I recently looked over the CDC’s website for their cold & flu prevention tips. While there was page after page of advice, it all boils down to two things: get the flu shot & practice good hygiene. That was it.
I’m not opposed to getting a flu shot and washing your hands, but a lot more can be done. So I wanted to share some of the most recent research and practices that are being used in my clinical world of nutritional & herbal medicine, which is one part of a growing field called “functional medicine” or “comprehensive medicine” that goes beyond a pharmaceutical-drug-only approach.
Almost anything you do to improve your health will help protect you from the those nasty winter-time upper respiratory infections like colds and flu. A nutritient-dense diet, exercise, good hygiene, stress management, good sleep, and in many yes, the flu vaccine, can all be protective in varying amounts. The exception being hand sanitizers and anti-bacterial soaps which, in my book, are almost totally ineffective and possibly even harmful.1http://www.slate.com/articles/news_and_politics/prescriptions/2010/02/how_to_sell_germ_warfare.html Stick with a good scrub of ol’ fashioned soap and hot water.
However, this article is about protecting yourself from winter viral infections with food & nutrients. It doesn’t mean those other things are any less important, they are just outside the scope of this article.Check out the 8 best researched food and nutrients for cold and flu prevention this season. Click To Tweet
Here we go.
Prevention Tool #1: Vitamin D
If there is just one thing you can do nutritionally, this is it. The bottom line is that people who have higher levels of Vitamin D just don’t get sick as much.
Some professionals will tell you that studies on Vitamin D helps prevent the flu and other upper respiratory infections (URI) show “mixed” results. And that’s true. Some studies show it lowers the risk of respiratory infections, like this one where 10% of children taking Vitamin D got the flu vs. 18% of children who did not.2http://www.ncbi.nlm.nih.gov/pubmed/20219962, while other studies show little to no benefit.
But here’s the catch: most studies that show no preventive benefit with Vitamin D never measured the amount of Vitamin D in participants’ blood! They only looked at their oral dose, which was often a very low in the first place.3for example, “Vitamin D3 supplementation and upper respiratory tract infections in a randomized, controlled trial” which used 1,000 IU ...continue
But when you look at the studies that tested blood levels — which is what really counts — I believe the evidence is overwhelming that when optimal amounts of Vitamin D are in the bloodstream, there is a lower risk of developing flu and upper respiratory infections.
In one of the largest trials on vitamin D and upper respiratory infection to date, looking at blood levels of Vitamin D from over 18,000 people, those with the highest levels of Vitamin D (above 30 ng/dL) were 30% less likely to get a respiratory infection over 6 years than those with levels below 10 ng/dL.4“Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition ...continue. One of the largest meta-analyses done to date showed similar reductions in respiratory infections for people with the highest blood levels of vitamin D.5http://www.ncbi.nlm.nih.gov/pubmed/23326099 Children under 5 are particularly vulnerable to respiratory infections, but particularly when they have low levels of Vitamin D, which in this Indian study was levels lower than 22 ng/dL.6Association of subclinical vitamin D deficiency with severe acute lower respiratory infection in Indian children under 5 y. ...continue
General Recommendation: Get your Vitamin D levels checked first by your medical provider. Then take whatever is recommended to get your levels up to an optimal level, which is usually recommended to be 30-50 ng/dL. It is generally safe to take 2,000 IU – 6,000 IU per day through the winter, but the amount you take should be based in part on your lab values.
Ideally, it’s best to get Vitamin D the ol’ fashioned way — by exposing our skin to sunlight. This is how our ancestors got lots of vitamin D and why traditional hunter-gatherer tribes today have average levels of Vitamin D around 50 ng/dL without supplementation.7A study of the Massai tribe showed average levels at 48 ng/dL. http://www.ncbi.nlm.nih.gov/pubmed/22264449 But most of us live inside Starbucks now, so we don’t get a lot of natural sunlight.
