A new genetics study found that drinking instant coffee may significantly increase the risk of developing dry age-related macular degeneration (AMD), a leading cause of vision loss in older adults.
Published in the Wiley journal Food Science & Nutrition and led by a research team from multiple universities in China, the study found no such risk with ground coffee, decaffeinated coffee or total coffee consumption.
“Instant coffee may increase the risk of AMD, and reducing its intake could help prevent dry AMD,” the researchers wrote. “People at high risk for AMD should avoid instant coffee. This study aids clinicians in identifying dietary factors, particularly instant coffee consumption, as potential risks for AMD.”
The findings are based on large-scale genome-wide association studies, known as GWAS, involving hundreds of thousands of people. Using a Mendelian randomization method — which mimics randomized trials by analyzing naturally occurring genetic differences — the researchers attempted to estimate the impact of coffee consumption on disease risk.
The authors suggested that the perceived link between instant coffee and dry AMD risk may be due to “processing byproducts, additives or chemical alterations resulting from dehydration and reconstitution” in soluble coffee production that are not present in standard coffee production.
Age-related macular degeneration is estimated to affect nearly 200 million people globally and is expected to impact 290 million by 2040, according to studies cited in the paper. Dry AMD, the more common form of the disease, progresses slowly but can lead to significant vision impairment. There is no known way to reverse damage from the disease.
The study was not funded by any specific grants, and the authors reported no conflicts of interest. However, they noted several limitations, including the use of data primarily from European populations and a lack of detailed classification for coffee types beyond preparation method.
“This study provides guidance regarding instant coffee consumption, suggesting that it increases the risk of dry AMD, and therefore high-risk groups should reduce their intake,” the authors wrote. “Furthermore, it is essential to identify harmful components in instant coffee and other types of coffee to reduce their content.”
As of this writing, there has been no widely published critical pushback against the study among either the scientific community or the instant coffee industry.
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