Vitamin C (ascorbic acid)

Dur­ing the Age of Explo­ration, when human beings start­ed mak­ing long jour­neys on sail­ing ships, the sailors were plagued by a poten­tial­ly dead­ly dis­ease called scurvy. Peo­ple with scurvy bruised eas­i­ly and often lost their teeth. If the dis­ease is allowed to progress, the poor vic­tim will even­tu­al­ly die of inter­nal bleed­ing. The pre­ven­tion and cure seemed to be fresh fruit and veg­eta­bles, which were hard to keep on long voy­ages.

One of the great land­marks in the his­to­ry of med­i­cine was the dis­cov­ery of the cure for scurvy. In 1747, while serv­ing as sur­geon on the British Roy­al Navy ship HMS Sal­is­bury, James Lind car­ried out an exper­i­ment to find the best treat­ment for scurvy in sailors. He select­ed 12 scurvy vic­tims and divid­ed them into 6 pairs. Each group received a dif­fer­ent treat­ment in addi­tion to their ordi­nary rations. Some were giv­en cider, oth­ers a mix­ture of gar­lic, mus­tard and horse­rad­ish. Some were giv­en sea­wa­ter. Some were giv­en spoon­fuls of vine­gar or dilute sul­fu­ric acid. Two men were giv­en oranges and lemons. Unlike the oth­er men, the ones who had received the oranges and lemons rapid­ly recov­ered.

By the ear­ly 20th cen­tu­ry, it was clear that no ani­mal could sur­vive on a mix­ture of puri­fied pro­tein, car­bo­hy­drate, fat, and min­er­als. They all need­ed trace amounts of sev­er­al organ­ic com­pounds that could only be found in plant or ani­mal tis­sue. There were sev­er­al dif­fer­ent syn­dromes that each seemed to result from defi­cien­cy of a par­tic­u­lar com­pound. At first, chemists sus­pect­ed that all of these com­pounds were amines, so they called them “vit­a­mines,” which was short for vital amines. After they real­ized that some of the com­pounds weren’t amines, the name was changed to vit­a­mins.

Sci­en­tists sus­pect­ed that there were at least four vit­a­mins, called A, B, C, and D. Vit­a­min A was fat-sol­u­ble and found in the but­ter­fat of cow’s milk. Vit­a­min B was water-sol­u­ble and found in the watery por­tion of cow’s milk. Lat­er on, it was dis­cov­ered that cow’s milk con­tains sev­er­al water-sol­u­ble vit­a­mins, so they were named B1, B2, and so on. Vit­a­min C was the com­pound found in fresh fruits and veg­eta­bles that pre­vent­ed and cured scurvy. Vit­a­min D was what­ev­er it was in cod-liv­er oil that cured rick­ets. Lat­er on, nutri­tion researchers dis­cov­ered vit­a­min E and vit­a­min K (from the Ger­man “Koag­u­la­tions-Vit­a­min,” because it was involved in coag­u­la­tion or clot­ting of the blood).

At first, sci­en­tists believed that you had to eat some fruit or veg­etable in order to pre­vent or cure scurvy, In 1928, how­ev­er, an Arc­tic explor­er named Vil­h­jal­mur Ste­fans­son showed that the Eski­mos avoid­ed scurvy on their essen­tial­ly plant-free diet, while Euro­peans got scurvy from eat­ing those same foods, because the Eski­mos ate their meat vir­tu­al­ly raw. In the late 1920s, a Hun­gar­i­an chemist named Albert Szent-Györ­gyi had iso­lat­ed a com­pound he called hex­uron­ic acid, which he sus­pect­ed was respon­si­ble for vit­a­min C activ­i­ty. When his the­o­ry was proved cor­rect, hex­uron­ic acid was renamed ascor­bic acid, and Szent-Györ­gyi was award­ed the 1937 Nobel Prize in Med­i­cine or Phys­i­ol­o­gy. In 1933, sev­er­al chemists inde­pen­dent­ly fig­ured out how to syn­the­size ascor­bic acid. Vit­a­min C, along with the oth­er vit­a­mins, quick­ly became avail­able cheap­ly in pill form.

The dis­cov­ery of ascor­bic acid cleared up a mys­tery that had dat­ed from the Age of Explo­ration. Why did the human beings on long sea voy­ages fall prey to scurvy, while the ship’s rats and the ship’s cat stayed in per­fect health? The answer is that near­ly all ani­mals, the notable excep­tions being human beings and oth­er pri­mates as well as guinea pigs, can make their own sup­ply of ascor­bic acid. Thus, vit­a­min C is a vit­a­min for human beings and a few oth­er species but is not an essen­tial nutri­ent for rats or cats or most oth­er ani­mals.

Ascor­bic acid per­forms many impor­tant func­tions in the body. It is an elec­tron donor for eight impor­tant enzymes, three of which are essen­tial for build­ing and repair­ing col­la­gen. This explains why vit­a­min C defi­cien­cy caus­es prob­lems with the con­nec­tive tis­sue. Two of the enzymes are essen­tial for the pro­duc­tion of car­ni­tine, which cells need in order to trans­port fat­ty acids into the mito­chon­dria (the pow­er­hous­es of the cell), so that they can be burned in order the release the ener­gy need­ed to pro­duce ATP, which is the main form of ener­gy used in the cell.

The fact that ascor­bic acid acts as an elec­tron donor means that it is an antiox­i­dant. It can there­fore help to pro­tect the body against the dam­ag­ing effects of high­ly reac­tive mol­e­cules called free rad­i­cals, which can be pro­duced by nor­mal metab­o­lism and the immune sys­tem. Free rad­i­cals are con­sid­ered to be a major cause of aging.

Since ascor­bic acid is so impor­tant to so many basic life func­tions, it’s hard­ly sur­pris­ing that most ani­mals can make their own sup­ply. Our inabil­i­ty to make our own vit­a­min C could be viewed as a genet­ic defect, albeit one that we share with our close rel­a­tives (pri­mates such as apes and mon­keys) and that is also found in some unre­lat­ed species, such as guinea pigs, bats, and some species of birds and fish. We can sur­vive despite this genet­ic defect because the food we are sup­posed to eat con­tains plen­ty of vit­a­min C. Thus, scurvy hap­pens only when peo­ple eat an abnor­mal diet.

Vit­a­min C is clear­ly essen­tial to pre­vent scurvy, and a health-opti­miz­ing diet that con­tains lots of fresh fruits and veg­eta­bles is cer­tain­ly rich in vit­a­min C. Yet for years some peo­ple have claimed that peo­ple need much larg­er amounts of vit­a­min C than they could get from eat­ing ordi­nary food. Linus Paul­ing, who had won two unshared Nobel Prizes, one for chem­istry and one for peace, was a promi­nent advo­cate of “mega­dos­es” of vit­a­min C, for every­thing from the com­mon cold to can­cer. Unfor­tu­nate­ly, there’s lit­tle or no evi­dence that these dos­es of vit­a­min C can do any­one any good, and they can cause prob­lems such as kid­ney stones.