Maintaining a Healthy Microbiome
Probiotics For Respiratory And Immune Health
The microbial residents of the throat, nose, and sinuses make up the upper respiratory microbiome and, much like the gut microbiome, help restrict the presence of harmful microbes and regulate immune function (Schenck 2016; de Steenhuijsen Piters 2015; Gao 2014). Healthy lungs, once thought to be sterile, are now one of the latest body sites known to be home to a unique microbiome (Roux 2017; Pichon 2017; Cui 2014). Some similarities with the oral and nasal microbial communities suggest that certain bacteria may be inhaled from these locations, but the lung also contains specific resident microbes (Hauptmann 2016). The lung microbiome is suspected to play important roles in health and disease, and in regulating immunity. Understanding these links is still at a very early stage (Wang, Li 2017; Cui 2014).
Oral probiotics have been found to reduce the frequency and duration of upper respiratory tract infections and the amount of antibiotic needed for treatment (Hao 2015; Quick 2015). In addition, emerging research suggests topical probiotics in the form of nasal sprays may be effective for restoring a healthy microbial balance in the upper airways (Santagati 2015). Pilot trials indicate that nasal sprays with Streptococcus salivarius 24SMB or S. sanguinis may be helpful in children with chronic or recurrent otitis media (Skovbjerg 2009; Marchisio 2015).
Asthma and Allergic Rhinitis
Lung dysbiosis has been reported in people with asthma, where less microbial diversity and changes in the composition of the microbial communities were observed (Chung 2017). Intestinal dysbiosis also appears to play a substantial role in allergy and asthma susceptibility. Factors such as Cesarean birth, formula feeding, and antibiotic exposure early in life, which negatively impact the infant gut microbiome, are associated with higher risks of asthma and allergies (West 2016; Moya-Perez 2017; Kolokotroni 2012).
A specialized dried yeast fermentate from S. cerevisiae (Epicor) has been shown to reduce seasonal allergies in two small studies. In one study, 25 healthy participants consumed Epicor or a placebo daily for five weeks during allergy season. The placebo group experienced increased seasonal allergy frequency, but the Epicor group did not. Interestingly, allergic symptoms returned within 1–2 weeks after the participants stopped taking Epicor (Jensen 2008). In a larger study, daily doses of 500 mg of Epicor or placebo were compared in 96 healthy subjects with a history of seasonal allergies. Subjects in the Epicor group had less severe nasal congestion and runny nose, and used less allergy medication than those taking placebo (Moyad 2009).
Allergies are mediated in part by an immune-signaling protein called immunoglobulin E (IgE). If the immune system produces too much IgE in response to a stimulus, an allergic reaction can ensue. A strain of Lactobacillus acidophilus called L-92 was shown in a preclinical screening study to reduce production of IgE in mice challenged with a pro-allergenic substance (Ishida 2003). Based on these intriguing results, three clinical trials of L. acidophilus L-92 were carried out. First, L-92 was administered to subjects over two allergy seasons. Dosages were 50 billion CFUs twice daily for six weeks during the first season and 20 billion CFUs once weekly during the second season. Twenty-three people participated during season one, and 20 did so during season two. During the first season, L-92 reduced eye-related distress related to allergies by 31%. During the second, a statistically significant reduction in overall allergy-related distress among the subjects receiving L-92 was observed (Ishida, Nakamura, Kanzato, Sawada, Yamamoto 2005). In the second study, 49 participants with allergic rhinitis took either 30 billion CFUs of L-92 or placebo daily for eight weeks. Nasal mucosal swelling decreased by 24% at week eight in the L-92 group. Also, nasal symptom scores decreased 19% in the L-92 group compared with placebo at week eight (Ishida, Nakamura, Kanzato, Sawada, Hirata 2005). In the third and slightly larger study, 80 subjects who had a cedar pollen allergy and were exposed to cedar pollen at baseline took L-92 or placebo for 8 weeks before re-exposure to cedar pollen. L-92 led to a significant reduction in nasal and eye allergy symptoms compared with placebo upon re-exposure (Caplpis Co. Ltd. 2012).
