Prevention is the Best Treatment During Flu Season

Ryan Bradley, ND, MPH    November, 2008


This is the time of year when I look nervously at all the people who sneeze on airplanes! Cold and flu season is upon us again, and taking steps to protect yourself from getting the flu are more important than you might think, especially if you have diabetes. Making a decision regarding the flu vaccine can be difficult; opinions are strong over the safety of vaccinations in general, and opinions can be very persuasive but not necessarily based on facts. Even protective strategies, like the flu vaccine, are not 100% effective every year, and so taking reasonable steps to protect yourself from viral illness is prudent if you are frequently out in the public - like going to the post office, grocery store or nearly any public place! In this article, I hope to provide some information useful in your decision-making process around the flu vaccine, remind you the basics for flu prevention and then highlight select nutrients with a probable role in supporting viral immunity.


What is the “Flu”?

The “flu” is short for influenza, a type of highly contagious virus that, upon infection, leads to symptoms including debilitating fatigue, high fever, sore throat, cough, runny nose and can lead to nausea and vomiting. The virus is spread through droplets of saliva that are spread during sneezing and coughing - and with contact with runny noses! The flu can be very serious in vulnerable populations, including the elderly, small children, pregnant women and individuals with chronic diseases like diabetes, asthma, and heart disease. Very serious outcomes from the flu include death from dehydration and bacterial pneumonia (having the flu makes one more susceptible to bacteria infection, even though the flu is a virus), and hospitalization due to worsening chronic diseases.[1]

One of the challenges in controlling the spread of the flu is that the virus is contagious for a day before the infected person, or host, has symptoms. Yes, before you even know you have the flu you could be spreading the flu. This is why taking steps to prevent the flu is critical to not only avoiding it yourself, but also helping to protect others from catching the virus. In addition to common-sense protective measures - washing your hands frequently, avoiding touching your eyes and mouth, staying home if you feel sick, and avoiding people you know to be sick - several interventions, including the flu vaccine, may offer protection against catching the flu.


Should I Get the Flu Vaccine?

Should you get the flu vaccine? If you have diabetes, the answer is a definite yes. The flu vaccine, although imperfect, clearly reduces the rates of transmission of the virus, reduces hospitalization related to severe respiratory disease (like pneumonia and asthma) and heart failure, and reduces the rate of death from all causes during the flu season [2,3]. All people may benefit from the flu vaccine, however groups that are strongly encouraged to get the flu vaccine include children (aged 6 months-19 years), health care workers including nursing home workers, adults over the age of 50, pregnant women, and those people with serious chronic diseases like asthma, diabetes and heart disease, especially those people with congestive heart failure [1].


I Have Heard They Don’t “Get It Right”- and that the Vaccine Contains Mercury?

The development of the flu vaccine is complex, and takes the work of lots of trained epidemiologists and infectious disease specialists to do the best they can to predict which strains of the influenza virus pose the greatest risk in the United States. Strains have to be chosen for the vaccination, and then the vaccine itself goes into production, so there is a limited period of time during which the spread of various flu strains can be monitored before decisions need to be made on which strains make it into the vaccine for a given year. Because this is a time limited process, and because flu surveillance is not 100% accurate, mistakes do happen. However, banking on the odds of the experts based on probabilities of spread after months of surveillance sure seems like a preferred approach to just “winging it” and hoping for the best!

According to the Centers for Disease Control and Prevention (CDC) most flu vaccine still contains thimerosal, a mercury-containing preservative[4]. Although the mercury in the flu vaccine is a very small amount, and the benefits of the vaccine appear to outweigh the risks in most populations, thimerosal-free preparations are available, although in limited supply. For most individuals, I would not be concerned about the small amount of mercury present in the vaccine, however I would be more careful if you are pregnant, or if you are considering the vaccination in children under age 4, despite the reassurances on the safety of thimerosal provided by the CDC [4]. In my opinion, if you have a choice in the vaccine preparation, there is too little known about the long-term, cumulative health risks of mercury exposure to take chances with a vaccination containing thimerosal; although if you do not have a choice, I reluctantly agree with the CDC’s recommendation for a thimerosal-containing vaccination, because the protective benefits are more fully established for vaccination than they are against thimerosal.

In order to provide health care consumers with accurate information on which vaccine preparations do, and do not, contain thimerosal, the organization Safe Minds has developed an advisory brochure, which can be accessed on their website:


Are there Nutrients that Help with Viral Immunity?

First of all, the disclaimer: Nutrients and natural agents have not been evaluated in nearly as many people, nor with the same degree of scrutiny, as have influenza vaccinations, and therefore vaccination remains the most proven means of prevention. However, there are data suggesting select nutrients can be helpful in improving viral immunity and immune response to viral infection; these nutrients will be discussed here.


Antioxidants: Vitamin E, Selenium and N-Acetylcysteine

Although we typically think of antioxidants in relation to cancer and cardiovascular disease (although the role of these nutrients as supplements in these conditions remains controversial), the antioxidant status of the potential “host” appears to influence both the susceptibility to viral infection, as well as, the amount of tissue damage that results from infection, and thus the severity of symptoms.

