and so on. All of these are vital to understanding and advancing the field of medicine.
What has been your favorite course or project?
One of my favorite projects I have completed was in Biology 407. I worked in the Buckhout greenhouse for a semester, growing tomato plants from seeds to investigate if adding support stakes to the plant impacted its secondary growth features. Although no significant data was found due to the low sample size, this opportunity taught me about the scientific process and experimental design, which helped prepare me for future projects.
Student Spotlight: Pradip Poudel
Poudel, of Chitwan, Nepal, is a fourth-year doctoral student studying agricultural and environmental plant science. Outside of the lab, he's involved with the Plant Science Graduate Student Association and Nepalese Society at Penn State.
A first-generation college student, he works in the lab led by Francesco Di Gioia, associate professor of vegetable crop science. Poudel's research focuses on enhancing food and nutritional security through zinc biofortification of crops using agronomic methods.
What sparked your interest?
Growing up in Nepal, I witnessed the challenges of nutrient deficiencies and unsustainable farming, which inspired my interest in sustainable agriculture and crop nutrition. I focus on zinc biofortification to combat hidden hunger and improve public health. My research on microgreens, soilless systems and alternative growing media aligns with my goal of enhancing food security and promoting environmentally sustainable farming practices, combining my passion for plant science with practical solutions for global challenges.
What does the "Ag Sciences community" mean to you?
The Ag Sciences community is a collaborative network of researchers, educators and practitioners dedicated to solving global agricultural and environmental challenges. It's a space where diverse ideas converge to advance sustainable farming, food security and crop nutrition. Being part of this community connects me with like-minded individuals, fostering a shared commitment to making a meaningful impact on agriculture and creating a healthier, more sustainable future.
What have you learned about yourself since coming here?
At Penn State, I've learned that I thrive in collaborative, interdisciplinary environments. I've deepened my passion for sustainable agriculture and crop nutrition, gaining confidence in conducting independent research and managing complex projects. I've also developed resilience and adaptability, enhancing my problem-solving and communication skills.
What has been your most memorable experience?
My most valuable college experience at Penn State has been the opportunities for both personal and professional growth. I've attended national and state conferences, presented my research, and connected with experts in agriculture. These experiences have expanded my professional network and kept me engaged with advancements in the field. Additionally, receiving the Paul Hand Award and the Frederick H. Brown Endowed Scholarship has motivated me to continue impactful research and contribute to the agricultural community.
By Adrienne Berard
Photos Michael Houtz
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