Bilberry Diarrhea: Dose Adjustment Protocol

Bilberry (2500 mg/day) improved your night vision — but now causing diarrhea. This is a known dose-dependent effect (tannins, anthocyanins stimulate gut motility).

Systematic Adjustment

1. Stop bilberry 14 days. Confirm diarrhea resolves (rules out other causes).
2. Restart at 500 mg/day (1 capsule if 500 mg, or ¼ tsp powder).
3. Increase by 500 mg every 5 days IF no loose stools.
4. Find your threshold: Max dose with normal bowels = your maintenance dose.
5. Typical therapeutic range: 500–1500 mg/day standardized extract (25% anthocyanins).

Form Matters

• Standardized extract (25% anthocyanosides): Lower dose needed. Less tannin load.
• Whole fruit powder: Higher tannins → more GI effect.
• Take with food — reduces irritation.

Alternative Vision Support

If bilberry intolerable:

• Lutein/zeaxanthin 20/4 mg (macular pigment)
• Astaxanthin 4–6 mg (retinal blood flow)
• Saffron 20 mg (clinical trials for night vision)
• Blueberry concentrate (lower tannin)

Pernicious Anemia Note

Sublingual B12 is correct. Monitor MMA (methylmalonic acid) and homocysteine annually — better than serum B12 for functional status.

Vision gains don't require GI distress. Titrate to your tolerance.