What is more, if you live above the 35th parallel in the northern hemisphere (Washington, D.C. where I live is around 38th) the sun is too far away in winter for you to make any vitamin D on your own anyway, so supplementation and high Vitamin D foods is almost your only option apart from moving south for the winter.8http://www.health.harvard.edu/newsweek/time-for-more-vitamin-d.htm
The second best source of Vitamin D is from foods such as eggs from pastured chickens and ducks, liver, wild fish, sardines, and oysters. Most of us aren’t eating anywhere near enough of these, so my all-time favorite recommendation is using a little bit of high-vitamin butter oil with some high quality cod liver oil — this provides a great blend of three fat-soluble vitamins A, D, and K2. Without going into details, I believe there is good evidence that Vitamins A, D, and K2 work best when taken together and are in balance with one another.9http://www.westonaprice.org/blogs/cmasterjohn/2012/01/22/new-evidence-of-synergy-between-vitamins-a-and-d-protection-against-autoimmune-diseases/.
Prevention Tool #2: Zinc
I think everyone in clinical nutrition has a kind of “favorite” nutrient. For me, I am fascinated with zinc.
Our immune system does not function properly if it doesn’t have enough zinc. And it blows my mind that there are more than 10 large randomized clinical trials, along with dozens of other studies, demonstrating zinc’s powerful ability to reduce and prevent upper respiratory infections – they are referenced here in the footnote.10Bhutta ZA, Black RE, Brown KH, et al. Prevention of diarrhea and pneumonia by zinc supplementation in children in developing countries: Pooled ...continue
I know a lot of people who, when they get sick, they reach for a zinc product such as Cold-Eeze. What most people don’t realize is that zinc works best before you get sick or within a few hours of your very first symptom.
That’s because the way zinc stops viruses is through stopping their replication. Viruses replicate very fast once you’re infected, and after they have multiplied, it’s hard for zinc at that point to do as much for you. So zinc is not completely useless after you’ve become sick, but it’s best taken as a prevention or at least in the very early hours of sickness.
General Recommendation: When it comes to zinc, more is not better. Once you have adequate levels, extra isn’t going to help. Except that when you’re sick, your need is actually increased (which is true for most nutrients, just like when you exercise you need more calories). So my general recommendation for most people is 15-30 mg per day during cold and flu season of a zinc chelate such as zinc glycinate, zinc picolinate, or zinc gluconate. My favorite brand is Zinc 30 from Pure Encapsulations or Zinc Supreme from Designs for Health.
Those are for before you’re sick. But what about if you are sick or getting sick? Here’s where I think Life Extension’s Enhanced Zinc Lozenges are your best bet.11Nutritional biochemist Christ Masterjohn also recommends ...continue They utilize a highly effective chelate of zinc called zinc acetate that is the most effective against viruses for acute situations. Start them at the very first sign you think you are getting sick to help stop the replication of the virus.
Taking zinc long term can overload some people and create a copper-zinc imbalance, so I don’t recommend supplementing every day with zinc all year round unless you are working with a professional clinician.
I do NOT recommend zinc nasal sprays or nasal gels because they have been shown to be mostly ineffective and can cause sinus pain and the loss of the sense of smell and taste, which is no good when you sit down to your favorite meal and can’t enjoy it anymore. I don’t mind the lozenges, but there is some evidence that flavorings in certain commercial products may reduce their effects.12Eby GA. Zinc ion availability—the determinant of efficacy in zinc lozenge treatment of common colds. J Antimicrob Chemother. 1997;40:483-493. For that reason, I really just recommend capsules taken with food.
