Vitamins - Why and how much to eat?

Author: Dr. Shunmukha Priya. S

**** In 1912, Casimir Funk, named “ Vitamine ” means “ vital amines ” which was similar to amino acids that were considered to be responsible for preventing a wide range of diseases that we recognised now as vitamin deficiencies. He coined the term “ vitamines ” to define these organic substances that were known as essential for life. Finally, when scientists identified that these compounds were not amines, the ‘ e ’ was dropped to form the term “vitamins.” 1

Vitamin are micronutrient required in small quantities for the normal functioning of the body. Though required in small quantities, the absence of vitamins can lead to abnormal functioning of the body as well as deficiency diseases. These vitamins can be alcohols, aldehydes, organic acids or their derivatives as well as nucleotides or their derivatives.

Classification of Vitamins

Vitamins is generally classified into fat-soluble vitamins and water-soluble vitamins based on their solubility.

Fig. 1

Fat-Soluble Vitamins

Vitamins such as A, D, E and K are fat-soluble. These vitamins are soluble in fat and fat solvents and insoluble in water. For absorption of these vitamins, bile salts or fat is required. These vitamins are usually stored in adipose tissues and the liver. Cooking will not destroy fat-soluble vitamins

Table:1 Vitamins, alternative form, source, functions and RDA

Vitamin	Alternative Forms	Sources	Functions	RDA****6
A	Retinol, Retinal, Retinoic Acid, Beta-Carotene (Plant Version)	**Animal sources (retinol):Fortified MilkCheeseCreamButterFortified MargarineEggsLiverPlant sources:**Dark green leafy vegetablesDark orange fruits such as Apricot, Papaya, MangoVegetables such as carrots, pumpkin sweet potatoes	Normal visionThe integrityof epithelial cells in the mucous membranes and skinReproductionEmbryonic developmentGrowthImmune response	M –1000 µg/dF-840 µg/d
D	Calciferol, Calcitriol(1,25-dihydroxy vitamin D1 or vitamin D hormone), Cholecalciferol (D3-plant version)Ergocalciferol (D2- animal version)	Egg yolks,liver,fatty fish,fortified milk,fortified margarine.When the skin is exposed to sunlight,particularly between**10 am to 3 pm IST,**vitamin D is synthesized.	Maintains the levels of calcium and phosphorus in the bloodProper mineralization of bonesSupports immune functionRegulates insulin levelSupports lung functionNervous system healthCardiovascular health	400 IU/d7
E	Alpha-Tocopherol, Tocopherol, Tocotrienol	Polyunsaturated plant oils (soybean, corn, cottonseed, safflower)Green leafy vegetableswheat germwhole-grain productsliveregg yolksnuts and seeds	Potent antioxidant;Interrupt free radical chain reactionsProtection of polyunsaturated fatty acidsCell membranesSlows theageingprocess	7.5 – 10 .0 µg/d7
K	Phylloquinone, Menaquinone, Menadione, Naphthoquinone	Green leafy vegetables such as kale, collard greens, and spinachGreen vegetables such as broccoli, Brussels sprouts, and asparagusProduced in the intestinal tract by bacteria	Clotting of BloodSynthesis ofproteinsBone metabolism	55 µg/d7

2. Water -Soluble Vitamins

Vitamins in B-group also known as B-Complex and vitamin C are water-soluble and cannot be stored in our body. These vitamins travel freely in the body, and excess amounts are excreted by the kidneys. Hence, our body needs water-soluble vitamins regularly in adequate quantities. Unlike fat-soluble vitamins, these vitamins are not as likely to reach toxic levels. But a few water-soluble vitamins such as niacin, vitamin B6, folate, choline, and vitamin C have upper consumption limits. Vitamin B6 at higher levels over a long period of time has been shown to cause irreversible nerve damage.

