Walk through the aisles of any health food shop and you can see pots of echinacea or zinc that promise to “support your immune system” or “maintain its healthy function.”
Read new age health blogging sites and you can find posts on how drinking hot lemon water or knocking back a shot of wheatgrass juice or the current green goo du jour would “boost your immune system” and make you less likely to get ill.
These are tempting prospects at this time of year, but ones that are foiled by an inconvenient truth — they do not work. The idea that any dietary supplement can boost your immunity makes very little scientific sense, and because of the way your immune system works, even if they did what they say they did, you definitely would not want them to.
Illustration: Mountain people
“People have this idea that the immune system is some kind of internal force field that can be boosted or patched up,” Imperial College London immunology and infectious diseases professor Charles Bangham said. “This couldn’t be further from the truth. As the name suggests, it’s not a single thing, but a system incorporating many organs and biological functions.”
The immune system can be broadly separated into two parts, the innate and the acquired response. On detection of infection, it is the innate response that acts first. Although fast, it lacks finesse, and deals with an invading pathogen in much the same way that the Ghostbusters might try to remove a ghost from a haunted hotel. It gunges the halls and doorways to try to flush it out, which is why you fill up with phlegm and snot. It yanks up the thermostat to try to boil it, which is why you run a fever, and it shuts down the building until the problem is solved — making you depressed and lethargic so you do not go out and pick up another infection while your immune system is at work.
What it does not do is eliminate the intruder from the body. That is the remit of the acquired system, a well-drilled SWAT team by comparison that identifies the enemy and makes the specific weapons, or antibodies, needed to destroy it.
“You might ask why we’ve kept this evolutionarily primitive innate system that makes us feel ill if we’ve all got perfectly good acquired systems,” Bangham said. “It’s because it takes around five to 10 days for the acquired system to identify the antibodies needed and clone them up to sufficient numbers to make a meaningful attack. The immune system is there to curb the pathogen’s multiplication in that window of opportunity before it finally gets clobbered.”
There is of course a way you can speed up this process and thereby boost your immunity: It is called vaccination. Vaccines contain harmless versions of the bug you want to protect yourself against so that the acquired system can remember them and act more quickly the next time it meets them. Given that the supplements you buy in health food shops are not vaccines and thus cannot be helping the acquired system, they must therefore be aiming to boost the innate one, which would be far from ideal.
“If a supplement actually stimulated the innate immune response then it would leave you with a constant feeling of being unwell, with a fever, a snotty nose, depression and lethargy without any obvious benefit. So in that respect, the whole idea is a bit of a con,” Bangham said.
Like most pseudoscientific concepts, immune-boosting supplementation has a grounding in misunderstood science. Vitamins, especially A, C and D, and minerals such as zinc do have a vital role in the functioning of our immune system, but they are also practically unavoidable components of our diets, present in large quantities in fruits, vegetables and meats. If you have a normal diet, you do not need supplemental vitamins or minerals, and giving more of them will not help.
“They [manufacturers of supplements] might not say anything untrue, but what they are doing is implying that if someone on a normal diet takes them, they will improve their immune function, which is plain wrong,” Bangham said.
Most of the studies that apparently support the effectiveness of such supplements are done in selected groups of patients with specific deficiencies and are incorrectly extrapolated to the general population, Royal College of General Practitioners vice chair Tim Ballard says.
“The only thing that seems to have a little bit of reasonable evidence behind it is zinc supplements to prevent colds in children,” he said, adding that methodological weaknesses in these studies, too, leave him unconvinced of a real effect.
“And the findings have never been replicated in adults,” he said.” I certainly haven’t been persuaded to recommend any immune-boosting supplements to my patients. People should be extremely careful before they part with their hard-earned money for any products that are sold to prevent the common cold or other infections.”
