B vitamins are crucial for eye health and vision

Healthy eyes and good vision are essential throughout life. It is widely known that we need vitamin A and other antioxidants. In addition, several B vitamins (B1, B2, B3, B5, B6, B9, and B12) play different biological roles in maintaining eye health and protecting against damage caused by free radicals and oxidative stress. This is highlighted in a review article published in Clinical Ophthalmology, in which the authors also discuss eye diseases such as AMD, cataracts, glaucoma, diabetic retinopathy, and dry eyes.

Our eyes - especially the retina and optic nerve - have a very high metabolic rate. This places considerable demands on the cells’ mitochondria, which are responsible for energy production. At the same time, the cells of the eye are particularly vulnerable to damage caused by oxidative stress, a condition in which exposure to free radicals exceeds the body’s antioxidant defenses. Major causes of oxidative stress include aging, smoking, poisoning, several types of medication, and chronic inflammation, which characterizes most chronic diseases.
For many years, it has been known that antioxidants such as vitamins A, C, and E, as well as carotenoids like lutein and zeaxanthin, play a protective role, and higher intakes are recommended for the prevention of advanced AMD (age-related macular degeneration). There is also growing evidence that various B vitamins play key roles in eye function and health, including reducing the risk of developing several different eye diseases. The purpose of the new review article was therefore to investigate the importance of the different B vitamins for vision and eye health.
Because B vitamins are water-soluble and cannot be stored in the body (except for vitamin B12), we need a daily supply. Overall, B vitamins are involved in a wide range of enzymatic processes related to cellular energy production, red blood cells, the breakdown of homocysteine, as well as the nervous system and the synthesis of myelin, which protects nerve cells. Although these functions are important throughout the body, several processes are particularly important for eye health, which according to the new review article can be summarized as follows:

Mitochondria and energy production

Vitamin B1 (thiamine) is involved in mitochondrial energy metabolism. The same applies to vitamin B3 (niacin), a crucial precursor of the coenzyme NAD+, which supports mitochondrial function. In addition, vitamin B2 (riboflavin) serves as a precursor for two enzymes that are also integrated into mitochondrial energy metabolism.
Mitochondrial dysfunction, including damage caused by chronic inflammation and oxidative stress, is a key factor in the development of many eye diseases. This includes AMD and glaucoma.

Oxidative stress

Vitamin B1 and vitamin B2 can reduce oxidative stress through different antioxidant functions. Vitamin B3 also counteracts oxidative stress by increasing NAD+ levels, thereby strengthening mitochondrial function and combating free radicals. The body’s NAD levels decline with age.

Homocysteine homeostasis

Homocysteine is an amino acid formed during the breakdown of the amino acid methionine. However, homocysteine levels must not become too high, as it can then act as a toxin that causes chronic inflammation and oxidative stress. Elevated levels of homocysteine in the eye are associated with dysfunction of the blood vessels’ endothelial cells, damage to the optic nerves, apoptosis (programmed cell death), and various vision-related dysfunctions.
In this context, vitamins B6, B9 (folate/folic acid), and B12 (cobalamin) are essential for breaking down and converting homocysteine into another amino acid (cysteine), which has several vital functions.
This means that deficiencies in vitamin B6, vitamin B9, and/or vitamin B12 may result in elevated homocysteine levels and an increased risk of AMD, diabetic retinopathy, glaucoma, cataracts, retinal vascular occlusion, and worsening diabetic retinopathy. On the other hand, an adequate intake of these B vitamins may lower homocysteine levels and thereby reduce the risk of several eye diseases.
It should also be noted that diabetes patients treated with metformin have impaired absorption of vitamin B12 and tend to have elevated homocysteine levels.

Protection of the retina and diabetic retinopathy

Studies reveal that patients with AMD generally consume fewer B vitamins than healthy control groups. Several studies have also shown that higher intakes of vitamins B1, B5, B6, B9, and B12 are inversely associated with the risk of developing AMD and with disease progression.
It should also be added that existing AMD treatments involving high-potency antioxidants (based on the AREDS and AREDS2 studies) do not include B vitamins.

