Think Beyond Carrots!

Soundharya Subramanian, BSc Clinical Nutrition,

M.Sc. Clinical Nutrition (Student), MMM College of Health Sciences, Chennai, India

Introduction

Vitamin A is a fat-soluble vitamin which plays a major role in vision, reproduction, growth, and maintenance of epithelial and bone structures. In the body, vitamin A exists as retinol, retinal and retinoic acid. The other two members of the vitamin A family of compounds are retinyl esters and β-carotene. ⁽¹⁾

Sources of vitamin A

• Vitamin A is obtained from the diet through animal (preformed vitamin A) and plant sources (pro-vitamin A) in the form of retinol and carotenoids. ⁽¹⁾
• Retinol is the principal dietary form of vitamin A which are readily absorbed into the body. They are commonly found in liver, meats, eggs, milk products, and fatty fish. ⁽¹⁾
• Carotenoids are lipid-soluble pigments responsible for the colour of a wide variety of fruits and vegetables. They are provitamin A which are subsequently transformed into vitamin A.⁽³⁾
• Carotenoids pigments are classified based on their chemical composition as either carotenes (hydrocarbon carotenoids) or xanthophylls (oxygen-containing carotenoids). ⁽³⁾
• There are about 700 carotenoids in nature, but only about 50 have provitamin activities. Of those 50 compounds, the three most important precursors of vitamin A in humans are α-carotene, β-cryptoxanthin, and β-carotene. β-Caroteneis the most prominent member of the group of carotenoids.⁽²⁾
• Carotenoids exist in four forms: beta-carotene, alfa-carotene, gamma-carotene, and beta-cryptoxanthin that can each be converted to retinol (vitamin A). The other carotenoids are lycopene, lutein, and zeaxanthin which function as antioxidants, but are not converted to retinol (vitamin A). ⁽³⁾
• Alpha-carotenes & Beta-carotenes: They are yellow, orange and greens pigments of fruits and vegetables.⁽⁴⁾

• Yellow-orange vegetables: Carrots, Sweet potatoes, Pumpkin, Winter squash. ⁽⁴⁾
• Dark-green-vegetables: Broccoli, Green-beans, Green peas, Spinach, Turnip greens, Collards, Leaf lettuce and Avocado. ⁽⁴⁾
• Beta cryptoxanthin: Foods that are rich in beta-cryptoxanthin include tangerines, persimmons and oranges, corn, and peaches. ⁽⁴⁾
• Lycopene: They are red pigments found in grapefruit, watermelons, and papaya and tomatoes. ⁽⁴⁾
• Lutein and zeaxanthin: Lutein and zeaxanthin are the most common xanthophylls in green leafy vegetables like kale, spinach, broccoli, peas and lettuce and egg yolks.⁽⁴⁾

     References:

• Srilakshmi, B. (2006). Nutrition Science. New Age International.
• Nieves, J. W. (2013). Alternative Therapy through Nutrients and Nutraceuticals. In Osteoporosis (pp. 1739-1749). Academic Press.
• Mander, L., & Liu, H. W. (2010). Comprehensive natural products II: Chemistry and Biology(Vol. 1). Elsevier.
• Caballero, B., Trugo, L. C., & Finglas, P. M. (2003). Encyclopaedia of food sciences and nutrition. Academic. Pg. 927 – 936.