Vitamin C

Introduction

Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component [1]

Vitamin C is required for the biosynthesis of collagen, L-carnitine, and sure neurotransmitters; vitamin C is also worried in protein metabolism [1,2]. Collagen is an vital element of connective tissue, which performs a crucial function in wound recuperation. Vitamin C is likewise an essential physiological antioxidant [3]] and has been proven to regenerate different antioxidants in the frame, such as alpha-tocopherol (vitamin E)

The intestinal absorption of diet C is regulated by at the least one precise dose-based, energetic transporter [4]. Cells collect diet C via a 2d specific shipping protein. In vitro research have determined that oxidized nutrition C, or dehydroascorbic acid, enters cells via a few facilitated glucose transporters and is then reduced internally to ascorbic acid. The physiologic significance of dehydroascorbic acid uptake and its contribution to standard nutrition C economic system is unknown.

Oral diet C produces tissue and plasma concentrations that the frame tightly controls. Approximately 70%–ninety% of diet C is absorbed at moderate intakes of 30–180 mg/day. However, at doses above 1 g/day, absorption falls to less than 50% and absorbed, unmetabolized ascorbic acid is excreted inside the urine [4]. Results from pharmacokinetic research imply that oral doses of one.25 g/day ascorbic acid produce mean top plasma vitamin C concentrations of 135 micromol/L, which can be approximately  instances higher than the ones produced by consuming 2 hundred–three hundred mg/day ascorbic acid from diet C-rich foods [10]. Pharmacokinetic modeling predicts that even doses as excessive as 3 g ascorbic acid taken every four hours could produce top plasma concentrations of only 220 micromol/L [10].

The overall frame content material of nutrition C stages from 300 mg (at close to scurvy) to about 2 g [4]. High stages of nutrition C (millimolar concentrations) are maintained in cells and tissues, and are maximum in leukocytes (white blood cells), eyes, adrenal glands, pituitary gland, and mind. Relatively low degrees of vitamin C (micromolar concentrations) are observed in extracellular fluids, inclusive of plasma, crimson blood cells, and saliva [4].

Recommended Intakes

Intake tips for vitamin C and other nutrients are provided in the Dietary Reference Intakes (DRIs) advanced through the Food and Nutrition Board (FNB) at the Institute of Medicine (IOM) of the National Academies (previously National Academy of Sciences) [8]. DRI is the general time period for a hard and fast of reference values used for making plans and assessing nutrient intakes of healthy people. These values, which range through age and gender [8], consist of:

Recommended Dietary Allowance (RDA): Average daily stage of intake sufficient to meet the nutrient necessities of almost all (97%–ninety eight%) healthful people; often used to plot nutritionally ok diets for individuals.

Adequate Intake (AI): Intake at this level is believed to make sure dietary adequacy; mounted whilst proof is insufficient to expand an RDA.

Estimated Average Requirement (EAR): Average each day degree of intake predicted to meet the necessities of fifty% of healthful individuals; normally used to evaluate the nutrient intakes of groups of humans and to devise nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals.

Tolerable Upper Intake Level (UL): Maximum daily consumption unlikely to motive adverse fitness consequences.

Table 1 lists the modern RDAs for diet C [8]. The RDAs for nutrition C are based totally on its recognized physiological and antioxidant features in white blood cells and are lots higher than the quantity required for protection from deficiency [4,8,11]. For toddlers from start to twelve months, the FNB hooked up an AI for vitamin C that is equal to the suggest consumption of diet C in healthful, breastfed babies.

Table 1: Recommended Dietary Allowances (RDAs) for Vitamin C [8]

Age Male Female Pregnancy Lactation

zero–6 months forty mg* 40 mg*  

7–12 months 50 mg* 50 mg*  

1–3 years 15 mg 15 mg  

4–8 years 25 mg 25 mg  

9–13 years 45 mg 45 mg  

14–18 years seventy five mg sixty five mg eighty mg 115 mg

19+ years ninety mg seventy five mg eighty five mg a hundred and twenty mg

Smokers Individuals who smoke require 35 mg/day

extra nutrition C than nonsmokers.

* Adequate Intake (AI)

Sources of Vitamin C

Food

Fruits and greens are the exceptional assets of nutrition C (see Table 2) [12]. Citrus culmination, tomatoes and tomato juice, and potatoes are foremost members of diet C to the American food plan [8]. Other true meals resources include purple and green peppers, kiwifruit, broccoli, strawberries, Brussels sprouts, and cantaloupe (see Table 2) [8,12]. Although diet C isn't naturally found in grains, it's miles introduced to some fortified breakfast cereals. The vitamin C content of food may be decreased by means of prolonged garage and by cooking because ascorbic acid is water soluble and is destroyed by using warmth [6,8]. Steaming or microwaving may reduce cooking losses. Fortunately, the various great meals resources of nutrition C, which include culmination and greens, are typically ate up uncooked. Consuming 5 numerous servings of end result and vegetables a day can provide greater than 2 hundred mg of vitamin C.

Table 2: Selected Food Sources of Vitamin C [12]

Food Milligrams (mg) per serving Percent (%) DV*

Red pepper, sweet, uncooked, ½ cup ninety five 158

Orange juice, ¾ cup ninety three a hundred and fifty five

Orange, 1 medium 70 117

Grapefruit juice, ¾ cup 70 117

Kiwifruit, 1 medium 64 107

Green pepper, candy, uncooked, ½ cup 60 one hundred

Broccoli, cooked, ½ cup fifty one eighty five

Strawberries, sparkling, sliced, ½ cup forty nine 82

Brussels sprouts, cooked, ½ cup forty eight 80

Grapefruit, ½ medium 39 65

Broccoli, uncooked, ½ cup 39 65

Tomato juice, ¾ cup 33 fifty five

Cantaloupe, ½ cup 29 forty eight

Cabbage, cooked, ½ cup 28 forty seven

Cauliflower, raw, ½ cup 26 43

Potato, baked, 1 medium 17 28

Tomato, raw, 1 medium 17 28

Spinach, cooked, ½ cup nine 15

Green peas, frozen, cooked, ½ cup 8 thirteen