Kidneys at Work

This project was inspired by my dad’s health journey. He developed chronic kidney disease and now requires hemodialysis. Seeing this firsthand helped me understand how challenging kidney disease can be for both patients and their families. When I accompanied him during home hemodialysis training, I became interested in how the kidneys work and why they can fail.

As I learned more, I discovered that kidney disease is a serious and growing public health problem. In Canada, more than 50,000 people are living with severe kidney disease requiring dialysis or a transplant, while many more have earlier stages that often go undiagnosed. In Manitoba, about 1 in 10 people are affected, with even higher rates in northern communities, where I live. Many people do not realize they have kidney disease until it becomes advanced, making early prevention important.

At the same time, I noticed that many young people regularly consume sugary and salty drinks. This made me wonder:

What snacks and drinks do students choose, and what do they know about kidney health?

How do these commonly consumed drinks affect filtration in a kidney model?

Hypothesis: Higher concentration results in slower filtration.

Through this project, I explored students’ snack and drink choices and their knowledge of kidney health, and investigated how these drinks affect filtration using a kidney model.

This project promotes early awareness of kidney health, encourages healthier choices, and highlights the gap between knowledge and behaviour, emphasizing the importance of prevention before kidney disease begins.

Background Research

I researched how kidneys filter waste and how a model can use coarse-to-fine layers to represent progressive filtration. I used reliable sources such as the Kidney Foundation of Canada and Kidney Health Manitoba, as well as educational science websites.

Survey

I conducted a survey with 63 students in Grades 6 to 8 to understand their snack and drink choices and their knowledge of kidney health. This helped me select drinks that students commonly consume. I included sugar and salt solutions to represent diets high in sugar and salt.

This ensured the experiment was based on real student habits, making results relevant.

Model Design

I built a kidney filtration model using four plastic bottles to represent fluid intake, two kidneys, and the bladder.

Inside the kidney bottles, I created filter layers arranged from coarse to fine using:

60 g pebbles

60 g rice

4 cotton balls

2 coffee filters

I first tested a fine‑to‑coarse arrangement, but it resulted in slow and unrealistic filtration. Changing to a coarse‑to‑fine design improved the flow and better represented real kidney filtration.

Testing Procedure

I tested seven liquids: distilled water (control), juice, pop, sports drink, milk, sugar solution, and salt solution.

Each trial used 150 mL of liquid

Sugar and salt solutions were prepared by dissolving 30 g of solute in 150 mL of distilled water

Before each test, 150 mL of distilled water was run through the system to standardize the filter.

For each test, I measured:

filtration time

volume collected

mass before and after filtration

and calculated specific gravity using mass and volume

Residue in the filter was also observed. New filter materials were used for each liquid, and each test was repeated three times to improve reliability, ensuring a fair and consistent comparison across all liquids.

The survey and experiment results help explain how students’ drink choices may affect kidney filtration.

Student Survey Results (n = 63)

Survey results showed that many students choose sugary and salty foods and drinks:

63% chose water as a favourite drink.

48% chose pop and 33% chose sports drinks.

56% preferred salty snacks and 49% preferred sugary snacks.

83% knew water is important for kidney health.

Only 27% correctly identified a kidney specialist as a nephrologist.

Although most students understood that water is healthy, many still preferred sugary or salty options.

Kidney Filtration Experiment

The experiment showed clear differences in how each liquid filtered through the kidney model.

Water filtered the fastest (60 seconds) and remained clear with no residue.

Milk filtered the slowest (246 seconds) and left a thick residue that coated the filter materials.

Salt and sugar solutions filtered slowly and left sticky residue.

Pop, sports drinks, and juice showed moderate filtration times and caused visible colour changes or residue.

Liquids with more dissolved substances or thicker composition slowed filtration and left more residue.

Data Analysis

Each test was repeated three times, and average filtration time was calculated to reduce variation between trials. Filtration rate and survey percentages were used to compare results and identify patterns. Specific gravity was checked using a hydrometer and calculated using mass and volume because some hydrometer readings were unclear.

Specific Gravity and Filtration

Specific gravity was used to understand how concentration affected filtration.

Liquids with higher specific gravity generally filtered more slowly.

Salt and sugar solutions had higher density than water and showed slower filtration times.

After filtration, their density decreased, suggesting that some substances were trapped in the filter layers.

Milk filtered even more slowly than the salt solution despite having a lower specific gravity, suggesting that fats and proteins also affect filtration.

