In today’s blog Nutrition Nourishment are reviewing Vitamin C with a quick Q & A for all your health related facts. Want to know what role Vitamin C plays in the body? How much do you need to have in your daily diet? What can Vitamin C do for you??Then continue to read on…
1. How stable is vitamin C?
The stability of ascorbic acid decreases with a rise in temperature and PH. This destruction by oxidation is a serious problem in that a considerable quantity of vitamin C contents is lost during processing, storage and preparation.
Vitamin C content can be affected by season, transport, shelf life, storage time, cooking practices and chlorination of water. Cutting, bruising, heating and exposure to copper, iron or mildly alkaline conditions can destroy ascorbate. It can also be leached into water during cooking.
2. How does dosage affect the absorption of vitamin C?
Transport of vitamin C is a saturable and dose dependent process that occurs by active transport. At the intestine and cells AA is oxidized to DHAA, which is more quickly transported across the cell membrane. Once inside the tissue or intestinal epithelium, the vitamin is reduced back to AA. The degree of intestinal absorption decreases as intake of AA increases. Intakes of 1 to 1.5 grams results in 50% absorption, but at intakes over 12 grams, only 16% of the vitamin is absorbed. In contrast, an intake of less than 20 mg, has a 98% absorption rate. Absorption of vitamin C is greater when several individual doses of vitamin C, in quantities less than one gram, are taken throughout the day rather than one megadose.
A single large dose saturates the enzyme kinetics for vitamin C, leading to excess AA in the intestinal lumen, which causes numerous gastrointestinal problems.
3. List five functions of vitamin C.
Structure of bone and teeth
Immune System Function
Production of hormones
Mineral absorption and utilisation
4. How does vitamin C affect iron absorption?
The absorption of heme iron is not significantly impacted by other foods, while non-heme iron is strongly influenced by foods that may enhance or inhibit its absorption.
The key role of ascorbic acid for the absorption of dietary non-heme iron is generally accepted. The reasons for its action are twofold: (1) the prevention of the formation of insoluble and un-absorbable iron compounds and (2) the reduction of ferric to ferrous iron, which seems to be a requirement for the uptake of iron into the mucosal cells.
5. What are the signs / symptoms of scurvy?
Vitamin C deficiency causes scurvy, symptoms include fatigue, pain in extremities, haemorrhages, a decrease in integrity of the blood vessels, oedema, ulcerations, muscle weakness due to defects in collagen metabolism and death. In infantile scurvy, the changes are mainly at the sites of active bone growth and include pseudo paralysis of the limbs. In severe scurvy, haemorrhages may be more severe and include epistaxis, bleeding into joints, periotoneal cavity, pericardial sack and adrenals.
6. Why do smokers have a higher recommended intake of vitamin C?
Smoking causes vitamin C to be used up much more quickly by the body, so smokers need to add an extra 35 milligrams per day to the RDI because of the great stress on their lungs form oxidative damage and toxic by-products of cigarette smoke. Adding an extra piece of fruit to the daily diet would more than cover this extra requirement for vitamin C.
7. How does the RDI for vitamin C compare to the amount required for disease prevention?
Vitamin C is a powerful functional food ingredient with numerous health applications. Proper intake over a lifetime helps to maintain our current health and prevent future ailments. At least 10 mg daily will prevent clinical deficiency and scurvy; but current research suggests 90-500 mg daily for optimal benefits. Much higher doses (many beyond the 2 g UL) are used in the clinical setting, with the greatest blood plasma levels achieved through IV injection. Proper doses for treatment are extremely variable, and depend upon the disease being treated. The risks of high- dose vitamin C supplementation are almost negligible when compared to some current treatments. That being said, extremely high-doses should be administered with caution and treated as a pharmaceutical agent. In regards to disease management, continued clinical and epidemiological research will help to further understand and confirm the positive health effects from vitamin C in the prevention and treatment of numerous conditions. In terms of the general public, studies on the long-term effects of over-the-counter oral supplementation should be focused on, due to increasing awareness of vitamin C benefits. Future studies should also focus on how to safely and effectively implement vitamin C into diets of populations at-risk for deficiency
8. What role does vitamin C play in the prevention of cardiovascular disease?
The ability of blood vessels to relax or dilate (vasodilation) is compromised in individuals with atherosclerosis. Damage to the heart muscle caused by a heart attack and damage to the brain caused by a stroke are related, in part, to the inability of blood vessels to dilate enough to allow blood flow to the affected areas. The pain of angina pectoris is also related to insufficient dilation of the coronary arteries. Impaired vasodilation has been identified as an independent risk factor for cardiovascular disease. Many randomized, double-blind, placebo-controlled studies have shown that treatment with vitamin C consistently results in improved vasodilation in individuals with coronary heart disease, as well as those with angina pectoris, congestive heart failure, diabetes, high cholesterol, and high blood pressure. Improved vasodilation has been demonstrated at an oral dose of 500 mg of vitamin C daily.
A recent meta-analysis of 29 short-term trials (each trial included 10 to 120 participants) indicated that vitamin C supplementation at a median dose of 500 mg/day for a median duration of eight weeks reduced blood pressure in both healthy, normotensive and hypertensive adults. In normotensive individuals, the pooled changes in systolic and diastolic blood pressure were -3.84 mm Hg and -1.48 mm Hg, respectively; in hypertensive participants, corresponding reductions were -4.85 mm Hg and -1.67 mm Hg. The significance of the blood pressure-lowering effect of vitamin C on CVD risk has not yet been determined. It is important for individuals with significantly elevated blood pressure not to rely on vitamin C supplementation alone to treat their hypertension, but to seek or continue therapy with anti-hypertensive medication and through diet and lifestyle changes in consultation with their health care provider. For information on dietary and lifestyle strategies to control blood pressure.
9. What is the relationship between vitamin C intake and the common cold?
The work of Linus Pauling stimulated public interest in the use of large doses (greater than 1 gram/day) of vitamin C to prevent the common cold. In the past 40 years, numerous placebbo-controlled trials have examined the effect of vitamin C supplementation on the prevention and treatment of colds. A recent meta-analysis of 53 placebo-controlled trials evaluated the effect of vitamin C supplementation on the incidence, duration, or severity of the common cold when taken as a continuous daily supplement (43 trials) or as therapy upon onset of cold symptoms (10 trials). Regarding the incidence of colds, a distinction was observed between two groups of participants: regular supplementation with vitamin C (0.25 to 2 grams/day) did not reduce the incidence of colds in the general population (23 trials); however, in participants undergoing heavy physical stress (e.g., marathon runners, skiers, or soldiers in subarctic conditions), vitamin C supplementation halved the incidence of colds (5 trials; RR: 0.48, 95% CI: 0.35-0.64). A benefit of regular vitamin C supplementation was also seen in the duration of colds, with a greater benefit in children than in adults: the pooled effect of vitamin C supplementation was a 14% reduction in cold duration in children and an 8% reduction in adults. Finally, no significant effect of vitamin C supplementation (1-8 grams/day) was observed in therapeutic trials in which vitamin C was administered after cold symptoms occurred.
Tegan, Nutrition Nourishment.