Prevention Tool #3: Epicor
There is a novel supplement that has been called a “multi-vitamin for the immune system.” While this is a bit of a marketing slogan, Epicor does contain several naturally occurring substances that are known to regulate the immune system, and I have found it to be useful for general immune system health. It has been shown in some smaller human trials to reduce colds and flus, and some evidence it reduces the symptoms and severity of an infection after you’ve become sick as well. For a summary of all the research on Epicor, see the Embria Research Page here, although I will warn you that this page is sponsored by the makers of Epicor
Epicor is a proprietary fermentation of a dried Saccharomyces cerevisiae (yeast culture). This fermentation process produces a kind of blend of compounds known to help promote a healthy immune system response. These substances include naturally occurring selenium, beta glucans (the immune boosting properties found in medicinal mushrooms), pre-biotics that support a healthy gut microbiome which is vital for proper immune function, as well as amino acids,
Overall, I think Epicor provides some very unique contributions to support the immune system that are not found in other immune-supportive supplements, particularly for people who consume very low amounts of fermented foods and who may also have digestive dysfunction.
General Recommendation: 500mg (1 capsule) of Epicor each day from October – March. My preferred brand is Source Naturals Epicor with D3. If you are already taking Vitamin D3, note that this brand contains 2,000 IU (international units) of Vitamin D already.
Prevention Tool #4: Astragalus (Astragalus membranaceus)
Astragalus is one of those superior tonic herbs that has almost universal benefits for the immune system. Of all the botanicals I could recommend for general winter viral protection, I think astragalus is my top choice. Other contenders include Ashwagandha, Tulsi (Holy Basil), Cordyceps, Reishi Mushroom, and Eleuthero (Eleutherococcus senticosus) — all fantastic alternatives if you don’t have astragalus.
Astragalus is rich in polysaccharides, minerals, flavonoids, and amino acids, which are all partly responsible for it’s ability to support your immune system. One benefit of using plants like this is that they have very broad, non-specific actions on your immune system, meaning they are able to benefit each person’s body slightly differently depending on where their immune system needs support.
In one mouse study, lab mice were infected with deadly Japanese viral encephalitis and oral administration of astragalus improved survival rates by almost 35%.13Kajimura K, Takagi Y, Ueba N, et al. Protective effect of Astragali radix by oral administration against Japanese encephalitis virus infection in ...continue
In another small, placebo-controlled study, healthy participants were given either astragalus, echinacea, or licorice root, or placebo, 3x a day for 7 days. Of these, astragalus had the strongest effect on the immune system.14Brush J, Mendenhall E, Guggenheim A, et al. The effect of Echinacea purpurea, Astragalus membranaceus and Glycyrrhiza glabra on CD69 expression and ...continue
General Recommendation: As a standardized extract capsule, about 1 gram (or three 300mg capsules) daily for prevention. My favorite standardized extract is from Vital Nutrients. It can also be found as an alcohol tincture, and depending on the preparation, about 30-50 drops a day in water for prevention. There is also a phyto-liquid extract from Gaia Herbs that I like called Astragalus Supreme, which also has Schisandra and Ligustrum berry. I would generally take at 2-3 capsules per day of this blend.
Don’t expect this to work overnight. Astragalus is kind of a food, not a fast-acting drug. It can take 6-8 weeks to reach its full potential in supporting your immune system.
Prevention Tool #5: N-Acetyl Cysteine (NAC)
There is some very good data that 600mg of NAC twice a day for 6 months lowers the incidence of influenza by more than 50%. Just 25% of elderly participants got the flu during those 6 months vs. 79% of the elderly participants not taking NAC.15De Flora S, Grassi C, Carati L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetyl ...continue
There is also good data that NAC protects against some of the most feared mutations of the flu virus such as Avian flu (H5N1)16Geiler J, Michaelis M, Naczk P, et al. N-acetyl-L-cysteine (NAC) inhibits virus replication and expression of pro-inflammatory molecules in A549 ...continue
NAC is also great to take once someone has developed the flu, as it protects lung cells from the severe damage often caused by influenza viruses.17Knobil K, Choi AM, Weigand GW, Jacoby DB. Role of oxidants in influenza virus-induced gene expression. Am J Physiol. 1998 Jan;274(1 Pt 1):L134-42 ...continue
General Recommendations: This is an easy one, take a high quality NAC supplement of 300 – 600 mg twice per day for the six months surrounding flu season. For the area I live around Washington D.C., that’s about October – March. My favorite brands of NAC are DaVinci Labs NAC (500mg capsules) and NuMedica NAC (600mg capsules). Or if you just want to take 1 higher-dose capsule per day and make it easy, Designs for Health NAC are 900mg capsules, and you just take 1 per day.
