By: Mohammad S. El-LuluMaster of Clinical nutrition

Palestine - Gaza

2

• Ascorbic acid, is a water-soluble micronutrient that iseasily excreted from the body when not needed.

• Person's age and health status can dramatically changehis or her need for vitamin C. (Levine M, 1986).

• Vitamin C is better absorbed in the presence offlavonoids.

• The buffered forms should combine vit-C with mineralslike calcium, magnesium, or potassium. Buffered vit-Cmay be helpful for individuals who have stomachsensitivity (Worthington-Roberts B., Breskin M., 1984).

3

• The protective role of vitamin C can help our skin andgums from pinpoint hemorrhage (scurvy disease).Cardiovascular diseases, cancers, and joint diseases areall associated with vitamin C deficiency and can be partlyprevented by optimal intake of vitamin C (Kurl S et al,2002).

• Vitamin C achieves much of its protective effect byfunctioning as an antioxidant and preventing oxygen-based damage to our cells. Structures that contain fat(like the lipoprotein molecules that carry fat around ourbody) are particularly dependent on vitamin C forprotection (Reaven PD, Witztum JL: 1996).

4

• The vitamin C deficiency disease called scurvy (including

bleeding gums and skin discoloration due to ruptured

blood vessels).

• Poor wound healing.

• Weak immune function, including susceptibility to colds

and other infections.

• The lining of respiratory tract depend heavily on vitamin

C for protection, respiratory infection and other lung-

related conditions can also be symptomatic of vitamin C

deficiency (Englard S, Seifter S, 1986).

5

• At high supplemental doses involving 5 or more grams of

vitamin C, diarrhea can result from the fluid in the

intestine becoming too concentrated ("osmotic diarrhea").

• Large supplemental doses of vitamin C can also increase

levels of uric acid in the urine, because vitamin C can be

broken down into uric acid. However, it is not clear that

increased uric acid in the urine can increase a person's

risk of forming uric acid kidney stones.

• Vitamin C can increase a person's absorption of iron from

plant foods (Levine M, Cantilena CC, Dhariwal KR,

1995).

6

• Collagen is one type of fiber found within connectivetissue. Collagen fibers are made from protein, and theyare somewhat unusual in having large amounts of twoamino acids, called hydroxylysine and hydroxyproline.These two amino acids seem to be important forformation of all types of collagen and are needed toprovide the different collagen types with their appropriateamount of strength and flexibility.

• Vitamin C is required to change proline intohydroxyproline (the collagen form) and lysine intohydroxylysine (once again, the collagen form) (Mirhadi SAet al., 1990).

7

• Poor intake of vitamin C-rich vegetables and fruits is acommon contributor to vitamin C deficiency.

• Smoking and exposure to second hand smoke alsoincrease the risk of vitamin C deficiency.

• The body's immune and detoxification systems makespecial use of vitamin C, and overload in either of thesesystems can increase risk of deficiency.

• The immune system protect the body from infection,including white blood cells, complement proteins,interferons; and vitamin C is especially important in thefunction of these immune components (Groff JL, GropperSS, Hunt SM, 1995).

8

• Most forms of cardiovascular disease, joint disease,

cancer, eye disease, thyroid disease, liver disease, and

lung disease require special emphasis on vitamin C

intake. The process of aging itself requires special

attention to vitamin C. In addition to these broader

categories, several specific health conditions also require

special emphasis on vitamin C. These specific health

conditions include (Subar A., Block G., 1990):

• Acne and Alcoholism, Alzheimer disease and asthma.

• Autism, depression and diabetes.

• Irritable bowel disease and Parkinsonism.

9

According to National Academy of Sciences which established the

following (RDA) Recommended Dietary Allowances in 2000 for vitamin C:

Age in years Male Female

1-3 (adequate intake) 15 mg

4-8 (adequate intake) 25 mg

9-13 45 mg

14-18 75 mg 65 mg

19 and older 90 mg 75 mg

Pregnant females 80-85 mg

Lactating females 115-120 mg

10

Food Sources

(adapted from world healthiest food; WHFood’s)

Food Serving size Calories Vit-C (mg)

Bell peppers, red, raw, slices 1 cup 24.8 174.8

Broccoli, steamed 1 cup 43.7 123.4

Strawberries 1 cup 43.2 81.70

Lemon juice, fresh ¼ cup 15.3 28.06

Grapefruit ½ each 36.9 46.86

Kiwifruit 1 each 46.4 57.00

Cantaloupe 1 cup 56.0 67.52

Oranges 1 each 61.6 69.70

Tomato, ripe 1 cup 37.8 34.38

Banana 1 each 108.1 10.75

Apples 1 each 81.4 7.87

Grapes 1 cup 61.6 3.68

Avocado, slices 1 cup 235 11.5311

12

• Every 500 mg increase in vitamin C intake, a man’s riskof gout was cut by 17 percent. And for men with vitaminC intakes of at least 1,500 mg/day, the risk of gout wascut by 45 percent, said the findings of a prospective studywith 46,994 men.

