Why We Need Vitamin C
Most of us will have heard of vitamin C. It’s in oranges and tablets that taste like oranges right? But what is it? And what’s it got to do with orangutans, the Royal Navy and rose hips?
Well, I’m glad you asked; grab a coffee and come on in…
Vitamin C is common in just about all fruit and vegetables as well as in many animals (especially in their livers and brains). In fact most living organisms make vitamin C and it turns out to be a fairly important ingredient in many types of metabolism (breaking stuff down to keep you alive).
Living things have genes that tell the cells in certain parts of their bodies (or stems, wobbly bits, etc) how to attack sugars with some enzymes and turn them into vitamin C. Which is pretty flippin amazing in it’s own right but by far not the most complex thing that happens in living organisms.
But if most organisms can make their own vitamin C why do we need to eat the stuff? Because as it turns out we are one of the few species that can’t roll our own. We have to eat plants and things that have already made vitamin C and our bodies get their supplies that way.
When we don’t have enough vitamin C we get scurvy.
Scurvy is a nasty illness. You get spots in all the wrong places, you bleed from your nose and gums and your teeth fall out. And then you die. Sailors used to get scurvy all the time and they couldn’t for the life of them figure out why. We know better now of course but you can imagine how this must have been quite difficult to figure out.
Enter James Lind of the British Royal Navy. In 1747 he made history by not only finding the cause of scurvy but by running the first ever documented clinical trial. What he did was he paired up sailors who had scurvy and gave each pair a different dietary supplement. The supplements included cider, vinegar, sea water and cirtus fruits among others.
It’s easy with hindsight but you can imagine their elation when the sailors who had the oranges got better. Presumably a lot better than the poor buggers who got sea water. They still didn’t understand what vitamin C was but they at least figured out that when on long sea voyages it was important to keep a stock of fruit or veges. The Brits had plently of access to limes and so they stocked up on those and subsequentally earned the name “Limeys” from the fine folks of the soon-to-be United States of Jesus.
So, now we know that we need to keep a fairly regular diet of fruit and veges if we are to aviod the nast side effects of being humans instead of, say, dogs or cabbages.
But why can’t we make vitamin C when all these other organisms can?
Well, it turns out that we do in fact have this same gene for making vitamin C but it’s got some broken bits in it which stop it from working properly. Somewhere in our dark past an ancestor must have been born with a mutation that didn’t get in the way of going on to have enough children that, in turn, went on to have you and me. With access to fruit and vegetables our ancestors did just fine. It was only when they went on very long voyages – which probably didn’t really happen in a big way until sea exploration – that this weakness cropped up.
Is there any way we can tell how long ago this happened and who the culpret might have been?
In the last decade or so we’ve been getting really good at sequencing the DNA of not only humans but lots of other living things and we’ve noticed that we all share many common genes. Every living thing contains DNA and all DNA is made of just four types of building block. We can look at the sequences of building blocks (that form genes) in dogs, horses and whales and see that they’ve got the same sequence as us for making vitamin C but that ours has some broken bits in them.
But there’s a suprise in store.
We can look at the same genes in other primates (chimpanzee, orangutan and macaque were tested) and we find they also have broken genes for manufacturing vitamin C. This is a strong indicator that the ancestor who first developed the mutation was common to all of us on the primate limb of the tree of life. Which means that we’ve lived with this mutation for at least 25 million years now.
Guinea-pigs are also odd in that they can’t produce vitamin C but it’s likely that their gene malfunctioned entirely independently and the ability wasn’t missed for much the same reasons we’re ok with it. Their gene for making vitamin C is really messed up.
All of this really just boils down to the mild inconvenience that we’re pretty much stuck with it so we’d better get used to eating our greens.
So what’s the best way to get our daily dosage of vitamin C?
There’s a bit of debate about what the ideal daily intake is but the US National Academy of Science recommends between 60 and 95 milligrams each day. Which isn’t really much good because what normal person knows what 60 milligrams of vitamin C looks like?
I’ve taken the liberty of making you some lunch packs that contain enough vitamin C to get you through the day. If you have more at dinner time don’t worry too much; the upper limit is quite high and your body will only absorb what it needs.
Lunch pack 1: 200 grams of raw calf liver or a raw lamb’s brain (nyummy!)
Lunch pack 2: A single kiwifruit or a single big, juicy orange
Lunch pack 3: A sprig of brocolli about the size of a kiwifruit
Lunch pack 4: Rose hip! It’s crazy-high in vitamin C
And should you take supplements (aka orange-flavoured pills) along with your normal food? Well, the jury is still out on that one. It seems that the health food companies are pretty convinced that you should (I wonder why?) and you’re not going to hurt yourself if you do but, realistically, if you have even a semi-normal diet you’re going to well exceed the amount you need to get by in life. Your great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great (+999,900) grand mother didn’t need them. You probably don’t either.
So, vitamin C. We need it because we’re broken but we don’t need it in a bad way in day-to-day living. Eat some fruit and veges and thank God you’re not being fed sea water through toothless and bleeding gums.
Tags: evolution, genetics, itsgoodtobealive, james lind, scurvy, vitamin c