Prevention Tool #6: Elderberry Syrup (Sambucus nigra)
If you’re just a big kid like me, then you’re going to love elderberry syrup because it tastes pretty awesome.
This is one of those herbs that is used both for prevention and treatment among herbalists. It was first shown by an Israeli virologist to be able to keep viruses from penetrating cell walls and thus, from replicating. It is approved in Europe by the German Commission E for use in upper respiratory infections.
Two larger clinical trials have been done on elderberry’s ability to reduce symptoms of influenza, and both favored the group taking the elderberry syrup, with most getting better days faster than the placebo group even though their antibodies to the flu virus were the same between both groups.18Zakay-Rones Z, Varsano N, Zlotnik M, et al. Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry ...continue This may be indicative that the way elderberry works is not by boosting the immune system but by inhibiting the virus directly.
General Recommendations: To be honest, Elderberry Syrup is probably better for treatment than prevention, especially when you can start using Elderberry within the first few hours of your first flu symptom, so it’s good to just have on hand. However, it tastes so good, I think it must be good for prevention too — how could something this good not help?
My favorite brands are Gaia’s Black Elderberry Syrup, Designs for Health ImmunoBerry, and the least expensive one I would recommend is Nature’s Answer Sambucus 8oz. Or find a local registered herbalist who makes it and sells it under the FDA’s Good Manufacturing Practices (GMP).
In truth though, I don’t think taking this every day is as necessary as perhaps taking it during times when you think you may have high exposure to someone who has a respiratory infection. But if you want to take it, about 1-2 teaspoons per day is sufficient. If you’ve had exposure to someone who has a cold or flu, or you are starting to get sick, then I recommend taking about 1 tablespoon (which is 3 teaspoons) 2-4x per day for adults or half for smaller children starting as soon as you feel like you may have had an exposure to a respiratory virus.
Prevention Tool #7: Garlic (Allium sativum)
Garlic has a long, traditional history for preventing (and treating) colds and flu. However, the research was, up until recently, very slim.
But in 2001, a very well-controlled clinical trial was conducted where 146 people received a garlic extract for 12-weeks (November – February) or a placebo. Those receiving the garlic supplement were about two-thirds less likely to develop an upper respiratory infection (such as cold or flu), and those who did fall ill got better a whole day faster.19Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. http://www.ncbi.nlm.nih.gov/pubmed/11697022 Another, smaller clinical trial showed almost identical results in children.20Andrianova IV, Sobenin IA, Sereda EV, et al. Effect of long-acting garlic tablets “allicor” on the incidence of acute respiratory viral ...continue
General Recommendation: Eat garlic. A lot of it. Get it fresh and put it in stuff — it’s great! Crushing it and letting it sit about 15 minutes actually increases its beneficial properties, but don’t over-heat it or it’s pretty useless for medicinal purposes. Eating some parsley afterwards controls garlic breath very well.
I am not really a fan of garlic supplements. The best way to use it is to crush and finely chop 1-2 cloves, and leave it out on the counter for 10-15 minutes which activates and converts its compounds into the beneficial allicin. Then mix it in a little olive oil and let it infuse, and then dip some bread in it and eat it up. Do this daily for prevention or 3-5x a day when you are sick.
Prevention Tool #8: Echinacea (E. augustifolia, E. pallida, and E. purpurea)
Many large trials looking at echinacea’s ability to prevent colds and flu have been conducted and large meta-analyses of these studies have shown, again, “mixed” results, meaning some showed a benefit, while others did not.21http://www.ncbi.nlm.nih.gov/pubmed/16437427. The authors of this analysis admitted however that it is hard to draw conclusions since each trial used a different herbal preparation and dosages, as well as entirely different parts of the plant and different species.
