Boost Your Immune System! 7 Best Supplements + 3 Nutrition Tips

November 15, 2019

[Disclosure: Some of the links below are affiliate links, meaning, at no additional cost to you, I will earn a commission if you click through and make a purchase.]




Below are some of my favorite, evidence-based supplements to help you boost your immune system and avoid getting sick during the fall weather change (or any time of the year!)... 



70% of the immune system is in the gut lining, and flora imbalance is a major contributor to suboptimal immune system functioning. When picking a probiotic, look for a mix of lactobacillus and bifidobacterium strains and at least 50 billion CFUs (colony forming units) per capsule. If this sounds like a lot, remember, you have approximately 100 TRILLION bacteria and yeast in your gut as it is. Product-wise I like Now Foods, Renew Life and Garden of Life Doctor Formulated Probiotics. Dosage suggestions: 50-100 billion CFU, 2-3x a day (up to 3 TRILLION CFU/day have been used in clinical studies). [1-9]




Silymarin, an extract from the milk thistle plant, is one of the most studied liver-supporting compounds out there. The liver is the body's main filter, and dealing with moderate to high amounts of alcohol, Tylenol, carbs and/or toxins in the blood can overwork it, making you more prone to infections. Look for a milk thistle capsule product around 500mg, standardized to 80% silymarin. Product-wise I like Now Foods Extra Strength Silymarin and Toniiq Milk Thistle. Dosage suggestions: 800-1200mg of silymarin, 2-3x a day (up to 13 grams of silymarin/day has been used in clinical studies without adverse effect; a very small percentage of people may be allergic to milk thistle and other members of the Asteraceae family which includes dandelion, chamomile, echinacea and wormwood; whether this is a legitimate allergy or a Herxheimer reaction remains a point of contention) [10-18]


Milk Thistle Plant (silybum marianum)



And you thought whey protein was only for building muscles! Perhaps the two most important roles amino acids play are 1) muscle building/repair and 2) immune system support. Grass-fed whey protein is a complete protein (unlike some plant proteins) and tends to be much less allergenic than conventional whey protein. My favorite powder is made by Raw Organic Whey (an "A2" milk protein powder, which is hard to find), and my favorite ready-to-drink product is made by Orgain. Dosage suggestions: 20 grams 1-3x a day. [19-22]




Perhaps the most well-known immune-boosting supplement, vitamin C also helps support adrenal health. Holiday stress can tax our adrenals, leading to excess cortisol and inflammation, which can then lead to a more compromised immune system. I'm a fan of what's called "high-dose vitamin C," a practice made popular in the 1970s and 80s by 2 time Nobel Prize winner Linus Pauling. Vitamin C is perhaps the least dangerous essential nutrient, and the most serious thing that happens with excess vitamin C is a laxative effect (called "vitamin C flush" or "bowel tolerance"). When shopping for products look for a clean ascorbic acid powder or you can also try acerola cherry powder if you want a "more natural" source (although ascorbic acid powder itself is also sourced from plants). I like BulkSupplements Ascorbic Acid and MicroIngredient's Acerola Powder. Dosage suggestions for ascorbic acid: 4 grams (or ~1 tsp) 2-3x a day (mix powder in cold water with a splash of your favorite organic fruit juice). Those battling serious infection may benefit from even higher doses. [23-35]




Vitamin D, which acts a little more like a hormone than a vitamin, plays a major role in immune system functioning as well as hormone balance and skeletal health. At least 40% of Americans are vitamin D deficient, and that number likely rises during the fall and winter months, since many aren't able to make vitamin D from sunshine since the UVB rays needed don't get through the atmosphere when the sun is lower on the horizon. You'll want to avoid toxic vitamin D2 products, and while most vitamin D3 supplements are made from lanolin (sheep's skin oil!), I prefer a fish oil-derived vitamin D source (less allergenic), like those made by BlueBonnet. Dosage suggestions: 5,000-10,000 IU a day (can take in 1 dose or divided doses). One study found that almost 10,000 IU/day was needed to get population D hydroxy levels to 40-80ng/mL levels, the "sweet spot" for immunity, bone building, hormones, mood and sleep benefits. [36-44]




Many are probably very familiar with zinc lozenges for immune system health. But did you know zinc also plays a major role in skin and hormonal health? While you might hear warnings to not take more than 50mg of supplemental zinc a day (and to take copper if you do), these warnings are a bit overblown. The clinical data says the "sweet spot" for taking zinc for immune-boosting effects is around 75-100mg a day. I like most forms of zinc with the exception of zinc oxide. Product-wise I like zinc lozenges made by Source Naturals, Nature's Way and Whole Foods brand. One of the additional benefits of zinc is its CHEAP!  Dosage suggestions: 15-50mg 2-3x a day (no more than 100mg every 24 hours). [45-49]




