Given the upcoming cold and flu season characteristic for this time of year, as social network users it is impossible for us not to see numerous media headlines on how to deal with them. Some are useful, and some are, unfortunately, just copied Facebook statuses of political, and other non-medical persons. As per usual, the most commonly mentioned therapy is with vitamin C.
Vitamins are compounds which our body can not synthesise on its own (or does in minimal quantities), which are necessary for the preservation of functionality and health. The water-soluble vitamin C, or ascorbic acid, cannot be synthesised in the body due to the lack of L-gulonolactone-oxidase enzyme and therefore must be ingested with food: citrus fruits, cabbage, rose hip, black currants, parsley, broccoli, kale, spinach, pickles, lettuce, but also liver, eggs, chicken drumsticks and others. Other than our species, we see a similar “problem” with synthesis in apes, guinea pigs, some species of bats and passerine birds. Native Americans knew the importance of ascorbic acid long before Europeans came to their lands, and their source was Thuja occidentalis. In the “newer” age, specifically the 18th century, the need for it was recognised on ships. A well-known story of thousands of seamen dying after spending more time on sea than on land, caused by scurvy, a deadly disease characterised by wounds easily appearing, hair deformation, gum problems and the eventual loss of teeth, fatigue, depression, skin rotting etc. Until a famous explorer James Cook noticed that after eating sauerkraut symptoms would recede and people would survive. For the discovery of the exact compound responsible for antiscorbutic action Albert Szent-Gyorgyi was awarded a Nobel prize in 1928.
Many scientists later searched for some more concrete evidence of its efficacy, but a strong correlation has never been found.
So, what is it about ascorbic acid that makes it so wondrous? For starters, it should be said that the human body only needs the L-enantiomer (diverges the plane of polarised light to the left). L-ascorbic acid helps the activity of several enzymes: proline-hydroxylase, procollagen-proline-2-oxoglutarate-3-dioxygenase (responsible for the firmness of collagen, the main protein in skin and hair), 4-hydroxyphenylpyruvate dioxygenase (enzyme involved in the metabolism of tyrosine, Tyr), dopamine-β-monooxygenase (synthesises norepinephrine) and others. Additionally, due to its chemical structure, it has excellent antioxidative properties (helps to prevent damage caused by free radicals), it is involved in redox reactions in the body, helps wound healing by activating thrombin (consequently large quantities of vitamin C are contraindicated with anticoagulant therapy), helps iron absorption (vitamin C is normally found in iron supplements), plays a part in the activation of immune cells and incites complement activation (important in recognising foreign organisms), lowers histamine concentration and thus helps with allergies, and there is evidence that it can be used in prevention and treatment of cataract and glaucoma as well as cancer prevention (exclusively by diet, not supplements, but it DOES NOT MEAN THAT ONE WILL NEVER GET CANCER). Positive effects of ascorbic acid have also been investigated in the treatment of sepsis. It should be mentioned that in sepsis it is recommended as ADJUVANT, not exclusive, therapy.
Although the previous section is only a shortened list of all the benefits gained by ingesting vitamin C, naturally it has negative sides as well. They may not have been so well researched if the double Nobel prize winner Linus Pauling had not become so obsessed with this “magical” compound. Namely, his theory was that for the prevention and therapy of colds, one should use mega doses of vitamin C (2000mg). He endorsed this by coming to a skiing school and testing the theory on 30 people, where it was allegedly proven to be true. Today we know that testing on 30 people is not viable proof of anything. Nonetheless, the avalanche was started and the trend of binge drinking orange juice the moment we get a runny nose is still here today. His awards and reputation did their psychological trick on the masses. Many scientists later searched for some more concrete evidence of its efficacy, but a strong correlation has never been found. On the contrary, they found some symptoms of overdose: diarrhoea, regurgitation, nausea, dizziness, cramps, irritation of the oesophagus etc. Perhaps the most concerning is the elevated risk of kidney stones (ascorbic acid metabolism ends with the formation of oxalate which combines with calcium in the kidney to form insoluble salts). And these high doses are exactly what all those “experts” recommend despite various refutations. The actual recommended dose backed by evidence is 95 mg for men and 70 mg for women (both refer to adults).
Therefore, wise up, discuss the treatment of your ailments with doctors and pharmacists, not celebrities… And arm yourselves with patience, warm blankets, and tissues. Good luck!