Supplements: Vitamin C

This is an overview based on internet sources about Vitamin C and its uses as a supplement. Please always consult a doctor when you are considering supplementing any kind of vitamins. Especially when you are already ill, take medicine or during pregnancy. I am not an expert or doctor and have reproduced, collected and commented on the information available to me. You can navigate the primary and secondary sources by clicking on the links in the article.

What is Vitamin C ?

Vitamin C is a water-soluble Vitamin which means that your body does not store it and you have to obtain it via your diet. In fact, humans are one of the fewer species which can not synthesize Vitamin C themselves. It acts as a reducing agent and is a cofactor in eight enzymatic processes. One of the most important roles of Vitamin C is related to synthesizing collagen while it also plays an important role in the immune system. Collagen is used to make skin, cartilage, blood vessels and tendons and therefore plays a vital role in wound healing, growth, and maintenance of bones and teeth. Vitamin C is furthermore highly concentrated in immune cells.

Vitamin C is derived from monosaccharides like glucose through enzyme-driven processes. Approximately 70-90% of Vitamin C is absorbed at moderate intake levels between 30 - 180mg daily. A study conducted in Canada showed the mean intake to be 133mg/d for males and 122mg/d for females while the American National Health and Nutrition Examination Survey from 2001 to 2002 found the mean to be 105.2mg/d for adult males and 83.6mg/day for adult females. The degree of absorption of Vitamin C diminishes with higher intake and falls to less than 50% when more than 1g/day is consumed. The total content of Vitamin C in the body ranges from 2g to a minimum of 300mg which is near to showing symptoms of scurvy.

Scurvy was at its height until the end of the 18th century when sailors undertook long journeys with little or no vitamin C intake. This even resulted in death in many cases and therefore became a topic of interest during the mid-1700s when Sir James Lind experimented and concluded that citrus fruits and juices can cure scurvy. It was not found out until 200 years later in 1932 that vitamin C was the active component influencing the health of people with scurvy in the Albert Szent-Gyorgyi papers.

While it is uncommon in modern days to suffer from insufficient vitamin c intake, supplementing the vitamin is quite common. According to data from 1999 - 2000 roughly 35% of adults in the United States take multivitamin supplements containing vitamin c and about 12% different vitamin c supplement. For children, this number is estimated at 29%.

There are about 100000 tonnes of vitamin c produced annually. The main bulk of this comes from China. There were cases of price fixing by Chinese companies being investigated as prices per kg rose from $2.50 to $7 kg from 2001 to 2002. There was no denial by the companies involved, but they pointed to being pressurised by their government into the price fix. There was another price spike during the 2008 Olympic games when plants were stopped as part of a shutdown of polluting industry in China for better publicity during the games.

You can purchase natural or synthetic vitamin C, in a variety of forms. Tablets, capsules, and chewables are the most popular forms. Vitamin C also comes in powdered crystalline, effervescent, and liquid forms. Doses are ranging from 25 - 1,000 mg.

"Buffered" vitamin C is also available if you find that regular ascorbic acid upsets your stomach. An esterified form of vitamin C is available for those prone to heartburn.

What is recommended Vitamin C intake ?

These numbers vary and are continuously adjusted so this article will reflect the standards by the time of writing in September 2016.

RDA: Recommended Dietary Allowance (RDA) is the average level of sufficient intake to meet the nutrient requirements of nearly all healthy people.

AI: Adequate Intake is established when there is not enough evidence to set an RDA

UL: Tolerable upper Intake Level is the maximum daily intake unlikely to cause adverse effects.

The RDAs fir Vitamin C in the United Staes are

90mg/d for an adult male
75mg/d for an adult female
85mg/d during pregnancy
120mg/d during lactation
40mg/d 0-6 months
50mg/d 7 - 12 months
15mg/d 1 - 3 years
25mg/d 4 - 8 years
45mg/d 9 - 13 years
75mg/d 14 - 18 years male
65mg/d 14 - 18 years female
Smokers need 35mg/ d more than nonsmokers

UL's for vitamin C are 2.000mg/d for adult males and females. You can find more detailed information in the Dietary Reference Intake report from 2000.

What happens when you have Vitamin C deficiency ?

Vitamin C deficiency shows in the following symptoms:

Splitting hair
Decreased ability to ward off infection
Nosebleeds
Inflammation of the gums
Bleeding gums
Rough, dry, scaly skin
Decreased wound healing rate
Easy bruising
Severe form of deficiency is scurvy

What happens when you take too much Vitamin C ?

The good thing about Vitamin C is that it is not believed to cause serious adverse effects at high intakes. Side effects of unabsorbed vitamin c in the body can be:

Diarrhea
Nausea
Abdominal cramps
Gastrointestinal disturbances
Vomiting
Headache
Fatigue
Disturbed sleep

What are good sources of Vitamin C ?

Here is an overview of Vitamin C as mg / 100g in descending order.