Colostrum (aka first milk, pre-milk, liquid gold or immune milk) is the breast milk first produced during lactation, which is distinct in composition to regular breast milk. For the newborn (human or animal), the ingestion of colostrum plays a major role in supporting the development of the innate immune system. Colostrum contains immune cells (lymphocytes), antibodies (ex. IgA, IgG, IgM, etc.), immunoglobulins, lactoferrin, proline-rich polypeptides (PRP) and several growth factors (ex. IGF-1). The use of bovine colostrum to boost the immunity of adult humans has become increasingly popular in the last decade, and several clinical studies have highlighted the positive effects colostrum-derived immunoglobulins and lactoferrin have on adult consumers. When sourcing colostrum look for a bovine colostrum from pasture-raised cows containing few (if any) additives. My favorite product is Sovereign Laboratories Colostrum Powder. Dosage suggestions: 5-10g 2-3x a day (taste is mild and mixes well in yogurt, applesauce, smoothie, coffee, water, etc.). [50-53]




Other immune-supporting supplements to consider include several natural antimicrobials such as oregano oil/carvacrol [54-58], garlic oil/allicin [59-64], echinacea [65-68], goldenseal/berberine [69-70], colloidal silver [71-76], and elderberry [77-80], as well as beta glucan [81-86] and natural vitamin A [87-88].





Staying properly hydrated ensures you have adequate body fluids for basic metabolic functioning, which includes healthy digestive processes, blood flow and lymphatic functioning (including lymph fluid, which plays a major role in immunity). Aim for a goal of drinking at least half your weight in ounces every day (high carb, high caffeine and high alcohol beverages don't count!) [89]



Dietary sugars and excess carbohydrate consumption can suppress the immune system by A) feeding pathogenic bacteria and yeast in the gut (these critters tend to thrive on sugar) and by B) driving elevated blood sugar levels which leads to glycation (tissue damage caused by chronically high blood sugar). Both of these phenomena also contribute to inflammation. [90-91]


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Several studies from the late 1970s to the early 2000s found that consumption of chicken and veggie soup had a positive impact on the immune system and helped to reduce inflammation and decongest the lungs and sinuses. [92-94]







1 (2018; review found 68% of probiotics reviewed had strong-moderate efficacy for at least 1 type of disease)

2 (2018; over past 40 years probiotics have been shown to impact the immune system, both in vivo and in vitro; microbial–immune system crosstalk has been linked to 1) SCFA production & signaling, 2) tryptophan metabolism, 3) nucleoside signaling in the gut and 4) activation of the intestinal histamine-2 receptor; several RCTs have shown that microbial modification by probiotics may improve GI symptoms and multiorgan inflammation in RA, UC and MS diseases; most lactobacilli and bifidobacilli are primarily small bowel colonizers, where they exert their immunologic effects; from 2000 - 2017 there was an explosion of interest in probiotics, with the annual # of RCTs ranging from 144-194; in 2017 there were also 49 meta-analyses; 4 significant conditions have consistently been shown to respond to probiotics in humans in meta-analysis: NEC, IBS, infant colic & respiratory infections)

3 (2018; probiotics confer immunological protection to the host through the regulation, stimulation, and modulation of immune responses; probiotics alone, or together with prebiotics, have potential to modulate the gut microbiota and immune responses in the host; probiotics have a positive influence on innate immunity, exerting several antiviral properties)

4 (2018; even lower doses [<100 million CFU/day] probiotics were safe & effective for fighting the common cold & flu-like respiratory infections by boosting the immune system) (2016; probiotics exhibit various beneficial properties such as prevention of bowel diseases & immune system support; one of the most known health effects of probiotics is preventing & ameliorating bowel diseases by improving the immune system)

6 (2014; L. rhamnosus, L. casei, B. animalis, B. lactis & S. boulardii are some of the most investigated probiotic cultures for their immunomodulation properties; probiotics can enhance nonspecific immune response characterized by activation of macrophages, natural killer (NK) cells, antigen-specific cytotoxic T-lymphocytes & the release of various cytokines; probiotic use in infancy could help prevent immune-mediated diseases in childhood; probiotic use in pregnancy could affect fetal immune parameters such as cord blood interferon (IFN)-γ levels, transforming growth factor (TGF)-β1 levels, and breast milk immunoglobulin (Ig)A; probiotics improve the gut mucosal immune system by increasing the number of IgA(+) cells and cytokine-producing cells in the effector site of the intestine)

