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Vitamin C – nature’s miraculous nutrient - is high-dose Vitamin C safe?

Dr Peter Baratosy MB BS FACNEM

This article is for general education purposes. Speak with your doctor or health care professional for further advice. Any treatment must be under the supervision of a suitably qualified health professional.

Before we look at Vitamin C, we must first look at it from a historical perspective. Vitamin C was not known till it was isolated in 1928, but a disease known as Scurvy has been around for a very long time. We now know that scurvy is caused by a Vitamin C deficiency but in the early days this was not recognised. The history of this nutrient goes far back in history, but it really came to prominence during the “Age of Sail” (1571–1862). Scurvy was documented by Hippocrates and was also known by the Ancient Egyptians – recorded as far back as 1550 BC!

With the “Age of Sail” (1571-1862), sailors in boats were at sea for prolonged times and many of the crew developed this disease known as scurvy. The conditions on the boats were poor – poor hygiene, poor water, poor food – all preserved – very little fresh foods. Symptoms included fatigue, nausea, diarrhoea, muscle and joint aches and pains – non-specific but as the deficiency worsened, so did the symptoms. Later manifestations include swollen spongy purplish gums prone to bleeding, loose teeth, easy bruising, scaly dry skin, slow healing wounds, opening of previously healed scars, bleeding into joints and muscles which causes areas of swelling over bones of arms and legs and finally death. This condition was so prevalent that the shipowners and the Navy Admiralty knew that at least 50% of the crew would not be capable of functioning due to scurvy, so they had double the crew number that were really needed. More sailors died from scurvy than from war, storms, shipwrecks and other diseases.

James Lind (1716-1794) was a Naval Surgeon who did much to help conquer this condition. He was the first to run a controlled trial of various remedies to treat scurvy. He tested 6 treatments 1/ cider, 2/ elixir of vitriol (sulphuric acid), 3/ vinegar, 4/ purging by sea water, 5/ a medicinal paste containing garlic, dried mustard seeds, dried radish root, balsam of Peru and gum myrrh and 6/ oranges and lemons. The consumption of oranges and lemons was the only treatment that worked! Though they still did not know why! His treatise was published but was not considered by the hierarchy. In the end, wort of malt emerged as the preferred treatment – largely due to cost – i.e. it was cheap!

Captain James Cook is also remembered as one who also involved himself in the treatment of scurvy. Although during his voyages sailors did get scurvy, none of them died. He used various treatments such as sauerkraut, wort of malt, carrot marmalade and oranges and lemons. Fresh fruits and vegetables were added to the food supply whenever possible.

Sir Gilbert Blane (1749-1834) was a doctor who became the personal physician to Admiral George Rodney. He was also from a prominent family, so he had more sway in decision making and finally in 1795, due to his input, the admiralty issues a decree that every sailor have a daily issue of three quarters of an ounce of lemon juice. Due to the wars with Europe, lemons and oranges were not available, so they switched to limes, as this was available from the British controlled Caribbean. This is the reason why British sailors are referred to as “limeys”. Today, especially in America, anyone from Britain is referred to as a “limey”. During the Napoleonic Wars, the success of the British Navy was largely due to the superior health of the sailors because scurvy had been prevented or properly treated.

They still did not know why this worked. They probably guessed that there was some factor in citrus and fresh vegetables that prevented and cured scurvy – but what was it?

In 1907, two Norwegians Holst and Frohlich theorised the existence of a factor we now know to be Vitamin C and the search was on! It was not until 1928 that Albert Szent-Gyorgyi, a Hungarian scientist isolated Vitamin C - and the link between Vitamin C, scurvy and fresh fruits were explained.

Many think that scurvy is no longer an issue – unfortunately this is not so. People have been diagnosed with scurvy though it may not be as florid as it was in the past. There is also a condition known as subclinical scurvy a mild form largely caused by a poor diet.

Scurvy is on the rise in England – the numbers may be small but between 2009 and 2014 admissions related to scurvy rose by 27%. (BBC News 22 Jan 2016) Why is this? There are many reasons and they include:

  1. Unhealthy diet due to neglect – alcoholism, drug use, mental illness

  2. Extreme dieting

  3. Young or elderly with poor care

  4. Eating disorders – anorexia, bulimia

  5. Smoking – smokers need more vitamin c to cope with the stress of smoke on their body

  6. Fussy eaters – kids who do not want to eat their vegetables!

The bottom line is that a healthy diet, with plenty of fresh fruit and vegetables will prevent scurvy. Food preparation is also an important factor. Eating vegetables is good but if they are over-cooked then the Vitamin C is destroyed.

Vitamin C is a simple water-soluble molecule with glucose as its starting point. Humans are one of the few species of animal that cannot make Vitamin C – other species include the apes, guinea pigs and some species of fruit bat. All other animal can make Vitamin C in their livers! Somewhere in our dim past, we could make Vitamin C because all the enzymes needed to make Vitamin C from glucose are all there – except for one – L Gulanolactone oxidase. Somewhere along the way, humans lost that enzyme via a mutation – so how did they survive. They probably ate lots of fruit that grew in the African continent – the birthplace of our species. Since humans cannot make it – we must get it from our diet. The Recommended Daily Allowance (RDA) of Vitamin C is largely based on the minimal amount needed to prevent scurvy, currently 90 mgs for males and 75 mgs for women daily.

The Guinea Pig, which is also another species that cannot make Vitamin C, has an recommended daily allowance (RDA) for Vitamin C of 20-30 mgs a day…. That is for a 1 kg animal!

