Dr. Joe Schwarcz on lemon, lime, scurvy and vitamin C

November 17, 2019 0 By William Morgan


Today, the story of lemons, limes, paprika,
vitamin C and sailors in the 17th and 18th centuries who spent a long time on
the ocean and problems that they encountered. All right, let’s start with
the lemon. You know the old song? Lemon tree: The flower is very nice but the
fruit of that tree is impossible to eat. Well not impossible, but but not great.
Malic acid and citric acid and lemon: pretty tart. However, believe it or not, there are bloggers out there who tell us that lemon juice is the cure-all for
almost everything from diseases of the liver to heart disease. Well there’s an interesting historical connection, realistic one with lemons and
that takes us back to sailors. One of the scourge of long ocean voyages was a
disease called scurvy. Scurvy manifests as as bleeding gums and eventually goes
on to attack the heart and you can die from this. Nobody knew what was
causing this disease but it was very very common on long ocean voyages. And
then a Scottish physician came along by the name of James Lind who thought that
there might be a dietary connection and he carried out what we can look at as
the first randomized clinical trial in history. Aboard a ship, he divided sailors
into groups. Some of them he gave sulfuric acid because he thought that
that might be protective against scurvy. Others got different foods and some got
lemons and oranges. It turns out that the sailors who got lemons and oranges
were the ones who were eventually spared of scurvy. Of course Lind didn’t know what the active ingredient in there was. That came much, much later. Today we know what it is. It is vitamin C. And vitamin C was finally isolated in 1932 by the
Hungarian scientist Albert Szent-Györgyi. And he did it from paprika because paprika
has a very high concentration of vitamin C. Anyway, Lind thought that perhaps the reason that lemons and oranges were protective
against scurvy was because they were acidic and it turned out that there were
other fruits that were acidic that were much more readily available to the
British than lemons: limes. Well it turned out that lime did not work quite as well
as the lemons in preventing scurvy because amazingly that has only about
half the vitamin C content that lemons had. So they switched back to lemons but
in the meantime British sailors started to be called limeys because they were
eating lime. Finally in the 1930s, as I said, vitamin C was isolated
from paprika and it is now available in pill form. Today scurvy is really non-existent in the Western world because we all have enough
vitamin C in the diet but there are other allegations about vitamin C — what
it can and cannot do. For example it’s supposed to prevent a common cold. The
fact is that numerous studies have shown that just doesn’t happen except in some very rare situations where soldiers are exposed to very cold
temperatures or marathon runners who are highly stressed when they take vitamin C,
anywhere from two hundred to a thousand milligrams a day, they have somewhat
fewer colds. But the evidence is not there for taking vitamin C randomly in
order to prevent the cold and certainly the evidence is not there for lemons
having any kind of medicinal value in terms of preventing heart disease or any
other medical condition. But I can tell you that if you just take the lemon and
you scrape the peel and you put it into a salad it will add a lot of zest to the
salad although I don’t think lemons will add much zest to your health.