Vitamin C Benefits the Immune System — and So Much More
Vitamin C
You don’t have to go out of your way to ensure that your dog’s daily chow contains enough vitamin C. Dogs and many other animals possess an enzyme that can synthesize vitamin C from glucose.
Humans, however, lack the necessary enzyme for this conversion and have to rely on food to meet their daily vitamin C needs.
Functions of Vitamin C
Vitamin C Acts as a Coenzyme
Vitamin C, also known as ascorbic acid, acts as a coenzyme that is needed to synthesize and use certain amino acids. In particular, vitamin C is needed to make collagen, the most abundant protein in your body. Collagen is plentiful in your connective tissue, which supports and connects all your body parts, so this protein is needed for healthy bones, teeth, skin, and blood vessels. Thus, a vitamin-C–deficient diet would affect your entire body.
Vitamin C Acts as an Antioxidant
Like beta-carotene and vitamin E, vitamin C acts as an antioxidant that may help reduce the risk of chronic diseases.
Vitamins
White blood cells as heart disease and cancer. It also helps you absorb the iron in plant foods such as grains and cereals and break down histamine, the component behind the inflammation seen in many allergic reactions.
Vitamin C Boosts Your Immune System
Vitamin C helps keep your immune system healthy by enabling your body to make white blood cells, like the ones shown in the photo above. These blood cells fight infections, and this immune-boosting role has fostered the belief that high doses of vitamin C can cure a common cold. (The “Gesundheit!
Daily Needs
Women need to consume 75 milligrams of vitamin C daily, and men need to consume 90 milligrams daily to meet their needs.
Smoking accelerates the breakdown and elimination of vitamin C from the body, so smokers need to consume an additional 35 milligrams of vitamin C every day to make up for these losses.
Food Sources
Americans meet about 90 per cent of their vitamin C needs by consuming fruits and vegetables, with orange and/or grapefruit juice being the most popular source in the diet. One serving of either juice will just about meet an adult’s daily needs.
Tomatoes, peppers, potatoes, broccoli, oranges, and cantaloupe are also excellent sources.
Too Much or Too Little
Brendan, the track athlete introduced at the beginning of this chapter, attempted to ward off a cold by taking vitamin C supplements. His attempt to solve one medical dilemma created another one that impeded his training more than his sniffling and sneezing.
Though excessive amounts of vitamin C aren’t known to be toxic, consuming more than 3,000 milligrams daily through the use of supplements has been shown to cause nausea, stomach cramps, and diarrhoea.
Brendan can attribute the diarrhoea he experienced to his daily 3,500-milligram supplement of vitamin
Once he stopped taking the supplement, his diarrhoea ceased.
The upper level for vitamin C for adults is set at 2,000 milligrams to avoid the intestinal discomfort that excessive amounts of the vitamin can cause. Too much vitamin C can also lead to the formation of kidney stones in individuals with a history of kidney disease. Because vitamin C helps to absorb the form of iron found in plant foods, those with a rare disorder called hemochromatosis (hemo = blood; chroma = color; osis = condition), which causes the body to store too much iron, should avoid excessive amounts of vitamin C.
Iron toxicity is extremely dangerous and can damage many organs in your body, including the liver and heart.
For centuries, scurvy, the disease of a vitamin C deficiency, was the affliction of sailors on long voyages. After many weeks at sea, sailors would run out of vitamin-C–rich produce and then develop the telltale signs of scurvy: swollen and bleeding gums, a rough rash on the skin, coiled or curly arm hairs, and wounds that wouldn’t heal. Because vitamin C is needed for healthy blood vessels, a deficiency also often causes purple colored spots, a sign of skin haemorrhages, to appear on the skin and in mucus membranes of the body such as the lining of the mouth.
In 1753, a British naval surgeon discovered that orange and lemon juice prevented scurvy. Decades later, the British government added lemon or lime juice to their standard rations for sailors to thwart scurvy. In 1919, vitamin C was discovered as the curative factor in these juices.
Table Tips
Juicy Ways to Get Vitamin C
Have a least one citrus fruit (such as an orange or grapefruit) daily.
Put sliced tomatoes on your sandwich.
Enjoy a fruit cup for dessert.
Drink low-sodium vegetable juice for an afternoon refresher.
Add strawberries to your low-fat frozen yoghurt.
