I have heard that it is beneficial to take vitamin C when you are experiencing cold symptoms.
I don't know there is any actual evidence that it works for colds, but it does prevent scurvy.
What exactly is scurvy?
Scurvy causes weakness, feeling tired and sore arms and legs.  It can cause death.
Has it been proven that vitamin C actually prevents scurvy?
Oh, yes!  Sailors routinely died of scurvy before limes were standard to be brought onboard ships.  Now it occurs mostly in those with alcoholism
I have never heard of limes being a staple for sailors in order to prevent scurvy!
Yep.  They were something that could last for a while onboard.  Lemons as well.  I believe the British Navy started the program.  It takes at least a month of too little or no vitamin C before scurvy sets in
It is good to know that such a debilitating illness is easily prevented.
James Lind
James Lind (4 October 1716 – 13 July 1794) was a Scottish doctor. He was a pioneer of naval hygiene in the Royal Navy. By conducting one of the first ever clinical trials, he developed the theory that citrus fruits cured scurvy. He argued for the health benefits of better ventilation aboard naval ships, the improved cleanliness of sailors' bodies, clothing and bedding, and below-deck fumigation with sulphur and arsenic. He also proposed that fresh water could be obtained by distilling sea water
Scurvy
Scurvy is a disease resulting from a lack of vitamin C (ascorbic acid). Early symptoms of deficiency include weakness, feeling tired, and sore arms and legs. Without treatment, decreased red blood cells, gum disease, changes to hair, and bleeding from the skin may occur. As scurvy worsens there can be poor wound healing, personality changes, and finally death from infection or bleeding.
It takes at least a month of little to no vitamin C in the diet before symptoms occur. In modern