Limitations

This model shows how filtration changes with different liquids, but it does not fully represent real kidneys. Real kidneys use blood pressure, specialized structures called nephrons, and reabsorption, which are not included in the model. Residue was observed visually, not measured quantitatively. The survey was limited to 63 students from one school.

Key Pattern

Students frequently choose sugary or salty drinks, and these same types of liquids slowed filtration and left more residue. This highlights a gap between knowledge and behaviour and suggests that everyday drink choices may increase stress on kidney filtration over time.

This study shows that both drink composition and student behaviour are important for understanding kidney health.

In the model, liquids with more dissolved substances or complex contents slowed filtration and left more residue. This suggests that these drinks may increase resistance during filtration and may increase kidney workload over time. Water filtered quickly and left no residue, supporting its importance for kidney health.

Specific gravity helped explain part of the pattern: liquids with higher concentration generally filtered more slowly. However, milk filtered even more slowly than the salt solution despite having lower specific gravity, showing that composition, such as fats and proteins, also matters.

The survey showed that many students understand healthy choices but still often choose sugary and salty drinks, highlighting a gap between knowledge and behaviour.

Based on expert interviews and kidney health resources, key recommendations include drinking plenty of water, reducing sugar and salt, eating more fruits and vegetables for fibre, exercising regularly, maintaining a healthy weight, using medications safely, and getting regular health checkups.

Overall, this project shows that everyday drink choices may affect kidney workload, and that healthy habits from a young age may help protect kidney health into adulthood.

As a next step, I would improve the model by using a more realistic filtration system, such as dialysis tubing or a membrane‑based setup, to better represent how real kidneys filter substances.

I would also like to develop a school‑based kidney health screening tool to identify possible lifestyle risk factors and encourage early medical checkups. This tool would not diagnose kidney disease but could promote early awareness and prevention, helping reduce the risk and severity of kidney disease over time.

First, I thank Lord Jesus Christ for His guidance and wisdom throughout this project. I am grateful to Dr. Leanne Stalker, National Research Director at the Kidney Foundation of Canada, for mentoring me and helping me think more deeply about kidney research. I also thank the Renal Health Program at Seven Oaks General Hospital, including Ms. Diana, renal dietitian, Mr. Curtis, pharmacist, and Mr. Dennis, RN, for expert advice on kidney health, diet, hydration, and prevention.

Thank you to Ms. Ripandeep Kaur and Mr. John Paul Beauchemin for supporting the school survey. I especially thank Mr. Sunday Abara and Mrs. Whittney Lennox for their ongoing guidance and encouragement.

I also thank Mr. Matthew Lennox for building the wooden stand, and my dad, mom, and sister, Mr. Prasanth Jonathan, Dr. Michelle Jonathan, and Ms. Joanne Jonathan, for planning, materials, feedback, presentation support, and encouragement. Finally, thank you to all survey participants.

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Kidney Foundation of Canada. (2024). Kidney disease in Canada: Facts and statistics. https://www.kidney.ca

Kidney Health Manitoba. (2019). Kidney disease statistics in Manitoba. https://www.kidneyhealth.ca

Kidney Research UK. (2023). Diet, hydration, and kidney health. https://www.kidneyresearchuk.org

Lian, R., & Wang, Z. (2025). Association of childhood health with adulthood chronic kidney disease: Results from the China Health and Retirement Longitudinal Study. Frontiers in Public Health, 13. https://doi.org/10.3389/fpubh.2025.1538744

Liu, C., He, Y., Venn, A. J., et al. (2023). Childhood modifiable risk factors and later life chronic kidney disease: A systematic review. BMC Nephrology, 24, 184. https://doi.org/10.1186/s12882-023-03232-z

Microsoft. (2026). M365 Copilot (GPT‑5 chat model) used for editing, formatting, and infographic creation.

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (2023). Keeping kidneys healthy. https://www.niddk.nih.gov

National Kidney Foundation. (2023). Healthy eating and kidney health. https://www.kidney.org

National Kidney Foundation. (n.d.). Better kidney health for kids: Seven golden rules. https://www.kidney.org/kidney-topics/better-kidney-health-kids-seven-golden-rules

National Kidney Foundation. (n.d.). Kidney filtration model demonstration instructions. https://www.kidney.org/sites/default/files/ykayth_nkf_kidney_filtration_demo_instructions.pdf

Pexels. (n.d.). Free stock photos. https://www.pexels.com

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YouTube. (n.d.). Kidney filtration explained (educational video). https://www.youtube.com/watch?v=tzkG93AKhs4

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AI tools were used to support editing, formatting, and the creation of an infographic, while all ideas, experimental design, data collection, and analysis are the student’s own.