Table: 2 Vitamins, alternative form, source, functions and RDA

Vitamin	Alternative Forms	Sources	Functions	RDA
Vitamin B1	Thiamine	Whole-grain foodsWhole wheatBran of riceUndermilled milletsLegumes and PulsesEnriched bread and cerealsNuts and seeds	Component of a coenzyme in the carbohydrate metabolismSupportsthefunctioning of the nervous systemConverts amino acid tryptophan to the vitamin niacinMetabolism of amino acids	M-1.2; 1.5; 1.9 mg/dF-1.2; 1.4; 1.8 mg/dFor sedentary, moderate and heavy activity
Vitamin B2	Riboflavin	Milk and milk productsGreen leafy vegetables – tender leaves and buds have more riboflavin content than mature onesWhole-grain foodsEnriched bread and cerealsLotus stemEggLiver	Acts as a component of coenzymes required for energy productionInvolved in the metabolism of lipids, vitamins, mineralsAntioxidantConverts amino acid tryptophan to the vitamin niacinProduction of hormones in adrenal glands	M-1.6; 2.1; 2.7 mg/dF-1.6; 2.0; 2.6 mg/dFor sedentary, moderate and heavy activity
Vitamin B3	NiacinNicotinic acid, Nicotinamide	Whole-grain foodsEnriched breadVegetables such as mushroomsGreen leafy vegetablespeanut butterMeatPoultryFish	Component of coenzymes many biological pathwaysUsed in the cellular metabolismOxidation of fuel moleculesSynthesis of fatty acids and steroidsSkin healthDigestive health	M-12; 15; 19 mg/dF-9; 12; 15 mg/dFor sedentary, moderate and heavy activity
Vitamin B5	Pantothenic acid	Fortified cerealsLiverChicken breastMushrooms.Avocado.Nuts, seeds.Milk and its products	Acts as a component of coenzyme AEssential for themetabolism of macronutrients.A cofactor for elongation of fatty acids	5mg/d8
Vitamin B6	Pyridoxine, Pyridoxal, Pyridoxamine	MeatFishPoultryGroundnutGarden cress seedsLegumesWheat bran and wheat germWhole cerealsDried Yeast	component of coenzymes in the metabolism of amino acids and other nitrogen-containing compoundsSynthesis of haemoglobinSynthesize neurotransmitters;Regulates blood glucose levelsImmunity	M-1.6; 2.1; 2.6 mg/dF-1.6; 1.6; 2.1 mg/dFor sedentary, moderate and heavy activity
Vitamin B7	Biotin	Present widely in foodsAlso produced in the intestinal tract by bacteria	Acts as a cofactor in the metabolism ofcarbohydrates, fatty acids, and amino acids.	40µg/d8
Vitamin B9Folic acid	Folate, Folacin, Pteroylglutamic acid	LiverAdded to most refined grainsDried YeastGreen leafy vegetablesLegumesSeedsOrange juice	Maturation of red blood cellscomponent of coenzymes in the DNA synthesisMetabolism of amino acidsRequired for cell divisionMaturation of red blood cells	M-250µg/dF-180µg/d
Vitamin B12	Cobalamin, Cyanocobalamin	MeatPoultrySeafoodEggsMilk and its productsnot found in plant foods	Cofactor for enzymes in the metabolism of amino acids (including folic acid) and fatty acidsEssential for the synthesis of new cellPreventsanaemiaNeurological function	2 µg/d6
Vitamin C	Ascorbic acid	Only in fruits and vegetables,Citrus fruits,Vegetables in the cabbage family,strawberries,Peppers,TomatoesLettuce,Papayas,Mangoes, Kiwifruit	Antioxidant;Synthesis of collagen, carnitine, amino acids, and hormones;Immunity enhancerImproves absorption of non-haeme iron (from plant foods)	M- 65mg/dF- 55mg/d

M- Male; F- Female; Here only RDA for adults were considered.

References

• Carpenter, K. J. (2003). A short history of nutritional science: part 3 (1912–1944). The Journal of nutrition, 133(10), 3023-3032.
• Bamji, M.S., Krishnaswamy, K. and Brahmam, G.N.V (2019)., The Textbook of Human Nutrition. Fourth Ed., Oxford & IBH Publishing Co Pvt. Ltd., New Delhi., 600P.
• Albahrani, A. A., & Greaves, R. F. (2016). Fat-Soluble Vitamins: Clinical Indications and Current Challenges for Chromatographic Measurement. The Clinical biochemist. Reviews, 37 (1), 27–47.
• https://openoregon.pressbooks.pub/nutritionscience/chapter/8a-classification-vitamins-minerals/