In this case, I think we need to rely on clinical experience, and most herbalists agree (including me) that echinacea is an effective herb for preventing upper respiratory infections, and that the fresh herb, rather than the dried plant, should be used.
General Recommendation: To start, I much prefer astragalus to echinacea for prevention of upper respiratory infections, as I think echinacea is better during treatment rather than prevention. However, if you want to use echinacea for prevention in winter, I recommend a tincture of the fresh herb over dried, powdered capsules. 30-50 drops twice per day of a tincture is usually sufficient. My favorite is David Winston’s Ultimate Echinacea. For those with an auto-immune condition, you should take extra care to first consult with a professional before taking this.
If you are becoming sick, this is when echinacea is probably best. It works well for treatment but most people don’t take nearly enough. A treatment amount would be close to 40 drops every 2-3 hours while sick.
Prevention Tool #9: Colostrum
Colostrum is one of those wonderful substances that modern medicine is only starting to understand. It is another one of those almost universally helpful substances for modulating the immune system and protecting the body from infections. Data from two well-controlled clinical trials has shown its powerful ability even to protect patients from septic shock, a common cause of death in patients with non-treatable bacterial and viral infections.22http://www.ncbi.nlm.nih.gov/pubmed/18538107
The primary way that colostrum probably protects people from upper respiratory infections is based in part on the fact that it is rich in a substance known as IgA (Immunoglobulin A).
IgA is the part of our immune system that lines every bit of our mucosal barriers throughout our body — from our mouth all the way down to the other end. As such, our mucosal barriers in our nose, mouth, and throat, are our very first line of defense against pathogens of all kinds. Having a healthy level of IgA can protect against all sorts of infections by keeping viruses from adhering to our cell walls and finding their way in.23Brinkworth GD1, Buckley JD. Concentrated bovine colostrum protein supplementation reduces the incidence of self-reported symptoms of upper ...continue
Some people naturally, or due to other infections and chronic stress, have low levels of this important IgA substance along their mucosal tract.24Yel L. Selective IgA deficiency. J Clin Immunol. 2010. http://www.ncbi.nlm.nih.gov/pubmed/20101521 If you’ve ever hear of “leaky gut,” it low levels of IgA that are often responsible for allowing this condition to develop.
Boosting our levels of IgA with colostrum has been shown to reduce upper respiratory tract infections.25Marcotte H1, Lavoie MC. Oral microbial ecology and the role of salivary immunoglobulin A. Microbiol Mol Biol Rev. 1998. ...continue and one small study showed action specifically against the incidence of the flu virus, though this was an epidemiological study and not a controlled trial.26Prevention of influenza episodes with colostrum compared with vaccination in healthy and high-risk cardiovascular subjects: the epidemiologic study ...continue
General Recommendations: The problem with bovine colostrum is finding a good quality source, of which I know very few. It is such a delicate and complex substance that it is very easily damaged in production. The colostrum must be low-heat processed and from grass-fed pastured bovine, and it’s just so hard to know who to trust anymore without personal contact with the manufacturers.
There are a few I can recommend simply based on my own experience and my trust in the people who produce them. The first is by far NuMedica’s ImmunoG PRP Powder which is rather expensive (about $65 per jar) and only available to professionals, so you have to find a provider near you to get it, although I have seen it elsewhere online. Another bovine colostrum powder I would trust is from Daniel Vitalis’ company, Surthrival. Again, very pricey, but probably very high quality from what I have seen. One scoop in water per day during the winter is usually sufficient, and one jar will last about one month. If you prefer capsules, Tegricel Colostrum is also one I would trust, but is also rather expensive, and taking 2-3 capsules per day is recommended.
