Previous clinical studies have shown that heat-killed Lacticaseibacillus paracasei MCC1849 suppresses subjective symptoms among healthy adults. However, the mechanism underlying this beneficial effect remains unclear. This clinical study aimed to investigate the effects of MCC1849 on immune functions in humans. In this randomized, double-blind, placebo-controlled, parallel-group study, 100 healthy adults were randomly divided into MCC1849 or placebo groups. Participants ingested test powder with 5 × 10¹⁰ MCC1849 cells or placebo powder for 4 weeks. Immune functions were evaluated using expression levels of CD86 and HLA-DR on dendritic cells (DCs), neutrophils, and natural killer cells. The expression levels of interferon (IFN)-α, -β, and -γ in peripheral blood mononuclear cells incubated with Cpg2216 in vitro were quantified. Efficacy analysis was performed on participants in the per-protocol set (placebo group; n = 47, MCC1849 group; n = 49). The expression level of CD86 on pDCs and the gene expression levels of IFN-α, -β, and -γ upon TLR9 agonist stimulation were significantly higher in the MCC1849 group at 4 weeks. No side effects were observed. This is the first report to show the positive effects of MCC1849 on human immune cells. These findings reveal one possible mechanism of how MCC1849 suppresses subjective symptoms.

Visceral fat accumulation is considered to be associated with a higher risk of chronic diseases. We investigated the effects of Bifidobacterium longum subsp. longum (B. longum) BB536 and Bifidobacterium breve (B. breve) MCC1274 on body composition, including visceral fat, in a randomized, parallel-group, placebo-controlled study. Participants were between 29 and 64 years of age and had a body mass index (BMI) of greater than 23 and less than 30. One hundred participants were randomly assigned to the probiotics group or placebo group. Participants were administered probiotic capsules containing 1 × 10¹⁰ colony-forming units (CFUs) of B. longum BB536 and 5 × 10⁹ CFU of B. breve MCC1274 or placebo capsules without bifidobacteria for 16 weeks. In the probiotics group, abdominal visceral fat area, total abdominal fat area, and serum triglyceride levels were significantly decreased compared to those in the placebo group. Additionally, the increase in BMI observed in the placebo group was significantly suppressed in the probiotics group. This study showed that B. longum BB536 and B. breve MCC1274 reduced abdominal visceral fat and total fat levels in healthy normal and overweight adults, suggesting their beneficial effects on body composition.

We previously reported that the intake of heat-killed Lacticaseibacillus paracasei MCC1849 suppressed the onset of cold-like symptoms in healthy young women who were susceptible to colds. This study aimed to investigate the effects of MCC1849 on subjective symptoms of physical condition in healthy adults of a wide age range. In this randomized, double-blind, placebo-controlled, parallel-group study, 200 healthy adults were randomly divided into the MCC1849 group or placebo group. The participants received test powder with 50 billion MCC1849 cells or placebo powder without MCC1849 for 24 weeks. Subjective symptoms were assessed by diary scores. Analysis was performed on 183 participants (MCC1849 group; n = 91, placebo group; n = 92) in the per-protocol set. The number of days of stuffy nose and cold-like symptoms was significantly reduced in the MCC1849 group compared with the placebo group. In addition, the duration of stuffy nose, sore throat and cold-like symptoms was significantly lower in the MCC1849 group. No side effects were observed. Therefore, oral intake of MCC1849 suppressed subjective symptoms in healthy adults of a wide age range. These data suggest that MCC1849 may help maintain physical condition.

Hypertension is defined as a systolic blood pressure (SBP) of over 140 mmHg or diastolic blood pressure (DBP) of over 90 mmHg. Hypertension is widely known to be a factor affecting human health, so its prevention is considered important. We investigated the effect of casein-derived tripeptide Met-Lys-Pro (MKP) on blood pressure in a randomized, placebo-controlled, parallel-group study. Participants were healthy adults with SBP between 120 and 139 mmHg, and/or DBP between 80 and 89 mmHg. A total of 121 participants were randomly assigned to the MKP group or placebo group. Participants received either a test powder containing 100 μg of MKP or a placebo powder without MKP for 12 weeks. As a result, SBP and DBP were significantly lower in the MKP group than in the placebo group. No adverse events associated with the MKP intake were observed. This study showed that MKP has a beneficial effect on lowering blood pressure in healthy adults with high-normal and elevated blood pressure and can be safely used for continuous intake.

As health issues associated with obesity typically develop or worsen owing to increases in body weight and visceral fat, weight loss is important to prevent severe obesity. This clinical trial evaluated the effects of a whey protein hydrolysate (WPH) on obesity-related parameters, including body composition and waist circumference. The effects on mood state were also assessed exploratively. The participants included 181 healthy adults with a BMI of greater than 25 kg/m² and less than 30 kg/m² who were assigned to the active or placebo groups. The active food was a powder that contained 1.0 g of whey protein hydrolysate (MWPH; WPH containing 0.1% functional tetrapeptide Leu-Asp-Gln-Trp [LDQW]) and the placebo was a powder containing no MWPH. The participants consumed the active or placebo foods for 12 weeks. Primary outcome was BMI. Secondary and exploratory outcomes were other obesity-related parameters, fatigue and mood state. No statistically significant decrease in BMI, the primary outcome, was observed at the end of this period. Regarding secondary and exploratory outcomes, waist circumference significantly decreased in the active group compared with the placebo group at 8 and 12 weeks. Furthermore, significant improvements in Profile of Mood States Second Edition scores including Total Mood Disturbance and Fatigue-Inertia scores were observed in the active group compared with the placebo group between baseline and 12 weeks. No significant differences between the groups were observed for the other outcomes. These findings suggest that the continuous intake of MWPH may help reduce waist circumference and improve mood state. THIS TRIAL WAS REGISTERED IN THE UMIN-CTR CLINICAL TRIAL REGISTRY: (ID: UMIN000047856).