Boost your immune system?

Boy is this stupid. Sorry to be so blunt, but when the media makes “news” out of a bunch of non-scientific advice from someone who has no business making health claims, I can’t help myself.

Where this starts: the CNN website today has a link to a story with the headline: “Boost your flu-fighting power.” That link takes you to an article by Ashley Johnson on with the subtitle, “Go to battle against colds and the flu by arming yourself with a supply of immune-boosting foods.” Johnson writes: “Even if you missed this year's flu shot, it's still possible to fight off the seasonal cold and flu viruses with a rainbow of tasty dishes.” Sounds yummy!

The article then lists the top 10 “most powerful immune-boosting foods.” The only problem is, none of these foods has been shown to “boost” the immune system at all. In fact, the whole notion of “immune-boosting” is seriously flawed: your immune system isn’t a muscle that you can strengthen by exercise or diet. The only remotely plausible step you can take to strengthen immunity is to get vaccinated. CNN should be ashamed of including this nonsense under their “Health” category.

But I digress. What does recommend? Well, they have some truly newsworthy ideas, beginning with #1: drink orange juice! While there’s no scientific evidence whatsoever that this will fight off the flu, the article breezily dismisses that concern with this: “While there's no real proof that loading up on the stuff will help once you've been bitten by the bug, there is power in keeping your immune system in top shape.” Huh? Sorry, OJ, there’s no evidence for this either. See my comment above: the immune system isn’t a muscle. Although orange juice is certainly good for you as part of a balanced diet, and it’s tasty.

I won’t go through the whole list, but here are a few more real howlers. Number 5 is oysters, which don’t have any particular health benefits. Not to be bothered by the lack of evidence, Johnson writes:
“Long hailed as an aphrodisiac ... oysters also offer a hearty punch of calcium, niacin, and iron. But the reason these slippery suckers have gotten the good date-night PR is their powerful zinc levels. Zinc, said to help fight off colds by boosting the production of immunity-boosting white blood cells, also controls progesterone levels, which can alter the libido.”
Look at how that first sentence is written: Johnson repeats the common but utterly unfounded claim that oysters are an aphrodisiac, and says they “also” offer other benefits – with that one word, “also,” she makes it clear she agrees with the aphrodisiac claim. What about zinc? Well, there was some weak evidence that zinc might help reduce the severity of colds, but the evidence has not held up to further, more careful scrutiny. So if you like oysters, go ahead and eat them, but don’t expect any health benefits. As for me, I’d rather leave the slimy suckers on the bottom of the bay where they belong.

Of course chicken soup is on the list, at number 10: “This magical elixir has long held the throne for cold and flu fighting foods. Whether it's the chicken (packed with zinc), the hot temperature (to loosen congestion), or the veggies (loaded with vitamins) that should get the credit, no one's sure.” That’s right, no one’s sure because there's no scientific evidence at all that chicken soup fights colds or flu. But hey, a bowl of hot soup always feels good when you’re miserable, so there’s no harm in eating it. At least it tastes better than oysters.

Every one of Johnson’s top 10 items is linked to a recipe, which at is what they’re pushing, of course. I have no objection to that – who doesn’t like good food? But I do object to her bogus health claims (and by the way, Johnson appears to have no medical or scientific training – she’s a food writer, and not even a good one). “Instead of a pill,” she argues, “a balanced diet of immune-boosters and bacteria balancers just might help you ride out the final months of winter's chill.” Bacteria balancers? What the ...? This kind of fluff is so stupid that I almost feel guilty ridiculing it. Almost, but not quite.


  1. Hi Steven! I think your opinion is very interesting:) I've added a link to your blog to my Boost immune system lens. I guess my readers should know some different opinions;)
    Thank you!

  2. This is indeed something worth a discussion. Does it mean that if the different types of food or treatments claim that they can boost the immune system, but has no scientific back-up whatsoever, is faux pas? Or is it that they indirectly support the immune system by promoting the health of other vital systems in the body? One such examples is an herbal supplement for the immune system which include Peppermint in its formulation do not necessarily strengthen immune system functioning, but helps in systemic health through detoxification. There is also the compound in Olive leaf that promotes the body's fight against pathogens. Holistic health solutions are recommended for cases such as these...

  3. Yes, it means that ALL claims to "boost the immune system" have no scientific basis. All the ones I have seen - including the not-so-subtle attempts in responses to my blog such as yours - are based on hype and pseudoscience.

