Labrador Tea Polyphenols: Surviving Digestion to Protect Proteins in Arthritis

Hi, my name is Aiden James Einish, and I am from Kawawachikamach, Quebec. This is a continuation from my last years' projects, where I proved that Labrador tea contains polyphenols that contain anti-inflammatory properties. My Naskapi background and the tradition of drinking Labrador tea are my inspiration for this project. In this project I wanted to see if polyphenols from Labrador tea survive after digestion and if they protect proteins in arthritis. The way I did this is using a human digestive simulation with chemicals and digestive enzymes ordered by my school and using TLC (thin layer chromatography) to visually analyze if polyphenols survived after digestion under UV light and iodine staining using a handmade iodine chamber, an egg albumin assay, GC-MS (gas chromatography mass spectrometry), which I used at Trois-Rivières University, and a survey I made, which I gave to my community. Thank you for listening, and I cannot wait to present my project at the Canada-wide Science Fair 2026.

The reason I did this project because, although Labrador tea has been consumed for its health-promoting properties, there is little scientific research on the behaviour of its bioactive compounds after digestion. This project aimed to address this by investigating the stability and functionality of the polyphenols after digestion.

This project was inspired by the traditional cultural knowledge of northern communities that have used Labrador tea for many years. Also, my last year’s science fair project using ultraviolet spectroscopy verified the presence of phenolic compounds in Labrador tea, which inspired me to extend the research to find how the compounds react after digestion, and if they remain functional.

My research question was:

Are polyphenolic compounds in Labrador tea stable to digestive conditions, and do the digestion-stable compounds have an effect on reducing arthritis-causing protein denaturation?

This study can help the following individuals:

Labrador tea-consuming Northern and Indigenous communities.

Scientists having interests in plant bioactives and digestion.

Nutritional and health sciences researchers looking for natural ways to stabilise proteins and prevent inflammation.

Consumers seeking proven information on herbal medicine.

Patients with arthritis. Arthritis affects almost 6 million individuals in Canada, or 20% of the population (Lagacé et al., 2010).

Through improved knowledge of the biochemical activity of traditional plant-based beverages and the translation of traditional knowledge into science, this research could transform the world. This research promotes further investigations of natural alternatives for the treatment of protein-related diseases like arthritis.

I conducted background research by reading scientific papers on polyphenols.

I relyed on peer-reviewed scientific journal, articles and studies.

My experiment was set up in several steps:

Prepare Labrador tea.

Simulate human stomach and intestinal digestion.

Study compound stability (TLC and GC-MS).

Evaluate functional activity (protein denaturation assay).

Assess protein-binding using an ELISA-test.

Community survey aided in mimicking real-world use in the lab.

I then designed the following biochemical model:

Digestion was simulated using pH and enzyme treatments.

TLC and GC-MS was employed for detecting chemical survival and compound identification.

Protein stability was tested using egg albumen under heat stress.

ELISA-test was performed to measure functional protein interaction protein binding to antibody.

Materials used:

Labrador tea leaves (Rhododendron groenlandicum)

Distilled water

Pepsin (stomach enzyme)

Pancreatin and bile salts (intestinal enzymes)

pH adjustment solutions (acid and base)

Silica TLC plates and methanol

GC-MS instrumentation

Egg albumen (protein model)

Heat source (70°C incubation)

ELISA kit

Survey questionnaire

How Data was collected:

Data was collected using multiple methods:

Thin layer chromatography: visualising spots (Rf, intensity, streaking)

GC-MS: peak recognition and intensity measurements

Egg assay: turbidity (cloudiness) comparison

ELISA: measurement of colour intensity (ImageJ mean values)

These methods yielded different data including qualitative (visual), semi-quantitative (image intensity) and quantitative (GC-MS peaks)

Samples:

For digestion experiments: 3 stages (undigested, stomach, intestinal)

For protein content: 5 conditions (blank, negative control, raw, stomach, intestinal)

For ELISA: 7 stages (albumin, buffer, negative, raw, stomach, intestinal, standard)

Community survey: several people (n=22)

Variables:

To allow comparison, variables were standardised:

Temperature (37°C for digestion, 70°C for protein denaturation).

Time of incubation (60 minutes).

pH (1-2 stomach digetion, 7-8 intestinal digestion).

Volume of reagents and samples.

Same protein concentration in all assays.

Same lighting and conditions for image analysis.

Only the treatment (digestion, tea) was modified.

