Chinese scientists have noticed an interesting pattern: people who drink a lot of instant coffee may have a higher risk of developing vision problems in old age – the so-called dry form of age-related macular degeneration. This is a disease in which central vision gradually deteriorates, and it most often affects older people, informs Ukr.Media.
But an important detail is that this risk is higher only in those who have a certain hereditary (i.e., inherited from their parents) predisposition to this disease.
Researchers have estimated that every time a person starts drinking significantly more instant coffee, their risk of developing this form of the disease increases almost 7-fold.
Interestingly, this connection was only observed with instant coffee — but regular ground or decaffeinated coffee did not have this effect.
How exactly was the research conducted?
In June 2025, the journal Food Science & Nutrition published a large study in which scientists examined the link between instant coffee and vision problems. They analyzed data from over half a million people from two large European databases — UK Biobank and FinnGen.
Unlike conventional studies that simply observe who eats what and how it might affect health, here the scientists went further. They used modern methods that help us better understand whether one thing actually causes another, and not just happens to be next to it.
To do this, Chinese researchers from a university in Hubei province used three different methods of gene analysis at once. All of them help to find connections between a person's habits (such as drinking instant coffee) and their hereditary characteristics that can affect health. Thanks to this approach, the results are considered more reliable than in conventional studies.
Why genes can influence the development of vision problems
Age-related macular degeneration (AMD) is an eye disease that is more common in older people. It develops for various reasons, but one of the most important is heredity, that is, which genes a person received from their parents.
There are several specific genes that can increase the risk of this disease:
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The CFH gene helps control the body's natural defenses (the so-called immune system). If a person has a modified version of this gene, their body is less able to cope with inflammation in the retina. For example, if there is one such change, the risk increases by 2.5 times, and if there are two, the risk increases by 6 times.
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The ARMS2 gene — its role is not yet fully understood, but scientists suggest that it is associated with the body's ability to remove “cellular debris” from the eye that forms after cell death. If this process is disrupted, it may contribute to the development of AMD.
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The C3 gene is also important in the functioning of the immune system, particularly in the fight against inflammation.
But the main thing is that even if a person has such hereditary changes, it does not mean that they will definitely get sick. This only increases the risk, but the development of the disease is influenced by both lifestyle and external factors, such as nutrition, sun, smoking, etc.
Why is instant coffee under suspicion?
Scientists suggest that it may not be so much about the coffee itself, but rather how it is made.
When instant coffee is made, it is heated, concentrated, dried, and sometimes added with various substances, such as sugar or powdered creamer. This can lead to the appearance of harmful compounds that are almost never found in regular ground coffee.
In particular:
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Acrylamide is a substance formed during high heat. It is considered harmful to the nervous system and some studies have linked it to the risk of cancer.
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AGEs (advanced glycation end products) are substances that can accumulate in the body and cause inflammation and cell damage. This is especially dangerous for the eyes, specifically the retina, where a crucial part of the vision process takes place.
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Additionally, vitamins, polyphenols, and antioxidants that protect cells can be partially destroyed during such harsh processing, meaning that instant coffee contains fewer of these nutrients.
That's why some scientists suspect that instant coffee—and not regular coffee—may be linked to certain age-related eye diseases.
Coffee is generally healthy, but instant coffee may be an exception
It's important to understand that this study doesn't mean that coffee is bad in general. On the contrary, coffee is considered one of the healthiest beverages in the world. It contains many substances that help protect cells from aging and damage. Some of them are called polyphenols and antioxidants.
Many previous studies have looked at how coffee or caffeine may affect the risk of diabetes, heart disease, memory problems, arthritis, certain cancers, and other diseases. Overall, there is no clear evidence that coffee causes these diseases. In some cases, it may even slightly reduce the risk.
In the case of age-related macular degeneration (AMD), the researchers found no link with all types of coffee in general. Importantly, the increased risk only applied to instant coffee, not to ground coffee or decaffeinated coffee.
What else is worth knowing about this study?
Although the results look convincing, the scientists themselves acknowledged that their study has several limitations.
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All data was collected only from European participants. This means we don't yet know whether these results would be the same for people from other parts of the world — for example, Asia, Africa, or South America. Therefore, more research is needed with different groups of people.
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The study did not specify in detail what kind of coffee each participant drank — for example, light roast, dark roast, with or without sugar. In the future, it is worth paying attention to these details, as they can affect health differently.
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Scientists have looked for common traits in the genes of people who drank a lot of instant coffee and had vision problems, but they haven't found any clear matches. This means that the connection between heredity, nutrition and disease is very complex, and much more research is still needed to understand exactly how it all works.
This study shows an interesting possible link between instant coffee consumption and the risk of developing vision problems in people with certain hereditary traits. But it's important to understand that this is just the first step in trying to understand how genes, nutrition, and eye health are connected.
This link doesn't mean that everyone who drinks instant coffee will necessarily have vision problems. It only applies to people who have specific hereditary changes in their bodies. For everyone else, there may be no risk.
Therefore, we should not rush to conclusions – more research is needed to better understand everything.
Research source
Title: “Genetic Correlation and Mendelian Randomization Analyzes Support Causal Relationships Between Instant Coffee and Age-Related Macular Degeneration”.
Authors: Qi Jia, Zhijian Zha, Si Li, Yong Zhang, Lan Ke, Siwei Liu.
Journal: Food Science & Nutrition, 2025.
