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Could this be true? Probiotics for seasonal allergies? A study by Univ. of Florida researchers reported that taking a combination probiotic of Lactobacillus gasseri, Bifidobacterium bifidum, and Bifidobacterium longum (sold as Kyo-Dophilus) for 8 weeks during spring allergy season resulted in an improvement in seasonal allergy symptoms. It must be noted that the people participating had mild seasonal allergies, not severe allergies. While they reported overall allergy symptom improvement, there was no significant improvement with eye symptoms. Too bad, because for those suffering from itchy eyes, it is a symptom that causes anguish during allergy season.

All participants had their stool (fecal) samples tested (with modern genetic sequencing) and it was found that the group taking the probiotic supplements had a beneficial shift in their overall microorganisms in the gut - with some bacteria such as Escherichia coli decreasing and the very beneficial and anti-inflammatory bacteria Faecalibacterium prausnitzii increasing. (See posts here and here on F. prausnitzii.) What was really good about the study was that it was a "double-blind, randomized clinical trial", meaning that people were randomly  assigned to the probiotic treatment or placebo group, and no one knew who was getting a placebo or the probiotic until the end of the study. The researchers say that why the probiotics improved allergy symptoms is s till not clear, but they have some theories. From Science Daily:

Allergies? Probiotic combination may curb your symptoms, new study finds

As we head into allergy season, you may feel less likely to grab a hanky and sneeze. That's because new University of Florida research shows a probiotic combination might help reduce hay fever symptoms, if it's taken during allergy season. Many published studies have shown a probiotic's ability to regulate the body's immune response to allergies, but not all of the probiotics show a benefit, UF researchers say. Scientists already know that the probiotic combination of lactobacilli and bifidobacteria, sold as Kyo-Dophilus in stores, helps maintain digestive health and parts of the immune system. They suspect that probiotics might work by increasing the human body's percentage of regulatory T-cells, which in turn might increase tolerance to hay fever symptoms.

UF researchers wanted to know if the components in this combination probiotic would help alleviate allergy symptoms. To do that, they enrolled 173 healthy adults who said they suffered seasonal allergies and randomly split them into two groups: Some took the combination probiotic; others took a placebo. Each week during the eight-week experiment, participants responded to an online survey to convey their discomfort level. Scientists also analyzed DNA from participants' stool samples to determine how their bacteria changed, because probiotics aim to deliver good bacteria to the human's intestinal system.

Participants who took the probiotic reported improvements in quality of life, compared to those taking the placebo, the study showed. For example, participants suffered fewer allergy-related nose symptoms, which meant that they were less troubled during daily activities. Researchers note that this study did not include severe allergy sufferers. But the combination of probiotics showed clinical benefit for those with more mild seasonal allergies, Langkamp-Henken said. [Original study.]

Interesting preliminary research that suggests that daily intake for 12 weeks of several beneficial bacteria species (Lactobacillus acidophilus, L. casei, L. fermentum, and Bifidobacterium bifidum) resulted in improved mental (cognitive) functioning in 52 people with Alzheimer's Disease. Could this be true - daily probiotics to improve mental functioning in those with Alzheimer's?

Many more studies need to be done, but this is definitely interesting. The nice thing in this study was that the patients were randomly assigned to the groups, and it was "double-blind" so no one knew who got just plain milk and who drank probiotic milk in the study (so no biases to distort results). There were also metabolic and inflammation improvements in those taking the probiotics. From Medical Xpress:

Probiotics improve cognition in Alzheimer's patients

For the first time, scientists have shown that probiotics—beneficial live bacteria and yeasts taken as dietary supplements—can improve cognitive function in humans. In a new clinical trial, scientists show that a daily dose of probiotic Lactobacillus and Bifidobacterium bacteria taken over a period of just 12 weeks is enough to yield a moderate but significant improvement in the score of elderly Alzheimer's patients on the Mini-Mental State Examination (MMSE) scale, a standard measure of cognitive impairment.

Probiotics are known to give partial protection against certain infectious diarrheas, irritable bowel syndrome, inflammatory bowel disease, eczema, allergies, colds, tooth decay, and periodontal disease. But scientists have long hypothesized that probiotics might also boost cognition, as there is continuous two-way communication between the intestinal microflora, the gastrointestinal tract, and the brain through the nervous system, the immune system, and hormones (along the so-called "microbiota-gut-brain axis"). In mice, probiotics have indeed been shown to improve learning and memory, and reduce anxiety and depression- and OCD-like symptoms. But prior to the present study there was very limited evidence of any cognitive benefits in humans.

Here, the researchers, from Kashan University of Medical Sciences, Kashan, and Islamic Azad University, Tehran, Iran, present results from a randomized, double-blind, controlled clinical trial on a total of 52 women and men with Alzheimer's between 60 and 95 years of age. Half of the patients daily received 200 ml milk enriched with four probiotic bacteria Lactobacillus acidophilus, L. casei, L. fermentum, and Bifidobacterium bifidum (approximately 400 billion bacteria per species), while the other half received untreated milk.

At the beginning and the end of the 12-week experimental period, the scientists took blood samples for biochemical analyses and tested the cognitive function of the subjects with the MMSE questionnaire, which includes tasks like giving the current date, counting backwards from 100 by sevens, naming objects, repeating a phrase, and copying a picture.

Over the course of the study, the average score on the MMSE questionnaire significantly increased (from 8.7 to 10.6, out of a maximum of 30) in the group receiving probiotics, but not in the control group (from 8.5 to 8.0). Even though this increase is moderate, and all patients remained severely cognitively impaired, these results are important because they are the first to show that probiotics can improve human cognition. Future research, on more patients and over longer time-scales, is necessary to test if the beneficial effects of probiotics become stronger after longer treatment.

Treatment with probiotics also resulted in lower levels of triglycerides, Very Low Density Lipoprotein (VLDL), high-sensitivity C-Reactive Protein (hs-CRP) in the blood of the Alzheimer patients, and likewise a reduction in two common measures (called "Homeostatic Model Assessment", HOMA-IR and HOMA-B) of insulin resistance and the activity of the insulin-producing cells in the pancreas. "These findings indicate that change in the metabolic adjustments might be a mechanism by which probiotics affect Alzheimer's and possibly other neurological disorders," says Salami. "We plan to look at these mechanisms in greater detail in our next study." [The original study.]