Effects of a Probiotic Formulation Based on SF68, Phytosterols, and 6S-5-Methyltetrahydrofolic Acid on Body Composition, Biochemical Parameters, Gut Microbiota, and Gastrointestinal and General Symptoms of Overweight/Obese Subjects: The PrObesity Study

Obesity and dyslipidemia are increasingly widespread. Considering gut microbiota's (GM) role in energy balance, probiotics represent a promising non-pharmacological approach. This study assessed a probiotic formulation (SF68 + phytosterols + (6S)-5-methyltetrahydrofolic acid) on anthropometric, biochemical, and GM parameters, as well as gastrointestinal and general symptoms, in overweight/obese individuals with low-to-moderate cardiovascular risk. Forty participants (30F, mean age 51.5 ± 11 years) were randomized to receive either the probiotic or placebo daily for 12 weeks. Anthropometric data, questionnaires, and biological samples were collected pre- and post-intervention. While both groups showed significant (p < 0.05) improvements, the probiotic group showed greater reductions in waist circumference (−1.8 cm), fat mass (−1.8 kg; −1.7%), total cholesterol (−11 mg/dL), and LDL-cholesterol (−10.3 mg/dL), along with an increased HDL/LDL ratio (+0.1). Both probiotic and placebo resulted in a significant reduction in HbA1c (−1.7 mmol/mol and −1.5 mmol/mol, respectively). The probiotic formulation also reduced erythrocyte ROS (−29.7%), granulocyte ROS (−28.4%), and plasma nitrite/nitrate (49.5%) and significantly increased erythrocyte glutathione (GSH; +81.9%). Gastrointestinal symptoms improved, and GM analysis showed an increased Evenness index and reduced Lachnospirales abundance after probiotic treatment. These findings suggest the multi-component probiotic formulation may support metabolic and gut health in overweight or obese individuals, although further research is warranted Patients were divided into two groups, each assigned to consume the probiotic formulation based on SF68® + Phytosterols + (6S)-5-methyltetrahydrofolic or placebo for 12 weeks. Total DNA was extracted from stools, amplified to collect amplicons of variable V3–V4 region of the bacterial 16S rRNA gene and sequenced in paired-end mode (2 × 300 cycles) on the AVITI™ System.