Algae, particularly certain species like Chlorella and Spirulina, are used to support eye health due to their rich content of bioactive compounds, notably carotenoids such as lutein and zeaxanthin. These carotenoids are well-studied for their roles in maintaining retinal health and protecting the eyes from oxidative damage induced by blue light and aging processes. A number of peer-reviewed studies have demonstrated that dietary intake of lutein and zeaxanthin can increase macular pigment density and may lower the risk of age-related macular degeneration (AMD), a leading cause of vision loss in older adults.

Algae are among the richest natural sources of these carotenoids. For example, Chlorella and Spirulina supplements can provide significant amounts of both lutein and zeaxanthin, making them a practical and vegetarian-friendly option for supporting eye health. Additionally, algae contain other nutrients like vitamin A (in the form of beta-carotene), which is essential for normal vision.

While most evidence is based on the effects of the individual nutrients rather than whole algae supplements, the justification for using algae to support eye health is grounded in scientific findings related to their nutrient content. However, direct clinical trials examining algae supplements specifically for eye health are limited, so the evidence is rated as moderate (3/5).