Fundamentals of Human Nutrition/Vitamin C

8.8 Vitamin C

8.8.1 Sources

Vitamin C is a water soluble, organic compound that is essential for a variety of the human body’s functions. Humans cannot produce it endogenously so it must be obtained through our diet. Vitamin C is found in a variety of fruits and vegetables, making deficiency rare. Below is a list of foods that contain vitamin C.

Food	Content (mg/100g)
Terminalia ferdinandiana (Kakadu plum)	3000-5000
Goji berry	2500
Sea Buckthorn	750
Guava	243
Blackcurrants	200
Parsley	170
Dried Goji Berry	148
Sweet red pepper tarragon Leaf cabbage	120
Fennel Pepper	100
Kiwi	80
Litch	75
Lemon	65
Strawberry Orange Cauliflower	60

Vitamin C is very fragile. It is oxidized immediately upon contact with air and destroyed when exposed to light (ultraviolet rays). The heat of cooking destroys vitamin C. The exact temperatures at which the vitamin is destroyed varies based on the food it is in and the cooking method applied. Fortunately, most of the foods that contain this compound are consumed raw. Generally, consumption of two to three servings of fruits and three to five servings of vegetables per day will be enough vitamin C to meet the recommended daily intake established by the U.S. Food and Nutrition Board of the Institute of Medicine. Their recommendations are 90 mg for men over the age of 18 and 75 mg for women daily.

8.8.2 Functions

Chemically, vitamin C is known as L-ascorbic acid. Vitamin C is an enzymatic cofactor involved in a number of physiological reactions. It is required in the synthesis of collagen and red blood cells and helps the immune system by maintaining the integrity of the epithelial cells. It also plays a role in iron absorption. Its use is therefore not recommended for people with iron overload, as is the case in people with hemochromatosis. The oxidized form of vitamin C, dehydroascorbic acid, crosses the blood-brain barrier to reach the brain and multiple organs. In the body, it acts as an antioxidant molecule that can counteract the harmful effects of free radicals. Free radicals are harmful compounds in the body that are spontaneously formed when oxygen interacts with certain molecules. They can also be found in air pollution, cigarette smoke, and UV light [1]. The buildup of free radicals in the body over time is partly responsible for the aging process. Vitamin C’s antioxidant abilities greatly enhance cell functioning and play a vital role in wound healing. Additionally, vitamin C role in the regeneration of other antioxidants such as vitamin E. Vitamin C is also important in the eye’s ability to deal with oxidative stress. It has been shown to delay the progression of age related vision loss and macular degeneration. Other functions of vitamin C include the role it plays in aiding the body in the production of collagen, a protein that helps heal wounds and gives structure to muscles and other tissues. Collagen is the most abundant protein in mammals and is found in all connective tissue in the body. As vitamin C builds up the collagen in the skin, bones, organs and blood vessels, it enables the body to function successfully. By maintaining the integrity of the skin- humans first line of defense- and quashing free radicals, vitamin C improves the immune system’s functioning. Vitamin C also aids the body in the absorption of iron from foods that are plant based. Nonheme (plant based) iron is not as readily absorbed as heme iron so it is important to consume vitamin C to maximize absorption. Another major role of vitamin C in the body is to repair and maintain bones, teeth, and cartilage. This is apparent in people with scurvy, a major vitamin C deficiency, because they are usually very weak and have little to no teeth at all. Vitamin C is also useful in the metabolism of some bile acids which may effect the body’s production of gallstones and its blood-cholesterol levels [2]. For a long time, vitamin C has been a recommended prevention method or treatment for the common cold. However, research shows that vitamin C does not cure a cold, but people who regularly take supplements of vitamin C might have slightly shorter colds or more mild symptoms. It can also act as an inhibitor of histamine, a compound that is released during allergic reactions. It has also been found to decrease or prevent the forming of possibly carcinogenic nitrosamines within the stomach [3]. The body is not capable of making vitamin C nor can it be stored. That is why it is very important to make sure to consume foods containing vitamin C. Overall, vitamin C has a broad range of functions throughout the body and is an extremely important part of the diet. These functions include immune stimulation, anti-allergenic action, eye health, iron absorption, teeth and gum health, would healing, antioxidant behavior, and collagen production.

8.8.3 Requirements

European guidelines advise a daily intake of 75 mg for women and 90 mg for men. For example, an orange give an average of 53 mg of vitamin C (40 to 80 mg per 100 g). The North American Dietary Reference Intake recommends 90 milligrams per day and no more than 2 grams (2,000 mg) per day. The people who is exposing to the harmful effects of oxidants, such as smokers have an increased need for vitamin C. Some scientists like Linus Pauling (Nobel Prize in Chemistry in 1954), consider that the recommended dietary intake should be at least 6000 mg, or 18 000 mg.

8.8.4 Deficiency

A major deficiency of vitamin C, very rare, causes scurvy, when the supply is less than 10 mg per day. The more discreet hypovitaminosis are widespread and result in fatigue, weight loss, headache, bone pain, increased susceptibility to infections and sometimes bleeding problems.

Symptoms of deficiency in this area are rare. There are several common signs of Vitamin C deficiency that can be observed. It includes anemia, which is the lack of adequate red blood cells or in some cases hemoglobin in the blood, gingivitis, bleeding gums, failure to overcome infections and a slower healing rate, more frequent bruising, increase in weight, rough and scaly skin, inflamed joints, and the weakening of tooth enamel.

In extreme and rare circumstances a lack of vitamin C leads to Scurvy or atherosclerosis. Scurvy is a disease most commonly found in older adults, and consists of the degradation of all joints, tendons, and blood vessels. Ultimately, this leads to vessel erupting, hemorrhages, and organ failure. This is due to the lack of collagen protein and connective tissue in the body that is formed majorly through vitamin C.

