Vitamin A doesn’t get a lot of press these days, at least not as much as the other fat soluble vitamins, such as Vitamin D, Vitamin E and Vitamin K. However, Vitamin A is vital for many bodily functions, and research is showing that it isn’t quite as easy to get adequate amounts through the diet as we once thought.
The Vitamin A Complex – When Vitamin A ISN’T Vitamin A
Vitamin A is actually a group of compounds that include retinol, retinal, retinoic acid and several provitamin A carotenoids, among which beta-carotene is thought to be the most important. Some of the carotenoids can be converted into vitamin A in the body; however, research is showing that this is not nearly as efficient as was once thought.
This can have dramatic implications for those of us that try to get most of our vitamin A through the consumption of fruits and vegetables (no fruits and vegetables contain vitamin A; however, many are good sources of the carotenoids). In fact, this newer research suggests that fruits and vegetables are not as useful for obtaining vitamin A as is often reported on the label, meaning that the IUs of vitamin A reported on the label of foods that contain only vegetables and fruit are ‘worth’ much less than the same number of IUs of vitamin A reported on fat-dissolved oils and supplements. This is vitally important for those that eat no or little meat and/or vitamin A rich oils or supplements.
Functions of Vitamin A
Vitamin A is essential for vision and night vision. Without it, signals are not sent properly and vision, especially at night, can suffer permanent loss over time. In addition, vitamin A plays several roles in proper immune function. Adequate vitamin A levels can reduce infections, maintain the integrity of the respiratory and GI tracts (which act as natural barriers to pathogens), improve antibody responses and increase white blood cell production.
Once more, vitamin A plays a vital role in maintaining normal skin health by switching on genes that help skin cells develop properly. This is why topical vitamin A creams are often recommended for those with acne or other skin issues. The real culprit in most of these cases is a deficiency of Vitamin A in the diet.
Lastly, vitamin A regulates growth and fetal development by promoting proper cellular differentiation and expression. With Vitamin A playing a role in so many vital bodily functions, it is very important to consume adequate quantities of this essential nutrient in the diet.
Vitamin A – Sources
The best food sources of vitamin A are cod liver oil and liver. As discussed above, many vegetables and fruits contain high amounts of carotenoids – including sweet potatoes, pumpkin, squash, carrots, broccoli, kale, spinach and collards – however, it is difficult for the body to convert these carotenoids into usable vitamin A.
Therefore, most people would benefit from taking a vitamin A supplement. Luckily, vitamin A supplements are very inexpensive and quite safe – chronic toxicity does not occur until doses reach 4000 IU/kg of body weight for 6-15 months, however, people with kidney or liver issues or that are pregnant should speak with their doctor/health care provider before supplementing with vitamin A.
Most people would benefit from 10,000-25,000 IU of vitamin A/day, with 50,000 IU/day being an upper limit.