• Mechanism: Vitamin C may reduce levels of uric acid inthe blood, thereby preventing the formation of the uratecrystal. This may be achieved by vitamin C having aneffect on the reabsorption of uric acid by the kidneys.This would increase the speed at which the kidneys workor protect against inflammation, all of which may reducegout risk, they added (Choi H.K., Gao X., Curhan G.,2009).

13

• Block and her co-workers recruited 242 women aged between18 and 21. Two-thirds of the women were African-American,while the other third was Caucasian. The blood levels ofvitamin C of the women ranged from 0.22 to 3.13 mg/dL.

• During follow-up over a ten year period, the researchers notedthat blood vitamin C levels were inversely associated with bothsystolic and diastolic blood pressure.

• Mechanism: due to potential role for vitamin C via anantioxidant mechanism, there is also possibility otherfunctions. These include a role in the function of smoothmuscle function, or prevention of nitric oxide which is avasodilator or compound that opens up the blood vessels(Block G et al., 2008).

14

• Vitamin C deficiency in the first weeks and months of life mayimpair the development of neurones in the brain, anddecrease spatial memory, says an animal study fromDenmark.

• The Danish researchers took 30 new born guinea pigs andrandomly assigned them to one of two groups: One group wasfed a vitamin C-sufficient diet, while the other group was fedthe same diet but low in vitamin C. Levels of vitamin produceddeficiency, but were not extreme enough to cause scurvy.

• After two months, the animals were tested in a water maze,and hippocampal neuron numbers were measured. ProfLykkesfeldt and his co-workers report that the vitamin Cdeficient animals had a lower number of neurons in thehippocampus, and also performed worse in the maze tests(Lykkesfeldt J. et al., 2009).

• Increased intakes of vitamin C may increase the risk ofdeveloping cataracts in some elderly people, according to anew study.

• Findings from 24,593 Swedish women aged between 49 and83 indicated that vitamin C use was associated with a 25percent increase in the incidence of cataracts.

• Among the older women – over the age of 68 – vitamin Csupplements were associated with a 38 percent increase inthe risk of cataracts, report the researchers in the AmericanJournal of Clinical Nutrition.

• The findings were further complicated in women on hormonereplacement therapy, where the supplements were associatedwith a 56 percent increase in cataracts (Rautiainen S. et al.,2009).

16

• Higher levels of vitamin C from the diet may reduce the

loss of bone mineral density in elderly men.

Protective mechanism:

• Sahni and co-workers state protective effects of vitamin

C for bone health could be expected since the vitamin

could counter the effects of oxidative stress, which plays

a role in weakening of the bone by resorption.

• Furthermore, vitamin C plays an important role in the

formation of collagen, which constitutes 90 percent of the

bone matrix (Sahni S. et al., 2008).

17

• Vitamin C may reduce the effectiveness of chemotherapyby protecting the cancer cells.

• Using lymphoma and leukemia cell lines with and withoutpre-exposure to dehydroascorbic acid (DHA), Heaneyand his co-workers investigated the effects of the anti-cancer drugs doxorubicin, cisplatin, vincristine,methotrexate, and imatinib.

• They found that the efficacy of the chemotherapy drugstested was greatly reduced if the cells were pre-treatedwith vitamin C, compared to untreated cancer cells.Indeed, the reduction ranged from 30 to 70 percent,report the researchers (Heany et al., 2008).

18

• Administration of a physiological dose of [6S]-5-MTHF

• [6S]-5-methyl-tetra-hydro-folate with L-ascorbic acid

significantly improved the measured serum folate

response in folate saturated healthy men.

• When [6S]-5-MTHF was concurrently administered with

289.4 or 973.8 mg [vitamin C], the total serum folate

response was significantly improved (46.54.0 and

53.04.0 versus 34.33.8 h nmol/l) (Verlinde P.H.C.J et al.,

2007).

19

• Increased blood levels of vitamin C may reduce the risk

of developing diabetes by 62 percent, says a study from

Cambridge.

• “Fruit and vegetable consumption may be protective for

diabetes risk, at least partially, through its effect on

obesity.”

• Oxidative stress, the situation in which an imbalance

between the levels of reactive oxygen species and

antioxidants exists, can lead to disturbed glucose

metabolism and hyperglycaemia (Harding A. et al).

20

• Increased blood levels of vitamin C may reduce the risk ofstroke by 42 percent, suggests a large European-based study.