7 (2012; significant positive health effects for 8 different strains of probiotics)

8 (2012; evidence supporting conventional probiotics for some clinical conditions)

9 (2011; several + effects of probiotics on the host intestinal mucosal defense system have been identified, including blocking pathogenic bacterial effects and competing with pathogens & toxins for adherence to the intestinal wall; for intestinal epithelial homeostasis, probiotics promote intestinal epithelial cell survival, enhance barrier function, and stimulate protective responses from intestinal epithelial cells; modulation of the immune system is one of the most plausible mechanisms underlying the beneficial effects of probiotics on human health; probiotics have been found to enhance the innate immunity & modulate pathogen-induced inflammation)



10 (2018; review/overview of milk thistle & its use with liver diseases)

11 (2014; liver-protective effects of milk thistle)

12 (2012; milk thistle for prevention and treatment of diverse liver diseases and liver cancer)

13 (2011; silybin phytosome more effective than silymarin; no adverse effects as doses <10g/day; silybin has proven antifibrotic, antioxidant and metabolic effects) 

14 (2011; silymarin as promising therapeutic agent for several diseases, due to antioxidant, anti-inflammatory and anti-apoptotic properties) (2010; review of milk thistle/silymarin for liver diseases)

16 (2001; silymarin plays a positive role in many liver diseases, including cirrhosis)

17 (1998; milk thistle as therapy for various liver diseases)

18 (1989; small RCT showing silymarin decreased 4-yr mortality rate in ppl with liver cirrhosis)



19 (2007; deficiency of dietary protein/amino acids impairs immunity & increases the susceptibility of infectious disease; amino acids play an important role in immunity by regulating: (1) the activity of T & B lymphocytes, natural killer cells & macrophages; (2) cellular redox state, gene expression & lymphocyte proliferation; and (3) the production of antibodies & cytokines; dietary supplementation of specific amino acids [including arginine & glutamine] enhances the immune status, thereby reducing morbidity & mortality)

20 (1998; immune system T cell functioning is affected by sulfur amino acid insufficiency [ex. methionine, cysteine, taurine, etc.])

21 (1990; protein malnutrition impairs host immunity w/ particularly detrimental effects on the T-cell system, resulting in increased opportunistic infection and increased morbidity & mortality; individual amino acids [ex. arginine] may also have a major influence on the immune system)

22 (1986; deficiencies of protein and some amino acids is associated with reduced immune-competence)



23 (2019 review found that doses of 3-10g of IV vitamin C had positive role in mortality)

24 (2018 review found that high dose IV vitamin C mitigates cardiovascular damage and has been associated with reduced oxidative stress, myocardial injury, arrhythmias and improved microcirculation, neurological outcome and overall survival)

25 (2018 review; vit C serves as a potent anti-oxidant, co-factor in collagen synthesis and a modulator of immune cell biology. An increasing body of evidence suggests high-dose vitamin C improves hemodynamics, end-organ function and may improve survival in critically ill patients. In 1 study in terminal cancer patients, vitamin C was associated with increased quality-of-life and survival. Vitamin C may have a variety of beneficial effects in patients undergoing cardiac surgical procedures, for acute burn injury, for the treatment of sepsis, in reducing pain, and in the treatment of cancer) 

26 (2018; trials in which IV C doses of 75–220g were given to patients with advanced malignancies found vit C to be safe and tolerable, providing some reduction in symptoms. Extensive literature demonstrates cancer patients experience vitamin C deficiency correlated with reduced oral intake, inflammation, infection, disease processes, and treatments such as radiation, chemotherapy, and surgery. Studies report reductions in inflammatory markers and suggest some improvement in symptoms, with a possible benefit in quality of life (qol) when IV C is used. The total human body store of vitamin C can range between 300 mg (at severe depletion such as scurvy) and 2g. Giving 5–25 g IV C over a period of 30–120 minutes is safe for cancer-affected adults of any sex and body mass to decrease inflammation, allow for optimal repletion of the body’s antioxidant stores, and possibly support qol. Doses of IV C >15 g given over <30 minutes have been found to have a pro-oxidative effect. IV C given 1–3x/week for 1–4 months in combination with oral vitamin C could improve or prevent deficiency, promote wound healing, lessen inflammation and improve qol or performance status)

27 (2018; high dose vit C is cytotoxic to cancer stem cells)

