Columbus, Ohio – Bananas thrive best in full sunlight. Interestingly, banana peels produce a natural sunscreen that helps protect sensitive skin from harmful UV rays. My teenager recently peeled a banana to uncover the secret behind this natural sunscreen. Her discovery might pave the way for more eco-friendly sunscreen options for everyone.
“My mother always taught me to be mindful of the ingredients in my cosmetics,” says 15-year-old Taylor Maguire. This prompted the sophomore from Garden City High School in New York to inquire, “What exactly is in my sunscreen?”
Sunscreens play a crucial role in safeguarding your skin from intense sunlight. However, there is a downside. Some of the chemicals found in sunscreens may increase cancer risk, Taylor pointed out. Additionally, when these chemicals wash off into the environment, they can damage aquatic life. For instance, certain mineral sunscreens impair freshwater animals’ navigational abilities, often resulting in fatalities.
Consequently, Taylor sought out a mineral-based alternative for sunscreen.
Bananas have a unique ability to naturally filter many of the sun’s harmful rays. Could their natural sunscreen serve as a substitute for mineral sunscreens? This question drove Taylor’s research, which ultimately earned her a place at the 2025 Regeneron International Science and Engineering Fair (ISEF) this May.
Extracting the Product
According to Taylor, bananas typically flourish in “UV-dense environments.” UV, or ultraviolet rays, represent a range of invisible light wavelengths that cause the majority of sun damage to our skin. Effective sunscreen must offer protection against specific UV rays.
Given that bananas develop in regions with intense UV exposure, Taylor hypothesized that they “must have their own protective mechanisms.”
Plants often produce flavonoids—colorful, iridescent pigments— to shield themselves from ultraviolet rays. Taylor wondered if the flavonoids in bananas could similarly protect human skin from UV rays.
Uncertain which banana flavonoid to focus on, Taylor heated, froze, and blended the banana peel’s outer layer. “That’s the section directly exposed to sunlight,” she notes, implying that the UV filtering compounds might be concentrated there.
By breaking down the cells, she released a variety of chemicals. From this mixture, she created two extracts: one that contained water-soluble components (the aqueous extract) and another that contained only non-polar chemicals that dissolve in oils rather than water.
Testing the Banana Extract
For sunscreens to work, they must absorb UV rays before they can reach the skin, and higher absorption rates lead to better protection. To evaluate how effectively each extract could absorb UV rays, Taylor employed lightweight tools, using a spectrophotometer to measure the amount of light absorbed by each liquid.
The results confirmed that both extracts absorbed UV rays, but the non-polar extract excelled, absorbing the entire spectrum of UV wavelengths, particularly the most damaging ones found in the UV-A range.
But are banana-based sunscreens also safe for the environment? Taylor expressed concerns about how conventional drugstore sunscreens can harm aquatic organisms. To investigate this, she used planarians (Girardia Tigrina) as her test subjects. These flatworms inhabit freshwater and are commonly utilized in drug safety research, with chemicals that harm them likely posing a risk to other aquatic species as well.
The experiment involved placing the planarians in dishes containing the different extracts, exposing them to bright UV light for 10 minutes. If the worms moved sluggishly or stopped entirely, it indicated light-induced damage. Her five test solutions included her two extracts, drugstore sunscreens, plain water, and glycerol.
Why glycerol? Both the non-polar extract and the sunscreen solution included this thick liquid, leading Taylor to evaluate its effects alone.
Her findings were compelling: “Non-polar bananas, glycerol, and mineral sunscreen” [were found to be] toxic to the worms,” she reported. “They ceased movement.”
Taylor was amazed; glycerol is a common ingredient in many sunscreens and is generally not recognized as harmful to humans, yet she is “fairly certain” it contributed to the planarians’ demise.
In subsequent tests, Taylor observed that glycerol negatively impacted the planarians’ skin, even without UV exposure. Given how commonly glycerol is used, her results suggest it may pose a threat to aquatic ecosystems.
However, the planarians that were exposed to the aqueous extract fared much better, demonstrating resilience compared to the plain water group.
Taylor confirmed her results by staining the same planarians with a special dye that highlights damaged tissue under UV light. Essentially, the more fluorescence, the greater the level of damage.
The groups exposed to glycerol showed the most damage, while the aqueous extract group exhibited the least. The areas of damage appeared “messy,” which likely indicated incomplete coverage.
The next step for Taylor involves identifying the specific chemicals responsible for UV protection in the aqueous extract. She believes this could lead to the development of a new category of banana-based sunscreens.
The Regeneron ISEF is a program organized by the Society for Science, which also publishes this magazine. Taylor was one of 1,657 students from 62 countries competing in the 75th annual ISEF, where they shared in prizes totaling around $9 million.
Source: www.snexplores.org
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