A review of human studies found that blueberry consumption was associated with a lower risk of age-related macular degeneration, while smaller trials involving goji berries reported improvements in retinal pigment measures linked to eye health.
By yourNEWS Media Newsroom
Blueberries and goji berries may have a role in supporting long-term eye health, according to a review by researchers at Queen’s University and the University of Toronto examining human studies on berry consumption and age-related macular degeneration.
The review, discussed in a report from NaturalHealth365, found that the available studies consistently pointed toward potential benefit rather than harm, although researchers cautioned that the evidence remains insufficient to establish that either berry can prevent or treat the disease.
Age-related macular degeneration, or AMD, affects the macula, the portion of the retina responsible for sharp central vision, and is a major cause of vision loss among older adults worldwide.
Because the condition often progresses gradually, researchers have increasingly examined whether nutrition and other modifiable lifestyle factors could influence its development or progression.
Large Study Finds Association With Blueberry Intake
The largest body of evidence reviewed came from the Women’s Health Study, which followed 37,653 women ages 45 and older for an average of 11 years.
Women who consumed at least one serving of blueberries per week had a 28% lower risk of developing total macular degeneration compared with women who ate them less frequently, according to the report.
The association remained after researchers adjusted for factors including smoking and physical activity.
The finding does not prove that blueberries themselves caused the lower risk. Observational studies can identify associations but cannot eliminate every difference between people who regularly eat particular foods and those who do not.
One unexpected result was that total anthocyanin intake alone was not associated with the same reduction in AMD risk.
Anthocyanins are the pigments responsible for the blue, purple and red colors of many fruits and have been studied for antioxidant and anti-inflammatory activity.
Researchers said the discrepancy may suggest that any benefit from blueberries comes from the food’s overall nutrient composition rather than a single isolated compound.
Blueberries also provide vitamin C, fiber and a variety of polyphenols that can interact in ways that may influence oxidative stress and inflammation.
Both processes have been studied in connection with retinal aging and macular degeneration.
Goji Berry Trials Examine Protective Macular Pigment
Four smaller human studies in the review investigated goji berries.
The orange-red fruit contains particularly high concentrations of zeaxanthin, a carotenoid pigment naturally present in the retina.
Three of the studies reported increases in macular pigment density after participants consumed goji berries.
Macular pigment, composed largely of the carotenoids lutein and zeaxanthin, filters portions of high-energy visible light and has antioxidant properties within the retina.
One trial also found that goji berry consumption was associated with reduced accumulation of drusen, fatty deposits that can develop beneath the retina and are a characteristic feature of early age-related macular degeneration.
The goji studies were considerably smaller than the Women’s Health Study, with sample sizes ranging from 56 to 133 participants.
That limits how broadly their findings can be applied.
Researchers therefore characterized the results as encouraging rather than conclusive.
Goji berries’ unusually high zeaxanthin content provides a plausible nutritional reason for continued study, but the existing trials do not establish that eating the fruit will prevent AMD in an individual person.
Whole Foods May Matter More Than Individual Nutrients
The difference between the blueberry findings and measurements of individual anthocyanins highlights a recurring issue in nutrition research.
Foods contain complex mixtures of nutrients and biologically active compounds that may work together differently than isolated vitamins, antioxidants or supplements.
Blueberries combine anthocyanins with fiber, vitamin C and numerous other polyphenols. Goji berries similarly contain zeaxanthin alongside other carotenoids, vitamins and plant compounds.
Researchers are therefore examining dietary patterns as well as individual nutrients when studying eye health.
The National Eye Institute’s AREDS and AREDS2 trials have separately demonstrated that specific combinations of antioxidant vitamins, zinc, copper, lutein and zeaxanthin can reduce the risk of progression to advanced AMD in certain people who already have the condition.
Those findings do not mean berry consumption produces the same effect as an AREDS2 formulation, nor should berries replace eye examinations or treatment recommended by an ophthalmologist.
Outdoor Time and Screen Habits Affect Different Aspects of Eye Health
The report also examined behaviors beyond diet that can influence vision and eye comfort.
Spending time outdoors during daylight has been associated with a lower risk of developing myopia, particularly in children and younger people.
Natural light is believed to influence retinal dopamine signaling involved in regulating eye growth. Some research suggests that even approximately 20 minutes of outdoor exposure can be beneficial, though recommendations vary and outdoor time is primarily studied in relation to nearsightedness rather than macular degeneration.
Screen use presents a different issue.
Extended periods of focusing on digital devices can contribute to eyestrain and dry-eye symptoms, in part because people tend to blink less frequently while looking at screens.
The commonly recommended 20-20-20 approach calls for looking at something approximately 20 feet away for 20 seconds after every 20 minutes of near-screen work.
Consciously blinking fully and regularly may also help maintain the tear film.
These practices can reduce digital eyestrain but should not be interpreted as methods for preventing macular degeneration.
Adding Berries to a Balanced Diet
For people who already enjoy berries, incorporating them into meals can provide nutrients without requiring major dietary changes.
Fresh or frozen blueberries can be added to oatmeal, yogurt, smoothies or other foods.
Frozen blueberries retain much of the nutritional value of fresh fruit and can make regular consumption more practical throughout the year.
Dried goji berries can be eaten on their own or softened in warm water before being added to salads, oatmeal or trail mixes.
As with other dried fruits, portion size and added sugar should be considered when selecting packaged products.
The strongest evidence currently supports viewing blueberries and goji berries as components of an overall nutrient-dense eating pattern rather than as treatments for eye disease.
The large observational study involving blueberries found a notable association with lower AMD risk, while the smaller goji trials reported changes in biological markers connected with retinal protection.
Researchers emphasized, however, that additional randomized and long-term human studies are needed before either food can be said to prevent macular degeneration.
For now, the findings add blueberries and goji berries to a broader body of research examining how diets rich in colorful fruits, vegetables, carotenoids and polyphenols may contribute to maintaining eye health as people age.
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