A Few Closing Notes
This is not an exhaustive list of things you can do — it’s just a list of some of the more researched and noted things, and some of what I think are the most effective. There’s so many other great practices such as eating dark berries like wild blueberries, lots of colorful vegetables, drinking tea, bone broths, taking some Vitamin C, eating medicinal mushrooms, and more can all be useful tools.
Remember that your body is a dynamic force and tends to respond well to variety, both in your diet and in supplementation. It’s probably not a good idea to take all these things above all the time. In fact, don’t ever do that.
All the recommendations above are general, and as such, may not apply to you.
The dosages above are for longer term and preventative use and probably don’t apply to you if you already have an acute infection. In many cases, these dosages are far to low or infrequent, and some of these recommendations may only be effective for prevention, and not treatment.
Stay well this winter everyone!
References [ + ]
|3.||↑||for example, “Vitamin D3 supplementation and upper respiratory tract infections in a randomized, controlled trial” which used 1,000 IU per day (many may need 4,000 – 8,000 IU per day) without checking actual blood levels of Vitamin D. http://www.ncbi.nlm.nih.gov/pubmed/24014734. And “Effects of vitamin D supplements on influenza A illness during the 2009 H1N1 pandemic: a randomized controlled trial” which gave children 2,000 IU per day and never tested blood levels. http://www.ncbi.nlm.nih.gov/pubmed/25088394|
|4.||↑||“Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey.” http://archinte.jamanetwork.com/article.aspx?articleid=414815 & http://www.ncbi.nlm.nih.gov/pubmed/19237723|
|6.||↑||Association of subclinical vitamin D deficiency with severe acute lower respiratory infection in Indian children under 5 y. http://www.ncbi.nlm.nih.gov/pubmed/15042122|
|7.||↑||A study of the Massai tribe showed average levels at 48 ng/dL. http://www.ncbi.nlm.nih.gov/pubmed/22264449|
|10.||↑||Bhutta ZA, Black RE, Brown KH, et al. Prevention of diarrhea and pneumonia by zinc supplementation in children in developing countries: Pooled analysis of randomized controlled trials. J Pediatr. 1999;135:689-697.
Sazawal S, Black RE, Jalla S, et al. Zinc supplementation reduces the incidence of acute lower respiratory infections in infants and preschool children: a double-blind, controlled trial. Pediatrics. 1998;102:1-5.
Hirt M, Nobel S, Barron E. Zinc nasal gel for the treatment of common cold symptoms: a double-blind, placebo-controlled trial. Ear Nose Throat J. 2000;79:778-781.
Mossad SB, Macknin ML, Medendorp SV, et al. Zinc gluconate lozenges for treating the common cold: a randomized, double-blind, placebo-controlled study. Ann Intern Med. 1996;125:81-88.
Petrus EJ, Lawson KA, Bucci LR. Randomized, double-masked, placebo-controlled clinical study of the effectiveness of zinc acetate lozenges on common cold symptoms in allergy-tested subjects. Curr Ther Res. 1998;59:595-607.
Prasad AS, Fitzgerald JT, Bao B, et al. Duration of symptoms and plasma cytokine levels in patients with the common cold treated with zinc acetate. A randomized, double-blind, placebo-controlled trial. Ann Intern Med. 2000;133:245-252.
Macknin ML. Zinc gluconate lozenges for treating the common cold in children: a randomized controlled trial. JAMA. 1998;279:1962-1967.
Marshall S. Zinc gluconate and the common cold: review of randomized controlled trials. Can Fam Physician. 1998;44:1037-1042.
Eby GA. Zinc ion availability—the determinant of efficacy in zinc lozenge treatment of common colds. J Antimicrob Chemother. 1997;40:483-493.
Belongia EA, Berg R, Liu K. A randomized trial of zinc nasal spray for the treatment of upper respiratory illness in adults. Am J Med. 2001;111:103-108.
Prasad AS, Beck FW, Bao B, et al. Zinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stress. Am J Clin Nutr. 2007;85:837-844.
