What Is Vitamin D

What Is Vitamin D?

For proper functioning, human bodies demand small amounts of multiple nutrients, such as vitamins and minerals. We receive most vitamins through a balanced diet and/or supplements. But vitamin D is generated by the human body with the help of sunlight. During the autumn-winter period, it can be problematic to keep the necessary concentration of this agent. For activation, vitamin D should be transformed twice in our bodies. In the liver, vitamin D changes to calcidiol. The second transformation occurs in our kidneys and generates physically active calcitriol. The mission of vitamin D is to maintain the correct concentration of calcium and phosphate in our bodies. It has many different characteristics and takes part in various processes, including those related to vision.

Foods that Provide Vitamin D

Scientists all over the world have proved that vitamin D deficiency triggers different diseases. To avoid expensive treatment, people should take sufficient doses of this substance. From March to September, there are no problems with having the necessary exposure to the sun. The standard is 10-15 minutes every 2-3 days with no SPF cream. But from October to February, humans need to take vitamin D with products added to their diets to reach the required intake. The list of recommended products is the following:

  • oily kinds of fish, including trout, sardines, etc.;
  • cod liver;
  • red meat;
  • egg yolks;
  • fortified foods, such as fat spread, cereals, juices, plant or cow milk, etc.;
  • dairy products, especially cheese;
  • some kinds of mushrooms.

However, the concentration of vitamin D in food is very small, and people should take supplements to receive daily doses.

Optimum Vitamin D Levels

Researchers continue to discuss the recommended dietary allowance of vitamin D. The established intake varies due to different characteristics, such as race or age. In general, the recommended allowance is:

  • 10 micrograms of vitamin D daily for everybody older than 1 year;
  • 5-10 micrograms per day for babies.

The optimum level of the nutrient is essential for pregnant and breastfeeding women and should be corrected by their therapist.

Vitamin D and Vision

Suggestions about vitamin D

There are various suggestions about vitamin D deficiency eye problems, and a lot of them are controversial, which can be confusing. However, many reliable scientific publications show an association between vit D and eyesight. Scientists mention that this vitamin plays an essential role in gene regulation. Also, it is a powerful immune modulator. A lack of vitamin D causes many problems with vision or at least can have an influence on their development. We have theories linking corneal disorders and an impaired immune system. All inter-linkages of vitamin D deficiency and vision problems are not determined, but their connection is proved.


chronic deficiency of vitamin D

In November 2016, Korean scientists found that chronic deficiency of vitamin D can provoke myopia in kids. It is only one example of studies that demonstrate the impact of the deficit on the development of short-sightedness. The mechanism behind this impact is not studied in full, but it is still clear that vitamin D affects the protective properties of the cornea. Additionally, an unbalanced diet and musculoskeletal system abnormalities connected with the lack of vitamin D along with genetic susceptibility can be a reason for myopia.


Retinoblastoma is a childhood disease

Retinoblastoma is considered a childhood disease. It is a type of eye cancer. Various studies show that lack of vitamin D can cause the active growth of retinoblastoma cells. The vitamin D receptor is expressed throughout different cell types, and retinoblastoma cells can also accept calciferol. Oncologists sometimes apply a treatment that includes this nutrient because calcium creates an alkaline environment, which detrimentally affects cancer cells. Also, the vitamin has an impact on glucose metabolism in cancer cells. Generally, vitamin D has a protective function in oncology.

Age-related Macular Degeneration

AMD is the vision problems

AMD is one of the vision problems. It is associated with the damage of the macula — a small area in the central part of the retina where the largest number of rods and cones are concentrated. This pathology is considered the main reason for old people’s blindness. Several scientific publications demonstrate relations between macular degeneration and lack of vitamin D. Aged people with high levels of vitamin D have fewer risks of AMD developing. Vitamin D has protective properties against macular degeneration due to its anti-inflammatory and anti-angiogenic effects.

Dry eye syndrome

DES relates to irritated eyes

DES relates to irritated eyes and a lack of tears to naturally moisturize the eye surface. Scientists have evidence that this syndrome can be minimized by sufficient vitamin D consumption because of its anti-inflammatory properties. This nutrient improves the characteristics of tears, and they can better moisture the eye surface. Deficiency of vitamin D can result in the worsened subjective perception of dry eye syndrome. Ophthalmologists recommend a balanced diet and receiving enough vitamin D as preventative care or a part of treatment.


Glaucoma is vision disease

Glaucoma is the name of the group of vision diseases caused by injury of the optic nerve. Scientists believe that there is a link between lack of vitamin D and primary open-angle glaucoma. The deficiency can increase the risk of glaucoma development among women, but further research is needed to provide more accurate data on that.

Diabetic Retinopathy

Ocular disease

This ocular disease refers to damages of the retina connected with the epiphenomenon of diabetes. There are several types of diabetes. Scientists found that vitamin D deficiency raises the risk of retinopathy development among young people with type 1 diabetes based on relations between inflammation and vitamin D deficiency. Also, many scientific studies demonstrate that people with various diabetes types have lower levels of vitamin D than people without diabetes. Hence, vitamin D supplements may have a positive effect on retinopathy prevention, in addition to other low vitamin D eye problems.


Uveitis is an inflammation

Uveitis is an inflammation of the uvea, which is the vascular middle layer of the eye. Redness, pain, light sensitivity, and some other symptoms characterize this disease. Researchers suggest some relations between vitamin D deficiency and eye floaters, which are a symptom of uveitis. Their studies demonstrate that increasing the level of this agent helps to minimize uveitis activity. Some ophthalmologists prefer to add vitamin D supplements to treatment, while others object. We need more studies for a decisive answer.

Ocular Surface Inflammation and Pathology

Causes of this disease

The eye surface consists of the cornea and conjunctiva covered with the layer of epithelium. OSI means that this layer is injured. There are many causes of this disease, from dry eye syndrome to vitamin D deficiency. Different studies show that lack of this nutrient can be related to ocular surface inflammation because the immune response worsens when the body does not get a sufficient amount of the vitamin. However, more research is required to clarify the mechanisms and prospects of using vitamin D supplements with other treatments.

How to Increase Your Vitamin D Intake

increase vitamin D intake

Most people in developed countries have low levels of vitamin D. As we know, it can cause a huge range of diseases, not only ocular ones. Hence, it is very important to increase vitamin D intake. There are 4 effective ways to avert vitamin D deficiency and eye problems associated with it.

  • Spend more time on fresh air. Even diffused sunlight serves as the main source of vitamin D. Spending 10-15 minutes in the sun every 2-3 days can help to receive the required amount of the nutrient. It is necessary to expose at least 10% of the body to the sun without sun cream and clothes. But be aware of skin cancer and do not sunbathe under the aggressive noonday sun.
  • Have a balanced healthy diet with different foods that include vitamin D: fatty fish, cod liver, fortified products, and so on. Look at the above list of recommended products.
  • Use ultraviolet lamps. Although indoor tanning provokes many discussions nowadays, if you use it for a short period (not more than 15 minutes) and do not burn your skin, it can be useful to increase the serum concentration of vitamin D.
  • Include supplements in your daily routine. There are many options on the market, and they can be of help during the autumn-winter period.

What to supplement and for how long

high-quality supplements of vitamin D

Manufacturers provide us with the option to choose between two forms of vitamin D: D2, also called ergocalciferol and taken from plants, and D3, known as cholecalciferol and sourced from animals. Studies demonstrate higher effectiveness of the D3 form in boosting the level of vitamin D; so, it is better to opt for ergocalciferol. It is also necessary to choose only high-quality supplements that were independently tested. Also, do not forget to consult with your therapist about the dozes and treatment duration before taking supplements. Different conditions may influence your particular situation, and you need to be tested on the level of vitamin D in your blood first.


All nutrients are essential for human health. The deficiency of any vitamin can cause many diseases. For example, lack of vit D is associated with vision and bone problems along with some types of cancer. We kindly ask you to control levels of vitamins in your blood to minimize risks for your health. Take care of yourself.