28 (2018; high dose vit C is cytotoxic to cancer stem cells via hydrogen peroxide-induced oxidative stress)

29 (2009; Cameron & Pauling reported in 1976 & 1978 that high-dose vitamin C (typically 10 g/day, by intravenous infusion for 10 days and orally thereafter) increased the average survival of advanced cancer patients and for a small group of responders, survival was increased to up to 20 times longer than that of controls. Other researchers reported benefit consisting of increased survival, improved well-being and reduced pain. However, two RCTs with oral ascorbate conducted by the Mayo Clinic showed no benefit. IV administration was found to increase plasma ascorbate concentrations by an order of magnitude compared to what may be achieved orally, which may explain the discrepancy between Cameron and Pauling's success and the negative results observed at the Mayo Clinic. Vitamin C accumulates in solid tumors to concentrations higher than in surrounding normal tissue. This phenomenon favors the positive outcome of high-dose intravenous vitamin C therapy in cancer patients. Vitamin C has been reported to have perhaps the lowest toxicity of all vitamins. Diarrhea, intestinal distension and gas are the most common complaints when it is consumed at higher dosages.)



30 (2018)

31 (2018)

32 (2017)

33 (2014)

34 (2013)

35 (2009)



36 (2018)

37 (2017; in case studies of 3 adult males, doses of 10k-60k IU/day for 2-6 yrs safely tolerated)

38 (2013)

39 (2012)

40 (2011)

41 (2011; evidence suggests vit D linked to several diseases including CVD & cancer; >40% of US population deficient in vit D, including >80% blacks and 69% of Hispanics [using 25-hydroxyvitamin D level of <20ng/mL as baseline])

42 (2010)

43 (2010)

44 (2010)



45 (2017; superiority of certain forms of zinc [acetate, gluconate, etc.] vs citrate in tx common cold) 

46 (2017; found zinc acetate & gluconate both effective for cold tx at 70-100mg/day & no addtl benefit w/ doses >100mg/day)  

47 (2015; found that zinc reduced cold symptoms by 18-54% at doses of 80-92mg/day)

48 (2011; meta-analysis finds zinc lozenges reduce duration of cold symptoms by 12-48% at doses of >75mg/day)

49 (1998 review found reduced cold symptoms when at least 13mg zinc taken every 2 hrs for 1st 1-2 days [104mg/day minimum])



50  (2018; immune system effects of bovine colostrum) 

51 (2014; immune system effects of lactoferrin found in bovine colostrum)

52  (2011 review of colostrum and immunoglobulins found in colostrum)

53 (2008; antimicrobial effects of bovine colostrum) 



54 (2018; comprehensive review of oregano and carvacrol and its impact on human health)

55 (2017; review of antimicrobial, antioxidant, anti-inflammatory, anti-cancer effects of oregano & carvacrol)

56 (2016; positive intestinal & immunity effects of oregano & carvacrol [chicken model])

57 (2016; positive intestinal & immunity effects of oregano & carvacrol [pig model])

58 (2014; positive antiviral effects of oregano/carvacrol on norovirus [mouse model])



59 (2019 review found sulfur-containing garlic extract products play important protective and regulatory roles within the immune system and in oxidative processes)

60 (2018 review found garlic able to maintain the immune system homeostasis and to exhibit beneficial effects on immune cells especially through regulation of proliferation and cytokine gene expression)

61 (2015; garlic appears to enhance the immune system by stimulating macrophages, lymphocytes, natural killer (NK) cells, dendritic cells, and eosinophils, and by modulation of cytokine secretion, immunoglobulin production, phagocytosis, and macrophage activation)

62 (2014; garlic elicits anti-inflammatory and anti-oxidative responses that help prevent cancerous tumor formation)

63 (2014; garlic has potent antimicrobial, antifungal, antiprotozoal and antiviral properties; garlic can target potentially harmful bacteria while not eradicating beneficial microflora; the antibacterial properties of garlic are widely attributed to allicin)

64 (2012; Allicin could partially protect host against malaria strains through enhancement of innate and adaptive immune responses)



65 (2012; in a study of 755 ppl over 4 months, echinacea was found to reduce total number of cold episodes, cumulative cold episode days within the group, and pain-killer medicated episodes. Echinacea inhibited viral colds and especially prevented enveloped virus infections. Echinacea showed maximal effects on recurrent infections and preventive effects increased with therapy compliance and adherence to the protocol)

66 (2007; Echinacea is a wide-spectrum immunomodulator that modulates both innate and adaptive immune responses [mouse model])