How does this work? Your body’s immune system is quite limited in the number of ways it can respond to infection, and one response is to mount an inflammatory reaction. Inflammation helps by bringing more immune cells to an area, and also by increasing blood flow in a particular site. However, inflammation can also lead to tissue damage, and if the host has inadequate antioxidant reserves, this local inflammatory reaction may increase the susceptibility of the tissues to increased spread, and thus worsening, of the viral infection, including influenza [5].

Drs. Melinda Beck and Orville Levander are the two researchers best published in the area of antioxidants and viral susceptibility. Selenium is a necessary co-factor in an enzyme system called glutathione peroxidase, a potent oxidant fighter. According to Beck, based on animal models of viral infection, reduced selenium status leads to dramatic increases in oxidative stress, an altered host immune response, and to changes in the virus, or mutations. These mutations may allow the virus to escape detection by our immune system by changing it’s surface markers [6]. Selenium deficiency also led to greater infectivity (or “virulence”) of the virus and deficient animals had a much greater occurrence of viral infection in their hearts! In their models of viral infectivity, vitamin E deficiency had the same results [5, 7].

In addition to vitamin E and selenium, research suggests the antioxidant N-acetylcysteine (NAC) may also assist in the protection of lung tissue against the inflammation caused by viral infection. NAC is an established precursor to the potent antioxidant glutathione in humans [8]. Glutathione depletion in the mucosal lining of our airways (e.g., mouth, nose, and throat) secondary to oxidative stress, appears to enhance susceptibility to influenza infection. In their animal experiment, Chai et al. provided mice with glutathione in their drinking water- and then tried to infect them with the flu virus; those animals that were fed glutathione showed dose-dependent protection against infection![9]

Although these results are not definitive proof that these nutrients help prevent flu infection, there are considerable data supporting the importance of optimal antioxidant status in reducing infection and reducing lung damage, if infection occurs. Since individuals with diabetes are known to be under significant oxidative stress (due to elevated blood sugar), and are known to have lower glutathione concentrations than those without diabetes[10], supplementation seems reasonable during the flu season.


Bioflavonoids: Quercetin and Pycnogenol

In addition to the antioxidant nutrients mentioned above, quercetin also appears to protect the lungs against damage caused by the influenza virus. Quercetin is an antioxidant polyphenol found naturally in fruits and vegetables, including apples, onions and grapefruit. According to Kumar et al. (as reviewed in Friel et al.[11]), quercetin helps preserve antioxidant defenses in lung tissue, including glutathione, and directly protects against tissue damage in the lungs when exposed to the influenza virus [12, 13].

In addition to quercetin, Pycnogenol®, a polyphenol antioxidant supplement derived from the bark of the French Maritime Pine tree, also appears to protect against virally-induced oxidative damage, may reduce viral replication, and protect against viral heart infection [14, 15].  Although these effects have no been demonstrated in influenza virus, two separate viral research models suggest Pycnogenol® is protective, including one in HIV.

Clinical trials support additional benefits of Pycnogenol® in diabetes, including as a blood pressure lowering agent, a blood sugar lowered agent, and it may protect the eyes from diabetic changes; See Complementary Corner July 2007 for more information on Pycnogenol® in diabetes.


Probiotics: Lactobacillus

Although not a nutrient per se, probiotic bacteria are critical to healthy immune function. Because the cellular linings of our body are where we are susceptible to viral infection - places like our mouth, nose, and digestive tract - it is important to keep them healthy. These linings are literally alive with bacteria - some good, some infectious - and the good ones help regulate our immune defenses against infection.

Lactic acid bacteria, like Lactobacillus species, appear to help regulate mucosal immunity by increasing antibody production against viruses, including the influenza virus, improving natural resistance to infection [16]. In addition, animal experiments have shown giving mice Lactobacillus reduced viral levels, and prevented infection [17]. Some Lactobacillus species appear to increase the effectiveness of the influenza vaccine [18].

In diabetes, maintaining normal mucosal health is challenged in other ways. As described in Complementary Corner September 2006, high blood glucose increases the chances of mucosal and bowel overgrowth of unhealthy bacteria! The effect of these probiotics on flu prevention in diabetes deserves research attention because diabetes is a risk factor for death and hospitalization from the flu, is associated with altered mucosal immunity, and because Lactobacillus species appear to impact viral transmission.



Viral infection in diabetes, especially the flu, is very serious and all steps should be taken to prevent both infection and spread. The flu vaccine is effective and has proven benefit in reducing hospitalization, and even death, in people with diabetes. Washing your hands regularly, avoiding sick people, and staying home if feeling ill are all common sense ways of preventing infection and spread of the flu virus. In addition, select nutrients, including the antioxidants selenium and N-acetylcysteine, the bioflavonoids quercetin and pycnogenol, and probiotics like Lactobacillus appear to improve viral immunity and reduce the chance of viral infection. Increases in oxidative stress, and abnormal changes in bowel bacteria, may make people with diabetes more susceptible to severe influenza infection! So, until we are through another flu season, bundle up, eat well, and please, cover your mouth.

In health- Ryan Bradley, ND, MPH



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