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Curcumin

Supplement polyphenol bone & jointgeneral nutrition
Aka: turmeric, Curcuma longa, C3 Complex, Meriva
Brands seen in Singapore: California Gold Nutrition, Doctor's Best, NOW Foods, NatureWise, Thorne
Third-party tested: Thorne lists a certified curcumin product with NSF Certified for Sport.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
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
Knee osteoarthritis pain — initial evidence only (NCCIH)
When to take
Daily
Take with
Piperine (black pepper) is one way to raise absorption
Studied for
NCCIH: standard forms likely safe 2–3 months
Pros & cons
Pros
  • Meta-analyses on knee oa: initial evidence positive
  • NCCIH: standard forms likely safe for 2–3 months
  • 7 systematic reviews exist on knee oa alone
Cons
  • Umbrella review: those 7 reviews are low quality
  • Bioavailable forms have been linked to liver damage
  • Nausea, reflux, stomach upset, diarrhea reported
Sources
  1. NCCIH — Turmeric (What Have We Learned: osteoarthritis) · read 2026-08-27
    what it says
    “Several meta-analyses have evaluated oral turmeric or curcumin for osteoarthritis measures related to relieving knee pain and stiffness … The initial evidence is positive; higher-quality evidence is needed to reach definitive conclusions”
  2. NCCIH — Turmeric (How Much Do We Know) · read 2026-08-27
    what it says
    “We don’t know enough to definitively conclude if turmeric or curcumin is beneficial for any health purposes.”
  3. NCCIH — Turmeric (What Do We Know About Safety: duration) · read 2026-08-27
    what it says
    “Conventionally formulated oral turmeric or curcumin (not modified to enhance bioavailability) is likely safe in the recommended amounts for up to 2 or 3 months.”
  4. NCCIH — Turmeric (Safety: side effects) · read 2026-08-27
    what it says
    “Oral turmeric can cause adverse effects such as nausea and vomiting, acid reflux, stomach upset, diarrhea, or constipation.”
  5. NCCIH — Turmeric (Safety: liver damage from bioavailable formulations) · read 2026-08-27
    what it says
    “Many curcumin products with increased bioavailability are on the market, and liver damage has been reported in some people who have consumed these bioavailable formulations.”
  6. NCCIH — Turmeric (What Have We Learned: product variability and piperine) · read 2026-08-27
    what it says
    “Oral curcumin products vary in how much curcumin they actually contain, and they often contain substances from other plants, such as piperine from black pepper. Combining curcumin with piperine is one way to improve the bioavailability”
  7. NCCIH — Turmeric (Safety: pregnancy and breastfeeding) · read 2026-08-27
    what it says
    “The use of turmeric supplements during pregnancy may be unsafe. Little is known about whether it’s safe to use turmeric in amounts greater than those commonly found in food while breastfeeding.”
  8. NCCIH — Turmeric (Keep in Mind: medicines) · read 2026-08-27
    what it says
    “If you take any type of medicine, talk with your health care provider before using any herbal product; some herbs and medicines interact in harmful ways.”
  9. A critical review of systematic reviews and meta-analyses of curcumin for knee osteoarthritis (Chen et al., Front Pharmacol 2026) · read 2026-08-27
    what it says
    “Seven SRs met inclusion criteria. Curcumins demonstrated potential efficacy and safety advantages over control treatments in KOA management. However, these reviews were of extremely low methodological quality, with poor reporting and significant information gaps.”
  10. Chen et al., Front Pharmacol 2026 — GRADE assessment of 48 outcomes · read 2026-08-27
    what it says
    “a total of 37 outcome measures had critically low quality evidence, 6 had low quality evidence, and only 5 had moderate quality evidence. Notably, there was no outcome measure with high quality evidence.”
  11. Chen et al., Front Pharmacol 2026 — variance in intervention protocols · read 2026-08-27
    what it says
    “The review identified a large variance in intervention protocols among the included SRs, attributed to differences in the types of curcumin, treatment durations, and doses, which significantly affect outcomes.”
  12. HSA — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev 001 (Oct 2025) · read 2026-08-27
    what it says
    “The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list [curcumin / Curcuma longa not listed in Annex A or B]”
  13. iHerb Singapore — Turmeric & Curcumin category (default order, 1 - 48 of 357 results) · read 2026-08-27
    what it says
    “California Gold Nutrition, Silymarin Complex … California Gold Nutrition, Curcumin C3 Complex® with BioPerine® … Doctor's Best, High Absorption Curcumin … NOW Foods, CurcuBrain™, 400 mg … NatureWise, Organic Turmeric Curcumin … Thorne, Curcumin Phytosome”
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Updated 2026-08-30. 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.