A Radiant Micronutrient for Health and Vitality: The Power of Vitamin A

“With Vitamin A by your side, you're on the path to a healthier, brighter tomorrow”

Prologue

Science

Benefits

Sources

Dosage

Recommendations

Vitamin A: An Important Micronutrient

For a healthy and vibrant life, we often overlook the incredible role played by essential nutrients. One such nutrient, Vitamin A, is a key nutrient in the world of human health. It plays a crucial role in maintaining various aspects of human health, offering several benefits that favorably influence our vision, immune function, growth and development, and overall well-being^[1,2,3,4,5]. In this article, we will learn how Vitamin A benefits overall human health.

Science of Vitamin A  

Vitamin A exists in two different forms in the human diet. Primarily, it occurs in animal tissues as retinol-a preformed Vitamin A. Vitamin A in its true form does not occur in foods of plant origin ^[4], but many foods of plant origin have a treasure trove of yellow and red carotenoids pigments in them which are called provitamins A carotenoids for the formation of vitamin A. The main provitamin A carotenoids in the human diet are beta-carotene, alpha-carotene, and beta-cryptoxanthin^[6,7]. In the human body, conversion of provitamin A carotenoids into vitamin A occurs in the intestine^[8,9]. Among all the provitamins, beta-carotene is invaluable as the most recognized carotenoid that can be converted by the body into retinol- the active form of vitamin A. Preformed vitamin A is prevalent in animal-based foods like liver, fish, eggs, and dairy products. Meanwhile, provitamin A exists in carrots, sweet potatoes, and leafy greens like spinach and kale^[10,11].

The Marvelous Benefits of Vitamin A

In the section below, we will explore the fascinating world of vitamin A's health benefits:

Vitamin A is the guardian of our vision and eye health

When it comes to maintaining good eye health, Vitamin A is indispensable^[4]. Vitamin A has a significant impact on our vision, ensuring our eyes function optimally. It forms an integral part of rhodopsin, a light-sensitive pigment in our retinas. Especially, vitamin A supports vision in low light and makes it possible to see clearly at night. Without sufficient vitamin A, we risk night blindness, and in severe cases, permanent vision impairment. Vitamin A helps maintain the integrity of the cornea, ensuring that it remains clear and functional for sharp vision^[12]. Recommended daily intake of Vitamin A prevents several eye diseases, like dryness of eyes (xerophthalmia)^[13], conjunctival problems^[14], and age-related macular degeneration (AMD)^[15].

Immune System Support

While it’s primarily known for its role in eye health, Vitamin A is a crucial organic compound that supports our immune system's battle against infections^[16,17]. It is known as an anti-inflammation vitamin because of its critical role in enhancing immune function ^[18]. It strengthens our defenses by supporting the production of cells of our innate immune system (White blood cells, T cells, production of specific antibody) and enhancing the resilience of mucous membranes in our respiratory, gastrointestinal, and urinary tracts^[18,19].

Antioxidant Properties

Vitamin A also serves as a powerful antioxidant in the human body^[20]. During the metabolism highly reactive and unstable molecules or atoms, known as free radicals, are generated that have the tendency to interfere in life sustaining reactions, develop oxidative stress and cause harm to the cells^[21,22]. Vitamin A and carotenoids are natural antioxidants that play a pivotal role in neutralizing harmful free radicals and in turn relieving cells from oxidative stress^[22,23].  

Cellular Growth, Reproduction, and Development

Vitamin A is a key regulator of the growth and development of various cells and tissues throughout life^[2,24]. During pregnancy, it is proven to play a vital role in ensuring the healthy development of the growing fetus^[25,26]. In addition to being essential for morphological and functional development and for ocular integrity, vitamin A exerts systemic effects on several fetal organs and on the fetal skeleton^[27]. In terms of reproduction, vitamin A plays a central role, it influences processes like sperm production in males and placental development in females, and the development of the male and female reproductive systems^[24].

Skin Health

Vitamin A is your skin's best friend and helps keep it healthy^[28]. It fosters the growth of fresh skin cells and mends damaged tissues^[29]. It is also used supposedly to treat conditions like acne and psoriasis^[30]. Due to its antioxidant, anti-inflammatory, and immune boosting effects, Vitamin A increases dermal defense and contributes to better skin health and appearance^[31].

