We've all heart the saying; "Feed a Cold, Starve a Fever." Mothers and grandmothers have been telling their children and grandchildren this for generations it seems. However, in this day and age of modern scientific analysis we don't have to rely on "Old Wives Tales" being true for medical advice. However do you wonder if modern science has ever explored whether there is any truth to this saying?

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What Exactly Is A "Cold"?

A "cold" is an upper respiratory infection (this means nose, throat and air pathways in the head). You are likely familiar with them (duhh), however do you think a cold, like many illnesses is caused by just one virus/bacteria? You read a lot about the cold being the Influenza virus a lot right?

Time for science A "Cold" is not actually caused by just one possible thing! You would not be alone in thinking that there is just one virus (influenza) that goes around causing colds, but there are actually many! These viruses include: rhinovirus, coronavirus, influenza (both A and B) which is actually the virus that causes the "flu" but can be milder and classified as just a "cold", parainfluenza (despite containing influenza in its name it's actually quite different from the influenza virus), adenovirus, and oddly enterovirus (which is weird because entero means intestine, and it's odd that an intestinally transmitted virus ends up causing an infection in the upper respiratory tract... hmmm what are you people doing with your noses so close to the intestines... wait! never mind... don't tell me). [1]

Ohhh, so this is how the enterovirus gets involved...

The most common way that you can catch a cold is by touching someone else's ... secretions (eww). They sneeze, get some nice boogies on their hand and touch something that you then touch and the virus goes along for the ride. Interestingly these viruses can be spread from anywhere between 3 days before you show symptoms to up to 3 weeks after (this I did not know!).[2], [3], [4]

So Should I Feed This Cold or Not?

There is surprisingly little research on the subject! Here is some information, we are often told to increase our fluid intake to help fight a cold. However research indicates that there is no beneficial link between increased fluid consumption and patient outcomes (aka no link between recovery time and drinking more liquids). [5] AND increased fluids may actually make outcomes slightly WORSE, but the authors clearly state that more work would need to be done before that information is believable.

Okay but what about feeding it. Should I do that? The answer to that one is seemingly a yes if this study done on viral and bacterial infections in rats is to be believed. [6]

What the authors saw here was that not eating was protective against bacterial infection, while a lack of glucose was lethal during viral infection. So in the case of a viral infection like a "cold" one should keep on eating, as not eating lead to worse outcomes for the rats with viral infections.

TL;DR

Yes! Feed a cold, but don't go out of your way to pound down those liquids (unless you are running a slight fever, then liquids may help with dehydration).

What About Starve A Fever?

Our body temperatures are regulated by a portion of our brain called the hypothalamus. When macrophages (macrophages are one of the classifications of white blood cells, they engulf invaders and then dissolve them) encounter an invader in our bodies they release a compound which signals to other macrophages "hey recruit thine brethren, and get thine ass over here and help me vanquish this foul demon." This compound is called Interlukin-1 alpha, and it is a member of a class of compounds called a pyrogen because when it reaches the hypothalamus it also induces an increase in body temperature (a fever!).

What is the point of the fever? Well from the body's perspective it causes an increase in the white blood cell division rate, so more white blood cells to fight the infection, and it also helps slow the reproduction rate of some bacteria and viruses which multiply most effectively at body temperature (98.6 °F or 37 °C). [7]

Yeah Yeah Yeah, but should I starve it when I am sick?

No. In fact fevers are actually quite beneficial and are associated with a better outcome when you have an infection. [8] Even treating a fever with a fever reducer is not associated with better health outcomes, and is typically done only for comfort. [9]. In general for a low grade fever, it is best to let it be.

See, even (Bruce Dickenson) Christopher Walken wasn't starving a fever... don't know why one would eat a cowbell though

So The Old Wives Tale....

It's correct for the cold, feed that, but wrong for the fever, don't starve it. Perhaps we should re-write the saying to "Feed A Cold, Feed A Fever. Damn It, Eat When You Are Sick. Give Your Body The Nutrients It Needs To Fight Off The Infection." You can use the easy to remember acronym FACFAFDIEWYASGYBTNINTFOTI... hmm that doesn't seem good... I'll keep working on that.

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Sources

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC104573/
2. http://www.racgp.org.au/afp/2015/januaryfebruary/a-is-for-aphorisms/
3. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(03)12162-9/fulltext
4. http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(05)70270-X/fulltext
5. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004419.pub3/abstract;jsessionid=D924BB6E0DDA31611E51D6AE7918E5EE.f03t03
6. http://www.cell.com/cell/fulltext/S0092-8674(16)30972-2
7. https://www.sciencedaily.com/releases/2011/11/111101130200.htm
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2590120/
9. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0031168/

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