Vitamin C's secrets held for 200 years

By Associate Professor Allan Blackman

This article was orignally published in the Otago Daily Times on Tuesday 5 April 2005.

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When I was a kid, our family used to go to Naseby for the summer holidays.

While Mum and Dad would be relaxing in the caravan, doubtless grateful for the temporary peace and quiet, I’d be outside, running around like a mad thing in the glorious Maniototo heat, until a combination of thirst and sunstroke would eventually force me indoors. Whereas all the other kids in the camping ground who were in a similar state got to slake their thirst by drinking L & P or Coke or some other such “fizzy” drink, I had to make do with a glass of the much less cool Rose’s Lime Juice.

As Dad never tired of explaining to me, “it’s full of vitamin C” (not to mention the mysterious vitamins X, Y and Z) “and you won’t get scurvy”.

Now, to the best of my knowledge, scurvy wasn’t exactly rampant in early 70s New Zealand, and I suspect Dad’s enthusiasm for lime juice was perhaps motivated by concerns of a more fiscal nature. But he was correct about lime juice preventing scurvy — a fact known since 1747 when James Lind, ship’s doctor on HMS Salisbury, cured scurvy patients by giving them citrus fruits to eat.

However, it was to be nearly 200 years before the exact compound responsible for the antiscorbutic (anti-scurvy) activity of citrus fruits was identified.

In the first week of April, 1932, the American chemists C. Glen King and William A. Waugh published a three paragraph paper entitled “The Chemical Nature of Vitamin C” in the prestigious journal Science. In this paper, they reported the isolation of pure vitamin C from lemon juice, but, most importantly, they showed their isolated material was identical to a compound which had been reported in 1928 by the Hungarian chemist Albert Szent-Györgyi. He had extracted less than a gram of an off-white material from the adrenal glands (located at the top of the kidney) of cattle and it took him four years to show that this compound, which he called hexuronic acid, was in fact vitamin C.

However, he was beaten to publication by King and Waugh by two weeks and this short time interval has been the cause of much controversy during the intervening years. The actual structure of vitamin C (Figure 1) was subsequently determined by Sir Norman Haworth and both he and Szent-Györgyi were awarded Nobe Prizes in 1937 for their work in this area (King and Waugh, notably, were not). They also proposed the name “ascorbic acid” for vitamin C — ascorbic being a contraction of antiscorbutic.

In chemical terms, vitamin C is a reductant, meaning it will react by donating electrons to other compounds. In popular parlance, it is known as an antioxidant, which means exactly the same thing. In addition to its role in preventing scurvy, it is also thought to protect the body from free radicals which can lead to genetic mutations and ultimately cancer.

The chemical structure of vitamin C resembles that of many sugars and in fact it can be prepared on an industrial scale using glucose as a starting material. A quite staggering 66 million kilograms of vitamin C are manufactured in the United States every year, much of which ends up in vitamin tablets. It is used as a food additive to restore amounts which may have been lost during processing, and it is also often added to flour during breadmaking to improve the texture and size of the loaf.

Despite my earlier protestations about lime juice, I actually quite like it.

It’s infinitely preferable to that other vitamin C-laden (well, according to Dad, anyway) staple food of my childhood, silver beet. I’d rather take my chances with scurvy than eat that stuff.