Bone Health

The recommended daily allowance (RDA) of vitamin A provides strength to our bones. Both bone building (osteoblasts cells) and its maintenance, repair, and remodeling (osteoclasts cells) are influenced by Vitamin A^[32]. Studies show that carotenoids probably produce a bone benefit through their antioxidant properties^[33].

However, hyper-vitaminosis A (Vitamin A intake more than the recommended range) results in low bone mineral density, osteoporosis, and increases fracture risk, especially in elderly people^[34].

Ongoing research and claims

There have been claims and studies regarding several other potential uses of vitamin A for various health conditions. One such condition is cancer. Some studies have suggested that it purportedly prevents some types of cancers^[35,36,37]. However, the evidence is inconclusive, and excessive vitamin A intake can have adverse effects, so it's not recommended as a cancer prevention strategy^[38,39,40]. Some research has explored the role of vitamin A in treating psoriasis^[41], its role in Alzheimer's Disease^[42], and heart disease^[23]. Overall, its effectiveness in treating these conditions have often been inconsistent or inconclusive and a topic of ongoing investigation.

Sources

Vitamin A comes in two primary forms: retinoids and carotenoids. Retinoids are preformed vitamin A found in animal products, while carotenoids are provitamin A compounds found in plant-based sources^[44,45,46]. FoodData Central of The U.S. Department of Agriculture’s (USDA’s) provides a comprehensive list of foods containing vitamin A^[47]. Some of the most common food rich in Vitamin A are,

Animal-Based Sources of Vitamin A

1. Liver: Organ meats, particularly liver, are among the most concentrated sources of vitamin A. Beef liver is packed with this micronutrient^[6].
2. Fish: Fatty fish such as salmon, mackerel, and trout provide significant amounts of vitamin A.
3. Dairy Products: Milk, cheese, and eggs are good sources of vitamin A, especially when they are fortified with this nutrient.

Plant-Based Sources of Vitamin A:

1. Spinach and Kale: Leafy greens like spinach and kale contain both vitamin A and other essential nutrients, making them an excellent choice for overall health^[6,7,3].
2. Carrots: Carrots are renowned for their beta-carotene content, promoting healthy vision and skin.
3. Sweet Potatoes: are rich in beta-carotene, a potent precursor to vitamin A.
4. Pumpkin: Pumpkin is also a vitamin A powerhouse.
5. Red Bell Peppers: The peppers are packed with beta-carotene, contributing to a strong immune system.
6. Mangoes: Along with their sweet flavor, mangoes offer a significant dose of vitamin A.

Recommended Amounts

To keep our bodies functioning optimally, we must meet our daily vitamin A requirements. The average daily level of intake sufficient to meet the Vitamin A requirements in healthy individuals, commonly known as the Recommended Dietary Allowances (RDAs), is measured in micrograms of Retinol Activity Equivalents (RAEs).

According to the Food and Nutrition Board (FNB) at the National Academies of Sciences, Engineering, and Medicine, the RDA for normal 14 and older is 900 mcg RAE for men and 700 mcg RAE for women. In pregnant and lactating women, it typically ranges between 770 to 1,300 micrograms of Retinol Activity Equivalents (RAEs) per day.

FNB has established a maximum daily intake amount or upper limit for Vitamin A between 2,800 and 3,000 micrograms of preformed vitamin A. This range represents the upper tolerable maximum daily intake, which is safe for healthy individuals ^[7].

Recommendations

Vitamin A is your secret weapon for radiant health and well-being. To unlock its full potential, embrace a balanced diet rich in vitamin A sources. Consult your healthcare professional or your registered dietitian to determine the right dietary sources and recommended daily intake of vitamin A for your specific needs. However, it's important not to overconsume vitamin A as excessive intake can be harmful because being lipid soluble, it can stay in the body for a significant period of time. If you have concerns about your eye health, such as night blindness or other eye problems, it's important to seek medical advice for a proper diagnosis and treatment.

References

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