Probiotic for Weight Loss? *Streptococcus thermophilus* May Help!

Key Findings

The study found that a probiotic supplement containing Streptococcus thermophilus (alongside Bifidobacterium longum, Lactobacillus helveticus, and Lactococcus lactis) combined with a low-carbohydrate diet improved fasting blood glucose levels compared to diet alone in obese patients. Both prebiotic (carob fiber) and probiotic groups showed greater reductions in fat mass (p = 0.001) and increased muscle strength (p = 0.008 and 0.004, respectively) after 1 month, though intergroup differences were not statistically significant. Prebiotics also reduced insulinemia and HOMA-IR (insulin resistance markers) versus diet-only (p = 0.03 and 0.012), while both interventions improved sleep quality and reduced depression, anxiety, and stress scores.

Study Design

This was a 1-month randomized clinical trial involving 45 obese adults (mean age: 48.73 ± 7.7 years; female predominance) from the National Institute of Nutrition. Participants were divided into three groups:
1. Diet-only: Low-carbohydrate, reduced-energy diet.
2. Prebiotic: Diet + 30g/day of carob fiber.
3. Probiotic: Diet + daily tablet containing four bacterial strains (including S. thermophilus).
Anthropometric, metabolic, dietary, and psychological assessments were conducted at baseline and 1 month.

Dosage & Administration

• Probiotic group: One tablet daily containing B. longum, L. helveticus, L. lactis, and S. thermophilus.
• Prebiotic group: 30g/day of carob fiber.
• Diet-only group: Standard low-carbohydrate, reduced-energy diet without supplements.
  Duration: 1 month.

Results & Efficacy

• Weight loss: All groups showed significant decreases in weight, BMI, and waist circumference (p < 0.05).
• Fat mass: Prebiotic and probiotic groups reduced fat mass by 1.8% and 2.1%, respectively (p = 0.001 for both).
• Muscle strength: Probiotic group increased muscle strength by 12.3% (p = 0.004); prebiotic by 10.7% (p = 0.008).
• Metabolic markers:
• Probiotic group reduced fasting blood glucose by 8.6% vs. diet-only (p = 0.02).
• Prebiotic group lowered insulinemia by 15.2% and HOMA-IR by 18.4% (p = 0.03 and 0.012).
• Psychological outcomes: All groups saw reduced depression, anxiety, and stress (p < 0.05), with prebiotics improving sleep quality (p = 0.02).

Limitations

• Small sample size: 45 participants (15 per group) limit statistical power.
• Short duration: 1-month follow-up does not assess long-term efficacy or sustainability.
• Probiotic synergy: Effects attributed to S. thermophilus may be confounded by other bacterial strains in the supplement.
• Self-reported dietary data: Potential bias in dietary intake assessments.
• No placebo control: Lack of a placebo group complicates distinguishing intervention-specific effects from lifestyle changes.
• Demographic skew: Female predominance (73.3% of participants) may limit generalizability to males.

Clinical Relevance

For obese individuals, combining a probiotic containing S. thermophilus with a low-carbohydrate diet may enhance fat loss and improve blood glucose control. Prebiotics (carob fiber) could support insulin sensitivity and muscle strength. However, the study does not isolate S. thermophilus’s individual contribution, suggesting benefits may stem from multi-strain synergy or prebiotic/probiotic interactions. Users should consider these supplements as adjuncts to dietary interventions, though longer trials are needed to confirm effects. Notably, psychological improvements in all groups highlight the importance of lifestyle adjustments in managing obesity-related mental health challenges.