I know that oranges contain vitamin C and eating them can prevent colds and flus. However, recently, I caught a bit of flu, and during this period of illness, I once wanted to eat oranges.

But I was told that oranges are good for preventing illness, but bad for you during your flu or cold.


Is this true?

  • 1
    I'm very interested in hearing "official" answers to this one. I must say I have never heard of this and logically I cannot imagine how it can be bad for you. My mother is a doctor and I don't recall her ever telling us not to eat fruit whilst growing up and having a flu. The only reason this might be bad I can think of is while in the midst of a flu or cold your sinuses are generally sensitive and the acidity of the orange might aggravate these. Otherwise I can't see how it could actually have negative effects on the illness.
    – DeVil
    May 24, 2011 at 14:46
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    we need some citation that this is an actual belief that others hold -- other than "I was told.." -- otherwise it is idle speculation Jun 19, 2011 at 6:15
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    I tried to google anyone claiming that oranges should not be eaten during a flu, but I couldn't find anything. Please provide some evidence that this is a notable claim that a significant amount of people believe, I'm closing this for now.
    – Mad Scientist
    Jun 19, 2011 at 8:29
  • I have tentatively re-opened this, because another user has claimed to have heard the same thing. Like @Fabian, I have also tried to find examples of people making this claim, and failed. It isn't yet clear whether this is a well-known claim. Please provide a reference showing it is, or I will re-close shortly.
    – Oddthinking
    Jul 2, 2011 at 7:19
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    @gunbuster363, if you have any scientific evidence for those claims, and an explanation of what conglomerated phlegm might be, please post an answer.
    – Oddthinking
    Jul 4, 2011 at 14:48

1 Answer 1


I present an article from my own website as evidence here is that ok?


In short the answer is this:

In 2007, the Cochrane Collaboration published a report which examined, collectively, all of the good studies that had investigated the role of Vitamin C in prevention and cure of the common cold. Their conclusions were unremarkable.

First of all, the good news. If you take high doses of Vitamin C (around 1g per day – approximately 16x RDA or 22 oranges) every day then there is a suggestion that, when you get a cold, you’ll experience a very modest 7% reduction in the length of the illness (for children the effect is larger – around a 13% reduction). This amounts to an average half a day’s reduction in service to Kleenex.

However, the investigation (analysing the results of up to 29 different studies, involving more than 11,000 people) found no reliable evidence that regularly dosing yourself with Vitamin C greatly decreases the risk of actually catching a cold in the first place. Nor has there been convincing evidence that you can shorten the duration of a cold or reduce the severity of its symptoms by upping your intake of Vitamin C after you’ve started feeling ill. One study, alone, suggested that an enormous 8g dose of Vitamin C taken at the onset of symptoms could modestly reduce the length of a cold, but the study was beset with methodological problems.

It seems, then, that the practise of reaching for the Jaffas at the first hint of a sniffle is misguided. It’s a popular belief drawn from the flawed hypothesis of an old scientist who was speculating about topics outside of his field. There admittedly is evidence that suggests long-term intake of high doses of Vitamin C (around 22 oranges worth, no less) may help you recover less than half a day quicker than usual, but this is confounded by the notorious difficulty in measuring the beginning and end of a cold. Can you say when the last cold you had ended with an accuracy of less than half a day?

So the evidence that eating jaffas help is weak and there has been no suggestion in the trials that doing so is harmful in any way.

It is possible to overdose on vitamin C but I suspect in the duration of an average cold you would have to consume a heroic amount of very potent oranges to suffer any ill effects.

  • Could you please add a reference supporting the final statement about overdose levels? Also, where I come from Jaffas aren't a fruit, and when I have a bad case of man flu, no flimsy Cochrane Review is going to stop me eating them if I want! :-)
    – Oddthinking
    Jul 4, 2011 at 15:07
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    @oddthinking en.wikipedia.org/wiki/Vitamin_C#Chance_of_overdose Apparently chances are so low that no LD50 for humans is known. LD50 for rats (11.9g per kg, or about 1.2% of body weight) suggests you'll sooner die from choking on a seed (WP gives 45mg of Vitamin C per orange: a 70kg individual would need to eat about 10,000 oranges ;-)
    – Dave
    Jul 4, 2011 at 17:16
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    The answer does not address the question. It explains that one assumption of the quesion is perhaps wrong (Vit. C not preventing illness), but it does not try to address whether eating oranges during a full has some adverse effects.
    – Suma
    Nov 3, 2011 at 11:30

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