Introduction
Vitamin A is a fat-soluble vitamin that plays a crucial role in various bodily functions, ranging from vision and immune system support to cell growth and development. It exists in two primary forms: preformed vitamin A (retinol and its esterified forms) found in animal-based foods, and provitamin A carotenoids (such as beta-carotene) found in plant-based foods which must be converted into the active form retinol in the body. In this blog we’ll talk about the benefits of vitamin A as retinol and why you need to source it from animals as beta-carotene is often an insufficient form of vitamin A.
Benefits of Retinol from Animal-Based Foods:
Bioavailability
Retinol boasts high bioavailability, meaning the body can readily absorb and utilise it. This characteristic makes it particularly advantageous for individuals with conditions affecting nutrient absorption or those with increased Vitamin A requirements, such as pregnant women.
Vision Health
Retinol plays a pivotal role in maintaining optimal vision, especially in low-light conditions. It supports the production of rhodopsin, a pigment in the eyes essential for night vision, thus reducing the risk of night blindness and other vision-related issues.
Skin Health
Another notable benefit of retinol is its contribution to skin health. It aids in cell turnover, promoting the growth of new skin cells and reducing the appearance of wrinkles and fine lines. Many skincare products harness the power of retinol for its anti-aging properties.
Immune Function
Vitamin A, in the form of retinol, is crucial for a robust immune system. It supports the development and maintenance of various immune cells, enhancing the body’s ability to fight infections and diseases effectively.
Cell Growth and Development
Vitamin A plays a vital role in cell growth, differentiation, and development. It is essential for the growth and maintenance of epithelial tissues, which line various organs and surfaces of the body, including the skin, respiratory tract, and gastrointestinal tract. Adequate vitamin A intake is particularly crucial during periods of rapid growth, such as childhood and pregnancy, to support proper development and tissue repair.
Reproductive Health
Vitamin A is also important for reproductive health in both men and women. It is involved in the production of sperm and the development of the placenta during pregnancy. Deficiency in vitamin A can lead to infertility, complications during pregnancy, and an increased risk of maternal and infant mortality.
Why Carrots and Plants are NOT a Good Source of Vitamin A
As mentioned in the introduction, carotene is not a good source for Vitamin A. This is because it needs to be converted into retinol in the body, and this conversion can be very poor in many individuals based on their genetics.
The absorption of β-carotene from plant sources ranges from 5% to 65% in humans. And to worsen the matter, conversion of the absorbed carotene into retinol is also reduced, depending on the function of their BCMO1 gene which converts carotene to retinol in the intestines. 2 common genetic polymorphisms of the BCMO1 gene were identified and were associated with a reduction in intestinal conversion of β-carotene to vitamin A of ∼32–69% in UK women!
Furthermore, deficiencies in Iron, Zinc and Protein – all best sourced from ANIMALS – can also worsen Vitamin A deficiency as they are required for the metabolism or mobilisation of Vitamin A in the body.
Symptoms of Vitamin A Deficiency
Vitamin A deficiency can manifest with a variety of symptoms, ranging from mild to severe. Some of the top symptoms include:
Night blindness
This is often one of the earliest signs of vitamin A deficiency. It refers to difficulty seeing in low-light conditions or at night.
Dry eyes
Lack of vitamin A can lead to dryness and irritation of the eyes due to inadequate tear production.
Xerophthalmia
This is a more severe form of eye dryness, characterised by a condition in which the conjunctiva and cornea become dry, leading to a range of eye problems including corneal ulcers and even blindness if left untreated.
Skin problems
Vitamin A deficiency may result in skin issues such as dry skin, rough skin, or follicular hyperkeratosis (bumpy skin).
Impaired immune function
Vitamin A is crucial for maintaining a healthy immune system. Deficiency can lead to increased susceptibility to infections and a weakened ability to fight off illnesses.
Delayed growth and development
In children, inadequate vitamin A intake can lead to stunted growth and delayed development.
Increased susceptibility to infections
Vitamin A deficiency can compromise the body’s ability to fight off infections, making individuals more prone to illnesses such as respiratory infections, diarrheal diseases, and measles.
Poor wound healing
Vitamin A is essential for tissue repair and wound healing. Deficiency can result in slower healing of wounds or injuries.
Reproductive issues
Inadequate levels of vitamin A can affect reproductive health, leading to infertility in both men and women.
Hair loss
While not as common as other symptoms, severe and prolonged vitamin A deficiency may contribute to hair loss or thinning hair.
It’s important to note that these symptoms can vary in severity depending on the extent and duration of the deficiency. If you suspect you may have a vitamin A deficiency, it’s essential to consult with a healthcare professional for proper diagnosis and treatment.
Best Sources of Retinol
Vitamin A1, as retinol, is only found in animal-sourced foods, such as oily fish, liver, cheese, and butter.
Here are some of the best sources of vitamin A1:
- Beef liver: 3.5 ounces (oz), or 100 grams (g), contains 7,730 mcg of retinol, or 859% of the DV!
- Lamb liver: 3.5 oz (100 g) contains 7,780 mcg of retinol, or 864% of the DV
- Cod liver oil: 1 tablespoon (tbsp), or 14 g, contains 4,080 mcg of retinol, or 453% of the DV
- Bluefin tuna: 3.5 oz (100 g) contains 757 mcg of retinol, or 84% of the DV
- King mackerel: 3.5 oz (100 g) contains 252 mcg of retinol, or 28% of the DV
- Salmon: 3.5 oz (100 g) contains 69 mcg of retinol, or 8% of the DV
- Eggs (yolk): One large (50 g) hard-boiled egg contains 75 mcg of retinol, or 8% of the DV
Conclusion
In the great debate between retinol from animal-based foods and carotene from plant-based sources, animal sources are a clear winner. If you want vibrant skin, a robust immune system and healthy fertility, then make sure you’re getting enough Vitamin A from animal sources like Beef Liver!
References
- Marjorie J Haskell, The challenge to reach nutritional adequacy for vitamin A: β-carotene bioavailability and conversion—evidence in humans1234, The American Journal of Clinical Nutrition, Volume 96, Issue 5, 2012, Pages 1193S-1203S, ISSN 0002-9165, https://doi.org/10.3945/ajcn.112.034850.
- Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism. 6th ed. Belmont, CA: Wadsworth, Cengage Learning; 2013.
- Ross AC. Vitamin A: metabolism and requirements in health and disease. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern nutrition in health and disease. 11th ed. Baltimore, MD: Wolters Kluwer; 2014: 260-277.
- Harvard T.H. Chan School of Public Health. The Nutrition Source – Vitamin A. Available at: https://www.hsph.harvard.edu/nutritionsource/vitamin-a/. Accessed on March 27, 2024.
- National Institutes of Health. Office of Dietary Supplements – Vitamin A. Available at: https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/. Accessed on March 27, 2024.
- Mayo Clinic. Nutrition and healthy eating – Vitamin A. Available at: https://www.mayoclinic.org/drugs-supplements-vitamin-a/art-20365945. Accessed on March 27, 2024.