In adults with allergies, the probiotic strain Bifidobacterium longum BB536 reduced some of the symptoms caused by pollen exposure significantly more than placebo (Xiao 2007). In a randomized controlled trial on children with pollen allergies, a mixture of B. longum BB536, B. infantis M-63, and B. breve M-16V significantly improved symptoms and quality of life (Miraglia Del Giudice 2017). In addition, probiotics have enhanced the effectiveness of allergen-specific immunotherapy in asthma and allergy patients (Liu 2016; Jerzynska 2016). In adults with seasonal allergic rhinitis, oral administration of B. lactis NCC2818 improved some immune parameters and allergy symptoms (Singh 2013).
For more information about allergies and asthma, please see the Allergies health protocol.
Upper Respiratory Tract Infections
Preclinical research suggests some probiotic Lactobacillus species can stimulate the antimicrobial immune response in the respiratory tract (Marranzino 2012), and clinical trials have shown their positive effects in preventing upper respiratory tract infections. Randomized controlled trials in healthy young, middle-aged, and elderly adults have shown that cultured milk products fortified with various probiotic strains of L. casei can decrease the incidence and shorten the duration of upper respiratory tract infections (Shida 2017; Fujita 2013; Jespersen 2015). Milk or yogurt products containing probiotic strains of L. paracasei have also been found to decrease upper respiratory tract infection risk in elderly subjects and children (Corsello 2017; Pu 2017). Findings from a small trial in children suggest the probiotic L. brevis KB290, found in a traditional Japanese pickle, has the potential to protect against influenza (Waki 2014).
In a randomized controlled trial, 78 healthy adults reporting high levels of psychological stress received either an oral tablet containing 10 mg of a heat-killed, non-viable form of the bacterial strain L. plantarum L-137 or a placebo daily for 12 weeks. Upper respiratory tract infections were diminished in number, severity, and duration in those receiving L. plantarum L-137. The heat-killed form of this organism has been shown to have immune-modulating actions, which may have contributed to the benefits seen in this study (Hirose 2013).
A randomized controlled trial in 198 college students found that a daily probiotic with at least 1 billion CFUs each of L. rhamnosus GG and B. animalis subspecies lactis BB-12 for 12 weeks reduced median duration and median severity scores of upper respiratory tract infections and the number of school days missed as a result (Smith 2013). B. animalis subspecies lactis BB-12 alone may also be effective in adults when used in capsules or when added to yogurt prior to fermentation (Meng 2016).
A randomized controlled trial in 465 healthy adults found that the single probiotic strain B. animalis subspecies lactis Bl-04, at a dose of 2 billion CFUs per day, prevented upper respiratory tract infections better than placebo or a probiotic combination (West 2014). Another randomized controlled trial in which undergraduate students were treated with probiotics or placebo found that B. bifidum R0071 supplementation reduced sick days due to upper respiratory tract infection (Langkamp-Henken 2015). In elderly subjects, 100 billion CFUs per day of B. longum BB536 reduced the incidence of influenza compared with placebo over a 14-week period (Namba 2010).
S. salivarius is a prominent bacterium in the healthy mouth (Burton 2006). The probiotic strain S. salivarius K12 is able to colonize the mouth and throat and may reduce the incidence of sore throat episodes caused by a common bacterium (Di Pierro 2014). Supplements with this probiotic strain have shown promise in preventing tonsillitis and pharyngitis (throat infections) and in reducing the occurrence and/or severity of otitis media (middle ear infections) (Zupancic 2017). Trials in children indicate S. salivarius K12 can prevent streptococcal throat infections, scarlet fever, and otitis media (Di Pierro, Colombo, Giuliani 2016), even in those with recent or recurrent episodes of streptococcal pharyngitis (strep throat) (Di Pierro, Colombo, Zanvit 2016; Di Pierro 2014; Di Pierro 2012) or otitis media (Di Pierro, Di Pasquale 2015).
In a randomized placebo-controlled trial on 721 participants and carried out over three winter cold seasons, various probiotic-prebiotic mixtures containing organisms such as L. plantarum LP02, L. rhamnosus LR04andLR05, and B. lactis BS01 led to reduced upper respiratory tract infection frequency (Pregliasco 2008).
In a 16-week randomized, double-blind, placebo-controlled clinical trial on 100 individuals between 60 and 74 years old, the administration of 2 billion B. subtilis CU1 spores daily for 10 years, repeated 4 times, with 18-day breaks, decreased the frequency of respiratory infections in a subgroup of 44 of the participants as compared with placebo. Consumption of the probiotics also led to beneficial changes in immune response (Lefevre 2015). B. subtilis CU1 was safe and well tolerated in elderly people, and its administration was not accompanied by any adverse effects (Lefevre 2017).