Part 4 of The Studies Behind Goji
In 2018, researchers published a human trial that examined goji berries, serum zeaxanthin, macular pigment, and visual acuity in adults with early age-related macular degeneration. It is one of the most frequently cited goji berry macular pigment studies.
The paper reported several changes after 90 days. Reading it carefully means looking at the design and limits alongside those results.
How the goji berry macular pigment study worked
The study enrolled 114 adults between 51 and 92 years old. All participants had early age-related macular degeneration.
Researchers randomly assigned 57 people to eat 25 grams of goji berries each day for 90 days. The other 57 continued their usual diets.
Measurements were taken at the beginning and after 90 days. The researchers tested serum lutein and zeaxanthin, macular pigment optical density, and best corrected visual acuity.
That design gives us a defined population, serving, time period, and set of outcomes. It does not test every adult or every kind of goji product.
What changed after 90 days
Serum zeaxanthin increased in the goji group, while serum lutein did not show a statistically significant change. Macular pigment optical density also increased from baseline and was higher than the control group's measurement at 90 days.
The researchers reported a change in best corrected visual acuity within the goji group as well. These results are why the paper remains relevant to conversations about goji and eye health.
The wording still matters. The study found changes in specified measurements over three months. It did not establish that goji prevents age-related macular degeneration, and its results should not be turned into that promise.
What the study tells us about zeaxanthin
The different results for lutein and zeaxanthin fit the reason researchers focus on zeaxanthin in goji. As explained in Part 2, goji is a dietary source of this carotenoid.
The trial links three steps within one study: participants ate whole goji berries, serum zeaxanthin rose, and the researchers measured a change in macular pigment optical density.
That sequence is more informative than a general claim. It is also specific to the conditions of the trial.
Where the limits sit
The control group continued its normal diet rather than eating a matched placebo food. Participants would have known whether they were eating goji berries. That makes full blinding difficult.
The trial lasted 90 days. It does not tell us whether the measured changes continued after the study or what would happen over years.
All participants already had early age-related macular degeneration. The findings cannot automatically be applied to younger adults, people with healthy eyes, or those with later-stage disease.
The study also tested whole berries at 25 grams per day. It did not test fresh goji purée, and it does not provide product-specific evidence for The Goji Reserve.
How this fits with eye care
The National Eye Institute's guidance on AREDS and AREDS2 concerns specific supplement formulas studied in defined groups of people with age-related macular degeneration. A goji food is not an AREDS2 formula.
Anyone with changes in vision or a diagnosed eye condition should speak with a qualified eye care professional. Food can be part of a diet, but it does not replace an examination, diagnosis, or treatment.
Our Research page follows the same line: describe the evidence, keep the study conditions attached, and avoid turning a finding into a guarantee.
What comes next
This trial adds a useful piece of human evidence. It also leaves questions about replication, longer follow-up, other populations, and different goji formats.
Part 5 compares this study with two other human trials and asks how strong the overall goji eye-health evidence is today.
References
- Li S, Liu N, Lin L, Sun ED, Li JD, Li PK. Macular pigment and serum zeaxanthin levels with Goji berry supplement in early age-related macular degeneration. International Journal of Ophthalmology. 2018;11(6):970-975. PMID: 29977809.
- National Eye Institute. AREDS/AREDS2 Frequently Asked Questions. Updated November 19, 2020.
This article is for general educational purposes and is not medical advice. A food product should not be used in place of diagnosis or treatment from a qualified eye care professional.