Beta-Carotene

Beta-Carotene is an oxidative stress marker.

– Beta-Carotene is involved in antioxidant protection.

– Beta-carotene is converted into vitamin A in the liver.

– Beta-carotene & other carotenoids are converted to vitamin A (retinol), involved in vision, antioxidant & immune function, gene expression & cell growth.

– The absorption of beta-carotene and its conversion to vitamin A varies among individuals.

– The most well studied carotenoid is beta-carotene.

– Carotenoids are the plant sources of vitamin A.

– A single beta-carotene is converted to 2 molecules of vitamin A.

– Of all the carotenoids, beta-carotene is converted into retinol most efficiently.

– Supplementation with beta-carotene is a safer alternative than vitamin A.

– The conversion of beta-carotene (provitamin A) to vitamin A (retinol) is accelerated by thyroxin and is increased in hyperthyroidism.

Beta-Carotene has antioxidant and other roles independent of vitamin A. Body pools of the two compounds are maintained independently so that, unless vitamin A levels are initially low, increased intake of beta-carotene may not affect higher levels of vitamin A.

Blood concentrations of carotenoids are the best biological markers of fruit and vegetable consumption. A large body of epidemiological evidence suggests that higher blood concentrations of β-carotene and other carotenoids obtained from foods are associated with lower risk of several chronic diseases.

Because vitamin A is a fat-soluble vitamin, GI conditions affecting the absorption of fats (cystic fibrosis, pancreatic insufficiency, IBD, or small-bowel surgery) may decrease the vitamin A absorption. Patients with low vitamin A levels may have an increased risk of respiratory infections or infertility issues. If you have low vitamin A levels, a check of fatty acid levels is advised.

Supplementation with alpha-tocopherol or beta-carotene does not prevent lung cancer in older men who smoke. 

Sources of beta-carotene:

– Carrot

– Pumpkin

– Sweet potato

– Spinach

– Kale

– Turnip greens

– Beet greens

References:

– Antioxidants in health and disease: overview. [L]

– Effects of 4 y of oral supplementation with beta-carotene on serum concentrations of retinol, tocopherol, and five carotenoids. [L]

– Beta-carotene, vitamin A and carrier proteins in thyroid diseases [L]

– The status of retinoids in women suffering from hyper- and hypothyroidism: interrelationship between vitamin A, beta-carotene and thyroid hormones. [L]

– National Institutes of Health Office of Dietary Supplements: Vitamin A Fact Sheet for Health Professionals  [L]

– Beta-Carotene Is an Important Vitamin A Source for Humans [L]

– High-serum carotenoids associated with lower risk for developing type 2 diabetes among Japanese subjects: Mikkabi cohort study [L]

– Diet and Bladder Cancer: A Meta-analysis of Six Dietary Variables [L]

– alpha-Tocopherol and beta-Carotene Supplements and Lung Cancer Incidence in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study: Effects of Base-line Characteristics and Study Compliance [L]