Vitamin A: How much is too much?

There is a lot of confusing info out there regarding Vitamin A. Some research warns of Vitamin A toxicity, especially regarding early pregnancy. On the other hand, much of the world is deficient. On top of that, there are several different forms...some readily available and others not. How much is too much, too little, and what kind is right for you?

The Basics

The importance of Vitamin A in the body cannot be understated. It’s a major player in immune function, eyesight, hair, skin, and nails. It comes in two major forms: preformed Vitamin A, a readily bioavailable source and found in animal foods; and Carotenoids, or pro-Vitamin A, found in plants and must be converted by the body in order to be used (WHFoods.com). Each form is significant and has slightly different benefits and recommended values, so it’s important to get both forms.

PREFORMED VITAMIN A is absorbed in the body as retinol and is the most readily available form. It is found in animal sources only and in highest concentration in organ meats, cheese, dairy, poultry, and fish. Vitamin A will help ensure healthy growth and development; support of the mucus membranes, skin and hair; encourage good eye sight; healthy immune functioning; fertility; antioxidant support; and cancer prevention. So it’s obvious that we need it but there is still controversy over how much is enough and how much will cause Vitamin A toxicity. Toxicity shouldn’t be of concern if Vitamin A is consumed in balance with Vitamin D (findings suggest around 10:1). Most unadulterated Vitamin A rich food sources are balanced. If the ratio of A to D is off, Vitamin D deficiency and Vitamin A toxicity are both possible (Mercola 2009). You’ll find many opinions on recommended daily doses but most sources appear to be ok with 10,000IU for adults provided Vitamin D intake is sufficient (around 1000IU).

CAROTENOIDS are fat-soluble plant pigments that are anti-inflammatory, anticancer, and eye protectants. Fat soluble refers to the need for bile in order to absorb it (good fats stimulate bile production!). This also means that you can store them so you don’t need them every day. In order to be converted to Vitamin A in the body, they depend on proper thyroid hormone levels, zinc, and Vitamin C, as well as Vitamins E and K. Chlorophyll activates the enzymes that produce E and K in the body so green leafies might help you convert more readily (Pitchford 2002). If you have deficiencies in any of these cofactors, then you won’t be able to get your Vitamin A through vegetable sources. There are still many, many benefits in the delicious and colorful sources of Carotenoids other than Vitamin A so you still have to eat them! The highest forms are sweet potatoes, spirulina, carrots, leafy greens, bell peppers, etc. There easy to find just look for COLOR! Toxicity isn’t a concern with Carotenoids. If supplementing, adults should have about 5000IU per day.

DEFICIENCIES can present themselves in the form of night blindness, skin disorders, premature aging, and low immune function. TOXICITY looks like liver damage, dry itchy skin, brittle nails, fatigue, vomiting, and hair loss (Bauman 2014). 

THE FINAL SPREAD

Get your Vitamin A from real food sources. This will ensure you’re getting the proper balance of Vitamins A and D which will decrease the chance of toxicity. If you struggle with deficiency, eat those foods highest in the retinol form of Vitamin A and/or take a real food supplement that contains a high dose of Vitamin A in the carotene form. As always, eat lots of colorful veggies! 

References

Bauman, E. & Friedlander, J. (2014). Foundations of nutrition. Penngrove, CA: Bauman College.

WHFoods.com. Vitamin A. Retrieved from http://www.whfoods.com/genpage.php?tname=nutrient&dbid=106

Mercola.Com. Take Control of Your Health. (2009, Jan). Why Vitamin A May Not Be as Useful or Harmless as You Thought. Retrieved from: http://articles.mercola.com/sites/articles/archive/2009/01/03/why-vitamin-a-may-not-be-as-useful-or-harmless-as-you-thought.aspx

(3rd ed.). Pitchford, P. (2002). Healing with whole foods. Asian traditions and modern nutrition (3rd ed.). Berkeley, CA: North Atlantic Books.

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