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Black walnut

Supplement botanical gut
Aka: Juglans nigra
Brands seen in Singapore: Nature's Answer, Swanson Vitamins, NOW Foods, Nature's Way, Kroeger Herb Co
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Folk use for gut complaints; no human trials found
Pros & cons
Pros
  • Cell studies show cytokine suppression — not people
  • Long folk history for gut complaints
Cons
  • No human trials — benefit in people is unknown
  • Evidence is cell-culture only, not clinical
  • Not on HSA's list — that is not proof of safety
Sources
  1. Black Walnut (Juglans nigra) Extracts Inhibit Proinflammatory Cytokine Production (Front Pharmacol 2019) · read 2026-08-27
    what it says
    “Native Americans traditionally valued kernels of black walnut … and utilized leaves for medical purposes to treat diarrhea, bilious, and cramp colic … We demonstrated cytokine suppressive properties of black walnut extracts using the human promonocytic cell line U-937”
  2. HSA — Guidelines on prohibited and restricted ingredients in health supplements and traditional medicines (Oct 2025), Annex A/B · read 2026-08-27
    what it says
    “This list is not exhaustive. Dealers should continue to: Conduct thorough safety assessments of their products”
  3. iHerb Singapore — category listing, default order · read 2026-08-27
    what it says
    “Nature's Answer · Swanson Vitamins · NOW Foods · Nature's Way · Kroeger Herb Co”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.