Do You Have a Vitamin A Deficiency?
By Dr. Mercola
Vitamin A is an important vitamin for healthy vision, immune system function, and cell growth. It works synergistically with a number of other vitamins and minerals, including vitamins D, K2, zinc, and magnesium, without which it cannot perform its functions.
“Vitamin A” actually refers to several different but related nutrients that can be divided up into two main categories:1,2
- Retinoids (aka retinol), the bioavailable forms of vitamin A found in animal foods
- Carotenoids, previtamin A found in plant foodsPlant-derived vitamin A precursors such as beta-carotene, or supplements containing “mixed carotenoids” are far better and carry a much lower risk of toxicity, as your body will not convert more than it needs. Of the carotenoids, beta-carotene is the most efficient converter. Compared to alpha-carotene or beta-cryptoxanthin, half as much beta-carotene is required to convert into the same amount of retinol. If you need to supplement, another option is to take desiccated liver pills.
Vitamin A Works in Tandem with Many Other Nutrients
In addition to zinc, vitamin A also works synergistically with vitamins D and K2, magnesium, and dietary fat. Vitamins A, D, and K2 interact synergistically to support immune health, provide for adequate growth, support strong bones and teeth, and protect soft tissues from calcification. Magnesium is required for the production of all proteins, including those that interact with vitamins A and D. Many of the proteins involved in vitamin A metabolism and the receptors for both vitamins A and D only function correctly in the presence of zinc.
Vitamins A and D also cooperate together to regulate the production of certain vitamin K-dependent proteins. Once vitamin K activates these proteins, they help mineralize bones and teeth, protect arteries and other soft tissues from abnormal calcification, and protect against cell death.
This kind of complexity is one of the key reasons why I strongly recommend getting most of your nutrients from real, whole food (and in when it comes to vitamin D, from sensible sun exposure). This is particularly true for vitamin A, as this will circumvent any toxicity issues. Consuming a well-rounded, nutrient-dense diet, with plenty of vegetables and healthy fats, will go a long way toward warding off nutritional deficiencies and serious nutrient imbalances. Any time you opt to supplement with any given vitamin or mineral, you run the risk of throwing it out of balance with its synergistic partners.
Sources and References
- 1, 13 Worldshealthiestfoods.org Vitamin A
- 2 Empowered Sustenance January 2, 2014
- 3 Journal of Nutrition 2004 Jan;134(1):237S-240S
- 4 Vitamin Stuff, Alpha Carotene
- 5 Medical News Today Beta Carotene
- 6 University of Maryland Beta Carotene
- 7 Phytochemicals, Beta Cryptoxanthin
- 8 Biochim Biophys Acta. 2012 Jan; 1821(1): 113–123
- 9 Medicinenet.com Canthaxanthin
- 10 Examine.com Fucoxanthin
- 11 Andrew Weil October 29, 2012
- 12 Am J Clin Nutr. 2000;71:878-84
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