The main results demonstrate that the polyphenols in Labrador tea survive partially after this simulated experimental digestion, but are still functional towards stability. Polyphenols have been shown by thin-layer chromatography (TLC) to survive digestion, but with less intense bands. From the results of gas chromatography-mass spectrometry, protocatechuic acid is significantly stable, quercetin-hexosides partially survive, and kaempferol-hexosides are mostly destroyed following intestinal digestion. These chemical analyses were further confirmed by functional assays. The egg albumen assay indicated a decrease in protein denaturation with the digestion-resistant polyphenols, suggesting their biological activity and protein stabalization. Additionally, the ELISA assay showed that digested samples decreased the signals, egg albumen produced higher antibody binding in comparison to the buffer sample. The raw tea-treated albumen samples displayed signal intensities comparable to albumin, suggesting that polyphenols may maintain protein structure or epitopes (antibody binding sites). These findings suggest that some polyphenols survive digestion and retain chemical and functional integrity.

The project is a two-part, step-wise biochemical model of digestion and chemical and functional activity. Labrador tea extracts are first digested using simulated stomach and intestinal conditions (pH and enzymes). Polyphenol chemical identification and stability are then determined by TLC and GC-MS. The functional integrity of the proteins is measured using a protein denaturation assay, subjecting egg albumen to heat. Also, protein-protein binding is assessed using an ELISA test where the albumen is bound to a surface and is reacted with a detection system that causes a colour change. The change in colour (measured by the mean value of the image) is related to the amount of protein available for recognition by the antibody.

Consistency is observed between the chemical and functional results. TLC and GC-MS reveal that digestion decreases the level of polyphenols without completely removing them, with protocatechuic acid being the most stable. These results are supported by functional assays. Digested tea samples were less denatured than the control, indicating a protective effect. The ELISA-assay also validated this, as the control demonstrated the strongest signal for antibody binding, whereas digestion-treated albumen had a weaker signal, suggesting less protein integrity. Raw tea had somewhat strong signals, indicating polyphenols may help maintain the structural integrity of protein or retain antibody-binding sites. Laboratory results were inconsistent with community survey data.

This study was mainly conducted with qualitative and semi-quantitative analysis. Results from TLC were evaluated visually based on UV fluorescence lamp and iodine staining intensity, and GC-MS results were used for quantitative peak analysis. The egg albumen assay was assessed by comparing turbidity, while the ELISA assay was assessed by comparing mean grayscale intensity values measured by image analysis. Averaging the intensity of the signal provides a reliable way to compare signal levels between samples, as it represents the average intensity within the measurement region. As the same conditions were used for all samples and measurement areas, the mean intensity is a suitable means of comparing relative antibody binding. Chemical analyses were performed in triplicate.

The results indicate that Labrador tea polyphenols are partly resistant to digestion and are bioavailable. TLC revealed the existence of polyphenols after digestion, gas chromatography-mass spectrometry demonstrated that protocatechuic acid is relatively stable. The chemical results are reflected in the functional assays. The egg albumen assay suggested that digestion-resistant polyphenols reduce protein denaturation, suggesting their protein-stabilizing effects. The ELISA experiment also showed the highest binding signal for the non-digested albumen, and that digestion diminished the signal, with intestinal digestion having the largest effect. The raw tea sample showed a higher signal, suggesting polyphenols might help prevent denaturation or reduce the loss of antibody-binding sites in the protein.

The overall findings suggest that some polyphenols in Labrador tea are chemically and physiologically stable after digestion, and this may explain its traditional therapeutic use in protein-related inflammatory illnesses like arthritis. The utilization of the community survey data also provide support that these results are relevant to how tea is made and consumed.

This investigation taught me that it is not true that chemicals in raw plant materials will always survive after digestion. The chemical profiles of bioactive substances may be significantly modified after digestion, although some of them , e.g. protocatechuic acid, are still active, and to examine their functional impacts (e.g., protein stabilization) in order to comprehend their larger biological value.

Finally, I learned that the use of traditional knowledge and laboratory analysis made the study more relevant and meaningful, and demonstrated that science can explore and confirm traditional practices.

The study could have been broadened to include different parts of the Labrador tea plant, such as leaves versus flowers. I could have also tested the sensitivity of polyphenols to slight changes in digestive conditions.

This project could be further improved by using a larger sample size. Comparing Labrador tea to other herbal teas could serve as a basis to see if its polyphenols are more stable than other herbal teas.

The following steps would be to extend comparative and functional studies. Future research could expand to biological systems to gain insights into how compounds behave in different environments.

Ms. Shaveta Sharma, my adult and scientific supervisor and mentor, guided and supervised the ethics of the fieldwork and laboratory work done at the university laboratory and the school laboratory.

Ms. Shannon Uniam, my Naskapi teacher, gave me Labrador tea leaves and the traditional knowledge of preparing and consuming the tea in the right manner.

Marc Lalande, president-treasurer, and Martine Couture, secretary of the Quebec Indigenous Science Fair (QISF), granted me ethics approval.

My community members filled out survey questionnaires.

Simon Ricard, Alexandre Custeau, and Raphael Boucher at Isabel Desgagné-Penix’s lab, the Université du Québec à Trois-Rivières (UQTR), helped me in preparing samples for gas chromatography-mass spectrophotometry.

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