Thursday, April 19, 2012

Ascorbic Acid

Ascorbic Acid

            Many of us are familiar with the story of European sailors and their struggle against scurvy during extended trips on the water.  The history books show that, at the time, scurvy was wiping out traveling sailors that had little access to perishable food and in turn were not getting the proper diet necessary for basic bodily upkeep.  In turn, they were developing bone weakness, tooth loss, excessive bruising, even lack of emotional stability.  Finally, a Royal Naval physicist by the name of James Lind discovered that citrus fruit could miraculously cure the ailing sailors.  At the time he was not certain exactly why, but it was later discovered that an essential vitamin, vitamin C, was the source of alleviation.  I have always been fascinated with the stories explaining the origin of scientific breakthroughs that are deemed to be common knowledge today.  Back in Lind’s time, his analysis of what would become known as vitamin C is credited as being one of the first clinical experiments in the history of medicine.  It’s pretty exciting when you realize how original his idea was at that moment.  My original intent was to take a look at vitamins in general and give an analysis as to what they do in the body and how it is best to obtain them.  However, I realized that there are countless reports on dozens of compounds that would just be too broad for our initial blog.  So I decided to focus on one that most of us have some familiarity to. I want to give some basic information that one can utilize when they approach any over the counter medicine or carton of juice or supplement that touts, “Get your vitamin C here”. What is the difference between dietary and supplemental vitamin C in the body?
            So let’s start with the chemical makeup of ascorbic acid.  The compound is

  Ascorbic acid has several functional groups that help it perform its certain functions in the body.  Obviously there are lots of hydroxyl groups capable of donating electrons (which we will touch on further) as well as a ketone.   I found a great overview in the Journal of Evidenced-Based Complimentary and Alternative Medicine, in which the author breaks down what vitamin C can actually do in the body.  The journal states that vitamin C works well in the body in redox reactions due to its ability to donate electrons in its stable ascorbic acid (vitamin C form) or gain electrons in oxidative processes in the dehydroascorbic acid (DHA).  Something that Vitamin C has been accredited as being beneficial for. Vitamin C, or more specifically DHA is especially important due to its role as an antioxidant.  The DHA form acts as a cofactor, or a reducing agent that will pick up electrons left over from other enzymatic reactions occurring in the body.  These left over electrons, or free radicals, can gather in the body to form chains, which will eventually mutate cells.  The vitamin C, in this case, keeps metals in a reduced state to allow for essential enzyme activity.  Specifically, it keeps iron in the ferrous (F2+) state, which is required for enzyme activity.  Three enzymes that are mentioned in the journal, prolyl 4-hydroxylase, prolyl 3-hydroxylase, and lysl hydroxylase, react with ascorbic acid for collagen biosynthesis.  Because of this, vitamin C is appearing in marketing campaigns for collagen enhancing skin products. Another interesting fact about vitamin C as an antioxidant is that although it is limited to the water-soluble free radicals (as opposed to fat-soluble) it is capable of working with vitamin E which is capable of preventing lipid cells from retaining free radicals.  Ascorbic acid can donate an electron to vitamin E radicals to produce a form of vitamin E that is capable of working in lipid cell membranes to reduce peroxidation.  
            Where does one get vitamin C? Most plant life is capable of converting glucose to ascorbic acid during growth.  Humans are not capable of producing their own ascorbic acid, yet are capable of recycling it within the body to use for extended periods of time. We need to get it from consumption of plants or other food products that contain the vitamin in them.  The highest concentrations of vitamin C can be found in the foods listed in the table below.  These foods have been researched and found to be, in general, the best foods to eat for vitamin C intake.  Also, the amounts in each are listed.  Currently, the daily recommended intake of Vitamin C for adults is 60 grams. Keep in mind that this is the minimum recommended intake which prevents deficiency; higher doses are recommended to provide the body with enough during times of high stress or low immunity. 