• Strokes occur when blood clots or an artery bursts in the brainand interrupts the blood supply to a part of the brain.

• Myint and co-workers followed the subjects for 9.5 years anddocumented 448 strokes during this time. The subjectscompleted a health and lifestyle questionnaire at the start ofthe study, and blood samples were taken to measure vitaminC levels.

• The highest average blood levels of vitamin C (greater than 66micromoles/litre) were associated with a 42 percent lower riskof stroke, compared to the lowest average blood levels (lessthan 41 micromoles/litre) (Myint P.K.et al, 2008).

21

References:• Block G, Jensen C.D., Norkus E.P., Hudes M., Crawford P.B., (2008). Vitamin C in plasma is

inversely related to blood pressure and change in blood pressure during the previous year in young

Black and White women. Nutrition Journal. 7:35 doi:10.1186/1475-2891-7-35.

• Choi H.K, Gao X., Curhan G., (2009). Vitamin C Intake and the Risk of Gout in Men: A Prospective

Study. Archives of internal medicine. 169 (5): 502-507.

• Englard S, Seifter S (1986). The biological functions of ascorbic acid. Ann Rev Nutr 1986;6:365-

406.

• Groff JL, Gropper SS, Hunt SM (1995). Advanced Nutrition and Human Metabolism. West

Publishing Company, New York, 1995.

• Harding A.-H, Wareham N.J., Bingham S.A., Khaw K., Luben R., Welch A., Forouhi N.G. Plasma

Vitamin C Level, Fruit and Vegetable Consumption, and the Risk of New-Onset Type 2 Diabetes

Mellitus - The European Prospective Investigation of Cancer - Norfolk Prospective Study. Archives

of Internal Medicine. 168 (14): 1493-1499.

• Heaney M.L., Gardner J.R., Karasavvas N., Golde D.W., Scheinberg D.A., Smith E.A., O’Connor

O.A, (2008). Vitamin C Antagonizes the Cytotoxic Effects of Antineoplastic Drugs. Cancer

Research. Volume 68: 8031-8038. doi: 10.1158/0008-5472.CAN-08-1490.

• Kurl S, Tuomainen TP, Laukkanen JA et al (2002). Plasma vitamin C modifies the association

between hypertension and risk of stroke. Stroke 2002 Jun;33(6):1568-73.

• Levine M (1986). New concepts in biology and biochemistry of ascorbic acid. N Engl J Med

1986;314:892-902.

• Levine M, Cantilena CC, Dhariwal KR (1995). Determination of optimal vitamin C requirements in

humans. Am J Clin Nutr 1995;62(suppl):1347S-1356S.

22

References:• Lykkesfeldt J., Tveden-Nyborg P., Johansen L.K., Raida Z., Villumsen C.K., Larsen J.O., (2009).

Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of

hippocampal neurons in guinea pigs. American Journal of Clinical Nutrition. doi:

10.3945/ajcn.2009.27954.

• Mirhadi SA, Singh S, Gupta PP (1990). Effect of Garlic Supplementation to Atherogenic Diet on

Collagen Biosynthesis in Various Tissues of Rabbits. Indian Heart J.;42(2):99-104.

• Myint P.K., Luben R.N., Welch A.A., Bingham S.A., Wareham N.J., Khaw K.-T, (2008). Fruit and

vegetables: think variety, go ahead, eat!. American Journal of Clinical Nutrition. Volume 87: 5-7.

• Rautiainen S., Ejdervik Lindblad B., Morgenstern R., Wolk A., (2009). Vitamin C supplements and

the risk of age-related cataract: a population-based prospective cohort study in women.

doi:10.3945/ajcn.2009.28528.

• Reaven PD, Witztum JL (1996). Oxidized low density lipoproteins in atherogenesis: role of dietary

modification. Ann Rev Nutr 1996;16:51-71.

• Sahni S., Hannan M.T., Gagnon D., Blumberg J., Cupples L.A., Kiel D.P., Tucker K.L., (2008). High

vitamin C intake is associated with lower 4-year bone loss in elderly men. Journal of Nutrition.

Volume 138: 1931-1938.

• Subar A, Block G (1990). Use of vitamin and mineral supplements. Am J Epidem 1990;132:1901-

1011.

• Worthington-Roberts B, Breskin M (1984). Supplementation patterns of Washington State

dietitians. J Am Diet Assoc 1984;84(7):795-800.

• Verlinde P.H.C.J., Oey I., Hendrickx A.M., Van Loey A.M., Temme E.H.M., (2007). L-ascorbic acid

improves the serum folate response to an oral dose of [6S]-5-methyltetrahydrofolic acid in healthy

men. European Journal of Clinical Nutrition. doi: 10.1038/sj.ejcn.1602840.

23

24