Amino Acids and Eye Health: What’s the Link?

Amino acids are not something you probably think about when you eat protein-rich foods like eggs, dairy, soy, or meat. But they play an essential role in the body and can impact eye health.

In this post, we explain the link between amino acids and proteins and eye diseases, including chronic dry eye disease, cataracts, and glaucoma.

But first, let’s understand what amino acids do.

What Are Amino Acids?

Amino acids are the building blocks of proteins. Proteins are complex molecules that provide the structure of the human body and enable its function and regulation.

Amino acids are also essential to the functioning of hormones and neurotransmitters. 

Your body needs 21 amino acids to stay healthy:

• Alanine
• Arginine
• Asparagine
• Aspartic Acid
• Cysteine
• Glutamic acid
• Glutamine
• Glycine
• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Proline
• Serine
• Threonine
• Tryptophan
• Tyrosine
• Valine
• Selenocysteine

There are 9 essential amino acids (bold) that the body can’t make on its own. These amino acids have to be consumed through food.

Amino acids can be combined in many different ways, which enables the body to make all the many different types of proteins that it needs to function well.

Apart from meat, fish, eggs, and dairy products, few foods provide all the essential amino acids.

Because of this, vegetarians and vegans need to consume complete protein sources like quinoa, soy, and buckwheat. It’s also possible to get the essential amino acids by combining foods that provide different amino acids, like rice and lentils.

The Link Between Amino Acids and Eye Health

Amino acids are necessary for the healthy functioning of the eyes. Science shows that some amino acids play an especially important role in eye health and may be involved in several eye diseases.

Amino Acids and Dry Eye Disease

Arginine deficiency has been noted in psoriasis, diabetes, and other conditions that may trigger dry eye syndrome. L-arginine is a precursor of urea, a moisturizer that is part of the tear film.

Some studies showcase the importance of amino acids in the homeostasis of the eye surface. Tears contain amino acids, whose proportion may change depending on the condition of the surface of the eye. This suggests that food supplements or eye drops containing specific amino acids may help heal the surface of the eye.

More research is needed to better understand what amino acids are most effective at protecting the surface of the eye from the effects of dry eye disease.

Amino Acids and Glaucoma

Older studies have linked an excess of the amino acid glutamate to the occurrence of glaucoma. However, a 2003 comparative study that measured glutamate and 15 other amino acids in people with glaucoma found no such association.

A 2022 study found that the dietary intake of branched-chain amino acids leucine, isoleucine, and valine reduced the risk of open-angle glaucoma in people over the age of 40.

So named because of their chemical structure, BCAAs play a key role in muscle maintenance and liver health. You can find them in eggs and dairy products. BCAAs are commonly added to muscle growth supplements.

Amino Acids and Cataracts

Cataracts occur when the lens of the eye loses its transparency. This happens when proteins in the eye start to break down and clump together.

Cataracts are a leading cause of blindness worldwide though it can often be corrected through surgery. Some research on animals shows that the depletion of the amino acid tryptophan may play a role in the formation of cataracts.

Older research found that the administration of lysine and amino acids in diabetic mice reduced the development of cataracts.

Amino Acids and Retinopathy

Retinopathy is caused by damage to the blood vessels in the retina at the back of the eye. It occurs in different forms in age-related macular degeneration (AMD) and diabetic retinopathy (DR), both leading causes of blindness worldwide.

Studies have associated retinopathy with specific amino acids. Notably, glutamine and arginine were higher in peripheral blood samples taken from patients with diabetic retinopathy and AMD. Meanwhile, histidine decreased in samples of AMD patients.

What’s more, abnormalities in the metabolism of glutamate have been linked to neuronal degeneration in the retina.

Meanwhile, supplementation with the amino acid proline may have a protective effect against oxidative stress on the retina. More research is needed to understand how specific amino acids may aid in the early diagnosis and treatment of different forms of retinopathy.

Glutathione and Eye Health

Glutathione is an antioxidant made from the amino acids glycine, cysteine, and glutamic acid. It occurs predominantly in the lens and the retina of the eye. Glutathione deficiency has been linked to glaucoma, diabetic retinopathy, and age-related macular degeneration.

Glutathione levels in the eye decline with age, leading to elevated oxidative stress that may affect the eye. Ensuring that your body takes in enough glutamate, cysteine, and glycine is one way to help your body maintain healthy levels of glutathione.

The same study cited above found that supplementing the diets of elderly people with cysteine and glycine, precursors of glutathione, stimulated glutathione synthesis and significantly reduced oxidative damage.

The Bottom Line

Amino acids play a key role in eye health, even though this role may not always be obvious.

Eating a healthy and varied diet that has all the essential amino acids is one way to support eye health. Consuming different protein sources is especially important if you are a vegetarian. Few plant-based foods have all the essential amino acids.

In addition to soy, quinoa, and buckwheat, make sure to combine foods to create meals that have all the amino acids. Peanut butter with wholegrain bread, hummus and pita bread, beans or lentils and brown rice are just some examples of delicious complete protein meals.

If you are suffering from an eye disease or are simply concerned about preserving your vision, you may want to discuss any potential amino acid supplements with your eye doctor.

Amino acid supplementation for eye health is still a new field and more research is necessary before such products become mainstream. That said, your doctor may be aware of specific treatments that could benefit you.

Meanwhile, a natural superfood blend can support eye health in the digital age.

SightC is a dry eye supplement that provides antioxidants like lutein and zeaxanthin and other nutrients that protect your eyes from environmental damage and support the healthy functioning of your tear glands. It’s easy to take and gluten-free.