Nattokinase for Peripheral Circulation
The human evidence that nattokinase improves peripheral circulation is very weak, resting on a few tiny short-term trials, so it cannot be considered a proven way to boost blood flow to the hands and feet.
Why this grade7-layer evidence engine
This earns a weak rating because only three small, short-term trials touch the question and none directly demonstrate a lasting circulation benefit. A 9-person, industry-funded single-dose crossover study (PMID 37483751) found hands rewarmed faster after cold-water immersion, but it used a skin-temperature surrogate and reported no numeric effect size. A 12-person trial (PMID 26109079) showed only brief, within-normal-range shifts in clotting markers such as D-dimer, which points to a fibrinolytic mechanism rather than a measured improvement in circulation.
The one study with a hard clinical endpoint, LONFLIT-FLITE (PMID 14565628), did cut flight-related deep-vein thrombosis, but it tested a pycnogenol-plus-nattokinase combination product, so the benefit cannot be credited to nattokinase alone. There is no meta-analysis and no large trial using peripheral circulation as a primary outcome.
Regulators and clinics reinforce the caution. The US FDA issued a 2020 warning letter against products claiming to 'improve blood flow and circulation,' and EFSA authorizes no circulation or fibrinolysis health claim. Mayo Clinic, Cleveland Clinic, Harvard Health and the NIH ODS offer no endorsement for this use. Because nattokinase has a real bleeding-risk signal, anyone on blood thinners should consult a doctor first.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.432
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status