Atherosclerosis is a condition where the body’s arteries are progressively filled with hardening plaque in arteries and blood vessels ultimately closing in the arteries and preventing oxygen flow throughout the body.

Linus Pauling Theory

Linus Pauling, American scientist and recipient of two Nobel Prizes, proposed that heart disease could be treated and by increasing vitamin C intake. He hypothesized and found that heart disease was another form of scurvy and the plaque that gradually builds up in the body’s arteries and blood vessels were formed to help the body heal those vessels.

Antioxidants and Redox Signaling

In the study Antioxidants and Redox Signaling, researchers looked into how deficiencies in vitamin C led to severe damage in developing brains and motor behaviors. They theorized that the speed of the brain developing would be affected by the lack of an antioxidant system, which vitamin C contributes greatly to. After testing neonatal Gulo mice, the results showed that without vitamin C, growth was at a significantly lower rate and many brain deficiencies including a delay in the formation of cerebral fissures, abnormalities in areas such as the cerebellum and hippocampus, and a change in purkinje cells. The change in purkinje cells led to mice facing a decline in their overall motor skills. The researchers concluded that in new born babies vitamin C deficiencies cause hemorrhages and cerebellum defects. This deficiency also leads to damage in the cerebellum in individuals with full developed brains, including basic function impairment.

To resolve and avoid these vitamin C deficiencies one should increase their daily intake to the Recommended Dietary Allowances (RDA) preferred amount.

8.8.5 Toxicity

Vitamin C is not toxic at doses usually absorbed for a healthy individual. Since its synthesis in the 1930s, vitamin C is used at all doses throughout the world. The only side effects associated with its use and that are developed are mild diarrhea and diuretic action. These occur when consumed too quickly and too much. The body can not store it, it eliminates excess. Clinical studies show:

• the consumption of vitamin C does not increase  · · and even reduces the incidence of kidney stones.
• that vitamin C has no mutagenic effect (study of doses up to 5000 mg per day)  ·.

In vivo studies show that vitamin C, even in the presence of transition metals has no mutagenic effect and instead it protects the cells of the mutagenic action of hydrogen peroxide.

Symptoms of an overdose of vitamin C may include: nausea, vomiting, headache, rash, and asthenia. For doses greater than 500 mg/day , an increase of production of oxalic acid could induce a risk of kidney stones oxalate. This side effect is controversial in some studies. Indeed, plants that provide vitamin C also bring oxalate , hence the confusion.

Vitamin C: 8.8.5 Toxicity Vitamin C is rather an uncommon vitamin to overdose on, especially from its natural foods. Vitamin C toxicity normally occurs due to taking too many supplements. Vitamin C Toxicity cannot lead to death though and anything above the recommended amount of 2,000 mg of Vitamin C can lead to the below symptoms. The common symptoms that can occur from Vitamin C toxicity are:

• Diarrhea
• Nausea
• Vomiting
• Heartburn
• Abdominal Bloating and cramps
• Headache
• Insomnia
• Kidney Stones

Diarrhea Consuming more than 2000 mg of the recommended intake of Vitamin C can lead to irritation of the gastrointestinal tract that can lead to diarrhea and also vomiting can occur as well. As a result of the toxicity causing diarrhea and vomiting, one can lose a significant amount of fluids leading to dehydration, fatigue, low urine discharge and a reduction in blood pressure. Vitamin C’s effects on other minerals

Copper: Pink eye or inflammation of the eyelids is caused by copper deficiency. When consuming too much vitamin C, which leads to a huge increase in high ascorbic, coupled with copper deficiency in the body can either cause the inflammation or make it worse. Chronic conjunctivitis, also known as pink eye, can occur due to Vitamin C toxicity depleting the cooper storage quickly.

Zinc: Vitamin C within the body has direct effects on Zinc and Zinc indirectly affects Iron. As a result a high Vitamin C toxicity would lead to worsened liver conditions, benign prostatic hypertrophy, or kidney diseases. Manganese: Large intake of Vitamin C can lead to insulin spikes which can affect people with hypoglycemic tendencies and have low sodium. Vitamin C toxicity can also affect the length of a woman's menstrual cycle because manganese has control over the liver’s ability to break down estrogen.

Kidney Stones: A substance in our body called oxalate breaks down Vitamin C and when we urinate, we secrete some oxalate. High urinary oxalate levels can build up causing deposits which are also known as kidney stones. Vitamin C toxicity is correlated with increased risk of kidney stones, and about 80 percent of all kidney stones are caused by Vitamin C toxicity.

Hemochromatosis: Hemochromatosis is a condition caused by excess iron build-up in the body. Within our body, Vitamin C helps absorb iron, and while Vitamin C toxicity does not cause Hemochromatosis, it can worsen the condition.

Work Citation Micronutrient Information Center. (n.d.). Retrieved December 1, 2015, from http://lpi.oregonstate.edu/mic/vitamins/vitamin-C Ohno, S., Ohno, Y., Suzuki, N., Soma, G., & Inoue, M. (n.d.). High-dose Vitamin C (Ascorbic Acid) Therapy in the Treatment of Patients with Advanced Cancer. Retrieved December 1, 2015, from http://ar.iiarjournals.org/content/29/3/809.long Vitamin C - All - Health Encyclopedia. (n.d.). Retrieved December 1, 2015, from https://www.kaahe.org/health/en/913-vitamin-c/all.html Vitamin C Supplementation. (n.d.). Retrieved December 1, 2015, from http://www.acu-cell.com/vitc.html Zeratsky, K. (n.d.). Nutrition and healthy eating. Retrieved December 1, 2015, from http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/vitamin-c/faq-20058030

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