Large study finds instant coffee may be linked to vision loss: Expert advise choosing freshly brewed coffee

Coffee is an essential daily pick-me-up for many in Hong Kong. A large study has found that habitual consumption of instant coffee may be associated with a significantly increased risk of "dry age-related macular degeneration" (AMD), with an increase of up to nearly 7 times. Experts urge people, especially the elderly and those with a family history of AMD, to choose their coffee carefully and consider switching to pour-over or freshly brewed coffee to protect their vision.

Nutritional and functional medicine expert Dr. Lau Pok-yan shared on his Facebook page about a patient diagnosed with AMD who came for treatment. The patient's vision was continuously deteriorating, and he hoped to improve his condition through lifestyle adjustments. After a detailed consultation, Lau discovered that the patient had a long-term habit of drinking instant coffee. Lau then cited the latest international research, indicating that this was not an isolated coincidence.

Lau explained that the macula is the most important part of the central retina, responsible for seeing fine details, recognizing colors, and reading. When macular degeneration occurs, common symptoms include blurred central vision, distorted vision (objects appearing wavy or bent), and even difficulty seeing facial expressions or text. The most common form is "dry AMD," which progresses slowly but continuously worsens, making it a leading cause of blindness in the elderly.

Genetic Analysis of 500,000 People: Instant Coffee Significantly Increases Risk

Lau cited a 2025 study published in Food Science & Nutrition that analyzed genetic data from over 500,000 people in the UK and Finland. The study found a significant genetic correlation between instant coffee and dry AMD. After statistical adjustment for genetic factors, people who habitually drank instant coffee had a nearly 7 times higher risk of developing dry AMD compared to non-drinkers.

Lau emphasized that this study found an increased risk only for "instant coffee." No such phenomenon was observed for freshly ground coffee brewed by methods such as pour-over, siphon, or espresso.

Why is Instant Coffee More Risky?

Researchers speculate that the increased risk may be related to the manufacturing process of instant coffee, which involves high-temperature extraction, spray drying, or freeze drying. These processes can easily generate two types of harmful substances:

1. Acrylamide: Classified as a Group 2A probable human carcinogen by the International Agency for Research on Cancer (IARC). It is also neurotoxic and can promote oxidative stress.
2. Advanced Glycation End-products (AGEs): These induce chronic inflammation and accelerate cellular aging.

When these substances enter the body, they may exacerbate oxidative damage and chronic inflammation in the retina, leading to the degeneration of macular cells, especially in individuals with genetic susceptibility. Freshly brewed coffee is manually prepared from freshly ground coffee beans without undergoing excessive processing. Therefore, it better retains natural antioxidants like chlorogenic acid and produces fewer harmful byproducts.

5 Health Benefits of Freshly Brewed Coffee

From a health perspective, pour-over coffee is undoubtedly a better choice. Dr. Liu notes that moderate consumption of high-quality freshly brewed coffee (not instant) offers several health benefits:

• Rich in antioxidants, combating free radicals and chronic inflammation
• Reduces the risk of type 2 diabetes and fatty liver disease
• Lowers the risk of Parkinson's disease and Alzheimer's disease
• Improves alertness, concentration, and work efficiency
• Promotes intestinal motility, helping to relieve constipation

Risk Factors for Macular Degeneration and Eye Protection Tips

Lau also listed the following common risk factors for AMD:

• Age: Risk increases significantly after age 50
• Smoking: Smokers have a 2-3 times higher prevalence
• Family history: Higher risk if a direct relative has the disease
• Obesity and hypertension: Affect blood circulation in the retina
• Long-term intense light exposure: UV and blue light damage the retina
• Diet low in lutein and zeaxanthin: e.g., eating few dark green vegetables

Lau advises that if you already have AMD, pay extra attention to eye care:

• Eat dark green vegetables (spinach, kale) and orange-yellow fruits (papaya, pumpkin) weekly
• Wear UV-protective sunglasses during outdoor activities
• Control high blood pressure, high cholesterol, and high blood sugar, as well as body weight
• Quit smoking
• Choose freshly brewed coffee and reduce instant coffee intake

Finally, Lau added that if you are accustomed to drinking instant coffee, consider gradually switching to freshly ground, freshly brewed coffee. This way, you can retain the benefits of coffee while reducing the burden on your eyes. If you have a family history of macular degeneration or have already noticed changes in your vision, consider adjusting your diet and habits starting today.