However, look at Web sites of reputable high street retailers, chemists as well as health food stores, and you can find hundreds of products that promise to boost, tune, support or enhance your immune system. Along with the classic vitamins and minerals, you will see echinacea, selenium, beta-carotene, green tea, bioflavonoids, garlic and wheatgrass supplements, all of which, pending any evidence that they actually work, are unlikely to do anything other than give you expensive urine — and as that is a fairly difficult thing to show off at a dinner party, it is probably not worth the investment.
So what can we do to avoid getting ill?
“Other than a healthy diet and regular light exercise, which increases the activity of helpful immune cells, simple personal hygiene is important,” Ballard says. “I’m not suggesting that people are pathologically dirty, but there’s evidence that washing your hands, being careful not to sneeze over people, keeping surfaces nice and clean all reduce the risk of transmission.”
So, basically, everything that your mom told you to do. Although we should stop short of becoming antibacterial wipe-wielding germaphobes.
“There’s increasing evidence that you actually want people to come across allergens and develop colds, especially children. It’s all part of the normal maturation of the immune system,” he said.
There is still much about the immune system that researchers have to discover. In only the past decade, with genetic sequencing technologies becoming more affordable, scientists have begun to learn not only how invading pathogens shape and strengthen our immune system, but also about how they interact with the communities of microbes that live in and on our bodies.
“Research around the microbiome is fascinating,” Ballard said of attempts to better understand the interplay between our immune system and the trillions of microbes that line our skin, gut and lungs, also called our microbiota. “A lot of people don’t realize that just over half the cells in our body are not human, but are actually bacteria and other micro-organisms. Certainly, to be in good health, you need a good balance between people and their various microbes.”
Liam O’Mahony is a molecular immunologist at the Swiss Institute of Allergy and Asthma Research in Davos. He wants to find out how to tweak people’s microbiota to improve their resistance to allergic and infectious diseases. It is a line of research that might one day fulfill the empty promises made by immune-boosting supplements.
The microbes in and on our body help defend us from pathogenic infection on several levels, he says.
The first is colonization resistance.
“By just being there, they’re taking up real estate, if you like, competing for space and food so that disease-causing bugs can’t establish,” he says.
The second is by secreting antimicrobial molecules that kill potentially dangerous pathogens. Bacteria and fungi secrete toxic proteins to fend off undesirable species; it is an evolutionary arms race that we have latched on to by extracting these proteins and using versions of them as antibiotic drugs.
The third is by regulating the inflammatory signals of our innate immune response and thus the feelings of sickness we get when that innate system jumps into action.
“The different composition of people’s microbiotas might explain why although we’re all exposed to the same bugs, some of us have only mild symptoms from infections and other people get knocked down by them,” he says.
O’Mahony hopes that by better understanding what an ideal microbiota is we can boost some people’s natural immunity to infection. That dream is not too far away — it is already happening in the clinic, albeit in a very basic form. In what sounds like something from a Roald Dahl recipe book for disgusting medical concoctions, the use of fecal transplants — taking the faeces from a healthy individual and transplanting it, along with all its friendly bacteria, to the gut of a patient through their bottom or nose — is gaining popularity.
“People are doing fecal transplants and getting incredible cure rates for Clostridium difficile infections,” he said.
These infections occur when a strong course of antibiotics kills the friendly bacteria in a patient’s gut, allowing the potentially deadly and highly drug-resistant Clostridium difficile bacteria to land-grab and colonize the gut.
“Fecal transplants obviously do not sound too appetizing and the application is limited, so what would be better is if we could define what the ideal five to six hundred bacteria for an individual are and grow them in a lab and give them to people as personalized medicine,” he said.
If he and others working in the field can figure out what an ideal microbiota looks like for different people, they can then supplement or patch up an individual’s bacteria, for example with a spray or a cream, to make them more resistant to infections.
“The technology is there from a laboratory point of view, but I think it’ll be another few years before it’s ready to start clinical testing and a few years on from that before anything hits the market,” he said.
Until that point, unless you fancy a DIY fecal transplant, if you want to maintain your immunity and stay in good health it’s best to eat well, do some exercise and save your money.
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