AMD (age-related macular degeneration)

Studies reveal that patients with AMD generally consume fewer B vitamins than healthy control groups. Several studies have also shown that higher intakes of vitamins B1, B5, B6, B9, and B12 are inversely associated with the risk of developing AMD and with disease progression.
Moreover, existing AMD treatments involving high-potency antioxidants (based on the AREDS and AREDS2 studies) do not include B vitamins.

Glaucoma

A 2024 meta-analysis (Nicola et al.) reported that glaucoma patients consume less vitamin B3 compared to healthy control groups.
Studies have also shown that sex, age, and BMI may be decisive factors in the relationship between deficiencies of various B vitamins and the risk of developing glaucoma. Women deficient in vitamins B1, B2, and B3 who also have a high BMI are at greater risk than men. In addition, women with higher intakes of vitamins B2, B3, and B6 appear to gain greater protection against glaucoma than men. Men who consume higher amounts of vitamin B6 also have a significantly reduced risk of developing glaucoma.
According to several studies, higher supplementation with vitamin B3 in particular appears to have several beneficial effects in the prevention of glaucoma.

Cataracts

The relationship between B vitamin intake, blood concentrations, and cataracts has not been studied as extensively as AMD and glaucoma. However, data from the AREDS study demonstrated an inverse association between the intake of vitamins B2, B3, B6, and B12 and the risk of developing the disease. Data from the Korean KNHANES population study showed that higher vitamin B1 intake reduces men’s risk of developing cataracts. In women, higher intake of vitamin B2 may reduce the risk of developing the eye disease.
Preclinical studies indicate that B vitamin supplementation may have potential benefits for cataract patients, particularly vitamins B2 and B3, which may improve lens function. In addition, vitamin B3 acts as a powerful antioxidant that protects the lens against oxidative damage. However, more studies are needed to better understand the role of B vitamins in the development and treatment of cataracts.

Dry eyes (sicca syndrome/DED) and diseases of the eye surface

The surface of the eye consists of the curved cornea, the white sclera, and the mucous membrane. The tear film protects the surface of the eye by cleansing it and keeping it moist.
Deficiencies in vitamins B1, B2, B3, B9, and B12 may be associated with dry eyes.
In patients with keratoconus (a progressive eye disease in which the cornea becomes thinner and bulges outward), a small study reported significantly lower levels of vitamin B2 compared to healthy controls.
Supplementation with B vitamins — especially vitamins B1, B3, and B12 - has shown beneficial effects in dry eye disease through different mechanisms

Sources of B vitamins and causes of widespread deficiencies

Good sources of B vitamins include whole grains, nuts, legumes, vegetables, fruits, herbs, as well as liver, meat, fish, eggs, and dairy products.
Since vitamin B12 is found only in animal foods, vegetarians and vegans are at risk of deficiency. A lack of the carrier protein intrinsic factor also impairs vitamin B12 absorption.
A highly refined diet and stress may also lead to deficiencies in various B vitamins. In addition, aging, alcohol abuse, low stomach acid, and several types of medication (metformin, diuretics, acid-reducing drugs/PPIs, methotrexate, corticosteroids, and antibiotics) may impair the absorption or utilization of several B vitamins.

Conclusion

B vitamins play an important role in several physiological processes that are essential for eye health. They are important for the structure and function of the eyes, help regulate blood homocysteine levels, and reduce damage caused by free radicals and oxidative stress.
Low intake of various B vitamins increases the risk of several eye diseases, including AMD, diabetic neuropathy, glaucoma, cataracts, and dry eyes. Preclinical data and studies suggest that B vitamin supplementation may be relevant in the prevention of eye diseases or in slowing their pathological progression.

Reference:

Elisabeth J Johnson et al. B Vitamins and Ocular Health. Clinical of Ophthalmology Journal. 2026