Plant sources:

Kakadu plum
Camu Camu
Acerola
Seabuckthorn
Indian Gooseberry
Rosehip
Baobab
Chili pepper
Guava
Blackcurrant
Red Pepper
Chili Pepper
Parsley
Kiwifruit
Broccoli
Loganberry
Redcurrant
Brussels sprouts
Wolfberry
Lychee
Persimmon
Cloudberry
Elderberry
Papaya
Strawberry
Orange
Lemon
Pineapple
Cauliflower
Kale
Melon
Garlic
Grapefruit
Raspberry
Tangerine
Mandarin Orange
Passion fruit
Spinach
Cabbage
Lime
Mango
Rutabaga
Blackberry
Potato
Melon
Tomato
Blueberry
Pawpaw
Grape
Apricot
Plum
Watermelon
Banana
Avocado
Crabapple
Onion
Cherry
Peach
Apple
Carrot
Asparagus
Horned Melon
Beetroot
Chokecherry
Pear
Lettuce
Cucumber
Eggplant
Raisin
Fig
Bilberry
Medlar

Animal sources:

Calf liver
Beef
Oysters
Cod roe
Pork
Lamb brain
Chicken
Lamb liver
Calf adrenals
Lamb Heart
Lamb tongue
Camel milk
Human milk
Goat milk
Cow milk

What does vitamin C interact with ?

This is a short overview of the most commonly observed possible interactions. Please always refer to a doctor, if you are already on medication and want to supplement vitamin c. Without checking you might be doing more harm than good with a well-meant intervention bought over the counter.

Vitamin C has been rarely reported to have interactions with Warfarinrarely reported to have interactions with Warfarin. If you do take any blood thinning medication, please consult a doctor before supplementing Vitamin C.

For tetracycline, vitamin c seems to promote higher levels of this antibiotic while decreasing the effects of vitamin c in the body. Similar antibiotics as tetracycline are minocycline (Minocin) and doxycycline (Vibramycin)

HIV / AIDS patients might want to consult a doctor before increasing vitamin c levels as it appears to slightly inhibit the level of indinavir (Crixivan), a medication used to treat these patients.

Vitamin C also seems to have interactions with estrogen, which are main components in birth control pills. Vitamin c can cause estrogen to rise even further and oral estrogens can decrease the level of vitamin c in the body. If you already have to monitor your estrogen or vitamin c levels also consult a doctor to get clarity on intakes.

The functions of Vitamin C as an antioxidant are debated in relation to chemotherapy. Some experts argue that it interferes with drugs taken for chemotherapy, others say that Vitamin C has a positive effect. Also in these cases sit down with the experts monitoring your chemotherapy before doing more harm than good by taking a vitamin c drink each morning.

Phenobarbital (Luminal), pentobarbital (Nembutal) and secobarbital (Seconal) may decrease the effect of vitamin c.

Maalox and Gaviscon are aluminium containing antacids which could increase the side effects of these medicaments in combination with vitamin c as it increases the body's ability to absorb aluminium.

Vitamin C can cause the levels acetaminophen (Tylenol) in blood levels to rise by lowering the amount of it being passed in the urine. Check with a doctor if you are taking Tylenol.

Aspirin and nonsteroidal drugs can lower the amount of vitamin c be increasing the loss through urine. High vitamin c levels can cause these drugs to stay in the body. If you regularly take aspirin consult your doctor before going over the RDA of vitamin c.

Does Vitamin C work ?

The broader and more randomised are getting the less impact vitamin c has on health. There are a lot of conflicting messages out there which will be represented here. Overall it seems to me, that Vitamin c does not play an active role in preventing diseases, but the lack of it will make you more prone to becoming ill.

A 2014 study found that vitamin c can not be recommended as an anti-cancer agent
A 2013 Cochrane study found no benefit for healthy or high-risk individuals for lung cancer
A 2013 meta-analysis found no evidence that vitamin C supplementation reduces the risk of myocardial infarction, stroke, cardiovascular mortality, or all-cause mortality
Meta-analysis of 44 clinical trials has shown a significant positive effect of vitamin C on endothelial function when taken at doses greater than 500 mg per day. The researchers noted that the effect of vitamin C supplementation appeared to be dependent on health status, with stronger effects in those at higher cardiovascular disease risk
It has not been shown effective in prevention or treatment of the common cold
A 2010 review in the journal Alternative Therapies in Health and Medicine found no role for vitamin C supplementation in the treatment of rheumatoid arthritis
A prospective cohort study following 2.000 residents of a rural Japanese community found risk of stroke to be 29% lower for the individuals with the highest serum levels of vitamin c
Trials involving marathon runners, skiers, and soldiers exposed to extreme physical exercise and/or cold environments, prophylactic use of vitamin C in doses ranging from 250 mg/day to 1 g/day reduced cold incidence by 50%.

Conclusion

Based on the fact that Vitamin C levels are generally already good in the average population and the benefits of supplementing seem to be minimal I would personally say it is a supplement you can skip provided you are generally healthy and eat a balanced diet. Of course, having a bit of taste to your water from time to time can be nice and that i how I use multivitamin and vitamin c supplements mostly as an alternative to sugar.