Do our immune systems need help? Walk into any health foods store. Browse the Internet. You will find a multitude of diet supplements advertised to “boost your immune system,” or “support immune function.” Do they work? Will they keep you healthier or reduce your chances of catching infectious diseases?
A typical product is the 4Life company’s “Transfer Factor,” which they claim will improve your immune system by 437%. They claim it helps the immune system recognize harmful elements, changes the immune response to suit the occasion, and supports immune memory. They tell us the immune system is “incapable of responding to the challenges of everyday living.”
In reality, TF has no proven value and its use is not supported by any evidence published in peer reviewed journals. Transfer factor is an extract of the colostrum that precedes milk production, something that is transferred from mother to baby that helps protect the infant from infections. As far as I can tell, it consists of maternal antibodies that give the baby only temporary passive immunity to the specific antigens targeted by those antibodies. It has no effect on the baby’s own immune system and its effects wear off quickly. The 437% claim is based on one study from Russia, apparently not published, showing that the natural killer cells increased by that amount, but not showing any clinical benefit to people. The company selling it is a multilevel marketing enterprise that has received warnings from the FDA, and its promotion of TF has been characterized by critics as a scam. When investigative reporter Brian Deer visited a booth selling TF and asked questions about the research behind the claims, he was ejected by security staff.
As for their claim that the immune system is incapable of responding to the challenges of everyday living, didn’t it evolve for just that capability?
Throughout human history, hasn’t it done a pretty good job of keeping us alive in the face of constant encounters with bacteria, viruses, and other threats? Why would it suddenly need help?
There are all kinds of recommendations for diet supplements that allegedly boost immune responses. There is some supporting research, but it mostly measures blood levels of immune components like IgA, lymphocytes, or cytokines. It seldom even tries to measure any meaningful clinical outcome like fewer colds.
We don’t really know what those blood levels mean in terms of health and the ability to fight infections. We are learning that some diet supplements have mixed effects. For instance, zinc supplementation decreases the diarrhea associated with amoebic dysentery, but it also increases the incidence of A. lumbricoides, an intestinal roundworm parasite. Vitamin E supplementation increases the risk of strokes. Vitamin C supplementation may increase the risk of cataracts.
The FDA and the FTC have been cracking down on dubious “immune boosting” product claims. For instance, Andrew Weil’s website was recently ordered to stop claiming that its products could help prevent swine flu and colds.
Food, Exercise, Sex, and Music
You can find all sorts of advice about how to boost your immune function with diet and lifestyle interventions. An ABC News article recommended 10 foods that boost your immunity: yogurt, turmeric, garlic, oregano, red bell peppers, green tea, pumpkins, ginger, oysters, and broccoli. Other sources have other lists, including other foods like mushrooms. Sure, you can identify foods that contain higher amounts of antioxidants and useful nutrients that help maintain a healthy immune system as well as maintaining health in general. But are people who eat those foods healthier than people who get adequate nutrition from other foods? Probably not. If A has twice as much of a nutrient as B, you can get the same amount by eating twice as much B.
It has been claimed that a study published in the journal Chest in 2000 showed that chicken soup could increase immune response. In fact, that study showed the opposite: chicken soup reduced symptoms by counteracting the inflammatory response of the immune system.
Moderate exercise has been shown to increase immunity, but too much exercise can have the opposite effect.
One claim I rather liked was that having sex gives immunity a healthy boost by increasing levels of IgA.
Music hath charms… maybe listening to your favorite tunes on your iPod will keep you healthy. In a recent study, stressed newspaper reporters had a sustained rise in IgA when they listened to music.
Perhaps the most useful lifestyle advice I found was about the effectiveness of frequent hand washing in reducing infectious disease.
What Does “Boosting” Really Mean?
What does “boosting the immune system” even mean? It sounds like a good idea to the layman; but to a scientist, it is just meaningless pseudoscientific quackspeak. Stop and think for a minute. What would it mean to “boost” the digestive system?
You could boost your production of saliva and drool more.
You could boost your stomach acid production and enjoy more heartburn.
You could boost your intestinal motility and have diarrhea.
