A natural sugar that shields proteins and switches on the cell's cleanup and recycling system. Its strongest proven use is as an eye drop for dry eye; taken by mouth it may soften blood-sugar and insulin spikes. Brain and longevity claims rest mainly on animal work. Cheap and well tolerated, but too much causes bloating and diarrhea. (Full Review)

Protocol

Oral Dose

~3–10 g/day

food-level ~1 teaspoon (3.3–5 g); research protocols up to ~100 g/day

Route

Oral or topical

oral powder in water/food for metabolic use; 3% eye drops for dry eye

Timing

With meals, split doses

divide daily total into two or more smaller doses to improve tolerability

Time to effect

Dry Eye Relief

Days to weeks

with regular topical eye-drop use

Blood Sugar

Immediate

gentler rise within a single meal

Longevity / Brain

Not demonstrated

long-term effects, if real, remain unproven in humans

Benefits

High: Dry eye disease relief (topical)

Medium: Improved postprandial glucose and insulin response

Low: Improved resistance artery endothelial function

Speculative: Autophagy-mediated proteostasis and neuroprotection; reduced hepatic stress and inflammaging

Contraindications

Known trehalase deficiency

Active or recent (within ~90 days) C. difficile infection

Severe irritable bowel syndrome or active inflammatory bowel disease

Key Interactions

Antidiabetic medications (insulin, sulfonylureas such as glipizide and glimepiride)

α-glucosidase inhibitors (acarbose, miglitol)

Broad-spectrum antibiotics (clindamycin, fluoroquinolones, cephalosporins)

Other autophagy-promoting supplements (spermidine, resveratrol)

OTC laxatives and high-FODMAP foods or sweeteners (sorbitol, mannitol)

Risk & Side Effects

High: Gastrointestinal intolerance

Medium: Caloric and glycemic load

Low: Trehalase deficiency reactions

Speculative: Clostridioides difficile virulence concern

Monitoring

Marker	Target	Why
Fasting Glucose	70–85 mg/dL	Trehalose adds a digestible glucose load
HbA1c	<5.3%	Captures longer-term blood-sugar control
2-Hour Post-Meal Glucose	<120 mg/dL	Directly tests trehalose's main metabolic claim
hs-CRP	<1.0 mg/L	General marker of the low-grade inflammation of aging

Cadence: baseline, recheck at 4–8 weeks, then every 3–6 months if use continues

Qualitative Assessment

Digestive comfort — absence of gas, bloating, cramping, or loose stools at the chosen dose
Dry-eye symptoms — reduced grittiness, burning, and fluctuating vision when using the topical form
Energy and general well-being — steadiness rather than post-meal crashes when using it as a sugar substitute

Trehalose for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment