Vitamin A: Top Health Benefits, Best Sources & Deficiency Risks

Introduction

Vitamin A plays a crucial role in maintaining vision, supporting immunity, promoting cell growth, and enhancing skin health. But how do you get enough, and when does it become too much? 

In this guide, we’ll explore the benefits of vitamin A, its best dietary sources, and the risks associated with both deficiency and excess intake.

What Is Vitamin A? Forms & Functions Explained 

Vitamin A is a fat-soluble vitamin that is essential for various physiological functions in the body, including vision, immune function, and cellular growth and differentiation. 

It comprises a group of chemically related compounds, primarily retinol, retinal (also known as retinaldehyde), and retinoic acid. Furthermore, provitamin A carotenoids, such as beta-carotene, form an essential part of this vitamin group.

The active form of vitamin A is retinol, with a chemical formula of C20H30O and a molar mass of approximately 286.459 g/mol.

There are two primary forms of vitamin A:

• Preformed Vitamin A: This includes retinol and retinyl esters, found predominantly in animal products.
• Provitamin A Carotenoids: These are plant pigments that our body converts into retinol. Beta-carotene is the most widely recognised example.

Vitamin A plays a vital biological role in our bodies. It assists in the formation of rhodopsin, a protein in our retina that is essential for low-light and colour vision. Retinoic acid, another derivative of vitamin A, regulates gene expression and plays a crucial role in cell differentiation and growth.

Top Food Sources of Vitamin A

Vitamin A can be obtained from various dietary sources that include:

• Oily fish
• Yoghurt
• Cheese
• Eggs
• Milk
• Liver and liver products
• Leafy green vegetables (kale, spinach and broccoli)
• Orange and yellow vegetables (carrots, sweet potatoes and pumpkin)
• Yellow fruits (mango, papaya and apricots)
• Tomatoes

Key Roles of Vitamin A in the Body 

Vitamin A plays a crucial role in several vital bodily functions. Here’s an overview of its primary roles:

• Vision: Vitamin A is essential for maintaining good vision. It forms a component of rhodopsin, a pigment in the retina that helps with low-light and colour vision. Deficiency can lead to night blindness and other visual impairments.
• Immune System: Vitamin A benefits the immune system and maintains the health of skin and mucous membranes, which act as barriers to infections. It also plays a role in the development and function of white blood cells.
• Cell Growth and Differentiation: Vitamin A plays a crucial role in cell differentiation, which is essential for the development and maintenance of tissues and organs. It helps regulate cell growth and supports normal embryonic development.
• Skin Health: Vitamin A plays a crucial role in promoting skin health by stimulating cell production and repair. Retinoids, a class of compounds derived from vitamin A, are commonly used in dermatology to treat acne and other skin conditions.
• Antioxidant Activity: Vitamin A possesses antioxidant properties that help protect cells from damage caused by free radicals. This can reduce oxidative stress and may lower the risk of chronic diseases.
• Reproductive Health: Vitamin A benefits the reproductive processes by aiding in the development of sperm and the health of the reproductive organs in both men and women.

7 Science-Backed Health Benefits of Vitamin A 

Vitamin A is essential for maintaining healthy vision, supporting immune function, promoting skin health, and facilitating cell growth and differentiation. It supports low-light vision, helps maintain healthy skin and mucous membranes, and aids in the development and function of cells. Adequate vitamin A intake is crucial for overall health and disease prevention. Here are its specific benefits, including its antioxidant properties, impact on eye health, skin health, and its role in reproductive and immune functions.

1) As an Antioxidant

Vitamin A exhibits antioxidant properties that help protect your body’s cells from oxidative stress caused by harmful free radicals. This protection may reduce the risk of chronic diseases, including heart disease and certain types of cancer. 

However, remember that while vitamin A supplements are available, natural food sources are still the preferred method of intake for these benefits.

2) For Eye Health

Vitamin A is vital for maintaining healthy vision. It is instrumental for the formation of rhodopsin, a pigment crucial for vision in low-light conditions found in our retina. 

Inadequate levels of vitamin A can lead to night blindness and other vision problems, including age-related macular degeneration (AMD). Thus, an adequate intake of vitamin A supplements can help decelerate the decline in eyesight associated with ageing.

Also Read: 5 Simple Tips for Healthy Vision

3) For Skin

Vitamin A plays a crucial role in maintaining healthy skin. It helps keep the integrity of skin cells and promotes cell turnover, which can improve skin tone and texture. Dermatologists often prescribe retinoids, a derivative of vitamin A, for topical application to treat acne, reduce fine lines and improve skin roughness.

Also Read: Top Home Remedies To Make Your Skin Glow

4) Anti-Cancer

Some studies suggest that vitamin A, particularly in its carotenoid form, such as beta-carotene, may reduce the risk of certain cancers by protecting cells from oxidative damage. 

While further research is needed to establish a definitive link, the antioxidant properties of vitamin A are believed to contribute to its potential anticancer effects.

5) Fertility

Vitamin A plays a crucial role in reproductive health in both men and women. In men, it supports sperm development, whereas in women, it is vital for egg quality and successful implantation during pregnancy. Ensuring adequate levels of vitamin A is essential for the normal growth and development of the foetus during pregnancy.

Also Read: Identifying Early Signs of Female Infertility

6) For Immune System

Vitamin A plays a crucial role in strengthening our immune system. It helps regulate the immune response by promoting the production of white blood cells, which are paramount for combating infections. 

A lack of vitamin A can lead to increased susceptibility to infections and illnesses, underscoring its importance in maintaining a robust immune system.

Also Read: 6 Natural Ways to Improve your Immunity

Vitamin A Deficiency: Symptoms & Risks 

Your body requires vitamin A for numerous essential functions, including maintaining your vision and ensuring the normal functioning of your immune system. However, a deficiency in this key nutrient can lead to several health complications. Here are some risks associated with vitamin A deficiency:

• Vision Problems: A lack of adequate vitamin A can lead to night blindness and an increased risk of eye infections. In severe instances, it might even lead to corneal ulceration and, ultimately, blindness.
• Weakened Immune System: Vitamin A plays a pivotal role in maintaining the health of your immune system. A deficiency can leave you more susceptible to various infections.
• Anaemia: Lack of adequate vitamin A in your diet could contribute to the development of anaemia.
• Increased Risk of Death in Children: Alarmingly, a deficiency of vitamin A has been associated with an increased mortality rate in children under the age of five.
• Birth Defects: During pregnancy, excessive consumption of preformed vitamin A could lead to an increased risk of congenital disabilities.

Vitamin A Toxicity: Dangers of Too Much 

Ensuring you get enough vitamin A is primarily about including the right foods in your diet. Here are some top foods rich in this vital nutrient:

• Cod liver oil: This is a potent source of vitamin A, with just 1 tablespoon containing a whopping 4,080 mcg of retinol, or 453% of the daily recommended intake.
• Sweet potatoes: One medium baked sweet potato provides over 1,400 mcg of vitamin A, mainly in the form of beta-carotene.
• Carrots: Half a cup of raw carrots contains 459 mcg of vitamin A, which is 51% of the daily recommended intake.
• Spinach: A half-cup of boiled spinach provides 573 mcg of vitamin A, or 64% of the daily recommended intake. A half-cup raw cantaloupe contains 135 mcg of vitamin A, which is 15% of the daily recommended intake.

Other food items that serve as excellent sources of vitamin A include fish, dairy products, eggs, and a variety of fruits and vegetables, particularly those with an orange or yellow hue.

Recommended Vitamin A Intake by Age 

The requirement of vitamin A varies with age and sex. The following are the recommended vitamin A doses:

Vitamin A Toxicity

When there’s an excessive accumulation of this vitamin in the body, it leads to a condition known as hypervitaminosis A or vitamin A toxicity. This can manifest in two forms:

1) Acute Vitamin A Toxicity

Acute vitamin A toxicity often results from a sudden, large intake of vitamin A, typically exceeding 300,000 international units (IU) for children and several hundred thousand IU for adults.

This could be due to accidental intake or consumption of foods exceedingly high in vitamin A, such as certain animal livers, notably polar bear liver.

The symptoms of acute toxicity can develop rapidly and may include:

• Nausea and vomiting
• Abdominal pain
• Headaches
• Increased pressure inside the head (intracranial pressure), leading to drowsiness or irritability
• Rash or skin peeling

In severe cases, the patient may even slip into a coma, or it can be fatal.

2) Chronic Vitamin A Toxicity

Chronic vitamin A toxicity occurs over an extended period due to consistently high intake, generally over 25,000 IU daily for adults. This is often associated with the long-term use of vitamin A supplements or certain medications containing retinoids, such as isotretinoin, used for the treatment of acne. 

Chronic toxicity can lead to more severe health issues, such as:

• Liver damage and hepatomegaly
• Bone pain and swelling
• Dry, rough skin and hair loss
• Blurred vision or other vision changes
• Increased pressure on the brain

In children, symptoms may include irritability, poor weight gain, and abnormal softening of the skull bones.

Doctors can diagnose vitamin A toxicity based on clinical symptoms, patient history, and blood tests. The primary treatment involves discontinuing vitamin A supplements. Most individuals recover within 1 to 4 weeks after discontinuation of vitamin A intake, depending on the severity of the symptoms.

Takeaway 

Vitamin A supports essential functions like vision, immunity, skin health, and cell growth, but both deficiency and excess intake can lead to problems. Focus on a balanced diet including colourful fruits, vegetables, eggs, dairy, and fish, and follow age-appropriate intake guidelines. When in doubt, consult your doctor or a registered nutritionist before starting any supplements.

Expert Quote:
“Vitamin A is essential for healthy vision, immunity, and skin maintenance, but both deficiency and excess can cause serious issues, so balance is key.”

–Dr Anubha Karol

FAQs

References

• https://medlineplus.gov/ency/article/002400.htm 
• https://ods.od.nih.gov/factsheets/VitaminA-Consumer/
• https://pmc.ncbi.nlm.nih.gov/articles/PMC6162863/ 
• https://www.aoa.org/news/clinical-eye-care/health-and-wellness/vitamin-a-good-for-the-eyes#:~:text=A%20group%20of%20antioxidants%2C%20vitamin%20A%20not,allowing%20our%20eyes%20to%20see%20at%20night.