Kurugol Z, Bayram N, Atik T. Effect of zinc sulfate on common cold in children: Randomized, double blind study. Pediatr Int. 2007;49:842-847.
Prasad AS, Beck FW, Bao B, et al. Duration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetate. J Infect Dis. 2008 Feb 15.
Singh M, Das RR. Zinc for the common cold. Cochrane Database Syst Rev. 2011;2:CD001364.
Science M, Johnstone J, Roth DE, et al. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ. 2012;184(10). E551-E561.
|11.||↑||Nutritional biochemist Christ Masterjohn also recommends these: https://chrismasterjohnphd.com/2016/12/26/zinc-definitely-fights-colds-youre-probably-using-wrong-kind/|
|12.||↑||Eby GA. Zinc ion availability—the determinant of efficacy in zinc lozenge treatment of common colds. J Antimicrob Chemother. 1997;40:483-493.|
|13.||↑||Kajimura K, Takagi Y, Ueba N, et al. Protective effect of Astragali radix by oral administration against Japanese encephalitis virus infection in mice. Biol Pharm Bull 1996;19:1166-1169. http://www.ncbi.nlm.nih.gov/pubmed/8889035|
|14.||↑||Brush J, Mendenhall E, Guggenheim A, et al. The effect of Echinacea purpurea, Astragalus membranaceus and Glycyrrhiza glabra on CD69 expression and immune cell activation in humans. Phytother Res 2006;20:687-695. http://www.ncbi.nlm.nih.gov/pubmed/16807880|
|15.||↑||De Flora S, Grassi C, Carati L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetyl cysteine treatment. Eur Respir J. 1997 Jul;10(7):1535-41.|
|16.||↑||Geiler J, Michaelis M, Naczk P, et al. N-acetyl-L-cysteine (NAC) inhibits virus replication and expression of pro-inflammatory molecules in A549 cells infected with highly pathogenic H5N1 influenza A virus. Biochem Pharmacol. Feb 1;79(3):413-20.|
|17.||↑||Knobil K, Choi AM, Weigand GW, Jacoby DB. Role of oxidants in influenza virus-induced gene expression. Am J Physiol. 1998 Jan;274(1 Pt 1):L134-42 & McCarty MF, Barroso-Aranda J, Contreras F. Practical strategies for targeting NF-kappaB and NADPH oxidase may improve survival during lethal influenza epidemics. Med Hypotheses. Jan;74(1):18-20|
|18.||↑||Zakay-Rones Z, Varsano N, Zlotnik M, et al. Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama. J Altern Complement Med 1995;1:361-369.
Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J Int Med Res 2004;32:132-140.
|19.||↑||Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. http://www.ncbi.nlm.nih.gov/pubmed/11697022|
|20.||↑||Andrianova IV, Sobenin IA, Sereda EV, et al. Effect of long-acting garlic tablets “allicor” on the incidence of acute respiratory viral infections in children. Ter Arkh.2003;75:53-56. http://www.ncbi.nlm.nih.gov/pubmed/12718222|
|23.||↑||Brinkworth GD1, Buckley JD. Concentrated bovine colostrum protein supplementation reduces the incidence of self-reported symptoms of upper respiratory tract infection in adult males. Eur J Nutr. 2003. http://www.ncbi.nlm.nih.gov/pubmed/12923655|
|24.||↑||Yel L. Selective IgA deficiency. J Clin Immunol. 2010. http://www.ncbi.nlm.nih.gov/pubmed/20101521|
|25.||↑||Marcotte H1, Lavoie MC. Oral microbial ecology and the role of salivary immunoglobulin A. Microbiol Mol Biol Rev. 1998. http://www.ncbi.nlm.nih.gov/pubmed/9529888|
|26.||↑||Prevention of influenza episodes with colostrum compared with vaccination in healthy and high-risk cardiovascular subjects: the epidemiologic study in San Valentino. http://www.ncbi.nlm.nih.gov/pubmed/17456621|