67 (2005; echinacea reduces cold symptoms; use of echinacea is associated with a significant and sustained increase in the number of circulating total white blood cells, monocytes, neutrophils and NK cells)

68 (2003; echinacea purpurea stimulates cellular immunity & antibacterial defense [mouse model])



69 2012; synergistic antimicrobial effect from using berberine, goldenseal aerial portions and goldenseal root, including against MRSA strains)

70 (2011; synergistic antimicrobial effect from using berberine, goldenseal aerial portions and goldenseal root)



71 (2018; nanoparticle silver size in most studies range from 5-40nm [to be considered nanoparticles the size must fall in the 1-100nm range])  

72 (2018; silver exhibits antimicrobial effects thru 3 activities- 1st, silver cations can form pores and puncture the bacterial cell wall by reacting with the peptidoglycan component; 2nd, silver ions can enter into the bacterial cell, inhibiting cellular respiration and disrupting metabolic pathways resulting in ROS generation; 3rd, silver can also disrupt bacterial DNA and its replication cycle)

73 (2016; silver used for centuries as antimicrobial agent; various medical products on the market that use silver [ex. dressings for healing chronic wounds]; out of all the metals (gold, platinum, copper, zinc, etc.) with antimicrobial properties, silver has the most effective antibacterial action; silver is comparatively non-toxic and non-mutageneic to human primary organ systems; silver considered a safe and promising antibactericidal agent against highly infectious drug-resistant bacteria such as E. coli, P. aeruginosa, and Staph. aureus)

74 (2013; silver ions shown to possess strong antimicrobial properties but cause no immediate and serious risk for human health)

75 (2013; antimicrobial properties of colloidal silver solution depend on nanoparticles concentration and interaction time with bacteria; 200ppm solution for 24 hrs in culture media was needed to inhibit all pathogenic bacteria in this study)

76 (2006; silver exhibits low toxicity in the human body; chronic ingestion or inhalation of silver preparations (especially colloidal silver) can lead to deposition of silver particles in the skin (argyria), eye (argyrosis) and other organs. These are not life-threatening conditions but cosmetically undesirable)



77 (2019 study of 180 participants found black elderberry effectively treats upper respiratory symptoms)

78 (2016 RCT of >300 participants found elderberry reduces cold duration & symptoms)

79 (2011; elderberry is active against human pathogenic bacteria as well as influenza viruses)

80 (2004; RCT of 60 Norwegians found elderberry extract safe and effective in treating influenza virus infections)  



81 (2019; in human studies, the tested (and suggested) daily dose remains in the range of 100–500 mg for stimulation of the immune system, whereas for a decrease in cholesterol levels a daily dose of 3 g is recommended; beta glucan is a strong activator of cellular immunity, with macrophages being the most important biological targets; glucan is recognized by various receptors present on membranes of cells such as macrophages, monocytes, dendritic cells, and NK cells; glucan exerts effects on various parts of the immune system including cytokine production and antibody response)

82 (2017; β-Glucans are known to have antitumor, anti-inflammatory, anti-obesity, anti-allergic, anti-osteoporotic, and immunomodulating activities)

83 (2014; the results of all studies examined indicate that beta glucans, a class of natural polysaccharides, have an immune strengthening effect)

84 (2011; β-Glucans are naturally occurring polysaccharides produced by bacteria, yeast, fungi, and many plants; their immunomodulatory, anti-infective and anti-cancer effects have been well studied; since β-glucans have large molecular weights, they must bind surface receptors to activate immune cells)

85 (2009; β-glucans act on several immune receptors and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells; both innate and adaptive immune response can be modulated by β-glucans and they can also enhance phagocytosis)

86 (2007; Beta-glucans are naturally occurring polysaccharides; beta glucans increase host immune defense by enhancing macrophages and natural killer cell function; The induction of cellular responses by beta-glucans is likely due to specific interaction with several cell surface receptors; beta-Glucans show anticarcinogenic activity; as an immunostimulating agent, beta-glucan can inhibit tumor growth, in part via anti-angiogenesis effects)



87 (2015; immune boosting properties of protein, vit C, vit A, vit D & zinc)

88 (2008; immune boosting properties of vitamin A & vit D)



89 (2015)



90 (2012; investigation of diet-induced dysbiosis and effects on immune system found that diets high in refined carbs reduced beneficial bacteria and increased pathogenic bacteria in the gut)

91 (2018; effect of dietary sugar on inflammation)



92 (1978 study on immune benefits of chicken soup)  

93 (2000)

94 (2003)

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