18 hours ago
Instant coffee warning as scientists discover it could cause disease that destroys your eye sight
DRINKING instant coffee could increase the risk of a sight-robbing eye condition, research suggests.
People at high risk of the disease should avoid instant brews, scientists from the Hubei University of Medicine in China said.
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Age-related macular degeneration (AMD) is a common eye condition that first affects people in their 50s.
While it won't cause total blindness, it can make things like reading and recognising faces difficult, and symptoms get worse without treatment.
A study used genetic data from more than 500,000 people found a statistically significant link between instant coffee intake and the risk of dry AMD - one of the forms of the sight-robbing disease.
In contrast, ground coffee and decaffeinated brews bore no links to AMD.
"Our results revealed a genetic correlation between instant coffee consumption and dry AMD," wrote corresponding author Siwei Liu, from the Department of Ophthalmology in Shiyan Taihe Hospital at the Hubei University of Medicine.
"Instant coffee may increase the risk of AMD, and reducing its intake could help prevent dry AMD.
"People at high-risk for AMD should avoid instant coffee."
AMD is a common eye disease and "one of the leading causes of irreversible blindness", researchers said.
There are two types of it, wet AMD and dry AMD.
Dry AMD is the most common form and it doesn't mean a person has dry eyes. It refers to damage to the macula - an area of the retina that allows you to see figures, shapes and details right in front of you - from abnormal protein deposits.
Three signs your dry eyes could be signalling a killer disease - when to see your GP
Wet AMD is less common but more severe, developing more quickly.
"Epidemiological studies indicate that AMD affects nearly 200 million people worldwide, with the number expected to reach 290 million by 2040," the study authors wrote in Food Science and Nutrition.
"Research has shown that genetic factors play a major role in the development of AMD.
"However, given the unclear disease mechanisms and the complexity of treatment, slowing disease progression and timely prevention are particularly important."
Previous research has suggested that drinking coffee may help lower the risk of AMD
"In contrast, our study provided a more detailed stratification of coffee types and yielded different results, indicating potential biases in previous research," the study authors stated.
Their results showed "a potential genetic correlation between instant coffee consumption and both dry and wet AMD".
"We found that instant coffee significantly increases the risk of AMD," researchers said.
Symptoms of age-related macular degeneration (AMD)
Age-related macular degeneration (AMD) affects the middle part of your vision, not the edges (peripheral vision).
You can get it in one eye or both.
The first symptom is often a blurred or distorted area in the centre of your vision.
If it gets worse, you might struggle to see anything in the middle of your vision.
AMD can make things like reading, watching TV, driving or recognising faces difficult.
Other symptoms include:
Seeing straight lines as wavy or crooked
Being sensitive to bright light
Seeing flickering or flashing lights
Seeing things that are not there (hallucinations)
Source: NHS
But the analysis couldn't show that coffee consumption can directly cause AMD, they noted.
To conduct their study, the Chinese researchers used data from the UK Biobank that included details on people's coffee consumption - including how much coffee they drank in total and whether it was instant, ground or decaffeinated.
They also obtained health data, including diagnoses of AMD.
The study authors conducted a genetic analysis, to find out if genetic variants associated with coffee preferences also are also linked to AMD risk.
They also looked at whether there were any shared genetic variants between intake of ground, decaffeinated or instant coffee and AMD risk.
Researchers found a significant overlap between the genetic predisposition to instant coffee intake and the risk of dry AMD, suggesting shared DNA signals between the two traits across the human genome.
There was no such link for other types of coffee.
There was also no link between coffee intake and the risk of wet AMD.
But researchers did find that drinking instant coffee was linked to increased risk of the sight-robbing disease. The risk increased along with instant coffee consumption.
These findings suggest that processing byproducts, additives, or chemicals found only in instant coffee may contribute to the risk of dry AMD.
The paper suggests that instant coffee can contain acrylamide, oxidised lipids, and other compounds not present in fresh brews.
Researchers said people with early-stage AMD and patients with a genetic predisposition to AMD should consider reducing their intake of instant coffee, opting for ground beans instead.