The daily vitamin C recommendation for captive, non-human primates is 25 milligrams per kilogram of body weight (Portman, O., 1970. Nutritional requirements (NTC) of non-human primates. In: Harris, R.S. (Ed.), Feeding and Nutrition of Nonhuman Primates. Academic Press, New York, pp 87–115). In contrast – the goat that can make Vitamin C in their liver at an outstanding rate of 200 mgs /Kg/day. (ScienceDaily. ScienceDaily, 21 March 2008) What about an 80 Kg human – is 90 mgs adequate? If we extrapolate the requirements of the non-human primates for an 80 Kg human – that would be 2000 mgs a day – a far cry from the 90 mgs RDA!

We really should be looking at the maximum needed for optimal health. How much is that? Opinions vary! A sick person needs more than a non-sick person. The more stressed we are – the more we need. A smoker needs more than a non-smoker. The Vitamin C from 1 orange approximately 25 mgs are needed to detox the cigarette smoke from 1 cigarette. What if you are a 20 cigarette per day smoker?

Up till now we have been looking at Vitamin C from a physiological point of view.

  • Humans cannot make Vitamin C.

  • A deficiency of Vitamin C can cause significant health issues

  • An adequate diet that contains Vitamin C can prevent deficiency

  • There is a minimum amount of Vitamin C that is needed to prevent deficiency – this does not address the question “what is the optimal amount?”

What about the use of Vitamin C in higher doses to influence the course of disease?

Vitamin C has been shown to have a positive benefit in the treatment of infections, and here I am talking about large doses! Oral dosing of Vitamin C is limited because of the gut absorption constraints. Any Vitamin C that is not absorbed sits in the gut and acts as an osmotic laxative. How much Vitamin C are we talking about? Doses of up to 10 grams can be given orally, though since people are different – some can tolerate less and others more. A sicker person can tolerate more! As the oral dose increases, there is a point where bowel symptoms develop – gurgling and diarrhoea. This can be used clinically – called “Bowel Tolerance”. Basically, increasing the dose of oral vitamin C till diarrhoea develops, then cut back to a dose that just doesn’t cause diarrhoea. Other ways of giving Vitamin C is intravenously (IV). In this way, large doses can be given without fear of bowel problems, here doses can reach 30 to 60 grams! Intravenous Vitamin C can achieve very high peak serum levels that cannot be matched by oral dosing.

Intravenous Ascorbate (Vitamin C) has been used in the treatment of viral infections such as Shingles (Med Sci Monit,2012;18 (4):CR215-24) and Epstein-Barr virus (Med Sci Monit,2014;20:725-32).

Intravenous Ascorbate (Vitamin C) has been used for infections in general. Vitamin C is an anti-infective substance: “In vitro experiments showed that pharmacological ascorbate killed not only isolated viruses, but also viruses from normal human bronchial epithelial cells. The antiviral effect of ascorbic acid appeared to be dose-dependent. 2.5 mmol/L ascorbic acid was able to eliminate 90% of the viruses and 20 mmol/L ascorbic acid totally blocked viral replication in vitro. The antiviral effect of pharmacological ascorbate varied at different phases of infection. Pharmacological ascorbate eliminated viral infectivity with treatment times as short as 4 hours at early stage of infection. ”(Zhonghua Jihe He Huxi Zazhi,2012;35(7):520-3)

There are many anecdotal accounts published about Vitamin C and viral infections but unfortunately very few peer reviewed studies. One study published in 1994 where elderly patients with acute respiratory infections were admitted to hospital and were either given 200 mgs of Vitamin C or a placebo. Note that 200 mgs of Vitamin C is relatively quite a low dose and note - it was given orally. (I should point out here that oral dosage of vitamin C produces a lower peak serum level than intravenous vitamin C. Therefore, studies that use oral dosing may not show the same positive results as intravenous vitamin C!) Above I was talking about large doses given intravenously! Despite this low oral dose, the ones given Vitamin C fared “significantly better” than those on placebo. (Int J Vitam Nutr Res,1994;64(3):212-9).

A newer study (Nutrients,2017;9(4):399) showed that Vitamin C does have anti-infective effects, even for the common cold! Some of the earlier studies used relatively low oral doses. Also, some of the positive studies were replicated but with oral dosing and this showed negative results. The difference was that the positive studies used intravenous Vitamin C. The replicated studies used oral dosing. This is a big difference - as mentioned earlier, peak serum levels are much higher with intravenous Vitamin C than oral dosing. This is possibly the reason for the many negative studies.

Vitamin C has been used in Intensive Care to treat severe sepsis. See:

Hydrocortisone, Vitamin C, and Thiamine for the Treatment of Severe Sepsis and Septic Shock: A Retrospective Before-After Study. Chest, 2017;151(6):1229-1238.

In a more General Practice setting, Intravenous Vitamin C can be useful in:

  1. Acute viral infections – influenza, colds, hepatitis,

  2. Shingles

  3. Glandular fever – either as an acute treatment – or to help the long-term post infection fatigue symptoms – post viral fatigue

  4. Chronic Fatigue Syndrome

  5. Adjunct treatment in bacterial infection,

  6. Adjunct treatment with almost any other condition - Inflammatory conditions, pain, etc

Is High dose intravenous Vitamin C safe?

The short answer is “YES” – however - There are a few contraindications!

  1. G6PD deficiency,

  2. Renal impairment.

“High dose IV vitamin C is in unexpectedly wide use by CAM practitioners. Other than the known complications of IV vitamin C in those with renal impairment or glucose 6 phosphate dehydrogenase deficiency, high dose intravenous vitamin C appears to be remarkably safe. (My emphasis!) Physicians should inquire about IV vitamin C use in patients with cancer, chronic, untreatable, or intractable conditions and be observant of unexpected harm, drug interactions, or benefit.” (PLoS One. 2010 Jul 7;5(7):e11414).

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