Vitamin C and common cold

DONE BY: EMAN AL-ZAWWAD

Vitamin C

It is an essential water-solube vitamin. known as Ascorbic acid and Dehydroascorbic acid Most animals are able to synthesize vitamin c However; Human, other primates, guinea pigs, fruit bats,

few birds and most fish are unable to synthesize it Because human are missing L-gulonolactone oxidase

enzyme , they can’t .

History

Back in history, Szent-Gyorgyi (1928) and King (1932) were the

discoverers of vitamin C when scurvy disease hit people and

caused huge numbers of deaths. At that time, they found that

there is an association between scurvy and lack of vitamin C and

were awarded the Nobel Prize in 1937.

https://www.youtube.com/watch?v=BOGO86Y_Chw

Sources of Vitamin C

Because the human body cannot synthesize vitamin C, the main source to get it from is food. There are many food sources of Vitamin C such as papaya, oranges, asparagus, cantaloupe, cauliflower, broccoli, Brussels sprouts, green peppers, grapefruit, kale, lemon, and strawberries.

Other source of vitamin C is from supplements. Vitamin C supplements contain free ascorbic acid, calcium ascorbate, sodium ascorbate, and ascorbyl palmitate. Moreover, vitamin C comes from rose’s seeds capsule which is used commercially in vitamin C supplements

Absorption –Transport- Storage and Excretion of Vitamin C

Vitamin C doesn’t need to be digested to go through the absorption process as other macronutrients. Ascorbate goes directly for absorption which occurs mostly in the ileum of the small intestine across the brush border by at least two different sodium-dependent co-transporters, designated SVCT1 and SVCT2.

Diffusion of vitamin C occurs faster through anion channels than Transporters

Cont. absorption

The degree of vitamin C absorption is affected by the amount of vitamin c intake and by glucose.

When vitamin C intake increases, the absorption of vitamin C decreases

When there is high intracellular glucose, the absorption of ascorbat decreases which refers to ascorbate transporter.

Transport of vitamin c

vitamin C is transported in plasma and into cells. It is present in plasma primarily as ascorbate complexed to albumin.

Vitamin C transports into cells as dehydroascorbate acid and is reduced to acorbate via dehydroascorbate reductase which means using Glutathion.

However, the content of vitamin C in cells is higher than plasma. For instance, in white blood cells, the concentration of vitamin C is actually 80 times higher than plasma.

Storage and excretion

Vitamin C can be stored in pituitary and adrenal glands because

they have the highest concentration of vitamin C. Also, it can be

stored in white blood cells in case of chronic intake and in the

eyes and brain. On the other hand, the excess amount of vitamin

C spills directly into urine.

Functions

Antioxidant capability ‘’ destroy superoxide radicals & other free radicals before they damage DNA & lipids – regenerate active antioxidant from vitamin E-

Reducing agent ‘’ donate electrons to metal ions such as ferric iron(Fe+3) and facilitate its absorption in the GI tract.

Synthesis of neurotransmitters, collagen, carnitine & tyrosine

Vitamin C has a preventive effect against cancer and cardiovascular disease

Support the immune system

RDA

Men: 90 mg/day Women: 75 mg/day pregnant women: 100 mg/day During lactation: 120 mg/ day Smokers need an additional 35 mg/ day

Vitamin C Intake above or below the RDA

Based on recommendations, deficient intake of vitamin C may

lead to a disease called scurvy, whereas higher increase intake

can lead to toxicity.

Vitamin c deficiency

Scurvy

It occurs when the daily intake of vitamin C is less than 10 milligrams and the total

body of acorbate falls to less than 300 milligrams

it takes 45-80 days after vitamin C intake stops to occur.

signs and symptoms: include decreased synthesis of connective tissue and collagen

everywhere in the body, pinpoint hemorrhages, easy bruising, skin discoloration,

bleeding gums and joints, loosing teeth, and impaired healing of wounds.

Individuals at risk

it develops in some people who take huge amounts of vitamin C and then suddenly stop.

Also, it develops in alcoholism and smokers, as well as people who have diabetes mellitus or cancers.

People who live in poverty are at risk of having vitamin C deficiency due to the poor diet that they have.

Moreover, infants who only take milk may get deficiency in vitamin c because milk is considered a very poor source of this type of vitamin.

Toxicity

It is usually not caused by eating a diet that is high in vitamin C, but it develops from taking too many supplements at one time. For example, taking two grams of vitamins as single dose

Also, There are groups of people that must avoid mega-doses of vitamin C, such as people who are prone to gout, and kidney stones and people with disturbance of iron metabolism such as in thalassemia, hemochromatosis, and sideroblastic anemia.

The adverse effects of toxicity include gastrointestinal problems such as abdominal cramps, nausea, and diarrhea.

Effect of Vitamin C on Common Cold

Because vitamin C has an immune function to fight disease to some extent, studies found vitamin c may used to treat and prevent the common cold.

A number of studies have found that vitamin C levels are decreased in plasma, leucocytes and in urine during various infections, including the common cold and pneumonia (Harri Hemila, 2003).

Literature Review

Sasazuki et al. (2006) in their study aimed to find the relationship between Vitamin C supplementation and the common cold. They did the study in countries that have the highest mortality from gastric cancer which are Japan and Akita. Thus, all people who were diagnosed as having atrophic gastritis were included in the population of the study. The research included 144 subjects which were assigned to get 50 mg of Vitamin C whereas 61 subjects which were assigned to receive 500 mg of Vitamin C. Researchers found that the incidences of the common cold were 21.3 % for the low dose and 17.1% for the high-dose groups. In addition, the reduction of severity and duration of the common cold were not really significant. Sasazuki et al. (2006) concluded that the Vitamin C supplementation is able to reduce the incidence, but it does not have an extreme impact on the duration or severity of common cold.

Cont.

Another study was conducted by Milne (2008) was aimed to find whether oral doses of 0.2 g/day or more of Vitamin C reduces the incidence, duration, or severity of the common cold if it used as continuous prophylaxis, or after the onset of symptoms. In this study, All ages and genders were included.

Milne (2008) concluded that Vitamin C supplementation when it is taken regularly can reduces duration and severity of common cold during the prophylactic supplementation period and therapeutic period for ordinary population, but it has no effect on incidence. Vitamin C decreases incidence only for athletic population who are under severe acute physical stress.

References

Gropper, S., Smith, J., & Groff, J. (2009). Chapter 9: The Water-Soluble Vitamins. Advanced nutrition and human metabolism (5th ed., pp. 309-372). Belmont:

Wadsworth/Cengage Learning Mechanisms of symptoms of common cold and flu. (2009). In R. Eccles & O.

Weber (Eds.),Common cold (pp. 23-45). Basel: Birkhauser. Milne, A. (2008). Summary of ‘Vitamin C for preventing and treating the

common cold’. EVIDENCE-BASED CHILD HEALTH: A COCHRANE REVIEW JOURNAL, 3(3), 721-722.

Sasazuki, S., Sasaki, S., Tsubono, Y., Okubo, S., Hayashi, M., & Tsugane, S. (2006). Effect Of Vitamin C On Common Cold: Randomized Controlled Trial. European Journal of Clinical Nutrition, 60(1), 9-17. Retrieved from

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