Published: February 2010
The baseline time span for this database is (publication years)
1999-October 31, 2009 from the fifth bimonthly update (a 10-year + 10-month
period). The resulting database contained 6,120 (10 years) and 2,679 (2
years) papers; 15,274 authors; 106 nations; 1,015 journals; and 4,014
institutions. See additional information below in the overview &
Probiotics have become quite the buzzword in nutritional marketing these
days, but what exactly are they, and what do they do? According to the
National Institutes of Health's National Center for Complementary and
Alternative Medicine, probiotics are live microorganisms, similar to
microflora found in the human gut, and can convey health benefits. Clinical
trials have been performed to explore the benefits of these "friendly
bacteria" in various conditions, and probiotics are commercially available
in food products and supplement forms, but their benefits to general health
and wellness are not fully proven; the field of probiotic therapy is still
in its infancy.
Scanning electron micrograph (SEM) of Bifidobacterium
bifidum. This image is from an article titled, "An
Introduction to Probiotics," from the NIH. NCCAM
Photo Credit: SciMAT/Photo Researchers, Inc.
This month, ScienceWatch.com examines the literature on probiotics
over the past decade and over the past two years. The initial data pool was
constructed using the keyword "probiot*" to
search titles, abstracts, and keywords of original articles, reviews, and
proceedings papers published between January 1, 1999 and October 31, 2009.
To make the paper lists more on-target to the topic, the search term was
restricted to the title only.
Over the past decade, the most-cited clinical trials include the comparison
of the probiotic Escherichia coli Nissle 17 with the
anti-inflammatory agent mesalazine for maintaining remission in patients
with ulcerative colitis; placebo-controlled trials of VSL#3 for maintaining
remission in patients with refractory or recurrent pouchitis; and perinatal
administration of Lactobacillus GG for the prevention of atopic
disease. Another trial showed that Lactobacillus GG did not help
patients with Crohn's disease.
Other studies garnering citation attention over the past decade include
fecal analyses of healthy subjects and patients taking probiotics; the role
of toll-like receptor 9 signaling in the anti-inflammatory effects of
probiotics; the probiotic potential of a variety of Lactobacillus
strains; and the effects of VSL#3 in mouse models of disease, including
colitis and nonalcoholic fatty liver disease.
Two trials with negative results headline the two-year list: the first
shows that probiotic prophylaxis is not beneficial for patients with
predicted severe acute pancreatitis, and the second shows that probiotic
supplements given during the first six months of life in high-risk children
do not reduce the risk for atopic dermatitis, and may in fact increase the
risk of allergen sensitization. Other clinical trials on this list show the
benefit of prenatal administration of probiotics and prebiotics; in
addition, probiotics can help prevent antibiotic-associated diarrhea in
adults and children, and are useful in the treatment of irritable bowel
syndrome and in eradicating Helicobacter pylori. On the other
hand, still more studies on this list show no benefit of certain probiotics
in Crohn's disease.
Meta-analyses examine the issues of probiotics for preterm neonates at high
risk for necrotizing enterocolitis, as well as the controversy of whether
or not probiotics can prevent and treat atopic dermatitis in children.
Other studies on the two-year list include a rat model of acute
pancreatitis, a mouse model of symbiotic gut microbial-host metabolic
interactions, and the role of VSL#3 in mucin gene expression.
Methodology: The baseline time span for this database
is (publication years) 1999-October 31, 2009 from the fifth bimonthly
update (a 10-year + 10-month period). The resulting database contained
6,120 (10 years) and 2,679 (2 years) papers; 15,274 authors; 106 nations;
1,015 journals; and 4,014 institutions.
Rankings: Once the database was in place, it was used to
generate list of authors, journals, institutions, and nations. Rankings for
author, journal, institution, and country are listed in three ways:
according to total cites, total papers, and total cites/paper*. The paper
thresholds and corresponding percentages used to determine scientist,
institution, country, and journal rankings according to total cites/paper,
and total papers respectively are as follows:
*Unless otherwise specified, all rankings have a
5 paper threshold for all measures.
SPECIAL TOPIC KEYWORDS: probiotics,
prophylaxis, atopic disease, pouchitis, probiotic
bacteria, intestinal epithelial barrier function,
anti-inflammatory effects, ulcerative colitis,
atopic eczema, enteric microflora, inflammatory
bowel diseases, antibiotics, prebiotics, toll-like
receptor 9, fecal microflora, tnf, nonalcoholic
fatty liver disease, antibiotic-associated
diarrhoea, crohn's disease, aquaculture, biological
control agents, lactobacillus spp, escherichia coli
spp, dairy foods, pancreatitis,
galacto-oligosaccharides, necrotizing enterocolitis,
irritable bowel syndrome, diarrhoea, allergic
diseases, neonates, children, beta-defensin 2, mucin
gene, symbiotic gut microbial-host metabolic
interactions, multispecies probiotic
supplementation, clinical trials.