A gut-friendly bacterium with dependable human evidence for healthier gums, faster recovery from digestive infections, calmer colic in breastfed infants, and, for one specific form, modestly lower cholesterol. Bone, mood, and skin signals remain thin. The headline longevity and hormone claims come almost entirely from animals. Effects are tied to the exact strain, and it is generally well tolerated. (Full Review)

Protocol

Standard Dose

~1×10⁸ CFU once daily

DSM 17938 drops or tablets for general gut and immune health; most conservative, best-tolerated approach

Cholesterol Regimen

~2.9×10⁹ CFU twice daily

NCIMB 30242 strain for lipid effects, studied as a twice-daily split dose

Timing & Continuity

With or after a meal

Buffers stomach acid; daily dosing needed as it clears within days to about two weeks

Time to effect

Digestive & Colic

Days to ~3 weeks

Digestive and colic effects appear soonest

Cholesterol

6–9 weeks

Typical time for cholesterol changes

Bone

Many months

Bone effects require prolonged continuous use

Benefits

High: Oral & periodontal health; reduction of infant colic crying

Medium: Total cholesterol reduction; recovery from acute gut infections; Helicobacter pylori eradication support; immune support and fewer sick days

Low: Preservation of bone density; bowel regularity and constipation; vitamin D status; mood and depressive symptoms

Speculative: Testosterone and reproductive aging; lifespan and healthspan extension; skin health and wound healing; social behavior and gut-brain effects

Contraindications

Severe immunocompromise

Chemotherapy

Critical illness or intensive care

Central venous catheter

Short bowel syndrome

Severe acute pancreatitis

Prosthetic heart valves or history of infective endocarditis

Premature infants outside medical supervision

Key Interactions

Antibiotics (amoxicillin, ciprofloxacin, metronidazole)

Antidiarrheal and antacid agents (loperamide)

Other probiotics and prebiotics

Cholesterol-lowering supplements and drugs (plant sterols, berberine, soluble fiber, statins)

Risk & Side Effects

High: Transient digestive symptoms

Medium: Bacteremia and systemic infection in vulnerable hosts; D-lactate production in short bowel contexts

Low: Histamine-related reactions; overgrowth symptoms from high-CFU home ferments

Speculative: Long-term effects of very-high-dose homemade yogurt; consequences of product mislabeling or strain substitution

Monitoring

Marker	Target	Why
Total cholesterol	<180 mg/dL	Tracks response to cholesterol-lowering strains
LDL cholesterol	<100 mg/dL	Main artery-clogging cholesterol targeted by NCIMB 30242
Apolipoprotein B	<80 mg/dL	Counts cholesterol-carrying particles, a sharper risk marker than LDL alone
hs-CRP	<1.0 mg/L	Gauges body-wide inflammation the microbe may lower
25-hydroxyvitamin D	40–60 ng/mL	May rise with NCIMB 30242; supports bone and immunity

Cadence: Recheck lipids and inflammation at about 8–12 weeks, then every 6–12 months; assess vitamin D and any bone markers every 6–12 months

Qualitative Assessment

Digestive comfort and bloating
Bowel regularity and stool form
Energy levels through the day
Sleep quality
Skin appearance and any dermatitis
Mood and stress resilience
Gum health and breath (for oral-health strains)

Lactobacillus reuteri for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment