4 Science-Backed Ways Cod Liver Oil Can Strengthen Eyesight

4 Science-Backed Ways Cod Liver Oil Can Strengthen Eyesight

A New Frontier for a Time-Tested Supplement


In 2023, 74% of Americans said that they take dietary supplements - chances are, you’re part of the club.

Whether you take your supplements religiously or just on occasion, you’ve likely heard of this famous supplement: cod liver oil.


Cod liver oil is a fish oil supplement, which has been used to promote strength and good health for hundreds of years.


It earned its fame as a powerful source of vitality, long before we were able to understand exactly why - even the Vikings used it to thrive in harsh Scandinavian winters.


Green Pasture began making their own cod liver oil back in 2007, after discovering that commercially available cod liver oil couldn’t match the standards that historical cod liver oil had set. The founder decided to recreate historical cod liver oil’s ancient formula, renowned by many ancient cultures as a powerful source of vitality.


Cod liver oil has long been recognised as one of nature’s richest sources of vitamin A, which is essential for healthy eyes and good eyesight. While its benefits for the bones, teeth, joints, heart, and skin are making headlines, the importance cod liver oil has for the eyes is often overlooked.


Modern day scientists have discovered that it’s not just vitamin A in cod liver oil that benefits our eyes, but many other nutrients working in tandem – provided they are preserved.


To preserve its natural nutrients, cod liver oil must be extracted and bottled using natural methods. This is what Green Pasture has achieved with its fermented cod liver oil.


Fermented cod liver oil is naturally rich in vitamin A, vitamin D, antioxidants, and omega-3 fatty acids, as well as many other naturally occurring nutrients.


These four essential nutrients are major players in protecting and promoting eye health.


To understand how cod liver oil works its magic, we’ll briefly break down the structure and function of the human eye.

The Inner Workings of the Eye

The light that you see passes through a few stages on its way from your eye to your brain.

  1. The first part of your eye that light hits is your cornea.

The cornea is like a clear film over the eye, which protects the eye from infection and dryness and helps to focus light as it passes through.

      2 . Light then enters your pupil. This is the hole in the middle of your eye, which looks like a black circle.

The coloured ring around your pupil is called the iris. This controls the size of the pupil, adjusting the amount of light allowed in so that you can see better in the dark, or in particularly bright conditions.

      3 . Next, light passes through the eye’s lens. The lens is like a clear disc, which changes shape to allow you to clearly see objects both up close and far away.

      4 . Finally, the light reaches the back of the eye. This area is called the retina.
The retina is lined with cone cells, which are activated by the light. They use this light to create electrical signals.

      5 . The electrical signals sent from the cone cells travel to the brain via the optic nerve.
There, they give your brain information from your eye.

      6 . Your brain then interprets this information to show you an image - this is what you see in front of you

Every stage of this process has to work well to enable you to see with clarity.

The eye is like a busy machine; we need to keep it well-oiled and maintained to ensure it runs smoothly.

The “oils” it needs can be found in abundance in cod liver oil: vitamin D, vitamin A, omega-3, and antioxidants all contribute to healthy eyes and clear vision.

Maintaining Nature’s Design

Some manufacturers of cod liver oil supplements use extraction methods which remove these essential natural nutrients. They are then re-added in their synthetic forms later in the process.


The fermentation process used by Green Pasture retains cod liver oil’s rich nutritional value, without the need to add any synthetic ingredients.


Using this method, Green Pasture cod liver oil can protect and improve your eye health exactly as nature intended.

Discovering Vitamin D

Vitamin D is known to support the role of calcium in the body and regulate several bodily functions, including the immune system, cell growth, and glucose metabolism.

While one type of vitamin D is mainly synthesised in the skin when exposed to sunlight, it’s possible to obtain another type - vitamin D2 - from your diet.

Green Pasture’s fermented cod liver oil is particularly rich in vitamin D2. This makes it an excellent source of dietary vitamin D, and a potential gamechanger for those who aren’t getting enough daily sunlight exposure.

