Benefits
Stress and anxiety scores in adults with moderate stress
In a 12-week placebo-controlled trial in 111 Malaysian adults with moderate stress, 1 billion CFU a day lowered stress and anxiety subscale scores on the DASS-42 questionnaire more than placebo from week 8, but those subscales were not registered outcomes. The registered perceived stress score is not given in the abstract and is described elsewhere as falling in both groups alike. Depression scores did not differ.
Memory and attention test scores in adults with moderate stress
Computerized cognitive testing was a registered main outcome. Summaries of the full paper report faster social-emotional and verbal learning tasks than on placebo and no difference on six other tasks. Adults over 30 improved more than placebo in attention, emotional cognition and associate learning. Many tasks and age groups were compared, and no other trial of DR7 alone has tested memory.
Upper respiratory symptom days in stressed adults
Cold symptoms were a registered secondary outcome, one of many measured, collected by monthly questionnaire. Nasal symptoms lasted about 5 fewer days over 12 weeks and episodes were less frequent at week 4 than on placebo. A re-analysis with two scientists from the rights holder found 5.9% vs 7.1% of days with symptoms and fewer months of related medicine use.
Bowel movement frequency and gut bacteria under stress
In the same stressed adults, the number of bowel movements rose over 12 weeks on placebo but not on DR7, a difference between groups, while diarrhea did not differ. Gut bacterial diversity was higher than on placebo. Bacterial counts are markers, and no trial has tested DR7 for digestive comfort as a main outcome.
Cortisol and inflammatory markers in blood
Plasma cortisol and the inflammatory signals interferon-gamma and TGF-alpha were lower, and the anti-inflammatory IL-10 higher, than on placebo after 12 weeks in stressed adults. Markers of mature natural killer cells were also higher. These are blood markers, not felt outcomes, and come from the same single trial.
Stress scores in teens and young adults with a blend containing DR7
A 12-week single-blind trial in 87 people aged 12 to 20 tested DR7 (as CECT 7481) with two other strains. Perceived stress fell and morning cortisol rose in both groups with no difference from placebo; only a saliva inflammatory marker, IL-1 beta, was lower. Its registered main outcome is not reported, the maker funded it, and blend results do not apply to DR7 alone.
Mechanism of action
Serotonin and dopamine pathway markers
In the stress trial, blood gene expression of enzymes that steer tryptophan toward serotonin (TPH2) rose, and enzymes of the kynurenine route (IDO, TDO) and dopamine conversion (DBH, TH) fell or stayed stable versus placebo. These are blood measures; brain levels were not measured in people.
Immune cell and cytokine signals
In the same trial, DR7 lowered plasma interferon-gamma and TNF-alpha in middle-aged adults, raised IL-4 and IL-10 in young adults, and increased markers of mature natural killer cells, which the authors propose as the route for fewer cold symptom days.
Gut bacteria and the gut-brain axis
DR7 changed gut bacterial diversity and composition, and some bacterial groups tracked the blood serotonin and dopamine pathway markers. These are correlations within one trial and do not show cause.
Brain and lipid effects in animals and cells
In aged rats on a high-fat diet, DR7 reduced anxiety-like behavior, improved memory tests and lowered brain inflammatory cytokines, and in another rat study it lowered triglycerides. In liver cells, its culture fluid reduced cholesterol buildup through AMPK. None of this has been tested in people.
Clinical trials
Randomized, double-blind, placebo-controlled trial at Universiti Sains Malaysia: 1 billion CFU of DR7 in a maltodextrin sachet or maltodextrin placebo daily for 12 weeks; registered NCT03370458 in December 2017 with stress (PSS), depression (DASS-42) and cognition (Cogstate) as primary outcomes and colds, diarrhea and cytokines as secondary. Reported in four papers: stress and cognition, respiratory, gut, and a re-analysis. Clinical Nutrition, a Malaysian company, supplied DR7 and was the industry sponsor; one author was from that company, Liong is an inventor of the DR7 patent, and two re-analysis authors were employees of AB-Biotics, which holds the commercial rights (Chong et al. 2019, Benef Microbes)
124 Malaysian adults aged 18 to 60 with moderate stress on the PSS-10 were randomized; 111 completed (56 DR7, 55 placebo) and 109 were analyzed for respiratory outcomes. Median age 29, 71% women. The registry lists an actual enrollment of 118.
DASS-42 stress (P=0.024), anxiety (P=0.001) and total scores (P=0.022) fell more than on placebo from week 8, but only DASS-42 depression was registered, and it did not differ; the abstract gives no perceived stress result. On Cogstate, summaries of the full paper report faster social-emotional and verbal learning tasks than placebo and no difference on six other tasks; adults over 30 improved more in attention, emotional cognition and associate learning (P<0.05). Nasal symptoms were 5.09 days shorter (95% CI 0.42 to 9.75). Plasma cortisol was lower. Many outcomes and age subgroups were tested. No adverse effects were reported.