    Many foods are indeed good for you, especially fresh fruits and vegetables. But they don't "boost" your immune system. And many people selling such "remedies" are just trying to make money by over-charging for foods, herbs, or "supplements" that don't do you any good.

  4. hi steven!!!! i think you have a point in this......we think that these things boost our immune.....but thanks for this eye opener.....its gud that someone like you have researched alot on this.....

    thank you
    keep it up!!!

  5. That was such an amusing article, thanks for the useful informations but now everything is a little hazy. What would be the best way to approach this subject... is there a alternative that could avoid getting anything from a doctor?

  6. lu15: I'm not sure why you want to avoid doctors - is it just the cost? Doctors are, for the most part, doing their best to help patients, and they should be your first resource if you feel you have a health problem.

    In general, if you are not sick, then your immune system is fine. "Boosting" it is nonsense. A diet that contains plenty of fresh fruits and vegetables, including leafy greens, will provide all of the nutrients you need to keep your immune system functioning normally.

    If you don't want to visit a doctor, try picking up a good book written by a reputable scientist - but alas, the bookstores are filled with junk science, especially in the area of diet and supplements. I recommend a book by Dr. Walter Willett, from Harvard, called "Eat, Drink, and Be Healthy", which I read and found to be very well researched and easy to read. For more on this book, see this link:

  7. I seem healthy but I'm not 100% sure, i was just looking for a way to reinforce that security (that's just my imagination getting the best of me). As for avoiding the doctor, it's not the cost. I'm very reluctant to go but there is no real big reason. Thanks for the recommendation, I found the book at my local library and on my way to pick it up.

  8. While I understand the lack of scientific proof, something in my brain disagrees. I wouldn't pinpoint an improved immune system to a certain food, but wouldn't you agree that someone who is eating healthy foods would have a better immune system than the same person eating lots of junk foods? (And by junk I mean overly processed and lacking in nutrients.)

  9. Julia,
    I agree that a person eating healthy foods will be healthier in many ways than someone eating only junk food. However, this does not mean that s/he will have a better immune system. The immune system is a very complex system of metabolic processes - it's not just one "system", even though we might call it that. If a junk food diet leads to a serious deficiency in vital nutrients, then one might get very ill, even die. (The simplest example is vitamin C deficiency, which causes scurvy and, in extreme cases, death.)

    But I don't know enough immunology to say what specific effects - if any - a junk food diet has on any component of our immune system. My main point in this post, to get back to it, is that if you are generally healthy, then your immune system is fine, and adding various foods to your diet will not "boost" your immune system.

  10. You know, Mr Steven, I'm having a serious case of blog-infatuation now! <3 I'll point people here next time they tout the "immune-boosting" nonsense, cos I'm sick of hearing about it.

  11. full article

    "A second experiment, using human volunteers, showed that immune system blood cells from tea drinkers responded five times faster to germs than did the blood cells of coffee drinkers."

    Now I would take that as proof that certain foods can boost your immune system. Maybe you fell differently...

  12. Steven, I looked at the full article, which appeared in PNAS in 2003. It's interesting, but it's a tiny study, just 11 test subjects and 10 controls, and the effect is a very limited one. I'm not inclined to take this "as proof that certain foods can boost your immune system," as you wrote.

    If you look at enough compounds and do small studies, then it's not surprising to find an effect purely by chance now and then. I suspect that's what happened here. I looked for follow-up - this study appeared 5 years ago - and I couldn't find any further studies supporting this particular health benefit for tea.

    It should be easy to find evidence that tea drinkers suffer fewer infections - as implied by the article you linked to - since there are literally millions of tea drinkers out there. But the evidence doesn't support it.

    I remain unconvinced. Just because an article appears doesn't mean we shouldn't continue to be skeptical - that's how science works, constantly questioning its own findings and revising them when future evidence says we must.

  13. Is it a good thing to boost your immune system? Are many people immunodeficient? Are colds and flu an indication of immunodeficiency?

    Getting a common viral infection is not a sign of weak immunity. It may be a sign of poor hygiene.

    In reality it may be very dangerous to boost your immunity. Autoimmune diseases are devastating and too active an immune system will cause widespread damage. I'm happy with the immune system I have and don't want to risk having it out of balance.


  14. Because I'm feeling punchy, I'd like to point out that, as far as I know, the only foods that will strengthen your immune system are spoiled, bacteria-laden foods...your body may develop antibodies in the process of resisting infection. (...what do you want to bet this will be the next health-food craze...?..."now with 20% more live staphylococcus"...)


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