“Eat your carrots! They’re good for your vision!” My mother used to tell me this when I was a youngster. She was no liar. Carrots are loaded with carotenoids – molecules with vitamin A-like activity – that help support healthy vision. But vitamin A comes in all different shapes and sizes (such as multiple kinds of carotenoids), and this has a direct impact on how effective they are at performing their many functions.
Important Functions of Vitamin A
#1 Vision
This is vitamin A’s principal call to fame. So much so that part of the eye is called the retina (one form of vitamin A is retinal). Having poor vitamin A intake and status can lead to night blindness, or even total blindness if deficiencies are not corrected soon enough. This is not an exaggerated claim, as is often the case when using phrases like, “if not corrected soon enough.” This is a well-documented fact, and vitamin A deficiency is actually the leading cause of childhood blindness throughout the world.
This is because vitamin A is a precursor to a compound called rhodopsin. Rhodopsin is a pigment found in the rods of the eye that are sensitive to light. When there is not enough vitamin A, there is also not enough rhodopsin, so vision in low-light is impaired. Over longer periods of time, vitamin A deficiency leads to keratinization of the eye and destruction of the cornea and total blindness, which is when vitamin A deficiency becomes irreversible.
#2 Skin
Did you know that Accutane, the drug used to treat bad acne, is actually just super high doses of vitamin A as Isotretinoin (see the “retino” in there? that means vitamin A)? At such a high dose, the treatment basically dries up the sebaceous glands, which produce oil and can cause pimples, but some mechanisms remain unknown. There are actually many side effects to such high doses, and that is why isotretinoin is by prescription only.
There are some good things too. Many skin creams contain vitamin A to facilitate or maintain a more youthful appearance, and in the form of retinol, vitamin A is one of the only ingredients in skin care products that have actually been found to work in a scientific setting. At the genetic level, vitamin A helps skin cells to mature. Vitamin A may also stimulate collagen production, which helps to firm the skin and get rid of wrinkles and age spots while also protecting against ultraviolet damage.
#3 Immunity and Role as an Antioxidant
Vitamin A has a number of functions within the immune system that all boil down to enhancing white blood cell function. The white blood cells, such as lymphocytes (B cells and T cells), macrophages, and neutrophils, locate and destroy pathogens. Perhaps most importantly, vitamin A can activate B and T cells, which are the primary “search and destroy” white blood cells.
Compared to other vitamins, vitamin A is a weak antioxidant. However, that does not mean it has less purpose. Vitamin A specializes in certain types of free radical quenching and supplementation may still reduce mortality. Because the A vitamins are fat-soluble, they are excellent for protecting the cell membrane (which is made of fat), unlike vitamin C, which is an antioxidant vitamin that is water soluble.
Types of Vitamin A
So far, we’ve talked about vitamin A and carotenoids, but these are 2 different things. On top of that, there are many different forms of vitamin A as well as over 600 different types of carotenoids. Which are the most important?
Vitamin A most often takes the form of retinoic acid, retinal, retinyl esters, and retinol within the body. More specialized forms that may be found in supplements, skin creams, or pharmaceuticals are isotretinoin, tretinoin (retin-A), retinyl palmitate, or retinyl acetate to name a few. Retinol or retinyl esters are the most biologically active forms of vitamin A, and therefore, they’re the best forms for supplementing. Vitamin A is fat-soluble, and the best sources are liver, salmon and other fatty fish (including supplements like cod liver oil), cheese, butter, and eggs! That’s right, the best sources of vitamin A are animal products!
Carotenoids are pro-vitamins – they can be converted into vitamin A. Common carotenoids are beta-carotene, zeaxanthin, and astaxanthin. For the body to form one unit of vitamin A, 2 units of beta-carotene or 24 units of other carotenoids need be consumed. Although, each carotenoid has a unique role that it can perform without being converted to retinol. For example, beta-carotene is actually a better antioxidant that vitamin A and astaxanthin has been found to improve eye health. Because of their diverse functions, a variety of carotenoids are good to consume. They are found in most orange, red, or yellow colored foods, such as carrots, sweet potatoes, and cantaloupe as well as cruciferous greens!
Vitamin A Needs for Endurance Athletes
Like most nutrients, athletes need more vitamin A than others. Unlike the B vitamins, iron, and other micronutrients, a vitamin A deficiency has not been directly tied to impaired performance. Although, as previously discussed, vitamin A deficiency causes much more serious problems. An examination of 19 endurance athletes found that 6 (31.6%) consumed less than 100% of the recommended intake, and 4 of those 6 athletes (21.1%) were below 50%.
For all of your vitamin and mineral needs, look no further than FOOD. But when you need to be sure, look for MultiElite – The Endurance Athlete’s Multivitamin (coming soon). MultiElite provides the biologically active forms of all vitamins and minerals in quantities sufficient to support good health without going 3,000% overboard like most multi’s - we know your diet is in pretty good shape already! MultiElite sets itself apart with additional joint, cardiovascular, and skeletomuscular system support with key ingredients such as pycnogenol and curcumin to ensure the endurance athlete has the best supporting cast possible.
References
- Wässle H, Boycott BB. Functional architecture of the mammalian retina. Physiol Rev 1991;71(2):447-80.
- Akhtar, S., Ahmed, A., Randhawa, M. A., Atukorala, S., Arlappa, N., Ismail, T., & Ali, Z. (2013). Prevalence of vitamin A deficiency in South Asia: causes, outcomes, and possible remedies. Journal of health, population, and nutrition, 31(4), 413.
- Mora, J. R., Iwata, M., & Von Andrian, U. H. (2008). Vitamin effects on the immune system: vitamins A and D take centre stage. Nature Reviews Immunology, 8(9), 685.
- Bendich, A. (1993). Physiological role of antioxidants in the immune system. Journal of Dairy Science, 76(9), 2789-2794.
- Machefer, G., Groussard, C., Zouhal, H., Vincent, S., Youssef, H., Faure, H., ... & Gratas-Delamarche, A. (2007). Nutritional and plasmatic antioxidant vitamins status of ultra endurance athletes. Journal of the American College of Nutrition, 26(4), 311-316.