Table 1
Food (raw)
Amount (cup)
Vitamin C content (mg)
½ cup
Red Pepper
½ cup
Orange juice
¾ cup
½ cup
Brussel sprouts
½ cup
½ cup
Tomato juice
¾ cup

            Given the importance of vitamins to our biological processes, scientists have been developing ways to ensure we get enough of them no matter what our diet may consist of.  Vitamin supplements are readily available to most Western consumers and come in many formulas, whether it is a pill, a liquid, a chewable tab, or a gummy bear infused with nutrients, we are bombarded with the idea that supplementation is a necessity for overall better health.    In our Western society, it would be almost impossible to consume a diet that didn’t have some vitamin C in it.  Although these foods are high in concentration, it can be easy to lose vitamin C due to its relative instability in certain environments.  It can be susceptible to oxygen and heat; almost unavoidable in most cooking processes, and continual reheating of leftovers can further reduce the content.  Interaction with foods that have other pH levels as well as with other metallic ions can also minimize the levels of affective vitamin C.  Even storing foods for prolonged periods of time can lead to vitamin loss in significant amounts.  This is not very encouraging considering the amount of time fruits and vegetables sit during harvest and transport to our local groceries. One cannot be sure if the amount of food they are eating is meeting the daily recommended intake.  So are these even affective?
I found many reports about the importance of vitamin C in the body as well as numerous articles about the importance of preserving the nutritional properties during extraction and processing into synthetic supplement.  What interested me most was finding a study that would help prove which form of the vitamin was better to utilize.  An article suggested by Dr. Moore proved most interesting, studying the difference between dietary and supplemental vitamin C and its effect on lower urinary tract symptoms in men.  Relating to our conversation about which form of the vitamin can produce better results in the body, this study shows that neither is the definite answer.  As mentioned before, Vitamin C is a known antioxidant, and in this study it was observed that this and other micronutrients could reverse the oxidative damage in men due to Lower Urinary Tract Symptoms (LUTS).  The study involved 1466 men between the ages of 30-79 years of age from various backgrounds.  They were observed for their either dietary or supplemental of Vitamin C and how it affected the symptoms associated with LUTS.  The results were interesting.  In the past, studies had been done that suggested there was an inverse relationship between dietary intake of vitamin C and beta carotene, but not from supplements.  The results showed that Vitamin C was inversely associated with the syptoms associated with LUTS, but the hight doses of Vitamin C and beta carotene showed positive associations.  I found it surprising that one form of the vitamins would cause different reactions in the body, but I was more interested about why an excess of Vitamin C could be proven to have negative effects on the body?  Later in the article, it was explained that there was suspected to be an “altered antioxidant capacity in the presence of catalytically active metal ions such as iron and that iron overload may cause oxidative stress…” As we saw earlier, vitamin C acts as a great oxidizing agent, especially with transition metals, but an excess of these metals in the body could prevent the vitamin C from being able to perform other oxidative reactions that would prevent complications such as LUTS.  The study realized that an increase in iron intake would require an increase in vitamin C intake to reduce the LUTS symptoms.  The final discussion stated that dietary vitamin C proved more effective in reducing the likeliness of men having LUTS.
            I think this journal helps make my final conclusion that any vitamin, whether Vitamin C or other, should be obtained through a balanced mix of food consumption and supplementation.  It seems that consuming raw foods provide the incentive in that the other elements in the food collaborate in the body to perform extra duty in our cells.  Also, it seems that mother nature has developed a way to create balance that supplementation may not be able to do in a regularly healthy body that is not suffering from any deficiencies.  Yet, because we cannot be sure exactly how much nutrient concentration we have lost in our food due to light, heat, and storage, it may be a good idea to augment with other sources. One cannot be used in place of the other.  It is these inconsistencies that should propel us as individuals to understand what we are putting into our bodies and how it works to improve or hinder our overall health.

1.      Review of Natural Antioxidants from Residual Sources
2.      Journal of Evidence Based Complementary and Alternative Medicine: Vitamin C: An Overview
3.      Wikipedia Pages:
a.       Vitamin C
b.      Ascorbic acid
c.       Flavonoids
4.   Dietary, but Not Supplemental, Intakes of Carotenoids and Vitamin C are Associated with Decreased Odds of Lower Urinary Track Symptoms in Men (The Journal of Nutrition, Dec 2010)

1 comment:

  1. I think the topic is very interesting. I believe that everyone has a general idea of the functions and benefits of Vitamin C but in reading your blog I got a deep understanding of these benefits. The table is very useful because the healthy foods that are listed there contain vitamin C and some of these foods I consume daily, so it good to know the amount of vitamin C they contain. Overall, I think the paper was very well done!