Can Supplements Slow Myopia? What the RCT Evidence Says

Nutrition has a biologically plausible role in eye health. It does not yet have a clinically proven role in myopia control. The best available systematic review of randomized trials found only nine studies of supplements for myopia, with different compounds, designs, doses, durations, and outcome measures. That is enough research to justify curiosity, but nowhere near enough to prescribe a supplement stack for a child whose eyeball is elongating.

Myopia progresses when the eye grows too long relative to its optical power. That makes axial length—the front-to-back length of the eye—a more useful endpoint than a vague claim about "vision support." A 2026 systematic review by Martinez-Perez and colleagues examined randomized trials of carotenoids, anthocyanin-rich extracts, polyunsaturated fatty acids (PUFAs), and combined nutraceutical formulas. Its conclusion was restrained: the trials were limited, heterogeneous, generally underpowered, and inconsistent across populations and regions. Read the Martinez-Perez et al. review.

Why the idea is plausible

Several nutrients could, in theory, affect processes involved in myopia. Carotenoids such as lutein and zeaxanthin accumulate in the retina and have antioxidant activity. The review also discusses oxidative stress, inflammation, scleral remodeling, and retinal or choroidal homeostasis as possible pathways through which carotenoids, vitamins, or PUFAs might influence ocular growth.

Those mechanisms make a hypothesis worth testing. They do not prove that taking a capsule slows axial elongation in humans. Biology contains many plausible stories that fail at the randomized-trial stage; the eye is not obligated to honor a supplement label.

The same distinction applies to anthocyanins. A meta-analysis of 18 randomized trials found that delphinidin-based anthocyanins improved some blood lipid measures, including triglycerides and LDL cholesterol, while cyanidin- and malvidin-based preparations did not show the same significant effects. Araki et al.'s anthocyanin meta-analysis supports the point that anthocyanins can have measurable biological effects in some settings. It does not show that they control myopia.

Likewise, a 24-week double-blind, placebo-controlled trial in 181 older adults at risk for dementia reported effects of oral anthocyanin supplementation on cognition-related and blood-based measures. The de Lucia et al. trial studied neurogenesis-related outcomes and dementia biomarkers, not axial length or refractive progression in children. A biomarker result in older adults cannot establish a mechanism for pediatric myopia.

What randomized myopia trials have actually tested

The Martinez-Perez review identifies four categories that have reached randomized-trial testing: carotenoids, including saffron-derived crocetin; anthocyanin-rich extracts; PUFAs; and multi-ingredient nutraceuticals. Researchers measured refractive error, axial-length progression, and macular pigment optical density (MPOD).

MPOD can be useful for studying retinal carotenoid status, but it is not the same as slowing eye growth. A supplement could change a retinal pigment measure without producing a clinically meaningful change in axial length or prescription. For myopia management, the question is simple: did the intervention slow refractive progression or axial elongation compared with its control group?

The review describes inconsistent findings for the overall nine-trial corpus. It also identifies crocetin as the compound with the most active recent trial interest. That makes crocetin worth watching, not worth declaring effective. The available published account does not provide the individual crocetin trial's effect estimate, confidence interval, dose, duration, and risk-of-bias rating in sufficient detail to judge the size or reliability of any apparent benefit.

The same caution applies to reports of null or inconsistent findings for bilberry, anthocyanin extracts, omega-3 fatty acids, and vitamin D. Without each trial's dosage, follow-up, endpoint-specific result, and precision estimate, readers should not infer that every preparation has been definitively ruled out. The defensible conclusion is narrower: current randomized evidence does not support a supplement protocol for myopia control.

Why the evidence cannot be pooled into a neat answer

Pooling studies only helps when they ask roughly the same question. Here, trials differed in the supplement used, participant populations, study design, treatment duration, and outcomes. A change in MPOD cannot be treated as interchangeable with a change in axial length, and a trial in one dietary and geographic setting may not generalize cleanly to another. The review therefore maps an early research field rather than delivering a single trustworthy effect size.

• Small trials can miss real effects and can also overstate early positive signals.
• Different doses and formulations make "carotenoids" or "anthocyanins" overly broad labels.
• Short follow-up may miss the outcome that matters most: sustained slowing of axial elongation.
• Inconsistent measurement and reporting prevent reliable comparisons across studies.

A useful next study would be double-blind, placebo-controlled, preregistered, and large enough to estimate an effect with reasonable precision—ideally more than 300 participants, with axial length as the primary endpoint and at least two years of follow-up. It should also report funding, adherence, adverse events, refractive outcomes, axial-length outcomes, and confidence intervals. A small shift in a surrogate marker cannot carry that burden alone.

How supplements compare with better-studied options

The contrast with established myopia research is stark. A 2025 network meta-analysis of prevention strategies in at-risk, pre-myopic children evaluated pharmacologic and behavioral approaches, including low-concentration atropine, orthokeratology, and outdoor-light exposure. Nutritional supplements did not appear as an active intervention category in the accessible comparison. See Lee et al.'s network meta-analysis.

Repeated low-level red-light therapy also has a larger trial literature, although its place in care requires its own safety and implementation scrutiny. A 2025 meta-analysis of eight randomized controlled trials in people younger than 18 reported less axial-length change with treatment than with control: mean difference −0.24 mm, 95% confidence interval −0.32 to −0.17, with p<0.00001. It also reported a spherical-equivalent refractive difference of 0.49, 95% confidence interval 0.27 to 0.71. Read Yang et al.'s meta-analysis.

Those numbers are not a direct comparison with crocetin or any other supplement because the nutritional review does not provide comparable extractable axial-length estimates. They do show the standard that a nutritional intervention must meet: a reproducible, precisely reported effect on an outcome that matters. A separate 2025 systematic review included 20 red-light studies involving 2,638 Chinese children ages 3 to 16, further illustrating how much more developed that literature is than the supplement literature. Read Fan et al.'s review.

What to do with this information

Do not use lutein, zeaxanthin, omega-3s, anthocyanins, or crocetin as substitutes for evidence-based myopia assessment and management. This matters most for children, whose progression can continue during years of rapid eye growth. Discuss proven options with an eye-care professional, including outdoor-time strategies, low-concentration atropine, and orthokeratology when appropriate.

A diet that includes carotenoid-rich plants and omega-3-containing foods can fit ordinary nutritional goals, but it should not be sold as a way to reverse myopia or reliably halt progression. Crocetin is the supplement candidate most worth monitoring because it has drawn recent trial interest. Until a well-powered study reports a clinically meaningful, reproducible reduction in axial elongation, the honest answer remains: you cannot meaningfully eat your way out of myopia.