Skeptics Stack Exchange is a question and answer site for scientific skepticism. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Whenever I'm sick I hear people say "Don't eat sugar. Sugar feeds infection". It seems a well-known concepts:

"Sugar feeds infection", "feeds infection and causes inflammation" and "contributes to a weakened defense against bacterial infection"

Recently, I had a throat infection, it seemed to be going away and I had a piece of (sugary, delicious) cake and got much, much worse.

But when I asked my doctor about it he said, "sugar doesn't feed infection and it was probably circumstancial".

Does sugar feed infection? For specificity, lets say refined cane sugar.

share|improve this question
up vote 2 down vote accepted

There is absolutely a correlation between high glucose levels and the increased risk of infection, so I understand the concern. Most of the time, high glucose levels would be a sign of diabetes, so for them, yes, eating sugar will cause infection. There are other reasons people sometimes have high glucose levels, such as infection (that's not a typo, they cause each other), pregnancy, surgery, and certain medications, such as steroids. From Wikipedia on steroid diabetes:

Treatment depends on the severity of the hyperglycemia and the estimated duration of the steroid treatment. Mild hyperglycemia in an immunocompetent patient may not require treatment if the steroids will be discontinued in a week or two. Moderate hyperglycemia carries an increased risk of infection, especially fungal, and especially in people with other risk factors such as immunocompromise or central intravenous lines. Insulin is the most common treatment

People with diabetes have a lot of difficulty keeping their glucose levels stable, so if they are frequently too high they will become sick more often. For healthy people, when we eat sugar, insulin is produced naturally by the body to bring the glucose level in the body down after the meal. It's important to remember that all foods are broken down into the same glucose molecules by the body. Some will be broken down faster and spike blood sugar levels, but there isn't a biochemical reason to assign special significance to table sugar, as opposed to fruit juice or white pasta, for example. WebMd explains in this article a diabetes diet.

So eating the cake didn't cause the relapse in your sore throat. Even if you had diabetes, it sounds like you only had one piece.

However, as a caveat, when you have an infection it's important to stay hydrated to recover faster and feel better. Liquids naturally thin and loosen mucus, so it helps relieve stuffiness and coughs. A stomach flu may make someone very ill if they become dehydrated, as well. Drinks with large amounts of sugar don't hydrate as well as water, so it is recommended to avoid soft drinks and sports drinks like Gatorade when you are sick, but it won't make a huge difference. Pedialyte is good if you have a very bad stomach flu.
According to WedMd:

What shouldn't sick children drink? Skip caffeinated drinks -- sick kids don't need it. As a rule, avoid sugary drinks or sodas. However, if a sweet drink is all your sick kid is willing to swallow, it may be OK to make an exception for now.


There is a fair amount of evidence that sugar can kill bacteria on surface wounds by dehydration and is being tested for internal use with antibiotics as in this case the sugar stops hidden bacteria avoiding the antibiotic. If i had a reoccuring infection i would consider using sugar water external or a sweat cuppa tea for internal. I believe sugar was used after surgery on the battlefields during the first and second world war where other meds were not always available. Big pharma can't sell their expensive drugs so sugar is not promoted as useful.

share|improve this answer
"There is a fair amount of evidence that sugar" - show me. – Buk Lau 10 hours ago
Also, lose a point for using "Big pharma" in your answer, and another for not substantiating that claim. – Shadur 6 hours ago

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.