Surprising Findings: Vitamin D and the Eye

Scientists first began to suspect a close connection between vitamin D and the eye in 1986.

They had discovered that the eye contains an abundance of cells which help to synthesise vitamin D. They even found cells on the cornea which made vitamin D when exposed to sunlight, just like the skin.

The scientists suggested that if the eye is able to synthesise so much of its own vitamin D, then it must put it to good use - implying vitamin D is particularly important to eye health and function.

Decades of further research went on to prove these scientists right.

In a research review published in 2022, scientists demonstrated evidence that vitamin D could help with a number of eye problems, from myopia - commonly known as near-sightedness - to macular degeneration, which occurs due to damage to the retina.

Additionally, Vitamin D’s role in protecting against dry eye syndrome is receiving particular attention in the research community.

Studies strongly support the use of vitamin D to improve dry eyes, as it may strengthen the cornea through its immunoprotective qualities.

The Central Role of Vitamin A

Vitamin A, also known as retinol, plays a crucial role in the eye’s visual processes. In fact, the name “retinol” comes from where it does its most essential work: in the retina.

The light-detecting cone cells in the retina use vitamin A to turn light into electrical signals. This means that without vitamin A, the eye is unable to send its visual information to the brain.

Vitamin A also helps to keep the cornea moist, preventing your eyes from becoming dry and irritated. Dry corneas can become a serious problem, resulting in opacity and impaired vision if left untreated.

This is why problems with vision and the eyes are often the first sign of an imbalance of vitamin A.

Green Pasture’s fermented cod liver oil contains a naturally high concentration of vitamin A, making it an excellent supplement for protecting and strengthening the eye.

Omega-3: Preserving and Protecting

Fermented cod liver oil also contains high amounts of an important fatty acid: omega-3.


Omega-3 is widely known for its positive effects on heart health, thanks to its ability to support the immune and cardiovascular systems.


When it comes to the eye, research has shown overwhelming support for the impact of omega-3 as a protective factor.


In the retina, omega-3 appears to support the membrane, the cone cells, and their signalling mechanisms by supporting immune function in the eye.


The immune-boosting action of omega-3 also protects the nerve cells that supply the cornea. This can help to protect the cornea from dryness and degeneration.


Omega-3 has been found to improve dry eye symptoms in only 30 days of daily supplement consumption. Scientists discovered that omega-3 supplementation quickly supports glands in the eyelid to produce moisture, and helps to reduce moisture evaporation.


Even more impressively, animal studies have suggested a potential regeneration effect of omega-3. This could explain why some research finds that omega-3 doesn’t just slow down the degeneration of the eye, but may actively improve it.


3 Ways Antioxidants Protect the Eye

Although vitamins D and A and omega-3 all have powerful antioxidant properties, they aren’t the only antioxidants present in cod liver oil.


Green Pasture’s fermented cod liver oil is also high in natural antioxidants, such as tocopherols - a common form of vitamin E.


Other cod liver oils lose these natural antioxidants during the manufacturing process. Because Green Pasture cod livers are fermented before extracting the oils, there is no need for harsh treatments necessitating the synthetic re-addition of its nutrients.


Naturally high antioxidants are therefore a distinguishing feature of Green Pasture’s fermented cod liver oil.


Antioxidants protect against oxidative stress, which can contribute to impaired vision and function of the eye through several mechanisms.


For example, oxidative stress can play a role in:


  1. Cataract formation. This happens when a cloudy layer forms on the lens, blocking light from reaching the retina.


  1. Macular degeneration, affecting the retina.


  1. The optic nerve, preventing messages from the eye from reaching the brain.


Antioxidants, therefore, have a vital role to play in protecting the entire eye and the visual process.

Stronger Together

Vitamins D and A, the fatty acid omega-3, and other antioxidants in Green Pasture’s fermented cod liver oil each have their own mission to fulfil for strong, healthy eyes, and clear vision.


When combined, they can be a powerful source of support for the visual system.


In the next article, we’ll further explore the protective effects of cod liver oil on dry eyes and eye irritation.

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