Retinol

Retinol is an unsaturated alcohol that occurs in marine fish-liver oils and is synthesized biologically from carotene. Retinol is also known as vitamin A1. It is a fat-soluble vitamin that plays a crucial role in various physiological processes, including vision, immune function, and cellular growth. It is an essential nutrient required for maintaining healthy skin, teeth, skeletal and soft tissue, and mucous membranes. Retinol is found naturally in some animal-based foods and can also be obtained through fortified foods and dietary supplements.

All trans Retinol

Dietary Sources of Retinol

Retinol is naturally present in a variety of animal-based foods, as well as some fortified plant-based foods. Some dietary sources of retinol include:

• Liver (beef, pork, chicken, turkey)
• Fish liver oils (cod liver oil)
• Dairy products (milk, cheese, butter, yogurt)
• Eggs
• Fortified foods (cereals, margarine, plant-based milk alternatives)

Functions in the Human Body

Retinol plays several important roles in maintaining overall health and well-being:

• Vision: Retinol is a vital component of the pigment rhodopsin, which is responsible for light absorption in the retina and is crucial for low-light and color vision.
• Immune function: Retinol supports the immune system by maintaining the integrity of mucous membranes, which act as physical barriers against infections.
• Cellular growth and differentiation: Retinol is essential for the proper growth and differentiation of cells, particularly epithelial cells in the skin, lungs, and gastrointestinal tract.
• Reproduction: Retinol is necessary for the proper functioning of the male and female reproductive systems, as well as fetal development during pregnancy.

Recommended Daily Intake

The recommended daily intake of retinol varies depending on age, sex, and life stage. The following are the recommended dietary allowances (RDAs) for vitamin A, as established by the Institute of Medicine:

• Infants (0-6 months): 400 micrograms (mcg) retinol activity equivalents (RAE) per day
• Infants (7-12 months): 500 mcg RAE per day
• Children (1-3 years): 300 mcg RAE per day
• Children (4-8 years): 400 mcg RAE per day
• Children (9-13 years): 600 mcg RAE per day
• Males (14 years and older): 900 mcg RAE per day
• Females (14 years and older): 700 mcg RAE per day
• Pregnant women (19 years and older): 770 mcg RAE per day
• Lactating women (19 years and older): 1,300 mcg RAE per day

Deficiency and Toxicity

Retinol deficiency is rare in developed countries but can lead to several health problems, including night blindness, xerophthalmia, and increased susceptibility to infections. In developing countries, vitamin A deficiency is a major public health concern, particularly among young children and pregnant women.

On the other hand, excessive intake of retinol, particularly from supplements, can lead to toxicity, causing symptoms such as dizziness, nausea, headaches, and even more severe issues like birth defects during pregnancy or liver damage.

Retinol in Skin Care

Retinol is widely used in the skincare industry due to its ability to improve skin texture, reduce the appearance of fine lines and wrinkles, and minimize hyperpigmentation. It is a common ingredient in various anti-aging and acne treatment products, including creams, serums, and prescription-strength formulations like tretinoin (Retin-A).

The benefits of retinol in skincare include:

• Stimulating collagen production: Retinol promotes collagen synthesis, which is essential for maintaining skin elasticity and reducing the appearance of wrinkles and fine lines.
• Accelerating cell turnover: Retinol encourages the shedding of dead skin cells and the growth of new ones, resulting in a smoother and more even complexion.
• Reducing hyperpigmentation: Retinol helps to even out skin tone by inhibiting melanin production, which can reduce the appearance of dark spots and age spots.

It is important to note that retinol can cause skin irritation, redness, and peeling, particularly when first introduced to a skincare routine. To minimize these side effects, it is recommended to start with a low concentration of retinol and gradually increase the frequency of use as the skin adapts.

References

• Institute of Medicine (US) Panel on Micronutrients. (2001). Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academies Press (US). [1]
• Penniston, K. L., & Tanumihardjo, S. A. (2006). The acute and chronic toxic effects of vitamin A. The American journal of clinical nutrition, 83(2), 191-201. [2]
• Mukherjee, S., Date, A., Patravale, V., Korting, H. C., Roeder, A., & Weindl, G. (2006). Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety. Clinical interventions in aging, 1(4), 327–348. [3]
• World Health Organization. (2011). Guideline: Vitamin A supplementation in infants and children 6-59 months of age. World Health Organization. [4]

Retinol Resources
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