Beef liver is a nutritious organ meet that is low in sodium, fat and calories and high in protein, vitamins and minerals. In particular, it is one of the richest sources of vitamin A which is an important vitamin that plays a role in a variety of biological processes. Deficiencies in vitamin A can lead to vision and skin problems, impaired immunity and blood cell production and diarrhea.
Forms
The term vitamin A is an umbrella term as it encompasses a variety of forms of the vitamin as well as compounds that are converted into vitamin A in the body. The two categories of vitamin A include the retinoids, which come from animals, and the carotenoids, which come from plants. The retinoids or preformed vitamin A include retinol, retinal and retinoic acid which are the active forms of vitamin A and retinyl palmitate, which is a precursor to retinol and the most common form found in animal products, according to the Linus Pauling Institute. The most common carotenoids include alpha-carotene, beta-carotene and beta-cryptoxanthin. These carotenoids are often called provitamin A because they are converted into vitamin A in the body.
Vitamin A Content of Beef Liver
A single slice or 68 grams of braised beef liver contains 21,565 International Units or IU's of vitamin A which is equal to 431 percent daily value of Vitamin A, based upon a 2,000 calorie diet, according to Calorie Lab. The Vitamin A in beef liver is in the form of retinol, retinol activity equivalents, beta and alpha carotene and beta cryptoxanthin. The majority of the Vitamin A is in the form of retinol and retinol activity equivalent with 6,411 mcg and 6420 mcg, respectively. There are 110 micrograms of beta-carotene and 7.5 mcg each of alpha carotene and beta cryptoxanthin.
Functions
Vitamin A is important for a variety of functions including vision, growth and development, cell reproduction and immunity. Vitamin A in the form of retinol and retinal helps produce the pigments of the retina in the back of the eye that convert light into nerve impulses. Vitamin A is essential for embryonic and fetal development as it regulates gene expression and supports the development of the heart, eyes and ear, according to the Linus Pauling Institute. Vitamin A also supports the immune system through its role in white blood cell development and maintenance of the integrity of defensive mucosal cells lining the airways, digestive tract and urinary tract.
Dietary Reference Intakes
The Institute of Medicine recommends 900 micrograms or 3,000 IU's per day for adult men and teenagers age 14 and older and 700 mcg or 2,333 mcg per day for adult women and teenagers age 14 and older. Lactating women need to consume approximately 1300 mcg of vitamin A per day or 4333 IU's. Adolescents between the ages of 9 and 13 should consume 600 mcg or 2000 IU's of vitamin A per day. Children and infants need 300 to 500 mcg per day or approximately 1000 to 1600 IU's, according to the University of Maryland Medical Center. The tolerable upper limit for vitamin A is 10,000 IU's per day, which is the maximum amount that can be taken per day that won't cause adverse effects.
References
- Calorie Lab: Beef, variety meats and by-products, liver, cooked, braised Nutrition Facts
- Institute of Medicine: Dietary Reference Intakes (DRIs)
- University of Maryland Medical Center: Vitamin A (Retinol)
- Oregon State University Linus Pauling Institute: Vitamin A
- MedlinePlus: Vitamin A
- Office of Dietary Supplements: Dietary Supplement Fact Sheet: Vitamin A and Carotenoids
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