You could boost the absorption of water from your colon and get a fecal impaction.
You could boost your production of insulin and go into a hypoglycemic coma.
You could boost the absorption of nutrients from food, but that might also increase the absorption of toxins, or it might interfere with your homeostatic balance by giving you too much of one good nutrient compared to another.
If you have a defect like lactose intolerance or achlorhydria (an absence of stomach acid,) you will want to do something to correct it. But if your digestive system is functioning normally, trying to “boost” it will probably do more harm than good. If it ain’t broke, don’t fix it!
The immune system is incredibly complex. If something could boost your immune system, exactly what parts would it be boosting? They never specify.
We have antibodies, immunoglobulins IgG, IgA, IgD, IgM, IgE. We have complement, composed of a series of proteins. We have macrophages, B-cells, killer T-cells, helper T-cells, and CD4 lymphocytes. We have chemokines and interferons and interleukins. We have the Toll system. We are only beginning to understand how the immune system works and how all the components interact, and we are far from being able to predict the consequences of boosting any part of it.
Boosting Can Be Bad
When you catch a cold, your symptoms are not due to the virus itself. They are due to your body’s immune response to the virus. Would you want to boost that response and get more fever, mucus, congestion and sneezing?
What about allergies? What about eczema, hives, hay fever, asthma, food allergies, and life-threatening anaphylactic reactions to beestings? These are all caused by an immune reaction to foreign proteins. Do we want to boost that reaction?
In autoimmune diseases like rheumatoid arthritis, lupus, and ulcerative colitis, the immune system is already over-active. It is attacking the body’s own cells because it mistakes them for foreign invaders. If you boosted the immune response, you would make these diseases much worse.
What about cancer? Doesn’t the immune system fight cancer? Isn’t there an ongoing immune surveillance that destroys most cancer cells in the early stages? Well, not really. Cancer cells are ordinary tissue cells that have mutated; they may not be recognized as “foreign.” The immune system sometimes even makes cancer worse. Macrophages can produce growth factors that encourage tumor growth. Lymphocytes can produce an inflammatory protein that makes breast cancer spread to the lungs. No “immune boosting” treatment has ever been found effective for cancer. In fact, some of the effective cancer treatments work despite a side effect of immune suppression.
Increased immune function often amounts to producing an inflammatory response. Inflammation is bad. It leads to things like heart attacks.
In HIV/AIDS, the immune system is impaired. The treatment could be said to “boost” the immune system, but it is really only returning it to normal function. And even that is problematic. There is a condition called immune reconstitution inflammatory syndrome. When patients start HAART (highly active antiretroviral therapy) they can develop fever, enlarged lymph nodes, abscesses, pneumonia, nervous system disease, hepatitis, skin changes, or sepsis syndrome.
Rather than “boosting” the immune system, we should try to keep it functioning normally. According to the Harvard Health Letter, “The immune system is precisely that — a system, not a single entity. To function well, it requires balance and harmony. There is still much that researchers don’t know about the intricacies and interconnectedness of the immune response. For now, there are no scientifically proven direct links between lifestyle and enhanced immune function.”  To maintain normal immune function, as well as to maintain good health in general, adequate nutrition, sleep and exercise are good. Stress is bad.
What Really Works
There is one thing that really does boost your immune system. It’s called vaccination. It improves your ability to fight off specific infections. It works. Unquestionably. Change to: There is one thing that doesn’t exactly “boost” but that activates a specific aspect of the immune system
We have two vaccines that even help prevent cancer: hepatitis B vaccine for liver cancer and human papilloma virus (HPV) vaccines for cervical cancer.
Researchers are now trying to develop vaccines to treat existing cancers, targeting specific antigens on cancer cells so that the immune system could eliminate those cells.
Advertisers and poorly informed health advocates are “boosting” the immune system in the sense of “to stir up enthusiasm for; promote vigorously.” But their claims are not supported by science. For normal people whose nutrition is adequate, no high-quality clinical study has ever shown that any intervention led to any meaningful improvement in immune function or to any decrease in the rate of disease.
This article was originally published as a SkepDoc column in Skeptic magazine.